Applying optimization methods to reduce arc flash in low voltage ...

APPLYING OPTIMIZATION METHODS TO REDUCE ARC FLASH IN LOW VOLTAGE SYSTEMS

A Thesis Presented

By

Mahmoodreza Arefi

to

The Department of Electrical and Computer Engineering

in partial fulfillment of the requirements for the degree of

Master of Science

in

Electrical Engineering

in the field of

Power Systems

Northeastern University Boston, Massachusetts

August 2014

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Table of Contents………………………………………………………………………………...………… i

Abstract……………………………………………………………………………………….…….……...iv Acknowledgements………………………………………………………………………………………....v List of Tables………………………………………………………………………………..……………..vi List of Figures…………………………………….…………………………………………………..…..viii

1.Introduction……………………………………………………………………………………………….1

1.1 Arc flash………………………………………………………………………………………..……..1 1.2 Motivations for the study……………………………………………………………………..…........2 1.3 Thesis Outline……………………………………………………………………………………..….2

2. Background and protection of low voltage systems ……………..…………………………………..….4

2.1 Literature review……………………………………………………………………………….…….4 2.2 Background of arc flash regulation and standards………………………………………….………..6 2.3 Behaviors of arcs………………………………………………………………………………..........7 2.4 Three phase faults…………………………………………………………….………………….…...8 2.5 Circuit breakers…………………………………………………………….……………………….10

2.5.1 Molded case circuit breakers……………..…....…………………………………………….......11 2.5.2 Low voltage power circuit breakers…………………..……..…..………………………………13 2.5.3 Insulated case circuit breaker……………………..……………..……………………………....15

2.6 Trip unit types…………………………………………………………………………………….....15 2.7 Low voltage fuses…………………………………………………………………………………...16

3. Arc flash calculation method and analysis…………………...…………………………….…….……..19

3.1 Fault current theory…………………………………..………………………………………….…….19

3.2 Significance of X/R ratio……………………………………………………………………….……..23

3.3 IEEE Method (Standard)………………………………………………………………..……………..24 3.3.1 Arcing current calculations………………………………..………………………………………24 3.3.2 Normalized energy calculations……………………………………………………………..…….25 3.3.3 Incident energy calculations………………………………………………………………...……..25 3.3.4 Flash protection boundary…………………………………………………………………..……..26 3.4 Protection boundaries definition……………………………………………………………………...27 3.4.1 Flash protection boundary…………………………………………………………………………27 3.4.2 Limited approach boundary……………………………………………………………………….27 3.4.3 Restricted approach boundary……………………………………………………………………..28 3.4.4 Prohibited approach boundary…………………………………………………………………….28 3.5 Arc flash pressure………………………………………………………………………………….…..28 3.6 Arc flash energy levels…………………………………………………………..…………..….……..29

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3.7 Coordination for protective devices……………………………………………………..…………….30

3.8 Motor contribution to short circuit current……………………………………………………………37

4. Feasible steps for arc flash calculation…………………………………………………………...…….38 4.1 Identification of locations for arc fault hazard…………………………………...……………………38

4.2 Data collection……………………………………………………………………..………………….38

4.3 Preparing single line diagram of the system………………………………….…………………….....55

4.4 Short circuit study…………………………………………………………….……………………….56

4.5 Determine arc current……………………………………………………...…………………………..59

4.6 Determine arcing time………………………………………………...……………………………….62

4.7 Determine incident energy……………………………………….…………………………………....63

4.8 Determine energy level……..…………………………………………………………………………64

4.9 Determine flash protection boundary……………………….…………………………………………65

4.10 Determine arc flash study……………………………………………………………………………66

4.11 Description of real case study………………………………….…………………………………….67 4.11.1 Circuit breakers configurations……….………………………………………………………….70 4.11.2 Short circuit study and related scenarios…………….…………………………………………...72 4.11.3 Protective device coordination study…………………….………………………………………75 4.11.4 Arc flash results………………………………………….………………………………………76

5. Arc flash optimization Methods and Cost Analysis…………………………………………………….80

5.1 Operation of electrical system with a lack of selective coordination………………………………….81

5.2 Temporarily modifying existing protective device settings…………………………………………...81

5.3 Arc flash resistant switchgear…………………………………………………………………………83

5.4 Increasing the working distance……………………………………………………………………….84

5.5 Applying a single main circuit breaker for building shutdown……………………………………….86

5.6 Applying low voltage circuit breakers before panels………………………………………………….90

5.7 Applying low voltage circuit breakers for step down transformers rated above 125 KVA…………...93

5.8 For transformers larger than 125 KVA applying two or more smaller transformers............................99

5.9. Cost analysis………………………………………………………………………………………...107

5.9.1 Cost analysis for transformers……………………………………………………………………108

5.9.2 Cost analysis for circuit breakers………………………………………………………………...110

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6. Conclusion and future work………………………………………………………………………...…113

6.1 Conclusions…………………………………………………………………………………………..113

6.2 Future Work………………………………………………………………………………………….116

References…………………………………………………………………………………………….….117

Appendix A: One Line diagram for 271 bus system…………………………………………………….120

Appendix B: Result of arc flash study (worst case) for 271 bus system………………………………...122

Appendix C: Result of short circuit study for 271 bus system………………………………………......133

Appendix D: Coordination curves……………………………………………………………………….134

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Abstract

Technicians working with low voltage power systems face a high risk of being exposed to arc

flashes due to their inadvertence. Reducing arc flash energy level can provide increased safety

for the technicians.

To avoid injury, the energy source must be completely shut-down when working on some

electrical equipment. Nonetheless, power distribution systems in mission critical facilities such

as commercial buildings and data centers must occasionally remain energized while being

maintained. In recent years the arc flash analysis has become an important safety tool that

provides skilled technicians with useful information on the energy level at the equipment to be

maintained and recommends appropriate protective equipment to wear. Because of codes,

standards and historically acceptable design methods, the estimated arc flash energy level is

often overly conservative and higher than the true level.

This thesis presents different scenarios and employs alternative strategies to be implemented at

the design stage of a 600 volt power distribution system facility in order to reduce the arc flash

energy level. A 271-bus power system is used as an example to illustrate how simulation based

analysis of arc flash energy level can be carried out by using typical mainstream code acceptable

methods. In order to show the implementation of arc flash optimization techniques at the system

design level, the system model (271 bus) will be changed. Use of optimization techniques

facilitates significant reductions in arc flash energy level as verified by computer simulations. A

cost analysis which compares the cost of the required protective relays and related safety

equipment against arc flash with and without applying optimization methods is also carried out.

The results show that applying these techniques may lead to significant cost savings.

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Acknowledgments

First, I would like to thank my advisor Prof. Ali Abur for his guidance. It was a great experience

to work with Prof. Abur, who advised me through the course of the work. I would like to express

my appreciation for his suggestions and valuable comments.

I am grateful to my committee members Prof. Brad Lehman and Prof. Bahram Shafai for their

valuable suggestions and help.

I would like to express my thanks to Mr. Bruce Swanton, Electrical Manager, at AHA consulting

Engineers that provided helpful comments about ETAP software and also provided necessary

data for this research.

Finally I would like to thank my parents and my wife ‘Ronak’. I could not have completed this

degree without their love, patience and never ending encouragement.

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LIST OF TABLES

Table 3.1 Test X/R ratios for protective devices…………………………………………………………23

Table 3.2 Conditions for which the IEEE 1584 equations are applicable………………………………..24

Table 3.3 Distance factor (x) for various voltages and enclosure types………………………………….26

Table 3.4 Protective clothing characteristics……………………………………………………………..30

Table 4.1 Utility parameters………………………………………………………………………………39

Table 4.2 Bus 1 parameters……………………………………………………………………………….41

Table 4.3 Switchgear A parameters………………………………………………………………………42




Table 4.7 Transformer 1&2 parameters…………………………………………………………………..47

Table 4.8 Motor 1&2 parameters…………………………………………………………………………48

Table 4.9 Static load parameters………………………………………………………………………….49

Table 4.10 Lump load parameters………………………………………………………………………..50

Table 4.11 High voltage circuit breaker parameters…………………………………………………......50

Table 4.12. Fuse parameters……………………………………………………………………………...51

Table 4.13 Current transformer parameter………………………………………………………………..52

Table 4.14 Over current relay parameters………………………………………………………………...53

Table 4.15 Three phase bolted short circuit………………………………………………………………57

Table 4.16 Arc flash result for five bus network ………………………………………………………...60

Table 4.17 Adjusted minimum arc current as a percentage of bolted fault currents……………………..62

Table 4.18 Final clearing time and source protection device ……………………………………………63

Table 4.19 Calculated total energy……………………………………………………………………….63

Table 4.20 Classification guide for the energy level………..………………………………………........64

Table 4.21 Result of risk category number………………………………………………………………65

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Table 4.22 Result of flash protection boundary…………………………………………………………..66

Table 4.23 Configuration of breakers at normal, emergency, normal ties closed and EMTC……………72

Table 4.24 Short circuit study scenario…………………………………………………………………...73

Table 4.25 Definition of scenarios for worst case arc flash…………………………………………........74

Table 4.26: Result of worst case analysis…………………………………………………………………78

Table 5.1 Lowering the instantaneous setting of LVCB3……………………………………………...…82

Table 5.2 Decreasing incident energy of Bus 03…………………………………………………………82

Table 5.3 Decreasing incident energy of Bus 03…………………………………………………………85

Table 5.4 without single main circuit breaker for building shutdown …………………………………...87

Table 5.5 with single main circuit breaker for building shutdown ………………………………………89

Table 5.6 Fuse disconnect for panel entrance before reduced arc ……………………………………….91

Table 5.7 Low voltage circuit breaker for panel entrance after reduced arc……………………………...92

Table 5.8 Low voltage circuit breaker for transformers rated above 125 KVA………………………….95

Table 5.9 Low voltage circuit breaker for transformers rated above 125 KVA with LSI………………..97

Table 5.10 Arc flash for trans 3 (250 KVA)…………………………………………………………….100

Table 5.11 Arc flash for trans 3 & 43 (125 KVA)……………………………………………………...103

Table 5.12 Energy level before and after applying optimization methods..……………………………105

Table 5.13 Downtime costs estimates……………………………………………………………….......108

Table 5.14 Cost of existing transformers before reducing arc flash…………………………………….109

Table 5.15 Cost of suggested transformers after reduced arc flash……………………………………..110

Table 5.16 List of circuit breakers connected to transformers rated above 125 KVA…………………..111

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LIST OF FIGURES

Figure 2.1 Circuit for source and arc resistance……………………………………………………………7

Figure 2.2 Current in a series R-L circuit …………………………………………………………………9

Figure 2.3 Time current curve for molded case circuit breaker…………………………………………..12

Figure 2.4 Time current curve for low voltage power circuit breakers…………………………………..14

Figure 2.5 Time current curve for low voltage fuse……………………………………………………...18

Figure 3.1 Series RL circuit………………………………………………………………………………20

Figure 3.2 One line diagram of a three motor distribution system….……………………………………31

Figure 3.3 Time current curves for a circuit breaker and a fuse………………………………………….33

Figure 3.4 Time current curves for a selectively coordinated circuit breakers…………………………...34

Figure 3.5 Time current curves with a lack of selective coordination………………………………........35

Figure 4.1 One line diagram of 13.8kV/480V distribution system……………………………………….40

Figure 4.2 Bus 01 (13.8 kV) editor page………………………………………………………………….41

Figure 4.3 Switchgear A (0.48 kV) editor page…………………………………………………………..43

Figure 4.4 Bus 2 (0.48 kV) editor page…………………………………………………………………...44



Figure 4.7 Transformer 1 & 2 editor page………………………………………………………………..47

Figure 4.8 Motor 1 & 2 editor page………………………………………………………………………48

Figure 4.9 Static load editor page………………………………………………………………………...49

Figure 4.10 Lump load editor page……………………………………………………………………….50

Figure 4.11 High voltage circuit breaker editor page……………………………………………………51

Figure 4.12 Fuse editor page……………………………………………………………………………..52

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Figure 4.13 Current transformer editor page……………………………………………………………..53

Figure 4.14 Over current relay editor page………………………………………………………………54

Figure 4.15 Low voltage circuit breaker (LVCB1) editor………………………………………………..55

Figure 4.16 One line diagram for five bus network……………………………………………………..56

Figure 4.17 Short current result for five bus network (one line)…………………………………………58

Figure 4.18 Arc flash result for five bus network(one line)……………………………………………...60

Figure 4.19 Arc flash report analyzer………………………………………………………………….....61

Figure 4.20 One line Diagram for 271 bus system……………………………………………………….69

Figure 4.21 Coordination curve for bus D3………………………………………………………………76

Figure 4.22 Arc flash category occurrence………………………………………………………………..77

Figure 5.1 Lowering the instantaneous setting of LVB3 (one Line)……………………………………..82

Figure 5.2 Increasing the working distance at Bus03 (one Line)………………………………………...85

Figure 5.3 Building without single main circuit breaker for shutdown (one line)…………………….…86

Figure 5.4 Building with single main circuit breaker for shutdown (one line)…………………………...89

Figure 5.5 Fused disconnect for panel entrance (one line)……………………………………………….90

Figure 5.6 Low voltage circuit breaker for panel entrance (one line)…………………………………….92

Figure 5.7 Low voltage circuit breaker for transformers rated above 125 KVA (one line)……………...94

Figure 5.8 Arc flash mitigation across 300 KVA………………………………………………………..96

Figure 5.9 TCC showing LSI breaker and arcing current at primary and secondary of T2………………98

Figure 5.10 One line diagram with 250 KVA transformer……………………………………………..100

Figure 5.11 Time current curve arc flash Hazard at panel D10…………………………………………101

Figure 5.12 One – line diagram showing two 125 KVA transformer…………………………………...102

Figure 5.13 Time current curve arc flash hazard at panel M1 and M2…………………………………..104

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1. Introduction

In the domain of electrical system design, operation and maintenance, the greatest concern

must be the safety and security of workers who operate and maintain the system. Electrical

systems’ designers must not only take necessary precautions to protect systems and equipment,

but also they must assess personnel safety for a given level of arc flash energy due to arcing

faults, generally referred to as arc flash or arc fault.

The issue of secure work practices and methods for staff working on energized electrical

equipment is therefore very significant and has widespread recognition. On the other hand,

shutdown of a segment of the distribution system may have an extensive influence on the

processes continuity, and widespread power loss can interrupt production and also may lead to

loss of revenues.

When working on an energized line, it is not possible to remove arc fault hazard, however it is

possible to decrease the amount of energy dissipated from an arc and the risk of injury or fatality

to the workers.

This study focuses on applying a variety of methods for low voltage distribution systems to

restrict the level of arc flash energy using the standard IEEE 1584. By diminishing the incident

energy, the arc flash energy level will also be reduced. Also, cost analysis to evaluate

optimization techniques is performed for a real case study.

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1.1 Arc Flash

Arc flash is product of fast release of energy which is caused by arcing fault between two phases

or phase and ground. Arc fault happens when there is a path of conduction and it could be

compared with electric welding.

An arc flash happens in the case of a fault, or short circuit, which passes through this arc gap.

The arc flash can be the result of unintended contact, negligence, use of equipment which is not

properly rated, contamination or crack over insulated surfaces, weakening or deterioration of

equipment and/or parts, and various other reasons.

1.2 Motivations for the study

Reducing the risk of injury to humans and improve safety of workers are the main objectives for

studying arc flashes and applying optimization techniques. Electric arcs create temperatures up

to 35.000 degrees Fahrenheit [1], some of the highest recorded temperatures on earth.

It is estimated that five to ten arc flash explosions occur across the US on a daily basis [2], and

80% of electricity-related accidents and casualties involving “skilled workers” are caused due to

arc flashes (arc blast) [2].

Thus the main motivation of this work was to apply optimization method for a large power

system to reduce energy level of arc flash for safety of workers.

1.3 Thesis Outline

This dissertation consists of 6 chapters, with the first chapter introducing arc flash and

importance of arc flash. The objectives of this research are briefly discussed and outlines are

described.

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Chapter 2 will present literature review and development of arc flash regulation and standards.

There will be discussion of behaviors of arcs and three phase faults.

Chapter 3 presents an overview of electrical power system studies for 480 volt power systems.

The process of a fault current calculation will be conceptually described to show the purpose of

the study and modeling approach.

Chapter 4 will explore practical steps for arc flash calculation, the procedure explains step by

step from data collection to documentation of arc flash study results and also the software

implementation. Arc flash calculation for a low voltage system which has 271 buses will be

implemented.

Chapter 5 will highlight applicable methods to help mitigate arc flash energy level. A low

voltage system with 271 buses that is in compliance with the NEC and acceptable for an

electrical building permit will be analyzed for reduction of arc flash energy level. Cost analysis

will be performed to compare cost before and after applying the optimization methods for the

case study.

Chapter 6 will discuss the conclusions and future work. The results of implementing the

recommended design techniques will be reviewed. Guidelines for future work will be discussed.

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2 Background and protection of low voltage systems

2.1 Literature Review

In 1982, a comprehensive paper entitled “The Other Electrical Hazard: Electrical Arc Blast

Burns” was published by Mr. Ralph Lee [1]. The contributions of this paper is regarded as one of

the most significant research improvements about arc in a non-closure equipment by many

researchers, since it quantified the potential burn hazards while training staff about the

significance of safety. Lee found that the “curable burn threshold for the human body is 1.2

cal/cm2”. He also published another related paper in 1987 [4] in which the pressure property of

an arc incident was evaluated.

The paper by Doughty, Neal, Dear, and Bingham, titled “Testing Update on Protective Clothing

and Equipment for Electric Arc Exposure” [5] that was published in 1997, described in detail the

incident energy levels correlated with low voltage arc flash occurrence. The paper was the first to

define how a situation would be escalated when the arc started in panelboards as well as

switchgears.

“Predicting Incident Energy to Better Manage the Electric Arc Hazard on 600 V Power

Distribution Systems” [6], by Doughty, Floyd, and Neal, which was published in 2000, semi-

experimentally evaluated the incident energy computation for low voltage systems. The paper is

considered as the derivation of the incident energy computation and is applied in the NFPA 70E

standard.

In 2000, Jones, Liggett, Capelli-Schellpfeffer, Macalady, Saunders, Downey, McClung, Smith,

Jamil, and Saporita: published “Staged Tests to Increase Awareness of Arc-Flash Hazards in

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Electrical Equipment” [7]. Experimental studies were conducted by applying manikins to better

understand how humans might be negatively concerned by arc flash occurrence.

“IEEE Standard 1584” That is the first copy of “IEEE Guide for Performing Arc-Flash Hazard

Calculations” [8] was issued in 2002. This standard employed considerable test data to establish

experimental equations resulted from analytical analysis. Tests data was made accessible from

different sources and are covered as an Appendix to the standard. A paper written by Gammon

and Matthews named “IEEE 1584-2002, Incident Energy Factors and Simple 480-V Incident

Energy Equations” [9] contains comprehensive statistical analysis and a brief explanation of the

IEEE 1584 test data.

Stokes and Sweeting published “Electric Arcing Burn Hazards” [10] in 2006, which critically

evaluates the testing methodology, specially the electrode orientation, applied to evaluate the arc

flash hazard for the IEEE 1584 standard development. Additionally, this paper encompassed a

comprehensive tabulation of arc flash history. The authors proposed that this information has

generally been ignored at the time the current IEEE 1584 standard development. A number of

discussion papers were printed which provided further analysis of the issues being discussed.

Further, Stokes and Sweeting published “Closure to Discussions of “Electric Arcing Burn

Hazards”“[11] to document their concerns.

“Effect of Insulating Barriers in arc flash Testing” [12] by Wilkins, Lang, and Allison was also

printed in 2006. As their testing methodology, the authors employed vertical conductors ended in

insulating barriers. The character of arc was analogous to horizontally oriented electrodes;

therefore the work of Stokes and Sweeting is reinforced.

Curtis Thomas Latzo: “Approaches to arc flash Hazard Mitigation in 600 volt power systems”

[38] was published in 2011. The author of this paper suggested design techniques to reduce arc

6

flash in low voltage systems and result showed significant lowering of the arc flash Hazard

Exposure.

2.2 Background of arc flash regulation and standards

‘The Occupational Safety and Health Act’ was approved on December 29, 1970, based on

which every employer “shall furnish to each of his employees employment and a place of

employment which are free from recognized hazards that are causing or are likely to cause death

or serious physical harm to his employees;” [3]

The Occupational Safety and Health Administration (OSHA), which was in charge of providing

safety for workers, started to develop Federal regulations, including those that addressed

detecting the electrical dangers and achieving procedures for safe work. In order to have a basis

for electrical regulations, OSHA mainly used the National Electrical Code (NEC), however,

since it generally does not address employee safety, the need for a new standard was felt.

Consequently, a new NFPA committee was formed in 1976. The committee was assigned to

assist OSHA with generating standards with concentration in electrical safety.

Arc flash recognized as an electrical hazard in 1991 by OSHA. The first edition of NFPA 70E

was published in 1979 and later in 1995 fifth edition of NFPA is published and used as the first

standard precisely indication arc flash hazard. The following two revisions emphasized on

analyzing arc flash hazard in details; and offered more technical information respecting the arc

flash protection boundaries and incident energy calculations. NFPA 70E-2004 provides sample

calculations of flash protection boundaries in Annex D. It is worth noting, as quoted on page

70E-98 of the standard: “This annex is not a part of the requirements of this NFPA document but

is included for informational purposes only.” [2]

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Besides the NFPA 70E standard and the OSHA , the NEC emphasized on the use of labels to

warn workers about probable arc flash hazards in 2002. At the same year, the standard IEEE

1584-2002, “Guide for Performing Arc-Flash Hazard Calculations”, was published by an IEEE

working group. The new standard provided a number of models to estimate incident energy

levels based on a large pool of data. As the above brief summary shows, till a while ago, the arc

flash hazard has not been widely acknowledged. The recent comprehensive research and vast

testing has resulted in better knowing of the arc flash hazard.

2.3 Behavior of arcs

An arc is defined as “the flow of current through a path containing the vapor of the terminal

material, which is initiated by flashover or from the introduction of some conductive material.

This vapor’s resistance is considerably higher than that of the solid metal, to the degree that

voltage drop in the arc ranges between 75 and 100 V/in, that is several thousand times its drop in

a solid conductor. Since the inductance of the arc path is not significantly different from that of a

solid conductor of the equal length, the arc current path is largely resistive in nature, resulting

unity power factor. (Voltage drop in a faulted large solid or stranded conductor is about 0.5 to 1

V/ft.)[1]” Further details can be found in [1].

When the arc length is more than 4 inches, the arc current becomes stabilized for 277/480 volt

circuits. The reason is that in low voltage systems arc consumes a considerable fraction of

existing voltage (75 to 100 V/in). Hence, the fault current passes through the impedance of

system and arc appearing between supply voltage and arc voltage [1].

8

Figure 2.1: Circuit for source and arc resistance

2.4 Three phase faults

A fault takes place when the system operation is disrupted unexpectedly due to a sudden

disturbance which results in unusually high currents and/or voltages. Some sources of faults can

include weather, insulation failure, wildlife, vehicle accidents, and destruction. When such an

unpremeditated electrical path is formed, the system produces undesirable current paths that

must be accounted for. It results in a failure in voltage and an extreme inrush of current toward

the fault location. When a fault occurs, the current from all sections of the electrical system is

oriented towards the short circuit.

This fault current level can range from 6.5kA amps at a 13.2kV substation, to around 100kA at a

480 volt system. It is found that the distance from the source reduces fault levels as a result of

system impedance [13]. It is essential to protect the system against possible negative impacts of

large scale currents. Faults in power systems can be classified into these four types: single line-

to-ground, line-to-line, double line-to-ground and balanced three-phase [14].

Nearly 87% of three-phase fault currents are composed of Line-to-line faults. Line-to-ground

faults can range from a few percent to probably 125% of the three-phase value, while line-to-

ground fault currents with higher than three-phase value are unusual in industrial systems. [15].

It is generally acknowledged that in equipment or cables, line-to-line faults rapidly escalate into

9

three-phase faults [16]. In an industrial system, the three-phase fault condition is often the only

one regarded, since it mostly results in maximum current [15]. All testing applied in arc flash

modeling has been three-phase tested, for three-phase arcs yield the utmost possible arc-flash in

equipment. As a result, this project will focus only on three-phase balanced faults.

It is favorable to investigate a fault current as an asymmetrical waveform including a

symmetrical AC wave superimposed on a DC current [17]. It is demonstrated that the resultant

waveform has an original peak value several times higher than the pre-fault conditions and is

asymmetrically formed from the x-axis. The peak value appearing during the first half cycle of

the fault is known as the Available Fault Current (AFC), the graphical representation of which

can be found in Figure 2.2.

Figure 2.2: Current in a series R-L circuit

e(t) = voltage waveform

iac(t) = original current waveform before fault occurs

10

idc(t) = DC component of the fault

i(t) = fault current waveform

When a fault happens, the fault current i(t) includes two major components which are original

sine wave iac(t) and the DC element idc(t). The peak magnitude of i(t) can be several times

higher than the original current, which depends to different factors as well as system condition.

The magnitude declines as a consequence of the DC exponential, which follows the system

reactance and resistance, known as the X/R ratio.

2.5 Circuit Breakers

Low voltage circuit breakers include Molded Case Circuit Breakers, Low-Voltage Power Circuit

Breakers, and insulated Case Circuit Breakers [18]. A circuit breaker is an equipment designed to

protect load and cables. All circuit breakers mainly protect the circuit conductors by detecting

and interrupting over-currents [19].

The opening of circuit breaker is a reaction to transient current situations, such as short circuit or

fault in the electrical system. Circuit breakers are rated based on available interrupting capacity

and rated continuous current. The interrupting capacity of a circuit breaker is the maximum

short-circuit current that circuit breaker can interrupt safely at a definite voltage. This short

circuit current described by current magnitude and its value is in rms symmetrical amperes [20].

The amount of current a circuit breaker can transmit until it achieves overload conditions and

opens the circuit is defined as continuous current rating.

The magnetic trip element is often referred to as the instantaneous trip time and responds

quickly in reaction to high level short circuit currents. The thermal element is normally some sort

11

of bi-metal that enlarges as a result of the heat in a circuit triggered by current at overload that is

less than the magnetic pickup threshold. The element then trips the Molded Case Circuit Breaker

MCCB after a time delay.

It is necessary to mention that all time current curve for circuit breakers are from Cutler-Hammer

manufacturer and this information obtained through the library of ETAP software.

2.5.1 Molded case circuit breakers

Graphical illustration of Circuit breaker trip curves helps better understand the time versus

current application of the device. When demonstrated as follows, the plot is referred to ‘a time

current curve (TCC)’. Figure 2.3 shows a common TCC for a 480 volt, 110 amp, non-adjustable

thermal magnetic MCCB. Here it is observable that the thermal element is 110 amps at 1000

seconds and the instantaneous sensor is at less than 0.03 seconds for short circuit currents greater

than 2000 amps. The interrupting time for a fault current level in the range of 300-350 amps is

demonstrated to be greater than ten second.

12

Figure 2.3: Time current curve for molded case circuit breaker

13

2.5.2 Low voltage power circuit breakers

Low voltage power circuit breakers (LVPSBs) were the subsequent accessible circuit breakers

made in the late 1960s. These circuit breakers which were designed to be rack mounted in

switchgear enjoys larger frame sizes and higher current ratings compared to MCCBs.

Maintenance for these circuit breakers can be performed by replacing parts such as contacts,

motors, opening and closing shunts.

The LVPCBs possess thermal-magnetic trip units which react to overloads in the same way as

MCCBs; however, LVPCBs had a 30-cycle short time current rating in accordance with ANSI

standards [21]. This short time current rating makes a second breaker adjustment possible

between the magnetic pickup and the long time sensor. These situations are generally referred to

as Long-Time (L), Short-Time (S) and Instantaneous (I), thus calling the breaker an LSI

protective device. A TCC for a LVPCB is presented in Figure 2.4. In this figure, the long time

setting is 2500 Amps (1), the short time is 6250 Amps (2.5) and Instantaneous setting is 15000

(6) Amps.

14

Figure 2.4: Time current curve for low voltage power circuit breakers

15

2.5.3 Insulated case circuit breaker

These devices were particularly designed molded case circuit breakers which encompassed a

number of low-voltage power circuit breaker features [20]. These features involved short time

current duty cycles and a stored energy mechanism [19]. The ICCB possessed an instantaneous

trip component that could be set at a much higher trip level than the MCCB, which made it

possible to achieve some short time current ratings.

2.6 Trip unit types

A brief definition of different types of trip units [22] mentioned in this study can be found

below, and also this definitions are based on circuit breaker manufacturers.

Thermal magnetic trip units trip under short circuit circumstances immediately, without any

intended delays. They have a long time delay under the instantaneous trip current, created to

protect conductors while allowing temporary current flows, as for motor starting and transformer

inrush. In a lot of cases, their instantaneous trip current conditions can be adjusted.

The magnetic trip units have no long time characteristic and will not trip below the

instantaneous trip current. These units are only applied for short circuit protection and usually

are used for motor protection.

Three characteristics are found in electronic trip units that might be used individually or in

combination: (L) long time,(S) short time, and (I) instantaneous. A trip unit might be designated

as LI type when it includes both long time and instantaneous features. Other common

combinations are LS and LSI.

16

• L— The long-time feature relates to lower overcurrent conditions to allow for temporary

current surges. It generally includes a current pickup adjustment and a time-delay adjustment.

• S—The short-time feature is applied for coordination purposes via the overload and short

circuit current levels. It typically includes a current pickup and a time-delay adjustment.

• I—The instantaneous feature determines a current level above which tripping occurs without

any premeditated delays. When using the short-time function, it is normally not present, or

turned off.

2.7 Low voltage fuses

Based on the NEC definition, “a fuse is an overcurrent protective device with a circuit-opening

fusible element which is heated and severed when an overcurrent passes through it”.[23]

The aim of using fuses in 480 volt electrical systems is to protect the system against over-loads

and short circuits. A fuse basically functions through a simple thermal process; the flow of

excess currents through specifically designed fuse elements causes them to melt, and so cut off

the faulty circuit [24]. The interrupting capability is changed by the fuse element and the filler

embedded in the fuse cartridge.

The fuses with current limiting capability open expedite within ½ cycle when a fault with high

current occurs. As a result, they are able to offer very good protection for electrical equipment

such as circuit breakers, static and dynamic loads. Fuses can be employed in switchboards, motor

control centers,etc.[25]

Since the fuse does not include any moving parts, it can act swiftly in the case of high fault

currents. A fuse actuation indicates the end of its useful life, hence the reliability and accuracy is

17

maintained when new fuses are embedded into the circuit. Due to lack of moving parts, it is not

possible to adjust the time domains of the fuse, which can be costly when attempting to protect a

system against fault currents. Figure 2.5 illustrates the TCC for a fuse. The fuse curve

demonstrates the interrupting times for different levels of overcurrent. These interruptions can

take place over a short period of time, as indicated by the minimum melt characteristic, i.e. the

time the fuse starts to melt, and the total clearing characteristic, i.e. the thorough interruption of

the current.

18

Figure 2.5: Time current curve for low voltage fuse

The inverse time characteristics of the TCC for the 60 ampere fuse are the same as those of the

circuit breakers. This specific device is revealed to have 60 amperes of over-load protection

beyond 100 seconds, and for a short circuit of 800 amperes, it interrupts at nearly 0.02 seconds.

19

3. ARC flash calculation method and analysis

Conducting a fault current analysis and a protective device coordination study makes it possible

for us to proceed with the arc-flash analysis, which should be accomplished together with or

following the coordination protective devices and short circuit study [25]. The outcomes of the

short-circuit study help us find out the available fault current at electrical equipment locations

and hence properly specify equipment withstand ratings and interrupting capabilities. Besides,

the results of the protective-device coordination study provide us with information on the time

the system needs to isolate overload or fault conditions. Further, the outcomes of both the short-

circuit study and protective device evaluation jointly offer the necessary information needed to

implement an arc-flash analysis. Finally, the results of the arc-flash analysis are employed to

determine the incident energy and flash protection boundary at specified ranges all over positions

or levels in the electrical distribution system [25].

3.1 Fault current theory

Fault current analysis on a theoretical basis is conducted by examining the reaction of the series

R-L circuit presented in Figure 3.1 below:

20

Figure 3.1: Series RL Circuit

When the switch SW closes at time t=0, the circuit’s reaction will be the same as that of a

balanced three phase fault with zero impedance between the phases [26]. Writing Kirchhoff’s

Law for the circuit when t>0.

+ Ri(t)=√2 for t>0

Solving this results in the fault current i(t):

i(t)=√ sin sin

i(t)=iac(t)-idc(t)

Z=

tan . tan .

21

T=

To find i(t) as its greatest value we allow ,then:

i(t)=√2 Iac[sin( )+ / ]

The main objective of the short circuit study is to identify the available fault current (AFC) at

different points throughout the system under fault conditions. Afterwards, the AFC is compared

to equipment withstand ratings and available interrupting capacity (AIC) of protective devices.

Equipment with a withstand rating do not interrupt fault current but must “ride through” a fault

without damage imposed by the magnetic forces caused by the large currents. Consequently,

withstand rating of each panel-board must be greater than the AFC calculated at its bus and the

AIC of each protective device must be greater than the AFC so that it can interrupt the maximum

fault current seen at its contacts. If a breaker or fuse is not rated to handle the maximum

available fault current it might meet, the device might not function appropriately and its internal

components might fuse together or buckle under the destructive stresses of a fault condition,

which can result in serious harm and/or property damage [27].

The AFC observed at any locations in an electrical system is a product of the fault contributions

imposed on the system and the impedances in their path to the fault location. The contributions

toward the system include the utility, generators, and motors. Besides, the impedances

throughout the system are provided by conductors and transformers.

The real process of fault current calculation has been admirably documented in the IEEE

standard. Nevertheless, the reduction of fault current can be valued through a point to point

calculation method using the following equation [28]:

22

F= (1.732*L*AFC)/(C*N*V) where L: Length of conductor AFC: Available fault current at beginning of run C: Constant representing conductor type n: number of conductor parallel runs V: Voltage line to line

The AFC at the service entrance is a crucial item in the calculation and is easily provided by the

local electrical utility. Traditionally, this figure is an overly conservative large one whose

intention is to assess the system during a worst case high fault current scenario. As a result, the

AFC is usually provided as an infinite bus calculation dependent on the service transformer size

and impedance. This brings about the highest possible fault current on the service transformer

secondary terminals. The simplified form of this calculation on the basis of infinite bus theory is

presented below [27]:

1. Step One: Calculate the full load current at the secondary of the transformer:

FLA (secondary)=√

2. Step Two: Calculate the Available Fault Current at the secondary of transformer

AFC (secondary) = ∗

%

For a 15kV-480V , 2000 KVA transformer with impedance (Z)= 4.5 %, the resulting infinite bus

calculation for AFC= 53547 amps.

The peak value of the first cycle is the product of the DC exponential decay value. The rate of

DC exponential decay ensues from the system impedance properties when looking from the fault

back to the short circuit contribution. In most power systems, the DC component of the current

generally decays quickly and reaches a non-significant value within 0.1 second [26]. The

conductor and transformer properties of resistance (R) and reactance (X) in calculation with the

23

utility source system properties are the reasons for this value which is recognized as the X/R

ratio and varies throughout the system in accordance with inherent properties. The protective

devices must be evaluated against this value as well as the AFC.

Once a fault occurs, the current is no longer a sine wave, so the wave form must now be

illustrated as the combination of a sine wave and a decaying exponential.

3.2 Importance of X/R ratio

The X/R value of the electrical system is crucial, since it presents the value of the fault current at

3-5 cycles after the fault that corresponds to the moment when the protective device activates to

isolate the fault. The higher the X/R ratio , the longer the DC component will exist [31]. System

X/R ratio should be compared to the X/R ratio associated with the tested protective device . In

case the system X/R ratio is larger than the equipment X/R ratio then additional research will be

necessary to decide whether the device can be safely used. .

If the resulting de-rated AIC is greater than the AFC, it means that the device is appropriately

rated for installation in the system at the determined location. All low voltage protective devices

are tested at previously planned X/R ratios as shown in table 3.1 [30].

Table 3.1: Test X/R ratios for protective devices

Device Test X/R Ratio

Low Voltage Power Circuit Breakers 6.6

Molded Case Circuit Breakers rated less than 10k AIC 1.7

Molded Case Circuit Breakers rated between than 10k & 20k AIC 3.2

Fuses, Insulated Case Circuit Breakers,Molded Case Circuit Breakers rated

Greater than 20k AIC

4.9

24

The short circuit study qualifies the equipment through its evaluation against two parameters:

1. The AIC rating of the equipment against the calculated system AFC.

2. The X/R ratio at which the device was tested against the calculated X/R ratio of the system.

3.3 IEEE Method (Standard)

IEEE Standard 1584-2002 recommends the following procedures for the evaluation of arc flash

hazard. An IEEE working group on arc flash has developed the empirically derived equations

based on test results, which can be applied in the following situations.

Table 3.2: Conditions for which the IEEE 1584 equations are applicable

Parameter Applicable Range

System voltage (kV) 0.208 to 15 kV

Frequencies (Hz) 50 or 60 Hz

Bolted fault current (kA) 0.7 to 106 kA

Gap between electrodes (mm) 13 to 152 mm

Equipment enclosure type Open air,box, MCC,panel,switchgear,cables

Grounding type Ungrounded,grounded, high resistance grounded

Phases 3 Phase faults

3.3.1 Arcing current calculations

For electrical distribution systems which voltage is less than 1000 V, the arc current is specified

by equation (3.1).

25

Ia=10 {K+0.622 log (I

bf)+0.0966V+0.000526G+0.5588V*log(I

bf)-0.00304G*log(I

bf)} (equation 3.1)

Where log is the log10 Ia=arcing current (kA)

K= -0.153; open configuration

= -0.097; box configuration

Ibf= bolted fault current for three phase faults (symmetrical RMS) (KA)

V=system voltage (kV)

G= gap between conductors, (mm)

For medium voltage systems (>1 kV), the arc current is given by equation

Ia= 10{0.00402+0.983 log(Ibf

)}

3.3.2 Normalized incident energy

The normalized incident energy is calculated by the following equation and formed on arc

duration for 0.2 second and distance from arc that is 610 mm.

En=10{K1+K2+1.081*log(Ia)+0.0011G}

Where En=Incident energy normalized for time and distance (J/cm2)

K1= -0.792; open configuration

=-0.555; box configuration

K2=0; ungrounded and high resistance grounded systems

=-0.113; grounded systems

G=gap between conductors (mm)

3.3.3 Incident energy calculation

The normalized incident energy is employed to calculate the incident energy at a normal surface

at a specified distance and arcing time with equation below:

E= 4.184 Cf En (t/0.2)(610/D)x

26

Where E=incident energy (J/ cm2)

Cf=Calculation factor =1.0; voltage>1kV

=1.5; voltage<1kV

t= arcing time (seconds)

D= working distance from arc (mm)

x= distance exponent as shown in Table 3.3.

Table 3.3: Distance factor (x) for various voltages and enclosure types

Enclosure Type 0.208 to 1 kV >1 to 15 kV

Open air 2 2

Switchgear 1.473 0.973

MCC and Panels 1.641

Cable 2 2

3.3.4 Flash protection boundary

The flash protection boundary is defined by NFPA as the distance at which a person with no

personal protective equipment (PPE) may get a second degree burn which is treatable. For the

empirically derived equation:

DB= 610* [ 4.184 Cf En (t/0.2)(1/EB)]1/x

For the theoretically derived equation,

DB= [ 2.142*106*V*Ibf*(t/EB)]1/x

Where DB= distance of the boundary from the arcing point (mm)

Cf= calculation factor =1.0; voltage> 1 kV

=1.5; voltage < 1kV

27

En=incident energy normalized

EB= incident energy at the boundary distance (J/cm2); EB can be set at 5.0 J/cm2 (1.2 Cal/cm2) for bare skin.

t= arcing time (seconds)

x= the distance exponent from table 3.3.

Ibf=bolted fault current (kA).

V=system voltage, kV

3.4 Protection boundaries definition

According to NFPA, The boundaries are classified into following 4 categories:

3.4.1 Flash protection boundary

Severe injuries are probable to occur within this area as a result of arc flash burns unless proper

PPE is used and everyone within this area must use appropriate PPE despite the activity he/she is

doing.

The distance from the arc source at which one set of a second degree burn happens 2

Cal/cm2>0.1 sec. is regarded as a second degree burn threshold.If bare skin is exposed to this

level of flash, medical treatment might still be necessary, while complete recovery is expected.

3.4.2 Limited approach boundary

Describes a boundary near energized parts that only qualified person can cross it. Might be closer

than flash boundary and defined exclusively on the basis of the nominal voltage. Limited

Approach Boundary according to NFPA is defined as "a shock protection boundary to be crossed

by only qualified persons (at a distance from a live part) which is not to be crossed by

unqualified persons unless escorted by a qualified person"[2].

28

3.4.3 Restricted approach boundary

Boundary near exposed live parts that might be crossed merely by “qualified” people who apply

suitable shock prevention techniques and equipment. A shock hazard is the main concern.

Defined exclusively on the basis of the nominal voltage. Restricted Approach Boundary

according to NFPA is defined as “A shock protection boundary to be crossed by only qualified

persons (at a distance from a live part) which, due to its proximity to a shock hazard, requires the

use of shock protection techniques and equipment when crossed”[2].

3.4.4 Prohibited approach boundary

A shock protection boundary which is merely crossed by “qualified” people who use the same

protection in such a way that it seems direct contact with live part is prearranged. It is defined

exclusively on the basis of the nominal voltage.

3.5 Arc flash pressure

This pressure is noteworthy since it can throw workers away from the arc and makes them fall

and injure more severely than they might in the case of burn occurrence. In his 1987 paper

“Pressures Developed by Arcs”, Ralph Lee [4] mentions several real cases. In one of these

cases, with available system three phase short circuit 100 kA and estimated arc flash current 42

kA for a low voltage system (480 V), hurled by arc flash pressure about 25 feet. Forcing the

electricians away from the arc decreases their hazard to the heat transfer and smelted copper, but

might put the workers at the risk of falls or impact injuries. As specified by following equation,

the introductory force is roughly 260 lb/ft2 at 24 inches.

Pressure= (11.58*Iarc)/D0.9

Where, pressure is in pounds per square foot.

29

D= Distance from arc in feet.

Iarc= Arc current in kA.

3.6 Arc flash energy levels

In addition to studies and research on incident energy prediction, some other studies are devoted

to ways of protecting workers in the event of an arc-flash. In 1997 and 1998, two papers were

published on the testing of personal protective equipment (PPE) for arc-flash analysis [32,33]. In

this project, the flammability of clothing was tested when disclosed to arc flashes with varying

incident energy magnitudes. Ultimately, the paper suggested protective clothing classes based on

incident energy ranges in line with a fire rated clothing system and description. Moreover, this

project incorporated the function of safety glasses, face shields, and work gloves when exposed

to an arc flash. Finally, this research offered the ground work for a standardized system with the

focus on worker safety in the case of an incident.

The arc flash analysis provides the energy level at a definite working range from the arc’s point

of supply. This allows us to select a personal protective equipment (PPE) that is rated above the

incident energy. Although the concept of using the PPE that matches the task seems simple, the

different incident energy levels can be extensive. For this reason, the application of energy level

was embedded into the PPE selection process.

According to NFPA, there are five energy levels of 0,1,2,3 and 4 which associate with the

maximum incident energy levels (cal/cm2) of 1.2, 4, 8, 25, and 40. This makes it possible for an

electrical device to be labeled per category, and consequently the selection of PPE can be

matched likewise, as shown by Table 3.4. In this thesis “hazard risk category” and “energy level”

are used interchangeably.

30

Table 3.4: Protective clothing characteristics

Energy Levels

Common FR clothing at this level Minimum (Cal/cm^2)

0 Non-melting, flammable materials 1.2 1 FR shirt and FR pants; Or FR coveralls; Single base layer of FR protection 4 2 FR under garments (undershirt, underwear), FR shirt, and FR pants; FR

under garments, FR coveralls; 2 or more layers of FR protection 8

3 FR under garments (undershirt, underwear), FR shirt, FR jacket, FR pants, and FR coveralls; 2-3 or more layers of FR protection;

25

4 FR under garments (undershirt, underwear), FR shirt, FR jacket/coat, FR pants, and FR coveralls; FR under garments (undershirt, underwear), FR shirt, FR pants, multi-layer flash suit; 3-4 or more layers of FR protection;

40

3.7 Coordination for protective devices

Protective device selective coordination is the reaction of circuit breakers and fuses throughout a

transient, aiming at isolating the faulted part of the system from service. The objective is to

minimize the damage to equipment and personnel located nearby, while preserving electrical

service in parallel branches. This is essentially important in mission critical systems which are

the basis of this thesis. According to IEEE Buff Book, “Coordination is a fundamental ingredient

of a well-designed electrical distribution system and is compulsory in certain healthcare and

continuous process industrial systems” [29].

This coordination is necessary from the sources of energy such as utility to the loads for all

protection devices which are in series. When circuit breakers are appropriately adjusted and

installed, a fault at any location has minimal influence on close panels and feeders. Figure 3.2

shows a one line diagram of an electrical system. If a fault occurred at Motor-1, appropriate

selective coordination would happen if circuit breaker CB154 is opened before CB153 or any

device further upstream.

31

Figure 3.2: One line diagram of a three motor distribution system

The protective devices causing system selective coordination comprise fuses and circuit

breakers. These devices enjoy a time versus current profile, called time-current curve (TCC), that

they will allow to pass before activating. Figure 3.3 illustrates a TCC for circuit breaker CB150

and fuse 19.

32

Figure 3.3: Time current curves for a circuit breaker and a fuse

Because the reference voltage is 480 volt and the current is presented at times 10, a 3kA fault

current would be cleared at less than 0.03 seconds by this circuit breaker and at 0.45 seconds by

this fuse.

Figure 3.4 shows the TCCs for the system with proper selective coordination. This plot

demonstrates all circuit breaker curves which are in series from Utility source to Motor-1.

33

Figure 3.4 Time current curves for a selectively coordinated circuit breakers

34

It is apparent that the breaker curves do not touch or overlap each other and as a result

appropriate selective coordination exists. Figure 3.5 illustrates the TCC for the above system

with a lack of selective coordination.

Figure 3.5: Time current curves with a lack of selective coordination

35

The overlap of breaker curves CB-150 and CB-153 suggests that selective coordination does not

exist. If a fault of 2000 amps were to take place on Panel B, then CB-150 would open before CB-

153. This would result in the power loss of the feeder to Motor-2 and Motor-3 , and therefore our

goal of isolating the fault without disturbing close devices would not be achieved. Selective

coordination is accomplished by suitable selection and adjustment of the protective devices. In

fact, all electrical systems carry some level of coordination, since the overcurrent protective

devices which are closer to the utility or generators have higher ratings in comparison to

downstream devices [34].

This project explores the coordination with circuit breakers, since they can encompass adjustable

settings, where fuses cannot. The adjustable features in a circuit breaker are divided by time

segments. The Long Time (LT) is the setting of the breaker for overload circumstances which is

also called the amperage rating. This is generally in the time period beyond 60 seconds and has a

similar reaction to a thermal element. The Short Time (ST) is the setting for the breaker which is

normally 0.5 seconds until the long time segment. This transitional period is vital for identifying

low level faults that might occur as a result of system impedances. The Instantaneous (I) element

is the setting for the initial transient of a fault which is frequently adjusted very high to

incorporate motor and transformer inrush currents in the first few cycles of start-up, however not

higher than the available fault current.

36

3.8 Motor contribution to short circuit current

When studying short circuit, motor contribution should be considered in analysis. Load such as

motors convert to generators and create current, this current adds up to short circuit which flows

to fault location.

Same as contribution from a generator, motor gives the full load ampere (FLA) of nameplate

divided by its per unit subtransient reactance. Meanwhile, at upstream panel board, related

impedance of the motor branch circuit conductors decreases the motor contribution current to

short circuit.

The results which illustrate the highest short circuit current to related devices should include

motors contribution to short circuit.

37

4. Feasible steps to arc flash calculations

A detailed arc flash study includes the following steps. A detailed engineering analysis is

preferred for large power systems with several sources and different mode of operation such as

normal, emergency and maintenance. Since it can determine the probable worst case situations

for arc flash.

To illustrate the steps using an example, data and model from a ETAP workshop were used after

being modified for a system with 5 buses.

4.1 Identification of locations for arc fault hazard

Arc flash hazard evaluation is only necessary for the places where workers are vulnerable by

risk. Hence, the assessment may not be required for every bus and equipment in the power

system. In case that the service transformer is less than 125 KVA, panels and switchboards with

voltages 208 volts or under this can usually be overlooked. The arc might not be viable for

lower voltages and lower available fault currents. Whenever a potential significant arc flash

injury is perceived, all electrical panels with circuit breakers and fuses should be considered in

the evaluation. Incidents are probable when circuit breakers or fuses are under operation and they

connects or disconnects, even though the panel door is closed. In the example below, all buses

are faulted.

4.2 Data collection

Although arc flash hazard evaluation may not be necessary for some equipment, data regarding

the equipment may be needed in a short circuit analysis. Table 4.1 shows typical data needed for

38

the study. Data on utility, generators, transformers, circuit breakers,cables, transmission lines,

motors, and etc. is required in short circuit analysis, however, most of the necessary data can be

obtained using the name plate of the equipment. Additionally, typical data can be collected from

handbooks and product manual data sheet. Power system software such as ETAP includes a

comprehensive collection of manufacturer’s data which covers most electrical equipment

available today. The following data for utility, buses, transformers, loads and motors has been

collected from an ETAP workshop with slight modifications.

Table 4.1: Utility parameters

Device ID Field Description Value Utility

Rated kV 13.8 kV 3 Phase MVAsc 150 MVA 1 Phase MVAsc 150 MVA X/R 3-phase 15 X/R 1-phase 15 Design % Volt 100% Grounding Solid Ground

The one line diagram in figure 4.1 illustrates utility, protection relay, step down transformer,

switchgear panel, protection devices and loads.

The rated voltage for utility is 13.8 kV, three phase and one phase short circuit is 150 MVA and

ratio of X/R is 15. Utility is grounded solidly.

39

Figure 4.1: One line diagram of 13.8kV/480V distribution system

Information regarding bus 01 can be found in table 4.2. The Nominal voltage for bus 01 is 13.8

kV since it is connected to utility. The gap between conductors is 150 mm. The following

information is recorded in the rating tab of bus editor in Figure 4.2. Limited approach exp. mov.

cond is 12 feet, limited approach FCP is 8 feet, restricted approach boundary is 4.16 feet,

prohibited approch boundary is 1 feet, distance X factor is 2 and working distance is 24 inches.

The Limited Approach Boundary (LAB) is defined according to NFPA 70E-2009 “as the

approach limit at a distance from an exposed live part within which a shock hazard exists”. The

LAB for movable conductors is the distance, that persons who are not trained can not come

nearer to conductor which is not braced in fixed position. The limited approach boundary for

40

fixed circuit parts is the distance, persons who are not trained can not come nearer to a not

movable conductor (fixed conductor).

Table 4.2. Bus 1 parameters

Device ID Field Description Value Bus 1

Nominal kV 13.8 kV Equipment Type Open Air Gap Between Conductors 150 mm Limited Approach Exp. Mov. Cond 12 ft. Limited Approach FCP 8 ft. Restricted approach Boundary 4.16 ft. Prohibited Approach Boundary 1 ft. Distance X Factor 2.00 Working Distance 24 in.

Figure 4.2: Bus 01 (13.8 kV) editor page

41

Information regarding Switchgear A can be found in table 4.3. The nominal voltage for

switchgear A is 0.48 kV since it is connected to secondary side of step-down transformer. The

gap between conductors is 32 mm. The following information is recorded in the rating tab of bus

editor in Figure 4.3: limited approach exp. mov. cond is 12 feet, limited approach FCP is 4 feet,

restricted approach boundaryis 1.5 feet, prohibited approch boundary is 0.2 feet, distance X

factor is 2 and working distance is 18 inches.

Table 4.3. Switchgear A parameters

Device ID Field Description Value Switchgear A

Nominal kV 0.48 kV Equipment Type Switchgear Gap Between Conductors 32 mm Limited Approach Exp. Mov. Cond 12 ft. Limited Approach FCP 4 ft. Restricted approach Boundary 1.5 ft. Prohibited Approach Boundary 0.2 ft. Distance X Factor 2.00 Working Distance 18 in.

42

Figure 4.3: Switchgear A (0.48 kV) editor page

The information regarding bus 2 is recorded in table 4.4. The nominal voltage for bus 2 is 0.48

kV since it is connected to Switchgar A. The gap between conductors is 20 mm. The following

information is recorded in the rating tab of bus editor in Figure 4.4: limited approach exp. mov.

cond is 12 feet, limited approach FCP is 5 feet, restricted approach boundary is 2 feet, prohibited

approch boundary is 0.2 feet, distance X factor is 2 and working distance is 24 inches.



Nominal kV 0.48 kV Equipment Type MCC Gap Between Conductors 20 mm Limited Approach Exp. Mov. Cond 12 ft. Limited Approach FCP 5 ft. Restricted approach Boundary 2 ft. Prohibited Approach Boundary 0.2 ft. Distance X Factor 2.00 Working Distance 24 in.

43


The information regarding bus 3 can be found in table 4.5. The nominal voltage for bus 3 is 0.208 kV

since it is connected to step down transformer 2 (0.480/0.208kV). The gap between conductors is 25 mm.

the following information is recorder in the rating tab of bus editor in Figure 4.5. Limited approach exp.

mov. cond is 12 feet, limited approach FCP is 5 feet, restricted approach boundary is 2 feet, prohibited

approch boundary is 0.2 feet, distance X factor is 2 and working distance is 18 inches.



Nominal kV 0.208 kV Equipment Type Panel Board Gap Between Conductors 25 mm Limited Approach Exp. Mov. Cond 12 ft. Limited Approach FCP 5 ft. Restricted approach Boundary 2 ft. Prohibited Approach Boundary 0.2 ft. Distance X Factor 2.00 Working Distance 18 in.

44


The information regarding bus 4 can be found in table 4.6. The nominal voltage for bus 4 is

0.480 kV since it is connected to switchboard A. The gap between conductors is 20 mm. The

following information is recorded in the rating tab of bus editor in Figure 4.6. Limited approach

exp. mov. cond is 12 feet, limited approach FCP is 5 feet, restricted approach boundary is 2 feet,

prohibited approch boundary is 0.2 feet, distance X factor is 2 and working distance is 24 inches.



Nominal kV 0.48 kV Equipment Type MCC Gap Between Conductors 20 mm Limited Approach Exp. Mov. Cond 12 ft. Limited Approach FCP 5 ft. Restricted approach Boundary 2 ft. Prohibited Approach Boundary 0.2 ft. Distance X Factor 2.00 Working Distance 24 in.

45


Transformer one and two data can be found in table 4.7. Both transformers are step down.

Transformer one (T1) is 5 MVA and decreases the voltage from 13.8 kV to 0.480 kV. Also its

positive sequence Z is 5.4% and X/R for both Positive sequence and Zero sequence is 10.21%

and grounding is Delta-Ysolid.

Transformer 2 (T2) is 0.5 MVA and reduces the voltage from 0.480 kV to 0.208 kV. Besides, its

positive sequence Z is 5.4% and X/R for both Positive sequence and Zero sequence is 3.51%.

Grounding for transformer 2 (T2) is the same as that of transformer1 (T1), which is Delta-Y

solid. At 2-winding transformer editor figure 4.7 related data is entered.

46

Table 4.7. Transformer 1&2 parameters

Device ID Field Description Value T1

Rated Prim. kV 13.8 kV Rated Sec. kV 0.480 kV MVA 5 MVA Max MVA 5 MVA Pos Sequence Z% 5.4 % X/R Pos Sequence 10.21 % X/R Zero Sequence 10.21 % Grounding Delta-Y solid

T2

Rated Prim. kV 0.480 kV Rated Sec. kV 0.208 kV MVA 0.5 MVA Max MVA 0.5 MVA Pos Sequence Z% 5.4 % X/R Pos Sequence 3.51 % X/R Zero Sequence 3.51 % Grounding Delta-Y solid

Figure 4.7: Transformer 1 & 2 editor page motors

47

Motors data can be found in table 4.8. The bus bar 2 is connected with four motors. The first two

motors are 120 HP with rated voltage of 0.460 kV, power factor of 91.49% and efficiency of

82.06%. The other two motors are 150 HP with rated voltage of 0.460 kV, power factor of

91.59% and efficiency of 85.16%. The data is recorded in induction machine editor figure 4.8.

Table 4.8. Motor 1&2 parameters

Device ID Field Description Value Motor 1

HP 120 Rated kV 0.460 kV Manufacturer Typical Data PF%=91.49 Eff%=82.06 Quantity 2

Motor 2

HP 150 Rated kV 0.460 kV Manufacturer Typical Data PF%=91.59 Eff%=85.16 Quantity 2

Figure 4.8: Motor 1 & 2 editor page

48

Load 1 data can be found in table 4.9. The value of load is 0.4 MVA and its rated voltage is

0.208 kV. The power factor is 95%. This data is recorded in static load editor figure 4.9.

Table 4.9. Static Load Parameters

Device ID Field Description Value Load 1

Rated MVA 0.4 MVA Rated kV 0.208 kV % PF 95%

Figure 4.9: Static load editor page

Load 2 (Lump 1) data can be found in table 4.10. The value of the load is 0.3 MVA and its rated

voltage is 0.480 kV. The power factor is 85%. This data is recorded in lumped load editor figure

4.10.

49

Table 4.10. Lump load parameters

Device ID Field Description Value Lump 1

Rated MVA 0.3 MVA Rated kV 0.48 kV % PF 85%

Figure 4.10: Lump load editor page

As table 4.11 shows, for high voltage circuit breaker, the rated max voltage is 15 kV while the

continuous current is 1200 Amps. This data is recorded in high voltage circuit breaker in figure

4.11. Cycle and CPT is necessary to determine the fault clearing time for HVCB.

Table 4.11. High voltage circuit breaker parameters

Device ID Field Description Value

High Voltage CB

Rated Max kV 15 Manufacturer Cutler-Hammer Model 150 VCP-W1000 Cycle 5 CPT 3 Continuous Amps 1200 Amps

50

Figure 4.11: High voltage circuit breaker editor page

As it can be seen in table 4.12, the rated max voltage for fuse 1 (high voltage fuse) is 15 kV,

continuous current is 200 amps and test PF is 3.95. This data is recorded in fuse parameter page

in figure 4.12.

Table 4.12. Fuse parameters

Device ID Field Description Value Fuse 1

Rated Max kV 15 kV Manufacturer Cutler Hammer Model BA-200 (Condenser) Size 200 E Continuous Amps 200 Interrupting 10 Test PF 3.95

51

Figure 4.12: Fuse editor page

Current transformer (CT9) is connected to over current protection relay as indicated in table

4.13. The primary turns’ value is 150 and secondary turns’ value is 5. This data is recorded in

current Transformer (CT) editor page in figure 4.13.

Table 4.13. Current transformer parameter

Device ID Field Description Value CT9 Primary turns 150

Secondary Turns 5

52

Figure 4.13: Current transformer editor page

The input of relay 1 is connected to CT9 and its output is connected to high voltage circuit

breaker (HVCB1), as it is observable in table 4.14. The other values are recorded in over current

relay editor in figure 4.14.

Table 4.14. Over current relay parameters

Device ID Field Description Value Relay 1

Input CT CT9 Output PD HVCB1 Relay Element Any Level/zone Any Action Open OCR Manufacturer GE Multilin Model IFC Curve Type Inverse (51) Pickup Range 1-12 sec-5A Pickup 12 Time Dial 2.3 Inst Pickup Range 30-150 Sec-5 A Pickup 100

53

Figure 4.14: Over current relay editor page

The nominal voltage for low voltage circuit breaker (LVCB1) is 0.480 kV, while the continuous

current is 4000 Amps. Circuit breaker is supplied with a solid state trip unit which is

characterized by Long time, short time and instantaneous trip features. The associated

information can be found at circuit breaker editor page in Figure 4.15. Considering the four

circuit breakers in this one line, the same procedures are followed for each of the other three

circuit breakers.

54

Figure 4.15: Low voltage circuit breaker (LVCB1) editor

4.3 Preparing single line diagram of the system

Single line diagrams are regarded as robust tools to document and communicate information

regarding power systems. They are not only easily readable and understandable, but also express

the way that equipment are connected and also shows the status of equipment, for instance circuit

breaker could be open or close. The results of analyses like short circuit studies and arc flash

evaluation can effortlessly be placed on the diagrams. The model illustrated in figure 4.16 below

is developed using ETAP software:

55

Figure 4.16: One line diagram for five bus network

The step down transformer (T01) reduces the voltage from 13.8 kV to 480 V. Together, there

are six loads which include four motors, one static load and one lumped load. Additionally,

transformer (T02) decreases voltage from 480 V to 208 V. Switchgear A is protected by circuit

breaker LVCB1, while motors 1 &2 are protected by circuit breaker LVCB2. Moreover, Load1

and Lump1 are protected by circuit breakers LVCB3 & LVCB4, and transformer T1 is protected

by high voltage circuit breaker. The major upstream device to protect faults probable in Bus 01

or downstream devices is Fuse 1.

4.4 Short circuit study

Performing arc flash hazard (AFH), merely three phase faults are considered. It might seem odd;

however it is compatible with the recommendations in IEEE-1548 and NFPA-70E. It is due to

56

several causes. First, three phase faults typically provide the highest probable short circuit energy

and specify the worst case. Second, it is indicated by experience that arcing faults happens in air

or equipment , which initiate as line to ground faults, can intensify instantaneously into three

phase faults, as the air ionizes through phases. Such an evolution from single phase to three

phase fault normally occurs within a few cycles. As a result, the majority of analyses done so far

on arc flash energy have been based on three phase faults.

IEEE 1584 recommends that the calculations for single phase systems are performed for a

corresponding three phase system. It declares that this will lead to conservative outcomes. Table

4.15 demonstrates the result for three phase bolted short circuit.

Table 4.15: Three phase bolted short circuit

ID kA (Three phase bolted short circuit)

Switchgear A 73.6

Bus 01 6.4

Bus 02 73.6

Bus 03 22.4

Bus 04 73.6

57

Figure 4.17: Short current result for five bus network (one line)

Figure 4.17 illustrates the short current outcome for each bus. The short circuit current at

switchgear A is 73.6 kA, and since there is no impedance between switchgear A and bus 02, the

short circuit current at bus 02 is identical with Switchgear A. The short circuit current at bus 03

is 22.4 kA, which is less than that of switchgear A due to Impedance transformer T02. To

identify maximum short circuit current, highly conservative estimates and assumptions are

employed in short circuit calculations. It is compelling if the purpose is to specify maximum

breaker or equipment duties. Nevertheless, employing excessively conservative short circuit data

for arc flash hazard AFH might produce non-conservative outcomes. This is because a very high

fault current might result in notably short arc duration caused by the operation of immediate trip

elements. The highest fault current does not essentially mean the highest probable arc flash

58

hazard, since the incident energy is a function of arcing time, which can be an inversely

proportional function of the arcing current.

4.5 Determine arc current

In this stage we calculate the arc fault current using IEEE formulas described in chapter 3. IEEE

procedure recommends the following steps to include the variance probable in arcs:

1. Determining the maximum expected bolted fault condition.

2. Determining the minimum expected bolted fault condition, which can be a light load

condition with numerous motor loads or generators that are not running.

3. Computing the arcing current at 100% of IEEE 1584 estimate for the above two

conditions.

4. Calculating the arcing current at 85% of IEEE 1584 estimate for the two above

conditions.

When evaluating these four arcing currents, determine the arc flash incident energy and choose

PPE base on highest incident energies. The minimum fault current in comparison with the

maximum fault current condition might need more time to clear and might lead to a higher level

of arc flash incident energy level. It is recommended main fault current source (Utility or

Generator) to be calculated, as its current can conclude the fault clearing time for the large part

of the arc flash incident energy level. The result of arc flash calculation on one line diagram is

depicted in Figure 4.18.

59

Figure 4.18: Arc flash result for five bus network (one line)

The result of the arc flash analysis is illustrated in table 4.16 and figure 4.19. The total released

energy at bus 02 is 10.81 cal/cm2, that is classified as level 3 and is considered dangerous. Arc

flash boundary is 4.5, final clearing time (FCT) is 0.05 seconds, and the arcing current at FCT is

41.573 kA. Circuit breaker LVCB2 is the primary protection device for clearing the fault at bus

02.

Table 4.16: Arc flash result for five bus network

ID kV Total Energy Cal/cm2

AFB(ft) Energy Levels

Final FCT (sec)

Ia at FCT (kA)

Source PD ID

Bus01 13.8 0.9638 1.3 Level 0 0.067 6.289 Fuse1 Bus02 0.48 10.81 4.5 Level 3 0.05 41.573 LVCB2 Bus03 0.208 1233.16 48.1 Level 4 38.052 7.183 LVCB3 Bus04 0.48 15.14 5.3 Level 3 0.07 41.573 LVCB4 Switchgear A

0.48 225.71 20.6 Level 4 1.044 41.573 High Voltage CB

60

Figure 4.19 shows arc flash report analyzer for one line with five buses.

Figure 4.19: Arc flash report analyzer for five bus system.

Having calculated the range of possible arc current, you must examine whether the computed

values are within the feasible range. To do so, following items should be checked:

Upper limit: The arc current cannot be larger than the bolted fault current. It is due to the

additional impedance of the arc. Hence, if the upper limit of the range of arc current is larger

than the bolted fault current, you must remove it and consider the bolted fault current as the

upper limit.

Lower Limit: According to the test data included in IEEE standard 1584, arc sustains for a

current which is 21% of bolted fault current at 208 volt for 0.2 seconds. Table 4.17 displays the

minimum arc current as a percentage of bolted fault current found as a result of the tests. The

61

lower limit of arc current is not clearly identified yet. Thus it might make sense to use table 4.17

as a percentage of the bolted fault current.

Table 4.17: Adjusted minimum arc current as a percentage of bolted fault currents.

Voltage (kV)

Min Measured Iarc % of Ibf

0.2/0.25 21% 0.4/0.48 21%

0.6 28% 2.3 51%

4.16 64% 13.8 84%

4.6 Determine arcing time

The trip time of a protective device is found using its time current characteristics (TCC). The

information can be gathered from manufacturers data sheets.

In general, the trip time for lower fault currents might be high. This is as a result of the reverse

relationship between the time and the current of the TCC. For higher currents, it is possible for

the arcing fault current to be greater than the instantaneous pickup of the protective device, and

as a result, the device might trip at the lowest response time.

Protective devices can withstand the defined trip time. Lots of low voltage breakers and fuses

determine the upper and lower limits of the trip time for various current values. In these cases,

the time current curve is similar to a wide band rather than a narrow line. Relays normally

display a narrow line for the TCC curve and determine specified tolerance.

The final clearing time for various buses (measured in seconds) in addition to the related

upstream protection device is illustrated in table 4.18 below. The fault at bus 01 will be cleared

62

by Fuse 1 at 0.067 second, while the fault at switchgear A will be cleared by high voltage CB at

1.044 second.

Table 4.18: Final clearing time and source protection device

ID Final FCT (Second)

Source PD ID

Bus01 0.067 Fuse1 Bus02 0.05 LVCB2 Bus03 38.052 LVCB3 Bus04 0.07 LVCB4 Switchgear A 1.044 High Voltage CB

4.7 Determine incident energy

The incident energy for the equipment must be evaluated at the specified working distances. The

equations needed to calculate the arc flash incident energy are presented in chapter 3. The

incident energy value depends on several factors such as arcing time, arc current, the distance

from arc and enclosure type. In addition, IEEE 1584 considers the gap between electrodes as a

variable.

Table 4.19: Calculated total energy

ID kV Total Energy

(cal/cm2)

Bus01 13.8 0.9638

Bus02 0.48 10.81

Bus03 0.208 1233.16

Bus04 0.48 15.14

Switchgear A 0.48 225.71

63

It is observable in table 4.19 that bus 01’s maximum incident energy is 0.9638 cal/cm2.

Comparing the low voltage buses, the highest incident energy belongs to bus 3 (i.e. 1233.16

cal/cm2 ). This is due to its maximum fault clearing time which is 38.052 seconds.

4.8 Determine energy level

Energy level (hazard risk category) is stated in the form of a number which shows the level of

danger. This level depends on the incident energy. Level 0 signifies little or no risk, while level 4

indicates the maximum danger. The categorizing guide for numbering the risk levels is provided

in table 4.20.

Table 4.20: Classification guide for the energy level

Category Energy Level

0 1.2 cal/cm2

1 4 cal/cm2

2 8 cal/cm2

3 25 cal/cm2

4 40 cal/cm2

As it can be seen in table 4.21, bus 01 is located in category Level 0 which means little or no

risk. Bus 02 and bus 04 belong to category level 3 which means being dangerous, while bus 3

and Switchgear A are shown to be the most dangerous ones. It is typically tried to decrease level

3 and 4 energy levels to zero, one and two categories by applying optimization techniques which

will be explained in next chapter.

64

Table 4.21: Result of risk category number

ID kV Energy Levels

Bus01 13.8 Level 0 Bus02 0.48 Level 3 Bus03 0.208 Level 4 Bus04 0.48 Level 3 Switchgear A

0.48 Level 4

It is recommended that workers first make provisions based on the energy level (risk category)

and then begin working or inspection close to unprotected, live conductors. It is also necessary to

use documentation and warning stickers. Although the energy level alone can offer an accurate

representation of the risk, the scale of 0 to 4 for the level of risk may provide workers with more

useful information. Thus it is necessary for the employers to completely assess the level of

hazard before initiating work close to unprotected conductors.

4.9 Determine flash protection boundary

The flash protection boundary by NFPA is defined “as the distance at which those endangered by arc

flash without proper PPE will receive second degree burns which are treatable.” The flash protection

boundary is a function of the arc flash incident energy in a way that as the arc flash energy increases, the

boundary distance will increases consequently. The flash protection boundary is calculated employing the

equation recommended by the standard as below. To determine the flash protection boundary, use the

following equation.

/ /

Where,

DB=distance of the boundary from the arcing point

65

D= working distance

E=maximum incident energy at working distance in cal/cm2

EB=incident energy at boundary, usually 2 cal/cm2 for arcing time>0.1 s.

For instance, considering table 4.22, the incident energy for bus 04 at a working distance of 18

inches is calculated to be 15.14 cal/cm2 based on the proposed NFPA 70E (2004) method. Then

the flash protection boundary for arcing time greater than 0.1 second is:

DB=18*(15.14/2)1/1.6= 5.31 feet

Table 4.22: Result of flash protection boundary

ID kV Total Energy (cal/cm2)

AFB(ft)

Bus01 13.8 0.9638 1.3 Bus02 0.48 10.81 4.5 Bus03 0.208 1233.16 48.1 Bus04 0.48 15.14 5.3 Switchgear A

0.48 225.71 20.6

4.10 Determine arc flash study

The recommended documentations by NFPA for arc flash hazard assessment results to be placed

on equipment are divided into two types as below:

1. Warning labels showing arc flash values: These are stickers on which a warning sign of

acceptable size is printed. The stickers must be pasted in such a way to be easily

noticeable and readable from a specified distance. They must include clear prints of the

incident energy at the determined working distance and its related risk energy level

number as well as flash protection boundary.

66

2. Arc flash evaluation outcomes: it is recommended that these results are placed on the

equipment like table formats and one line diagram as explained in the preceding section,

at a spot effortlessly available for workers.

4.11 Description of real case study

In this section of the research, a power distribution system is analyzed which is located in a

commercial building in Boston. The building was constructed before 1990. Several years later,

the owner made up his mind to perform an arc flash hazard analysis in order to meet the terms of

NFPA. They intended to obtain a hazard risk of level 2 or below at all electrical breaker panels in

the system.

The plant’s power system includes a 15 KV system formed by the utility feed and six step down

transformers each 2500 KVA. These transformers stepdown the 15 KV system to 480 Volt

networks. The plant’s maximum load is 9000 KVA and the network has 271 buses. The 480 Volt

system is located throughout the plant and includes two Main Tie Main (M-T-M) breaker

configurations on the 480 volt side.

The emergency power to supply the loads is provided by three diesel generators with the

capacity of 1000 KVA (each) connected via two tie breakers for maintenance mode. Figure 4.20

illustrates the one line and annex A includes the related details.

The computer model, the short circuit requirements and the TCC curves were developed on the

basis of manufacturer’s printed equipment data together with the information given by client.

The studies are conducted applying ETAP software.

67

There are three electrical operating modes in a commercial building: normal mode, maintenance

mode and emergency mode. These three scenarios form the basis for the content of this

simulation. The definition for each mode is found below:

Normal mode: The normal operating mode is the situation where the power system is energized

and the power is being fed to loads without any human interactions. In case that a non-arcing

fault takes place, the protective devices such as circuit breaker will identify the fault and will

disconnect the faulted equipment rapidly and securely since there is no arc to

68

Figure 4.20: One line diagram for 271 bus system

cause equipment failure. On the contrary, whenever an arcing fault happens, the protective

relaying and other protective device would spot the fault, however the current value will not be

D0.48 kV

D5

0.48 kV

D6

0.48 kV

D7

0.48 kV

D32

0.48 kV

D41

0.48 kV

D43

0.48 kV

D45

0.208 kV

D49

0.208 kV

D48

0.208 kV

D47

0.208 kV

D46 0.208 kV

D44

0.48 kV

D42

0.208 kV

D33

0.208 kV

D36

0.208 kV

D38

0.208 kV

D40

0.208 kV

D39

0.208 kV

D37

0.208 kV

D35

0.208 kV

D34

0.208 kV

D8

0.48 kV

D19

0.48 kV

D20

0.48 kV

D27

0.48 kV

D31

0.48 kV

D30

0.208 kV

D29

0.208 kV

D28

0.208 kV

D21

0.208 kV

D25

0.208 kV

D24

0.208 kV

D23

0.208 kV

D22

0.208 kV

D26

0.208 kV

D9

0.48 kV

D10

0.208 kV

D16A

0.208 kV

D17

0.208 kV

D13

0.208 kV

D16

0.208 kV

D15

0.208 kV

D14

0.208 kV

D12

0.208 kV

D11

0.208 kV

D4

0.48 kV

E0.48 kV

C

13.8 kV

A13.8 kV

B

13.8 kV

D50

0.48 kV

D51

0.48 kV

D61

0.208 kV

D63

0.208 kV

D64

0.208 kV

D62

0.208 kV

D52

0.48 kV

D55

0.208 kV

D56

0.208 kV

D53

0.208 kV

D54

0.208 kV

D57

0.48 kV

D58

0.208 kV

D59

0.48 kV

D60

0.208 kV

D65

0.48 kV

D66

0.48 kV

E8

0.48 kV

E7

0.48 kV

E6

0.48 kV

E5

0.48 kV

E3

0.48 kV

E4 0.48 kV

E2

0.48 kV

E10.48 kV

D1

0.48 kV

D2 0.48 kV

D3

0.48 kV

Lump32

0 MVA

CBL-52

L4

240 kVA

CBL-51

L3

275 kVA

CBL-6

Lump7

0 MVA

L5 50 kVA

CBL-50

Lump133

0 MVA

L6 512 kVA

CBL-53

L8

60 kVACBL-55

L7 310 kVA

CBL-54

L9

504 kVA

CBL-56

L10

504 kVA

CBL-57

L11

504 kVA

CBL-58

L12

40 kVACBL-59

NORMAL SERV

401.559 MVAsc

NORM SERV

ALTERNITE SERV

0 MVAsc

ALT SERV

TRANS 1

2500 kVA

FUSE3

CBL-60

L13

80 kVA

Fuse15

CBL-187

Lump3

0 MVA

TRANS 12

45 kVA

CBL-197

Lump4

0 MVA

TRANS 11

45 kVA

CBL-196

Lump6

0 MVA

CBL-195

TRANS 9

45 kVA

CBL-194

Lump5

0 MVA

CBL-193

TRANS 10

30 kVA

CBL-192

LUMP RL1PSH1

10 kVA

CBL-190

Lump1

0 MVA

CBL-205

Lump2

0 MVACBL-213

CBL-212

CBL-204

FIRE PUMP

50 HPCable2

BM2

BM1

CBL-1

FUSE1

FUSE2

CBL-2

FUSE4

TRANS 2

2500 kVA

CBL-3

Open

L1

122 kVA

CBL-8

Lump35

0 MVA

CBL-29

Lump36

0 MVA

CBL-31

Lump38

0 MVA

CBL-34

Lump39

0 MVA

CBL-30

Lump40

0 MVA

CBL-33

Lump37

0 MVA

CBL-32

Lump41

0 MVA

CBL-35

Lump33

0 MVA

CBL-36

TRANS 3

225 kVA

FUSE7

Lump31

0 MVA

CBL-23

FUSE 6

Lump25

0 MVA

CBL-38

Lump28

0 MVACBL-44

Lump27

0 MVACBL-45

Lump29

0 MVACBL-39

Lump26

0 MVA

CBL-41

TRANS 4

225 kVA

FUSE9

Lump23

0 MVA

CBL-48

Lump22

0 MVA

CBL-49

TRANS 5

45 kVA

FUSE10

Lump24

0 MVA

CBL-47

CBL-46

Lump30

0 MVA

CBL-37

FUSE 8

CBL-14

CBL-12

Lump16

0 MVACBL-15

Lump15

0 MVACBL-16

Lump13

0 MVA

CBL-17

Lump11

0 MVACBL-18

Lump10

0 MVACBL-21

Lump12

0 MVACBL-20

Lump14

0 MVACBL-19

TRANS 6

150 kVA

FUSE11

Lump9

0 MVA

TRANS 7

113 kVA

FUSE13

Lump17

0 MVACBL-28

FUSE14

Lump18

0 MVACBL-24

Lump19

0 MVA

CBL-25

Lump20

0 MVACBL-26

Lump21

0 MVACBL-27

TRANS 8

113 kVA

RL2-FS02

CBL-13

Lump8

0 MVA

CBL-22

FUSE12

CBL-11

CBL-10

CBL-9

FUSE5

Lump34

0 MVA

L2

145 kVA

CBL-4

CBL-5

CBL-8

CBL-4

Open

FUSE5

CBL-50

CBL-53

CBL-58

CBL-56

CBL-54

CBL-57

CBL-59

NORMAL SERV

401.559 MVAsc

ALTERNITE SERV

0 MVAsc

NORM SERV

ALT SERV

FUSE2

CBL-1

CBL-2

FUSE1

FUSE3

FUSE4

TRANS 1

2500 kVA

TRANS 2

2500 kVA

CBL-51

CBL-52

CBL-23

FUSE7

TRANS 3

225 kVA

CBL-36

CBL-35

CBL-33

CBL-30

CBL-34

CBL-32

CBL-31

CBL-29

CBL-37

FUSE9

TRANS 4

225 kVA

CBL-44

CBL-45

CBL-39

CBL-41

CBL-38

CBL-47

FUSE10

TRANS 5

45 kVA

CBL-48

CBL-49

CBL-16

CBL-19

CBL-17

CBL-20

CBL-18

FUSE11

TRANS 6

150 kVA

CBL-15

CBL-21

CBL-22

TRANS 7

113 kVA

CBL-28

RL2-FS02

TRANS 8

113 kVA

CBL-24

CBL-25

CBL-26

CBL-27

CBL-55

CBL-12

CBL-11

CBL-14

CBL-13

CBL-46

CBL-10

CBL-3

CBL-5

CBL-6

CBL-60

CBL-9

L5 50 kVA

L6 512 kVA

L7 310 kVA

L8

60 kVA

L4

240 kVA

L3

275 kVA

L1

122 kVA

L2

145 kVA

BM2

BM1

CBL-187

CBL-196

TRANS 9

45 kVA

TRANS 11

45 kVA

CBL-197

TRANS 12

45 kVA

TRANS 10

30 kVA

CBL-193

CBL-190

CBL-192

CBL-194

CBL-195

L13

80 kVA

CBL-204

CBL-205

L11

504 kVA

L10

504 kVA

L9

504 kVA

CBL-212

CBL-213

L12

40 kVA

LUMP RL1PSH1

10 kVA

Cable2

FIRE PUMP

50 HP

Fuse15

FUSE12

FUSE13

FUSE 6

FUSE 8

FUSE14

Lump1

0 MVA

Lump2

0 MVA

Lump3

0 MVA

Lump4

0 MVA

Lump5

0 MVA

Lump6

0 MVA

Lump7

0 MVA

Lump8

0 MVA

Lump9

0 MVA

Lump10

0 MVA

Lump11

0 MVA

Lump12

0 MVA

Lump13

0 MVA

Lump14

0 MVA

Lump15

0 MVA

Lump16

0 MVA

Lump17

0 MVA

Lump18

0 MVA

Lump19

0 MVA

Lump20

0 MVA

Lump21

0 MVA

Lump22

0 MVA

Lump23

0 MVA

Lump24

0 MVA

Lump25

0 MVA

Lump26

0 MVA

Lump27

0 MVA

Lump28

0 MVA

Lump29

0 MVA

Lump30

0 MVA

Lump31

0 MVA

Lump32

0 MVA

Lump33

0 MVA

Lump34

0 MVA Lump35

0 MVA

Lump36

0 MVA

Lump37

0 MVA

Lump38

0 MVA

Lump39

0 MVA

Lump40

0 MVA

Lump41

0 MVA

Lump133

0 MVA

D0.48 kV

E0.48 kV

D6

0.48 kV

E10.48 kV

E2

0.48 kV

E3

0.48 kV

E5

0.48 kV

E6

0.48 kV

E7

0.48 kV

E8

0.48 kV

A13.8 kV

B

13.8 kV

C

13.8 kV

D1

0.48 kV

D2 0.48 kV

D3

0.48 kV

D4

0.48 kV

D7

0.48 kV

D5

0.48 kV

D8

0.48 kV

D32

0.48 kV

D9

0.48 kV

D10

0.208 kV

D19

0.48 kV

D16A

0.208 kV

D17

0.208 kV

D16

0.208 kV

D15

0.208 kV

D14

0.208 kV

D13

0.208 kV

D12

0.208 kV

D11

0.208 kV

D20

0.48 kV

D21

0.208 kV

D26

0.208 kV

D22

0.208 kV

D23

0.208 kV

D24

0.208 kV

D25

0.208 kV

D27

0.48 kV

D30

0.208 kV

D28

0.208 kV

D29

0.208 kV

D31

0.48 kV

D35

0.208 kV

D33

0.208 kV

D36

0.208 kV

D37

0.208 kV

D38

0.208 kV

D39

0.208 kV

D34

0.208 kV

D40

0.208 kV

D41

0.48 kV

D42

0.208 kV

D43

0.48 kV

D45

0.208 kV

D46 0.208 kV

D44

0.48 kV

D49

0.208 kV

D47

0.208 kV

D48

0.208 kV

E4 0.48 kV

D66

0.48 kV

D65

0.48 kV

D52

0.48 kV

D57

0.48 kV

D53

0.208 kV

D54

0.208 kV

D58

0.208 kV

D59

0.48 kV

D60

0.208 kV

D55

0.208 kV

D56

0.208 kV

0.48 kV

D61

0.208 kV

D62

0.208 kV

D63

0.208 kV

D64

0.208 kV

D50

0.48 kV

D51

69

as much as the non-arcing fault and it could take longer to clear the fault depending on the

estimated settings and the equipment installed. The setting of protection relays of circuit breakers

and low voltage fuses must be adjusted to reduce the incident energy level to the minimum

probable caloric value without threatening selectivity.

Emergency Mode: Diesel generators supply electricity in the case of utility failure. This can be

considered as a perfect way to protect against all potential interruptions of the main supply. In

the case studied here, three generators with output of 3000 KVA (each 1000 KVA) provide

electricity for the critical loads; e.g. water pumps and elevators.

Maintenance Mode: when workers implement electrical switching processes to disconnect

loads or to recover power to previously disconnected equipment which was being maintained or

repaired, it is said that the equipment is in switching operation mode, during which setting

protection relays of low voltage breakers and fuses merge to define the fault clearing time and

the level of incident energy produced in the case of an arcing fault occurrence. In the course of

switching processes of the power system, there are risks of an arcing fault for the workers; hence

the workers’ safety and protection is superior to the selectivity of the protection device. The

protective device must be adjusted to assure the decline of incident energy levels by rapidly

tripping the up-stream breakers in order to decrease the fault clearing time.

4.11.1 Circuit breakers configurations

Having defined the operating modes, it is crucial to know what operating condition is supposed

to be normal for a power system. The following situations were considered as being normal for

this commercial building:

70

1. The tie circuit breakers are normally open in the power system, except for the

maintenance operation, during which the tie breakers are closed to create a higher arc

flash level.

2. In the case that the normal power does not exists (emergency), diesel generators supply

all buses and panels. Throughout maintenance operation, the tie breakers are closed to

create a higher arc flash level.

Four configurations are defined in ETAP software: A) Normal, B) Emergency Ties Closed

(EMTC), C) Normal Ties Closed, and D) Emergency.

In the normal mode, the automatic transfer switches (ATS) are in position A. But in the case of

utility failure, they switch to position B and the loads are supplied by emergency generators.

At both normal and emergency modes when the tie breakers are open, the main breakers are

closed. At EMTC and “normal ties closed modes” when the ties are closed, the main circuit

breakers are open. The summary of circuit breakers configurations which are defined for arc

flash analysis can be found in tables 4.23.

71

Table 4.23: Configuration of breakers at normal, emergency, normal ties closed and EMTC

Configuration list of circuit breakers

ID NORMAL EMTC Normal TIES CLOSED

EMERGENCY (EM)

ATS-D1 POSITION A POSITION B POSITION A POSITION B ATSG01 POSITION A POSITION B POSITION A POSITION B

ATSG02 POSITION A POSITION B POSITION A POSITION B ATSG03 POSITION A POSITION B POSITION A POSITION B ATSS01 POSITION A POSITION B POSITION A POSITION B

BM1-ATSF01

POSITION A POSITION B POSITION A POSITION B

BM1-ATSS01

POSITION A POSITION B POSITION A POSITION B

BM1 TIE OPEN CLOSED CLOSED OPEN BM2-ATSS01 POSITION A POSITION B POSITION A POSITION B

BM2 TIE OPEN CLOSED CLOSED OPEN BM TIE OPEN CLOSED CLOSED OPEN CB115A CLOSED OPEN OPEN CLOSED

CB-1 CLOSED OPEN OPEN CLOSED CB-246 CLOSED OPEN OPEN CLOSED

F1A POSITION A POSITION B POSITION A POSITION B MTSG01 POSITION A POSITION B POSITION A POSITION B

4.11.2 Short circuit study and related scenarios

The existing three-phase fault current at the 13.8 kV service entrance is 16800 amps with an

X/R=3.0. It is 5700 amps for a single phase with an X/R=1.0. The utility information was

acquired from NStar.

The highest fault current does not essentially mean the highest probable arc flash energy level,

since the incident energy is a function of arcing time, which can be an inversely proportional

function of the arcing current. The three-phase bolted fault current is calculated in RMS

symmetrical amperes for each bus and all operating mode such as normal, emergency and

maintenance.

72

Four case studies are defined in order to determine the worst one:

1) Arc flash Least, with the pre-fault voltage of 95% and a three-phase fault current decay.

2) Arc flash Min, with the pre-fault voltage of 100% and a three-phase fault current decay.

3) Short circuit, with the pre-fault voltage of 100% and a three-phase symmetrical ½ cycle.

4) Arc flash Max, with the pre-fault voltage of 104% and a three-phase symmetrical ½ cycle.

The above mentioned short circuit scenarios are listed briefly in table 4.24.

Table 4.24: Short circuit study scenario

Case Type Prefault Voltage AF Method Bus Fault Current AF Least 95 IEEE-1584 3 Phase-Fault Current decay AF MIN 100 IEEE-1584 3 Phase-Fault Current decay

Short Circuit

100 IEEE-1584 3 Phase-Symmetrical ½ cycle

AF MAX 104 IEEE-1584 3 Phase-Symmetrical ½ cycle

A short circuit/arc flash case is established for each operating mode. ETAP scenario manager

offers an easy method for documentation and analysis of each operating mode to be used for

rapid repeatable studies. Sixteen scenarios were developed to find out the worst case arc flash for

panels and buses, which are shown in table 4.25.

For example, in scenario 1 the arc flash current is calculated based on the normal configuration

(ties open) where the utility supplies the loads. The case type for the short circuit study is “AF

MAX” with the pre-fault voltage of 104% and the bus fault current of three-phase symmetrical ½

cycle. As another example, in scenario 16 the arc flash current is calculated based on the

situation where the utility does not exist and the electricity is supplied by the emergency diesel

generators (ties open). The case study type for the short circuit study is “AF Least” with the pre-

fault voltage of 95% and the bus fault current of three-phase fault current decay.

73

Table 4.25: Definition of scenarios for worst case arc flash

Scenario Config. Status Study Case Output report Remarks

Scenario 1 Normal AF MAX NAFMAX Normal Config with 104%,1/2 cycle with motors

Scenario 2 Ties Closed AF MAX TCAFMAX Ties closed with 104% V,1/2 cycle with motors

Scenario 3 EMTC AF MAX EMTCAFMAX ATS in EM,Ties Closed with 104% V,1/2 cycle with motors

Scenario 4 EM AF MAX EMAFMAX ATS in EM, Normal Config. With 104%,1/2 cycle with motors

Scenario 5 Normal AF MIN NAFMIN Normal Config with 100%,1/2 cycle with motors

Scenario 6 Ties Closed AF MIN TCAFMIN Ties closed with 100% V,1/2 cycle with motors

Scenario 7 EMTC AF MIN EMTCAFMIN ATS in EM,Ties Closed with 100% V,1/2 cycle with motors

Scenario 8 EM AF MIN EMAFMIN ATS in EM, Normal Config. With 100%,1/2 cycle with motors

Scenario 9 Normal SC NAFSC Normal Config with 100%,Fault Current Decay

Scenario 10 Ties Closed SC TCAFSC Ties closed with 100% V, Fault Current Decay

Scenario 11 EMTC SC EMTCAFSC ATS in EM, Ties Closed with 100% V, Fault Current Decay

Scenario 12 EM SC EMAFSC ATS in EM, Normal Config. With 100%,Fault Current Decay

Scenario 13 Normal AF Least NAFLEAST Normal Config with 95%,Fault Current Decay

Scenario 14 Ties Closed AF Least TCAFLEAST Ties closed with 95% V, Fault Current Decay

Scenario 15 EMTC AF Least EMTCAFLEAST ATS in EM, Normal Config. With 95%,Fault Current Decay

Scenario 16 EM AF Least EMAFLEAST ATS in EM, Normal Config. With 95%,Fault Current Decay

All 271 devices locations were assessed in terms of capability to interrupt or withstand the

maximum three-phase. Annex C includes the summary of short circuit study for the pre-fault

voltage of 100 volt with a three-phase symmetrical ½ cycle. The short circuit analysis shows

that the interruption rate of 37 circuit breaker is less than that of the short circuit current, the

reason is that these circuit breakers are series rated [45] protection. When a short circuit happens

74

it will be designated to connection of two or more circuit breakers that are series. Available fault

current for downstream device is more than interrupting rating of that circuit breaker and

available fault current is less than interrupting rating of upstream circuit breaker.

4.11.3 Protective device coordination study

A protective device coordination study is conducted with the purpose of attaining the most

effective and consistent coordination for the existing equipment. The aim of the study is to

describe the best device settings to achieve selective coordination, in a way that the nearest

device to the fault tries to operate first, and interrupt the fault current and clear the downstream

fault. Additionally, these protective devices must operate in the least probable time to avoid or

reduce damages to equipment, cables, or other protective devices, and also the interruption of

service caused by loss of power.

Besides, the setting has been examined for the case study. The coordination of the main circuit

breaker for the equipment with main circuit breakers has been evaluated with the biggest branch

feeder circuit breaker to the upstream feeder breaker in the upstream switchgear.

The coordination study demonstrates that on the whole, the appropriate coordination between the

various circuit breakers is achievable. Annex D displays the coordination curves for five buses of

D3, F55, F76A, I21 and F70A together with their upstream and downstream equipment as an

example. Coordination for three circuit breakers CB-200, CB-201 and CB-211 are shown in

figure 4.21.

75

Figure 4.21: Coordination curve for bus D3

4.11.4 Arc flash results

Two hundred and seventy one (271) buses were studied to calculate the worst arc flash incident

energy level that might endanger a worker during an arc flash event. The premier category for

applying the personal protective equipment is category 4. Working live for equipment with the

76

‘Over 40 cal./cm2 is not recommended. Figure 4.22 illustrates the arc flash energy level

occurrence.

Figure 4.22: Arc flash category occurrence

Table 4.26 includes the worst case study for arc flash energy levels based on the sixteen (16)

scenarios defined previously in section 4.11.2. Note the following dimensions of the analysis for

each configuration as an instance. The results for buses E to F9 are displayed in the following

table, while the complete analysis of the result is presented in annex B.

0

10

20

30

40

50

60

70

80

90

100

Level 0 Level 1 Level 2 Level 3 Level 4 Level>4

Level 0 Level 1 Level 2 Level 3 Level 4 Level>4

77

Table 4.26: Result of worst case analysis

Emergency Mode (EM): The total energy and the arc flash boundary for Bus “F8” at the

emergency configuration are 30.87 cal/cm2 and 10.9 feet respectively. According to NFPA, its

energy level is 4, which is considered a dangerous category. Here, the fault clearing time is 6.614

seconds, the arc flash current at the fault clearing time (FCT) is 1.602 kA, and the main protection

device affects FCT is CB-119.

Normal with closed ties: The total energy and the arc flash boundary for bus “E” at the normal

configuration with closed ties are 75.25 cal/cm2 and 11.9 feet respectively. Based on NFPA, the

energy level is greater than 4, i.e. dangerous. Here, the fault clearing time is 0.657 seconds, the

arc flash current is 29.366 kA, and the main protection device affects FCT is CB-2.

ID kV (kV

)

Output Rpt.

Configuration

Total Energy (cal/cm2)

AFB (ft)

Energy Levels

Final FCT (sec)

Ia at FCT (kA)

Source PD ID

E 0.48

TCAFMAX

Ties Closed

75.25 11.9 > Level 4 0.657 29.366 CB-2

E2 0.48

TCAFMAX

Ties Closed

9.29 5.2 Level 3 0.2 13.639 CB-77

F 0.48

EMAFMAX

EM 1392.24 51.1 > Level 4 57.882 6.935 CB-

GEN1

F1 0.48

NAFMIN

Normal 56.07 10.3 > Level 4 0.668 21.64 CB115A

F1E

0.48

EMAFMIN

EM 221.94 20.4 > Level 4 31.79 2.195 CB-107

F2 0.48

EMAFMIN

EM 115.91 14.7 > Level 4 17.132 2.084 CB-102

F4 0.48

EMAFMIN

EM 129.98 15.6 > Level 4 22.107 1.848 CB-102

F5 0.48

EMAFMIN

EM 218.53 35.8 > Level 4 36.025 2.064 CB-107

F6 0.48

EMAFMIN

EM 29.93 10.6 Level 4 6.136 1.664 CB-119

F7 0.208

EMAFMIN

EM 24.85 9.5 Level 3 7.674 1.157 CB-116

F8 0.48

EMAFMIN

EM 30.87 10.9 Level 4 6.614 1.602 CB-119

F9 0.208

EMAFMIN

EM 18.12 7.8 Level 3 8.86 0.758 CB-120

78

Normal with open ties: The total energy and the arc flash boundary for Bus “F1” at normal

configuration with open ties are 56.07 cal/cm2 and 10.3 feet respectively. As reported by to

NFPA, the energy level is regarded dangerous. Fault clearing time is 0.688 seconds and the arc

flash current is 21.64 kA, while the main protection device affects FCT is CB115A.

Emergency with closed ties (EMTC): The total energy and the arc flash boundary for Bus “I50”

(Annex B) at emergency configuration with closed ties are 54.24 cal/cm2 and 10.1 feet

respectively. According to NFPA, the energy level is considered dangerous. The fault clearing

time is 0.529 seconds, the arc flash current is 26.536 kA, and the main protection device affects

FCT is CB-247. In next chapter different optimization techniques will be investigated to reduce

arc flash energy level and also related cost analysis will be considered.

79

5. Arc flash optimization methods and cost analysis

Arc flash accidents can be decreased by following the procedures in an appropriate manner,

using suitable tools, applying proper preventive maintenance, coordinating protection devices as

well as developing skills and practical experience. Additionally, the mental and physical status of

the workers is equally important, so that the events like dropping the tools, accidental touch, and

etc. can be avoided. The key strategy to avoid exposure is to watch for the sources or reasons of

arc flash.

The approach of changing work methods for optimizing arc flash energy level is based on the

current calculations and modifications of the environment to reduce arc flash energy level.

Approaches that decrease incident energy level by changing work methods include changing

work procedures, adjusting existing settings, and increasing work distances [35].

There are numerous work procedures that can be applied to decrease arc flash energy level, the

best of which is to work in the de-energized state [36]. A complete section of NFPA 70E is

devoted to de-energizing or the process of developing a condition that is electrically safe.

Nonetheless, this is not normally possible in mission critical facilities, since in these places, life

support equipment depends on a continuous power supply. Energized work might be acceptable

in the case the employer is convinced that deenergizing leads to additional or greater hazards,

such as the disruption of life support equipment, deactivation of emergency alarms, and power

failure in hazardous location ventilating equipment [37].

In spite of precautions taken to avoid hazards, accidents are probable to happen. Therefore, it is

logical to keep the incident energy level in the lowest level possible, and to equip the workers for

the worst by means of proper personnel protection equipment (PPE).

80

This chapter is dedicated to various methods of decreasing the arc flash energy level. The

methods presented in sections 5.5 to 5.8 are proposed by Curtis Thomas Latzo in 2011 [38].

These methods are applied for a low voltage power system with 271 buses. Moreover, an

analysis is conducted to compare the cost of using optimization techniques to decrease the arc

flash energy level with the general costs of damage to equipment, injury of workers and down

time of the system.

5.1. Operation of electrical system with a lack of selective coordination

The purpose of protective device coordination is to separate the faulted section of the electrical

system and to prevent the interruption of proximate or parallel feeders. To this end, protective

devices are organized as illustrated in Chapter 2. Nevertheless, while protecting the system for

arc flash, the faulted section must be separated immediately in order to avoid any harm to

electrical equipment and maintenance workers. In case that a protective device system is

selectively coordinated with the aim of isolating faults, the optimal arc flash protection might not

exist.

If it is made possible for the electrical system to operate with a lack of selective coordination, the

arcing current interruption time and consequently the incident energy level might also be

reduced.

5.2 Temporarily modifying existing protective device settings

One of the most prevailing and straightforward arc flash optimization techniques is to

temporarily modify the existing settings of the first upstream protective device. To do this, we

can lower the instantaneous setting of the circuit breaker which is protecting the equipment that

we are going to work on. Figure 5.1 illustrates an example by the partial one-line diagrams.

81

Figure 5.1: Lowering the instantaneous setting of LVCB3 (one line)

As it is also displayed in table 5.1 and table 5.2, lowering the instantaneous setting of circuit

breaker LVCB3 from 5 (3200A) to 1.5 (960A) results in the reduction of incident energy from

318.62 cal/cm2 to 1.16 cal/cm2 and the reduction of the energy level from dangerous to level 0.

Table 5.1: Lowering the instantaneous setting of LVCB3

Description LVCB3 LT PICKUP 640 AMPS (0.8) 640 AMPS (0.8) LT BAND FIXED FIXED INST. PICK UP 3200 AMPS (5) 960 AMPS (1.5)

Table 5.2: Decreasing incident energy of bus 03

Description BUS03 Incident Energy (IE) 318.62 cal/cm2 1.16 cal/cm2

PPE DANGEROUS LEVEL 0 AFB 24.44 ft 1.47 ft Arcing Current 8.45 kA 8.45 kA

82

This solution must be applied cautiously, since protective device coordination may be influenced

by decreasing the clearing time of protective devices [36]. Besides, no devices must be

downstream, needing sudden in-rush of current that could trip the lowered instantaneous setting.

Starting a motor or energizing a transformer may possibly draw up to six times the operating

amps for that device and consequently lead to a circuit breaker trip in the instantaneous time

domain.

5.3 Arc flash resistant switchgear

Arc flash hazard properties can be included when selecting and specifying the electrical

equipment. Nonetheless, purchasing the equipment requires careful revision of the design and

manufacturing specifications. Low voltage switchgear and control gear assemblies are examined

for short time and short circuit withstand based on IEEE C.37.20 [39]. Manufacturers produce

various new designs to decrease the arc flash energy level [40]. One of the new manufacturing

procedures to optimize incident energy level is arc flash resistant switchgear. In this method, the

arc resistant switchgear is examined in terms of withstanding an internal arc to ensure the safety

of the person operating the switch or working on the equipment against hazard [41]. To do so,

the energy is usually ventilated out of the top of the switchgear or some direction away from the

worker. While it is an excellent way to protect personnel when the equipment is closed, the

worker usually works on the devices when the enclosure is open.

5.4 Increasing the working distance

The calculations from IEEE-1584 for incident energy include a number of unknowns which

need to be collected to attain an accurate result. But the most important variables are the distance

83

from the arc and the time to interrupt the fault. As the incident energy is proportional to the

square of the distance (in open air), increasing the working distance will considerably decrease

the incident energy [42]. However, this solution must be implemented cautiously and carefully,

as increasing the distance might hamper a person’s ability to work on the equipment [36]. The

ways to easily increase working distance include using devices which have remote racking

capability, remote operating equipment, and extension tools. If possible, depending on the

equipment design, it will be favorable to accomplish all switching operations remotely; i.e. away

from the switch gear [37]. Racking and switching of a low voltage power circuit breaker can be

assumed as the highest exposure which can happen in industrial facilities [43]. One solution for

decreasing the exposure is to extend the tool which is used to rack the breaker, or to apply

remote racking/switching equipment which can be obtained from manufacturers or other

suppliers [43]. The effectiveness of increasing the working distance is illustrated in one-line

diagrams in figure 5.2.

84

Figure 5.2: Increasing the working distance at bus03 (one Line)

Table 5.3 shows that the working distance increase from 18 inches to 13.3 feet through the use

of a remote racking device at bus03 results in the incident energy reduction from 381.36 cal/cm2

to 4.82 cal/cm2 and energy level reduction from dangerous to level 2.

Table 5.3: Decreasing incident energy of bus 03

Description BUS03 Incident Energy (IE) 381.364 cal/cm^2 4.827 cal/cm^2 PPE DANGEROUS LEVEL 2 AFB 26.73 ft 26.73 ft Arcing Current 7.18 kA 7.18 kA Working Distance 18 160

85

5.5 Applying a single main circuit breaker for building shutdown

The main distribution panel in mission critical facilities must be appropriately maintained, since

arc flash energy level at these locations is important. According to the national electrical code, an

electrical service may shut down using a maximum of six grouped devices, which can include

circuit breakers, fused switches, or disconnect switches. It is frequently performed by having a

main panel with no main circuit breaker and a maximum of six feeder breakers. Figure 5.3

illustrates one line diagram of this scenario. This installation is acceptable by the NEC and is

typically found in 480 volt electrical distribution systems.

Figure 5.3: Building without single main circuit breaker for shutdown (one line)

The simulation displays a utility serving a main distribution panel ‘Panel A’. Panel A is

constructed without any main circuit breakers and four feeder breakers represented as CB1-4. In

86

this situation, the four feeder breakers are acceptable for being applied as the building

disconnecting means based on NEC 230.

As it is indicated in the simulation in figure 5.3, the fault current of the panel A is calculated

38.9kA, which can be considered a moderate level. The arcing current is illustrated to be 10.8 kA

which is assumed a reasonable level for this type of facility.

Nevertheless, the arc flash energy level for this kind of installation is particularly high, since the

only device to protect panel A is the utility fuse located on the primary side of the transformer.

As it can be seen in table 5.4, the incident energy at panel A is 5656.32 cal/cm2, which

corresponds to the dangerous energy level (level 4) in classification.

The service entrance can be studied from the time current analysis viewpoint. Table 5.4

demonstrates the utility fuse which interrupts the arcing current beyond at 145.635 seconds, and

therefore justifies the high level of energy.

Table 5.4: without single main circuit breaker for building shutdown

ID kV

(kV) Total Energy

(cal/cm²) AFB (ft)

Final FCT (sec)

Ia at FCT (kA)

Source PD ID

% Ia Variation

Bus1 13.8 0 6.195

Bus2 0.208 5121.47 98 129.609 10.977 Fuse-Utility

15%

Panel A 0.208 5656.32 103 145.635 10.803 Fuse-Utility

15%

Panel A1 0.208 1.08 1.4 0.026 11.41 CB1 Panel A2 0.208 1.07 1.4 0.026 11.395 CB2 Panel A3 0.208 1.08 1.4 0.026 11.41 CB3 Panel A4 0.208 1.07 1.4 0.026 11.395 CB4

This is regarded as an unacceptable scenario in a mission critical facility, since the incident

energy is above 40 cal/cm2 and consequently the energy level is located in dangerous category.

Based on NFPA-70E, energized electrical work is not allowed on this device, as a result, periodic

87

maintenance or facility changes including this panel cannot be accomplished with an electrical

shutdown. The electrical shutdown is normally not feasible in a mission critical facility;

therefore, a different design and construction is required for the system.

Here, the aim is to decrease arc flash level and it can be achieved by installing a low voltage

power circuit breaker before panel A.

This low voltage power circuit breaker should be detailed with modifiable settings in the long

time, short time, and instantaneous time domains. Modifying the main breaker settings to

optimize the arc flash energy level will generate a safer working environment at the panel A.

Having implemented the recommended circuit breaker installation, the case study was simulated

again. The one-line diagram in figure 5.4 illustrates the result of the simulation. Here, the new

2000 amp main panel circuit breaker is positioned before Panel A, which is referred to as CB6.

The available fault current, the arcing fault and incident energy are specified for each panel. The

available fault current and the arcing current level at the panel A are still almost the same.

Nonetheless, the new main breaker placed before the panel A results in an incident energy lower

than 5656.32 cal/cm2, and changes the energy level of dangerous to level 1 (1.39 cal/cm2). It is

considered as a significant change which would make technicians able to implement energized

maintenance on this panel.

88

Figure 5.4: Building with single main circuit breaker for shutdown (one line)

The consequences of this change can be further validated by analyzing the results shown in table

5.5 which includes the new main device CB6.

Table 5.5: with single main circuit breaker for building shutdown

ID kV (kV) Total

Energy (cal/cm²)

AFB (ft)

Final FCT (sec)

Ia at FCT (kA)

Source PD ID

% Ia Variation

Bus1 13.8 0 6.195

Bus2 0.208 5121.47 98 129.609 10.977 Fuse-Utility

15%

Panel A 0.208 1.39 1.6 0.03 12.71 CB6 Panel A1 0.208 1.08 1.4 0.026 11.41 CB1 Panel A2 0.208 1.07 1.4 0.026 11.395 CB2 Panel A3 0.208 1.08 1.4 0.026 11.41 CB3 Panel A4 0.208 1.07 1.4 0.026 11.395 CB4

89

The table shows the arcing current interruption by CB6 at 0.03 seconds with total energy of 1.39

cal/ cm2, which is in energy level 1. Now the panel A can be maintained while it is energized and

the facility continues its normal operation.

5.6 Applying low voltage circuit breakers before panels

The National Electrical Code, Article 230 is allocated to building main shutdown and proper

disconnecting methods. Every facility requires an easily reached device for disconnecting the

electrical service.

This device is often a main fused disconnect switch which is located at the service entrance

usually close to the electrical meter. Figure 5.5 illustrates a one-line diagram of this scenario.

Figure 5.5: Fuse disconnect for panel entrance (one line)

90

This electrical system involves a utility 800 KVA transformer which serves a main disconnect

fused at 3000 amps. The fuse is protecting a main distribution panel (Panel B) that includes two

feeders and two fuses. The arc flash energy level for this form of installation can be high or low

depending on the available fault current and the resultant arcing current. Table 5.6 displays an

incident energy of 31.43 cal/ cm2 at the panel B, which results in a energy level of dangerous.

This is unacceptable for a mission critical facility, since the electrical system must continue to be

energized, and based on NFPA 70E , energized work is not permitted where an arc flash energy

level is this extreme.

Table 5.6: Fuse disconnect circuit breaker for panel entrance before reduced Arc

ID kV (kV) Total Energy

(cal/cm²) AFB (ft)

Final FCT (sec)

Source PD ID

% Ia Variation

Bus2 13.8 0.05915 0.3 0.004 Fuse1 Bus3 0.208 31.19 7.6 Fuse2 15%

Panel B 0.208 31.43 7.7 Fuse2 15% Panel B1 0.208 0.875634 1.3 0.021 CB1 Panel B2 0.208 1.26 1.5 0.029 CB2 panel B3 0.208 0.329746 0.8 0.008 Fuse3 Panel B4 0.208 0.34426 0.8 0.008 Fuse4

In this research, a low voltage power circuit breaker with LSI adjustments is applied instead of

the fused disconnect switch to minimize the energy level. It results in forming the protection

curve based on the available fault current and arcing current. The one line diagram in figure 5.6

shows this system.

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Figure 5.6: Low voltage circuit breaker for panel entrance (one line)

As expected, the simulation of the revised circuit demonstrates that the arcing current stayed at

12.73 kA. But the incident energy dropped to 1.39 cal/ cm2, leading to energy level 1.

Table 5.7: Low voltage circuit breaker for panel entrance after reduced arc

ID kV (kV) Total Energy (cal/cm²) AFB (ft) Final FCT (sec) Source PD IDBus2 13.8 0.05915 0.3 0.004 Fuse1 Bus3 0.208 1.41 1.6 0.03 CB-PANELB

Panel B 0.208 1.39 1.6 0.03 CB-PANELBPanel B1 0.208 0.875634 1.3 0.021 CB1 Panel B2 0.208 1.26 1.5 0.029 CB2 panel B3 0.208 0.329746 0.8 0.008 Fuse3 Panel B4 0.208 0.34426 0.8 0.008 Fuse4

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Table 5.7 demonstrates an instantaneous interruption of the arcing current at 0.03 seconds and

consequently a quicker extinguish of the arc compared to using the fuse. The table shows it

occurs within energy level 1.

5.7 Apply LSI low voltage circuit breakers for step down transformers rated above 125 KVA

The service voltage in the facilities being investigated is 480 volt, three-phase. However, there

are numerous loads in a building which need 120/208 volt service; for instance, air conditioning

equipment, service receptacles and lighting. Therefore, 480 volt service is required to be

transformed down to 120/208 volts. To do so, a lower voltage leg in the system is created by

putting in a large step down transformer which is fed by the main panel to serve 120/208 volt

loads downstream. Figure 5.7 includes a one line diagram of this situation in which a thermal

magnetic breaker (CB4) protects a 300 KVA transformer that feeds bus 2.

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Figure 5.7: Low voltage circuit breaker for transformers rated above 125 KVA (one line)

The challenge with this setup is the reduction of fault current and arcing current occurring across

the transformer. Considering the amount of impedance which is represented by the transformer

in this circuit, which is predictable. Figure 5.7 displays the simulation of the available arc fault

current on the primary side of the 300 KVA transformer at 23.87 kA and the available arc fault

current at the secondary side at 5.75 kA. The decrease in the arcing current at the secondary side

will result in the increase in the time of an arc flash interruption by the primary side breaker.

The time required to interrupt the arc has a direct relationship with the arc flash incident energy.

Table 5.8 demonstrates an increase in incident energy from 1.68 cal/ cm2 on the primary side

(bus6) of transformer to 1209 cal/cm2 on the secondary side (bus 2), and the resultant change in

the energy level from 1 to 4. This is a noteworthy increase in the protection equipment essential

to work on this energized equipment.

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Table 5.8: Low voltage circuit breaker for transformers rated above 125 KVA

ID kV (kV) Total Energy (cal/cm²) AFB (ft) Final FCT (sec) Ia at FCT (kA) Source PD IDBus1 0.48 2.8 2.3 0.03 24.272 CB1 Bus2 0.208 1209.32 47.6 61.609 5.746 CB1 Bus3 0.208 0.41635 0.9 0.018 6.689 CB2 Bus4 13.8 0.310415 0.8 0.004 28.717 Fuse1 Bus5 0.48 2.83 2.3 0.03 24.531 CB1 Bus6 0.48 1.68 1.7 0.018 23.865 CB4

It is revealed that the circuit breaker CB4 interrupts the arc at nearly 61.609 seconds, which

exceeds all energy levels and thus considered hazardous for energized work. Nevertheless, IEEE

1584 limits the maximum exposure time for computing incident energy at 2 seconds and

therefore it also limits the calculations in the simulation report at 1209 cal/cm2 which

corresponds to energy level 4. Although personal protective equipment for energy level 4 is

available, when possible, it is preferable to reduce the energy level to a category 0 or 1 to

minimize the potential hazard of the operators. We concluded through this analysis to use a low

voltage power circuit breaker containing adjustable LSI instead of standard thermal magnetic

circuit breaker to protect these transformers. Although the thermal magnetic breaker includes

instantaneous adjustment, it is indicated that the change in arcing current potentially attenuates

the short time region and delays the interrupt time. The low voltage power circuit breakers with

LSI are adjustable in the short time and consequently can optimize the arc flash energy level by

quicker interruption of the arc. Figure 5.8 illustrates the simulation one line diagram of this

optimized system.

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Figure 5.8: Arc flash mitigation across 300 KVA transformer

The simulation of the new system demonstrates that the available fault currents on the primary

and secondary sides of the transformer have not changed; thereby the arcing currents on the

primary and secondary sides of the transformer have not changed either. Yet, as a result of the

quicker interrupting time of the LSI circuit breaker, the results shown in table 5.9 indicate

decreased incident energy of 1.65 cal/ cm2 on the primary side (bus6) and 0.42 cal/ cm2 on the

secondary side (bus 2) of the transformer. The primary side of the transformer is lowered to

energy level 1 and the secondary side is reduced to energy level 0.

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Table 5.9: Low voltage circuit breaker for transformers rated above 125 KVA with LSI

ID kV (kV) Total Energy (cal/cm²) AFB (ft) Final FCT (sec) Ia at FCT (kA) Source PD IDBus1 0.48 2.8 2.3 0.03 24.272 CB1 Bus2 0.208 0.421182 0.9 0.018 6.76 CB4 Bus3 0.208 0.41635 0.9 0.018 6.689 CB2 Bus4 13.8 0.310415 0.8 0.004 28.717 Fuse1 Bus5 0.48 2.83 2.3 0.03 24.531 CB1 Bus6 0.48 1.65 1.8 0.018 23.865 CB4

The new LSI circuit breaker CB4 and the arcing current on the primary and secondary sides of

the transformer are illustrated in figure 5.9. The breaker curve demonstrates instantaneous

interruption of the arcing current and consequently a quicker extinguish of the arc than that of the

thermal magnetic breaker. The result of incident energy simulation at 0.018 second is in

accordance with this finding.

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Figure 5.9: TCC showing LSI breaker and arcing current at primary and secondary of T2.

Figure 5.9 above displays the reduction of fault current and thus the reduction of arcing

interrupting current across the transformer T2. This makes the arcing current level to move

inside the adjustable instant time range of the LSI breaker. Setting the short time inside the

arcing current makes short exposure time and low arc flash energy level possible. It is found that

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circuit breaker CB4 interrupts the arcing current at approximately 0.018 seconds; hence low

incident energy is calculated and the secondary side of the transformer is located in energy level

0. This is in line with the incident energy simulation which is calculated 0.42 cal/ cm2 at the

secondary side of transformer (Bus 2).

5.8. For transformers larger than 125 KVA applying two or more smaller transformers

As stated in previous section when the 120/208 volt load is significant, the stepdown

transformer can be 150 KVA and larger. Transformers larger than 125 KVA can be replaced by

two or smaller transformers. In this case fault and arcing current decreases because of higher

impedance of smaller transformers and cables. The smaller rated circuit breaker can stay lower

than this arcing value. Figure 5.10 illustrates a one line diagram of this situation including a 250

KVA transformer which feeds panel D10.

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Figure 5.10: One line diagram with 250 KVA transformer

The computer simulation of the circuit in figure 5.10 indicates an incident energy of 31.46

cal/cm2 and energy level 4.

Table 5.10: Arc flash for trans 3 (250 KVA)

ID kV (kV) Total Energy (cal/cm²) AFB (ft) Ia at FCT (kA) Source PD IDD10 0.208 31.46 7.7 3.319 Fuse 7

The time current curve for this configuration is illustrated in figure 5.11 which shows the circuit

breaker CB-12 interrupts the arcing current beyond 2 seconds, which confirms the high level of

energy.

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Figure 5.11: Time current curve arc flash hazard at panel D10.

To minimize level of energy, it is recommended to replace one large step down transformer with

multiple smaller transformers which are less than 125 KVA. The increase of impedance of the

smaller conductors and transformers results in the decrease of fault current and arcing current.

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The smaller rated circuit breaker is able to stay lower than this arcing value. This also allows for

application of NFPA 70E option of reporting energy level 0 for any bus served by a transformer

less than 125 KVA and 240 volts. Figure 5.12 represents the one line diagram of this system.

Here, the 250 KVA transformer feeding panel D is replaced by two 125 KVA transformers

feeding panels M1 through M2.

Figure 5.12: One – line diagram showing two 125 KVA transformer

The result is an incident energy of 0.2722 cal /cm2 and energy level 0. The final clearing time

decreases from above 2 seconds to 0.018 second. Table 5.11 illustrates the results.

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Table 5.11: Arc flash for trans 3 & 43 (125 KVA)

ID kV (kV) Total Energy (cal/cm²) AFB (ft) Final FCT (sec) Ia at FCT (kA) Source PD IDM1 0.208 0.272278 0.7 0.018 3.985 CB-37 M2 0.208 0.272278 0.7 0.018 3.985 CB-12

The time current curve for this pattern is demonstrated in figure 5.13. It shows that the circuit

breaker CB-12 interrupts the arcing current at 0.018 seconds; therefore, the incident energy and

energy level are reduced.

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Figure 5.13 Time current curve arc flash hazard at panel M1 and M2.

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Table 5.12 illustrates the collective results of optimization methods and sums up the reduction of

the arc flash energy level for methods described in sections 5.2 to 5.8 as well as the case study

(271 bus). For eleven buses, the setting of trip unit changed, so the arc flash energy level

decreased from level 4 to less than 2. For instance, for bus F76B after changing the setting of trip

unit the total energy is reduced from 688.52 cal/cm2 to 5.19 cal/cm2 which means that energy

level reduced from level 4 to 2.

Table 5.12: Energy level before and after applying optimization methods

ID Status Total Energy

(cal/cm²) Category

Temporarily Modifying Existing Protective Device Settings

Not Reduced 318.62 > Level 4 Reduced arc flash 1.16 Level 0

Increasing the Working Distance Not Reduced 381.364 > Level 4

Reduced arc flash 4.827 Level 2 Applying single circuit breaker for building shutdown

Not Reduced 5656.32 > Level 4 Reduced arc flash 1.39 Level 1

Applying LVCB before panels Not Reduced 31.43 Level 3

Reduced arc flash 1.39 Level 1 Applying LVCB before for transformers rated above 125 KVA

Not Reduced 1209 > Level 4 Reduced arc flash 0.42 Level 0

Applying two or more smaller transformers for transformers larger than 125 KVA

Not Reduced 31.46 Level 3

Reduced arc flash 0.2722 Level 0

Case Study (271 Bus)

BUS ID Status Total Energy

(cal/cm²) Category

F70 Not Reduced 685.12 > Level 4


F70B Not Reduced 681.86 > Level 4






F76 Not Reduced 691.39 >Level 4


F76B Not Reduced 688.52 > Level 4


I51 Not Reduced 62.65 > Level 4

Reduced arc flash 0.129 Level 0 I52 Not Reduced 49.43 > Level 4

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Reduced arc flash 0.273 Level 0 Transformer Replacement

Trans 3 (D10) Not Reduced 31.46 Level 4


Trans 6 (D33) Not Reduced 50.92 > Level 4


Trans 4 (D21) Not Reduced 31.52 Level 4


Trans 24 (F27) Not Reduced 203.02 > Level 4

Reduced arc flash 155.28 > Level 4









Trans 39 (I36) Not Reduced 223.37 > Level 4










Transformers shown in table 5.12 are larger than 125 KVA and according to section 5.8 are

replaced by two or more smaller transformers. For example, transformer 40 is 750 KVA and

replaced by three 225 KVA transformers, result of analysis shows that the incident energy is

reduced from 983.28 cal/cm2 to 1.23 cal/cm2 which means energy level is reduced from level 4

to level 1.

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Also, it is necessary to mention that for bus F70 arc flash level reduces from Level 4 to Level 1

when setting of trip unit is changed and in case that transformer replacement method is used arc

flash level changes from level 4 to level zero.

For bus F76 energy level changes from level 4 to level 2 when setting trip unit is changed and

for transformer substitution method arc flash level changes from level 4 to level 3.

It is necessary to mention that for both buses F70 and F76, applying trip unit method instead of

replacing transformers is better because energy level is reduced to acceptable level and also it

has less cost.

5.9 Cost Analysis

Studies indicate that [43] an average electrical accident costs $750k. According to the National

Safety Council estimates, work-related harm can cost businesses well over $30M. The expenses

include fines, medical costs, legal processes, lost business and equipment expenditures.

Information provided by NFPA and IEEE reveals that during years 1992-2002 more than 2000

workers each year (at least 6 workers a day) injured by arc flash.

Alternatively, an OSHA assessment may actually help reveal problems. A study conducted in

May 2012 on over 800 California companies [43] shows that all were entitled for inspection, but

just half of them went under investigation. The companies which were inspected experienced a

decline of 9.4% in injuries. The average company saved $350,000 during period of five years

after the OSHA assessment. Thus despite the fact that OSHA obliges companies to work in a

safer environment, it’s best not to wait for an inspection much less a fine. The downtime costs

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estimated based on the US Department of Energy office of Industrial Technologies (1996) are

shown in table 5.13.

Table 5.13: Downtime costs estimates

Downtime Costs Estimates

Industry Average Downtime Costs, per hour

Forest Products $7,000

Food Processing $30,000

Petroleum/Chemical $87,000

Metal Cating $100,000

Automative $200,000

5.9.1 Cost analysis for transformers

In order to examine the cost of replacing above 125 KVA transformers (optimization technique

used in section 5.8), cost analysis is conducted for low voltage systems (271 buses). As it is

shown in table 5.14, thirteen transformers are above 125 KVA. The cost data and definitions are

extracted from “RSMeans Electrical Cost Data”, 37th annual edition [44].

Material costs: The costs of fasteners for a normal installation are included within material costs.

The manufacturer’s warranty is also considered. However, extended warranties are not included

in the material costs. Furthermore, material costs exclude sales tax.

Labor Costs: Labor costs demonstrate productivity based on actual working conditions. Besides

actual installation, these costs include time spent during a normal weekday on responsibilities

such as material receiving and handling, mobilization at site and clean up.

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Equipment Costs: These costs include the renting cost as well as the operating costs of the

equipment under normal use. Equipment costs do not include operators’ wages or the cost of

moving equipment to a jobsite or from a jobsite.

As it is shown in table 5.14, for item 1, the total unit bare costs for a 150 KVA transformer is

5,115 dollar which includes material, labor and equipment costs. Moreover, since there are 3

transformers of this type, the total price is $15345. Also, the total amount for thirteen

transformers is $107,055.

Table 5.14: Cost of existing transformers before reducing arc flash

Item Description 2014 Bare Costs (Unit Price $) QTY Total

Price $ Material Labor Equipment Total

1 3 Phase,480/208 V,150 KVA 3700 1250 165 5115 3 15345

2 3 Phase,480/208 V,225 KVA 5000 1625 215 6840 4 27360

3 3 Phase,480/208 V,300 KVA 6325 1925 255 8505 5 42525

4 3 Phase,480/208 V,750 KVA 18400 3025 400 21825 1 21825

Total Price $ 107,055

To reduce arc flash, each 150 KVA transformer will be replaced with two 75 KVA transformers,

each 225 KVA transformer will be replaced with two 112.5 KVA transformers, each 300 KVA

transformer will be replaced with two 150 KVA transformers and each 750 KVA transformer

will be replaced with three 225 kVA transformers. Table 5.15 illustrates the price of transformers

which are required for reducing the arc flash energy level:

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Table 5.15: Cost of suggested transformers after reduced arc flash

Item Description 2014 Bare Costs (Unit Price $) QTY Total

Price $ Material Labor Equipment Total

1 3 Phase,480/208 V,75 KVA 2125 1225 3350 6 20100

2 3 Phase,480/208 V,112.5 KVA

2825 1175 156 4156 8 33248

3 3 Phase,480/208 V,150 KVA 3700 1250 165 5115 10 51150

4 3 Phase,480/208 V,225 KVA 5000 1625 215 6840 3 20520

Total Price $ 125,018

If the total costs of existing transformers are subtracted from the cost of suggested transformers,

the difference would be $17,963 dollar, which seems cost effective for taking preventive action

and avoiding risk of damage to workers, equipment and related expenses.

5.9.2 Cost analysis for circuit breakers

In sum, there are 13 circuit breakers which are linked to transformers rated above 125 KVA

(optimization technique used in section 5.7) and the price will be discussed here for adding trip

units (Long, short and instantaneous). Three 200 ampere circuit breakers are connected to 150

KVA transformers, four 300 ampere circuit breakers are connected to 225 KVA transformer,

Five 400 ampere circuit breakers are connected to 300 KVA transformers and one 1000 ampere

circuit breaker are connected to 750 KVA transformers. This circuit breaker (1000 A) is

equipped to LSI trip unit. Table 5.16 demonstrates the list of related breakers.

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Table 5.16: List of circuit breakers connected to transformers rated above 125 KVA

Item Description LSI Trip

(Unit Price $)

QTY Total

Price $

1 Circuit breaker 200 A 500 3 1500

2 Circuit Breaker 300 A 700 4 2800

3 Circuit Breaker 400 A 700 5 3500

4 Circuit Breaker 1000 A Included 1 -

Total Cost: $ 7800

The LSI trip unit costs are estimated roughly. They are obtained from different sources on the

Internet. Since twelve trip units are needed, the total cost would be $ 7800.

Comparing the result of optimization to the cost of downtimes estimates from table 5.13, it is

observed that the cost of optimization of transformers is 17,963 dollar, while the cost of

optimization of circuit breakers is 7,800 dollar, so the total cost would be 25763 dollars. It is a

reasonable investment for both optimization methods, since the arc flash level is reduced and

therefore it is safer for technicians to work on panels when they are energized. Furthermore, the

probability of downtime is reduced. Meanwhile, it is cost effective, as the minimum four hours

(lowest) downtime from table 5.13 is more than the cost of replacing transformers and circuit

breakers.

This chapter has emphasized on introducing and implementing some techniques to optimize the

arc flash energy level at specific locations in a 480 volt electrical distribution system. The last

four techniques [38] were described and simulated in locations of an electrical system where a

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high arc flash energy level is normally present as a result of intrinsic properties of the system

design. As it can be seen in this chapter, the application of these methods made it possible to

significantly decrease the arc flash energy level. Thus electrical design engineers can use these

techniques in planning commercial buildings to develop systems with lower arc flash energy

level.

Besides, the cost analysis is accomplished for replacing the transformers and circuit breakers.

The result indicates that it is reasonable to both consider optimization techniques for reducing arc

flash energy level and to invest more at the design stage of low voltage systems, since the cost of

implementing optimization techniques is much less than the cost of retrofitting damage to

equipment, injury of workers and downtime of critical facilities.

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6. Conclusion and future work

The thesis has focused on optimization techniques to decrease arc flash energy level in electrical

systems operating at 600 V or below. The procedures for calculating fault current, coordinating

protective devices and analyzing arc flash have been presented. A number of mainstream arc

flash optimization products and techniques have been described. A 271-bus existing facility was

used for arc flash studies involving different scenarios. Results of applying optimization

solutions have been presented.

The study conducted on short circuit shows that to achieve maximum fault currents from three

phase faults, the interrupting ratings of existing equipment are sufficient, with the exceptions

(shown in red) found in Annex C. These circuit breakers are series rated protection [45]. The

results of the study on protective device coordination demonstrate that there is a satisfactory

coordination between the circuit breakers considered in this study.

The study compared the cost of applying optimization methods with that of the arc flash

consequences. The results indicate that the cost of implementing the techniques to reduce arc

flash energy level at the design stage is much less than the downtime costs.

6.1 Conclusions

The impact of using four optimization techniques to reduce the arc flash energy level at specific

places in an electrical distribution system has been studied.

The first technique is applied at the electrical service entrance whose aim was lowering the arc

flash energy level at the main distribution panel. The simulations showed that when multiple

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electrical disconnects are applied as allowed by NEC, the arc flash energy level can be

enormously high. When the system is designed using one main circuit breaker, the main

distribution panel needs an interrupting device to reduce the energy level of an arc flash.

Applying this optimization technique for this particular case resulted in the arc flash energy level

reduction from 5656.32 cal/cm2 to 1.39 cal/cm2. This improved the PPE category from a

dangerous level to a category 1. Therefore, a qualified technician can now accomplish

maintenance on this device with minimal arc-flash energy level.

The second technique is applied at the electrical service entrance whose aim was reducing the arc

flash energy level at the main distribution panel. The simulation revealed that when fused

disconnects are applied as allowed by NEC, the arc flash energy level can at times be particularly

high at the main distribution panel. However, when the system is designed with a low voltage

power circuit breaker with LSI modifications as the main circuit breaker, the energy level of an

arc flash is reduced.

Applying this optimization technique for this particular case analyzed, caused reduction in the

arc flash energy level from 31.43 cal /cm2 to 1.39 cal /cm2. This altered the PPE category from a

dangerous level down to a category 1. Now it is possible for a qualified technician to accomplish

maintenance on this device with minimal arc flash energy level.

The third technique is used at a feeder circuit from the main distribution panel which is serving a

step down transformer. The simulation revealed that when a transformer that is larger than 125

KVA is protected by a thermal magnetic breaker, the secondary side arc flash energy level can

be exceedingly high. However, when the feeder is designed with a low voltage circuit breaker

with LSI modifications, the arc flash energy level can be optimized to a safer (lower) level.

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Applying this technique for this particular case caused the arc flash energy level reduction from

1209.32 cal /cm2 to 0.42 cal/cm2. This made the PPE category to change from energy level 4

down to level 0. It is now possible for a qualified technician to do maintenance on this device

with minimal arc flash energy level.

The fourth technique is applied at a feeder circuit from the main distribution panel which is

serving a step down transformer. The simulation indicated that when a transformer which is

larger than 125 KVA is protected by a thermal magnetic breaker, the secondary side arc flash

energy level can be tremendously high. Nonetheless, when the feeder is designed with two

smaller circuits with reduced KVA transformers, the arc flash energy level decreases

significantly.

Using this optimization technique for this case study resulted in the arc flash incident energy

reduction from 31.46 cal /cm2 to 0.27 cal/cm2. This made the PPE category to change from level

4 level down to 0. Thus a qualified technician can implement maintenance on this device with

minimal arc-flash energy level. In all four cases, the application of the recommended design

technique has caused a significant reduction in the energy level.

For the case study, the settings of 11 circuit breakers which were connected to transformers

above 125 KVA has changed. The result demonstrates that arc flash energy has changed from

Level 4 to Levels 0, 1 and 2. This makes it possible for the technicians to work on energized

panels.

Moreover, cost analysis is conducted for replacement of transformers and circuit breakers. The

result reveals that it is reasonable to apply optimization techniques for reducing arc flash energy

level and to invest more at design stage of low voltage systems, since the cost of executing

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optimization techniques is much less than that of retrofitting, damage to equipment, injury of

workers and downtime of system.

The result of optimization of case study is compared to the cost of downtimes estimations from

table 5.13. It is found that the optimization of transformers costs 17,963 dollar and the

optimization of circuit breakers costs 7,800 dollar and total cost is 25,763 dollars. It is a

reasonable investment for both optimization methods, since the cost of investment is less than

that of the downtime and the arc flash energy level is reduced, so it is safer for technicians to

work on panels when they are energized, while the probability of downtime is also reduced. As it

is mentioned earlier, it is cost-effective, as the minimum cost of a four-hour downtime (lowest) is

more than the cost of replacing transformers and circuit breakers.

6.2 Future Work

Future efforts on arc flash analysis should focus on additional development of time domain

models of system faults. New models should yield better estimates of incident energy values,

which will offer better protection to workers, without needing excessive PPE.

Designing industrial power systems for arc flash safety is the least costly method of following

current safety standards. Constant development of innovative low cost protective devices results

in less expensive alternatives for retrofitting existing systems to comply with the standards. So,

the performance of new devices should be analyzed.

Additional detailed cost analyses should be conducted for various low voltage systems and for

the related optimization methods using different alternatives, so that the most cost effective

strategy can be selected for optimization methods.

116

117

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119

[32] Thomas E. Neal, Allen H. Bingham, Richard L. Doughty, “ Protective Clothing Guidelines for Electric Arc Exposure,” IEEE Trans. Vol.33,No. 4 July/August 1997.

[33] Thomas E. Neal, Allen H. Bingham, Richard L. Doughty, Terrence A. Dear, “Testing Update on Protective Clothing & Equipment for Electric Arc Exposure,” IEEE Paper No. PCIC-97-35..

[34] Ed Larson, Jim Degnan, “Selective Coordination in low Voltage Power Distribution Systems: Is the Level Important?” IEEE/IAS Industrial and Commercial power Systems Technical Conference, May 2008.

[35] H. Wallace Tinsley III,Michael Hodder, Aidan M. Graham, “ Beyond the Calculations: Life After arc flash Analysis”.

[36] Catherine Irwin,Udo Kerssebaum, Helmut Eichinger,Daniel Doan, “ Mitigating Personnel Exposure to the arc flash Hazard”.

[37] NFPA 70E,Standard for Electrical Safety in the Workplace, 2004 Edition.

[38] Curtis Thomas Latzo, “Approaches to arc flash Hazard Mitigation in 600 Volt Power Systems”, January 2011.

[39] IEEE Standard C37.20, Standard for Metal Enclosed Low Voltage Power Circuit Breaker Switchgear.

[40] G.E. Heberlein Jr., J. A. Higgins, and R. A. Epperly, ‘Report on Enclosure Internal Arc Tests”, IEEE Industry Applications Magazine, Vol 2, Issue 3, May/June 1996,pp 35-42.

[41] Christopher Inshaw, Robert A. Wilson,” arc flash Hazard Analysis and Mitigation”.

[42] Daniel R. Doan, Jennifer Slivka, Chris Bohrer, “ A Summary of arc flash Hazard assessments and Safety Improvements”.

[43] Salisbury Assessment Solutions (SAS),www.arcsafety.com.

[44] “RSMeans Electrical Cost Data”, 37th annual edition, 2014.

[45] “Cooper Bussman handbook”, edition 2005,pp 35-40

120

Annex A One line diagram for 271 bus system

F55

0.48 kV

F88

13.8 kV

F76

0.208 kV

F86

0.208 kV

F85

0.208 kV

F84

0.208 kV

F83

0.208 kV

F82

0.208 kV

F81

0.208 kV

F80

0.208 kV

F79

0.208 kV

F78

0.208 kV

F77

0.208 kV

F70

0.208 kV

F71

0.208 kV

F75 0.208 kV

F74

0.208 kV

F73

0.208 kV

F72

0.208 kV

F10.48 kV

F87

13.8 kV

F3

0.48 kV

F89

0.48 kV

F

0.48 kV

F92

0.48 kV

F67

0.48 kV

F56

0.48 kV

F59

0.48 kV

F58

0.48 kV

F57

0.48 kV

GEN 1 BUS

0.48 kV

G 0.48 kV

F970.48 kV

GEN 2 BUS

0.48 kV

F95

0.48 kV

F96

0.48 kV

F91

0.48 kV

F100

0.48 kV

F66

0.48 kV

F90

0.48 kV

F1E

0.48 kV

F5

0.48 kV

F21

0.208 kV

F20

0.208 kV

F18

0.208 kV

F19

0.208 kV

F16

0.208 kV

F17

0.208 kV

F14

0.208 kV

F15

0.208 kV

F10

0.48 kV

F11

0.208 kV

F12

0.48 kV

F13

0.208 kV

F6

0.48 kV

F7 0.208 kV

F8

0.48 kV

F9

0.208 kV

H0.48 kV

GEN 3 BUS

0.48 kV

F94

0.48 kV

F69

0.48 kV

F63

0.48 kV

F65

0.48 kV

F64

0.48 kV

F93

0.48 kV

F68

0.48 kV

F60

0.48 kV

F61

0.48 kV

F62

0.48 kV

F2

0.48 kV

F4

0.48 kV

F22

0.48 kV

F23

0.48 kV F35

0.48 kV

F38

0.208 kV

F37

0.48 kV

F36

0.48 kV

F39

0.208 kV

F43

0.208 kV

F42

0.208 kV

F41

0.208 kV

F40

0.208 kV

F44

0.48 kV

F46

0.208 kV

F48

0.208 kV

F47

0.208 kV

F49

0.208 kV

F50

0.208 kV

F54

0.208 kV

F51

0.208 kV

F52 0.208 kV

F53 0.208 kV

F45

0.48 kV

F240.48 kV

F27A

0.48 kV

F32

0.48 kV

F34

0.48 kV

F33

0.208 kV

F31

0.208 kV

F30

0.48 kV

F27

0.208 kV

F28

0.208 kV

F29

0.208 kV

F25

0.48 kV

F26

0.48 kV

BM1-ATSS01

Lump85

0 MVA

CBL-133

FUSE18

Lump84

0 MVA

CBL-116

FUSE17

Lump82

0 MVA

CBL-135

Lump83

0 MVACBL-134

TRANS 24

150 kVA

FUSE19

Lump81

0 MVA

CBL-136

FUSE20

Lump77

0 MVA

TRANS 25

75 kVA

FUSE21

Lump80

0 MVA

AL3-T02

30 kVA

FUSE22

Lump76

0 MVA

CBL-138

FUSE23

CBL-137

CBL-115

CBL-120

Lump70

0 MVA

CBL-148

FUSE27

Lump79

0 MVA

CBL-146

Lump78

0 MVA

CBL-152

Lump75

0 MVA

CBL-147

TRANS 30

225 kVA

FUSE29

Lump71

0 MVACBL-145

Lump72

0 MVA

CBL-214

Lump74

0 MVACBL-151

Lump73

0 MVA

CBL-150

TRANS 29

300 kVA

CBL-149

FUSE28

CBL-139

Lump69

0 MVA

CBL-141

Lump68

0 MVACBL-142

Lump67

0 MVA

CBL-143

Lump66

0 MVA

CBL-140

TRANS 27

113 kVA

FUSE24

Lump63

0 MVA

CBL-117

FUSE25

Lump64

0 MVACBL-144

FUSE26

Lump65

0 MVA

TRANS 28

113 kVA

CBL-121

CBL-119

CBL-118

FUSE16

L29

450 kVA

CBL-111

L19115 kVA

Lump59

0 MVA

CBL-162

L18112 kVA

Lump57

0 MVA

CBL-163

CBL-161

CBL-7

CBL-160

L20 155 kVA

CBL-166

L21

220 kVA

Lump58

0 MVACBL-167

CBL-165

CBL-42

CBL-164

A3-EGS03

800 kW

CBL-200

CBL-215

Open

Lump93

0 MVA

TRANS 16

30 kVA

CBL-123

Lump94

0 MVA

TRANS 15

45 kVA

CBL-122

Lump91

0 MVA

TRANS 18

30 kVA

CBL-125

Lump92

0 MVA

TRANS 17

45 kVA

CBL-124

Lump90

0 MVA

CBL-127

TRANS 19

45 kVA

CBL-126

Lump89

0 MVA

CBL-129

TRANS 20

45 kVA

CBL-128

Lump88

0 MVA

CBL-131

TRANS 21

45 kVA

CBL-130

Lump87

0 MVA

TRANS 22

45 kVA

CBL-132

Lump86

0 MVA

TRANS 23

30 kVA

CBL-114

CBL-43

CBL-112

L1775 kVACBL-154

CBL-153

BM1-ATSS01

CBL-188

BM2-ATSS01

CBL-191

GEN 2

800 kW

CBL-199

BM1-ATSF01

CBL-203

CBL-189

Open

GEN 1

800 kW

CBL-198

L1460 kVA

Lump60

0 MVA

CBL-157

L15

69.9 kVA

Lump61

0 MVA

CBL-159 L16 60 kVA

Lump62

0 MVA

CBL-158

L22 40 kVA

CBL-156

CBL-40

CBL-155

CBL-60

CBL-113

Lump95

0 MVA

CBL-210

B

CBL-208

AL1 HV FUSE A

TRANS 13

2500 kVA

Open

CBL-201

Lump53

0 MVACBL-185

Lump54

0 MVA

CBL-183

Lump55

0 MVACBL-184

Lump56

0 MVA

CBL-182

Lump52

0 MVA

CBL-186

CBL-181

TRANS 31

300 kVA

CBL-180

Lump42

0 MVACBL-178

Lump43

0 MVACBL-177

Lump44

0 MVACBL-176

Lump45

0 MVA

CBL-175

Lump46

0 MVA

CBL-174

Lump47

0 MVA

CBL-173

Lump48

0 MVACBL-172

Lump49

0 MVACBL-171

Lump50

0 MVA

CBL-170

Lump51

0 MVA

CBL-179

CBL-169

TRANS 32

300 kVA

CBL-168

BM2-ATSS01

CBL-206

CBL-211

C

CBL-209

AL1 HV FUSE B

TRANS 14

2500 kVA

CBL-207

~Bot1

~Left5

FIRE PUMP1

50 HP

CBL-60

C

~Bot1

B

CBL-201

Open

FUSE16

CBL-118

CBL-119

CBL-120

CBL-121

CBL-116

CBL-133 CBL-134

CBL-135

CBL-139

CBL-115

FUSE19

TRANS 24

150 kVA

CBL-136

FUSE21

TRANS 25

75 kVA

FUSE24

TRANS 27

113 kVA

CBL-117

CBL-144

TRANS 28

113 kVA

CBL-141

CBL-140

CBL-143

CBL-142

CBL-148

CBL-137

FUSE29

TRANS 29

300 kVA

TRANS 30

225 kVA

CBL-151

CBL-214

CBL-145

CBL-147

CBL-152

CBL-146

FUSE22

CBL-138

AL3-T02

30 kVA

TRANS 23

30 kVA

TRANS 21

45 kVA

TRANS 20

45 kVA

TRANS 19

45 kVA

GEN 1

800 kW

GEN 2

800 kW

A3-EGS03

800 kW

Open

Open

CBL-189

CBL-215

CBL-157

CBL-159

CBL-158

CBL-162

CBL-166

CBL-163

CBL-167

TRANS 31

300 kVA

CBL-186

CBL-185

CBL-183

CBL-184

CBL-182

TRANS 32

300 kVA

CBL-178

CBL-177

CBL-176

CBL-175

CBL-174

CBL-173

CBL-172

CBL-171

CBL-170

CBL-179

CBL-122

CBL-124

CBL-111

CBL-112

CBL-113

CBL-114

CBL-123

CBL-125

CBL-126

CBL-127

CBL-128

CBL-129

CBL-130

CBL-132

CBL-149

CBL-150

CBL-153

CBL-154

CBL-155

CBL-156

CBL-160

CBL-161

CBL-164

CBL-165

CBL-168

CBL-169

CBL-180

CBL-181

TRANS 15

45 kVA

TRANS 16

30 kVA

TRANS 17

45 kVA

TRANS 18

30 kVA

TRANS 22

45 kVA

450 kVA

L1460 kVA

L15

69.9 kVA

L16 60 kVA

L1775 kVA

L22 40 kVA

L18112 kVA

L19115 kVA

L20 155 kVA

L21

220 kVA

BM1-ATSS01

BM2-ATSS01

BM1-ATSS01

BM2-ATSS01

CBL-188

CBL-191

CBL-200

CBL-199

CBL-198

CBL-203

CBL-210

BM1-ATSF01

CBL-211

~Left5

CBL-131

AL1 HV FUSE A

AL1 HV FUSE B

TRANS 13

2500 kVA

TRANS 14

2500 kVA

CBL-209

CBL-208

FUSE23

FIRE PUMP1

50 HP

CBL-7

CBL-40

CBL-42

CBL-43

CBL-206

CBL-207

FUSE18

FUSE20

FUSE27

FUSE28

FUSE25

FUSE26

FUSE17

Lump42

0 MVA

Lump43

0 MVA

Lump44

0 MVA

Lump45

0 MVA

Lump46

0 MVA

Lump47

0 MVA

Lump48

0 MVA

Lump49

0 MVA

Lump50

0 MVA

Lump51

0 MVA

Lump52

0 MVA

Lump53

0 MVA

Lump54

0 MVA

Lump55

0 MVA

Lump56

0 MVA

Lump57

0 MVA

Lump58

0 MVA

Lump59

0 MVA

Lump60

0 MVA

Lump61

0 MVA

Lump62

0 MVA

Lump63

0 MVA

Lump64

0 MVA

Lump65

0 MVA

Lump66

0 MVA

Lump67

0 MVA

Lump68

0 MVA

Lump69

0 MVA

Lump70

0 MVA

Lump71

0 MVA

Lump72

0 MVA

Lump73

0 MVA

Lump74

0 MVA

Lump75

0 MVA

Lump76

0 MVA

Lump77

0 MVA

Lump78

0 MVA

Lump79

0 MVA

Lump80

0 MVA

Lump81

0 MVA

Lump82

0 MVA

Lump83

0 MVA

Lump84

0 MVA

Lump85

0 MVA

Lump86

0 MVA

Lump87

0 MVA

Lump88

0 MVA

Lump89

0 MVA

Lump90

0 MVA

Lump91

0 MVA

Lump92

0 MVA

Lump93

0 MVA

Lump94

0 MVA

Lump95

0 MVA

F10.48 kV

F55

0.48 kV

F22

0.48 kV

F23

0.48 kV

F240.48 kV

F35

0.48 kV

F27

0.208 kV

F25

0.48 kV

F26

0.48 kV F28

0.208 kV

F29

0.208 kV

F27A

0.48 kV

F30

0.48 kV

F31

0.208 kV

F39

0.208 kV

F40

0.208 kV

F41

0.208 kV

F42

0.208 kV

F43

0.208 kV

F36

0.48 kV

F37

0.48 kV

F38

0.208 kV

F44

0.48 kV

F45

0.48 kV

F32

0.48 kV

F46

0.208 kV

F54

0.208 kV

F47

0.208 kV

F49

0.208 kV

F50

0.208 kV

F51

0.208 kV

F52 0.208 kV

F53 0.208 kV

F34

0.48 kV

F33

0.208 kV

F4

0.48 kV

F3

0.48 kV

F5

0.48 kV

F21

0.208 kV

F6

0.48 kV

F10

0.48 kV

F14

0.208 kV

F16

0.208 kV

F18

0.208 kV

F

0.48 kV

G 0.48 kV

H0.48 kV

0.48 kV

F56

0.48 kV

F58

0.48 kV

F59

0.48 kV

F60

0.48 kV

F63

0.48 kV

F64

0.48 kV

F61

0.48 kV

F62

0.48 kV

F65

0.48 kV

F70

0.208 kV

F71

0.208 kV

F72

0.208 kV

F73

0.208 kV

F74

0.208 kV

F75 0.208 kV

F76

0.208 kV

F77

0.208 kV

F78

0.208 kV

F79

0.208 kV

F80

0.208 kV

F81

0.208 kV

F82

0.208 kV

F83

0.208 kV

F84

0.208 kV

F85

0.208 kV

F86

0.208 kV

F2

0.48 kV

F90

0.48 kV

F89

0.48 kV

F1E

0.48 kV

F8

0.48 kV

F12

0.48 kV

F15

0.208 kV

F17

0.208 kV

F19

0.208 kV

F48

0.208 kV

F91

0.48 kV

F100

0.48 kV

F92

0.48 kV

F67

0.48 kV

F93

0.48 kV

F68

0.48 kV

F94

0.48 kV

F69

0.48 kV

F7 0.208 kV

F9

0.208 kV

F11

0.208 kV

F13

0.208 kV

F20

0.208 kV

F96

0.48 kV

F95

0.48 kV

GEN 3 BUS

0.48 kV

GEN 2 BUS

0.48 kV

GEN 1 BUS

0.48 kV

F970.48 kV

F57

0.48 kV

F88

13.8 kV

F87

13.8 kV

F66

L29

121

I44

0.48

kV

I2

13.8

kV

I1

13.8

kV

I3

0.48

kV

I36

0.20

8 kV

I41

0.20

8 kV

I42

0.20

8 kV

I43 0.20

8 kV

I37

0.20

8 kV

I38

0.20

8 kV

I39

0.20

8 kV

I40

0.20

8 kV

I4

0.48

kV

I5

0.48

kV

I6

0.48

kV

I9

0.48

kV

I17

0.48

kV

I22

0.48

kV

I62

0.20

8 kV

I29

0.20

8 kV

I31

0.20

8 kV

I30

0.20

8 kV

I61

0.20

8 kV

I27

0.20

8 kV

I24

0.20

8 kV

I250.

208

kV

I26

0.20

8 kV

I23

0.48

kV

I32 0.48

kV

I18

0.48

kV

I19

0.20

8 kV I2

10.

208

kVI2

00.

208

kV

I11

0.20

8 kV

I16

0.20

8 kV

I15

0.20

8 kV

I14

0.20

8 kV

I13

0.20

8 kV

I12 0.20

8 kV

I10

0.48

kV

I7 0.48

kV

I8

0.20

8 kV

I33

0.48

kV

I35 0.

48 k

VI3

4 0.20

8 kV

I50

0.48

kV

I60

0.20

8 kV

I52 0.

208

kVI5

40.

208

kV

I53 0.

208

kVI5

5 0.20

8 kV

I57

0.20

8 kV

I59 0.20

8 kV

I56 0.2

08 k

V

I58 0.

208

kV

I51 0.2

08 k

V

I45

0.48

kV

I46

0.48

kV

I47

0.48

kV

I48

0.48

kV

I49

0.48

kV

L28

405

kVA

Lump

960

MVA

CBL-

95

L26

40 k

VAL2

740

kVA

CBL-

98

L25

40 k

VA

CBL-

96

L24

40 k

VA

CBL-

97

L23

380

kVA

Lump

970

MVA

CBL-

99

Lump

980

MVA

CBL-

110

Lump

105

0 MV

ACBL-

103

Lump

103

0 MV

A

CBL-

105

Lump

106

0 MV

ACBL-

102

Lump

104

0 MV

ACBL-

104

Lump

102

0 MV

ACBL-

106

Lump

100

0 MV

ACBL-

108

Lump

101

0 MV

ACBL-

107

Lump

990

MVACB

L-10

9

CBL-

101

TRAN

S 40

750

kVA

CBL-

100

CBL-

61

Open

Lump

112

0 MV

A

TRAN

S 38

30 k

VA

FUSE

42

Lump

111

0 MV

A

CBL-

64

FUSE

43

CBL-

68

Lump

113

0 MV

A

TRAN

S 33

30 k

VA

FUSE

34

Lump

114

0 MV

ACBL-

63

FUSE

33

Lump

115

0 MV

ACBL-

70

FUSE

35

Lump

116

0 MV

A

CBL-

72

Lump

117

0 MV

A

CBL-

73

Lump

118

0 MV

A

CBL-

71

Lump

119

0 MV

A

CBL-

74

Lump

120

0 MV

A

CBL-

75

TRAN

S 34

300

kVA

FUSE

36

Lump

123

0 MV

ACBL-

78

Lump

122

0 MV

ACBL-

77

TRAN

S 35

113

kVA

FUSE

37

Lump

121

0 MV

A

CBL-

76

Lump

124

0 MV

A

CBL-

83

FUSE

41

Lump

125

0 MV

ACBL-

88

FUSE

38

Lump

128

0 MV

A

CBL-

85

Lump

127

0 MV

A

CBL-

86Lu

mp12

60

MVA

CBL-

84

Lump

129

0 MV

A

CBL-

87

TRAN

S 36

300

kVA

FUSE

39

Lump

131

0 MV

ACBL-

81

Lump

132

0 MV

ACBL-

82

Lump

130

0 MV

ACBL-

80

TRAN

S 37

225

kVA

FUSE

40

CBL-

79

CBL-

69

CBL-

62

CBL-

67

CBL-

66

CBL-

65

FUSE

32

Lump

108

0 MV

ACBL-

93Lu

mp10

90

MVA

CBL-

92

Lump

110

0 MV

A

CBL-

91

Lump

134

0 MV

A

CBL-

90

Lump

107

0 MV

ACBL-

96A

CBL-

95A

CBL-

94CB

L-20

4

TRAN

S 39

150

kVA

CBL-

89

TRAN

S 41

2500

kVA

FUSE

30

F87

CBL-

210

Open

F88

CBL-

211

FUSE

31

TRAN

S 42

2500

kVA

BM1-

ATSF

01

Cabl

e1

~Bot

1~T

op1

~Lef

t2

~Rt3

~Top

1F8

8~B

ot1

Open

CBL-

61

FUSE

32

CBL-

65

CBL-

66

CBL-

67CB

L-68

FUSE

42

TRAN

S 38

30 k

VACB

L-64

CBL-

63

CBL-

62FU

SE34 TRAN

S 33

30 k

VA

CBL-

70

FUSE

36

TRAN

S 34

300

kVA

CBL-

72CB

L-73

CBL-

71CB

L-74

CBL-

75

CBL-

69

CBL-

76

CBL-

79

FUSE

37

TRAN

S 35

113

kVA

CBL-

77CB

L-78

CBL-

83CB

L-88

FUSE

39FU

SE40

TRAN

S 36

300

kVA

TRAN

S 37

225

kVA

CBL-

80CB

L-81

CBL-

82

CBL-

85

CBL-

87

CBL-

89

CBL-

90

CBL-

91

CBL-

92

CBL-

93

CBL-

94

CBL-

95A

CBL-

96A

TRAN

S 39

150

kVA

TRAN

S 40

750

kVA

CBL-

102

CBL-

103

CBL-

104

CBL-

105

CBL-

106

CBL-

107

CBL-

108

CBL-

109

CBL-

110

CBL-

99CB

L-97

CBL-

96

CBL-

98CB

L-95

L23

380

kVA

L28

405

kVA

CBL-

86

CBL-

84

CBL-

100

CBL-

101

CBL-

204

~Lef

t2

~Rt3

BM1-

ATSF

01

Open

FUSE

31

FUSE

30

TRAN

S 42

2500

kVA

TRAN

S 41

2500

kVA

CBL-

211

CBL-

210

L26

40 k

VAL2

740

kVA

L25

40 k

VA

L24

40 k

VA

Cabl

e1

FUSE

35

FUSE

33

FUSE

38

FUSE

43

FUSE

41

Lump

960

MVA

Lump

970

MVA

Lump

980

MVA

Lump

990

MVA

Lump

100

0 MV

A

Lump

101

0 MV

A

Lump

102

0 MV

A

Lump

103

0 MV

A

Lump

104

0 MV

A

Lump

105

0 MV

A

Lump

106

0 MV

A

Lump

107

0 MV

A

Lump

108

0 MV

A

Lump

109

0 MV

A

Lump

110

0 MV

ALu

mp11

10

MVA

Lump

112

0 MV

ALu

mp11

30

MVA

Lump

114

0 MV

A

Lump

115

0 MV

A

Lump

116

0 MV

ALu

mp11

70

MVA

Lump

118

0 MV

ALu

mp11

90

MVA

Lump

120

0 MV

A

Lump

121

0 MV

A

Lump

122

0 MV

ALu

mp12

30

MVA

Lump

124

0 MV

A

Lump

125

0 MV

A

Lump

126

0 MV

A

Lump

127

0 MV

A

Lump

128

0 MV

A

Lump

129

0 MV

A

Lump

130

0 MV

ALu

mp13

10

MVA

Lump

132

0 MV

A

Lump

134

0 MV

A

I3

0.48

kV

I50

0.48

kV

I4

0.48

kV

I5

0.48

kV

I6

0.48

kV

I33

0.48

kV

I34 0.20

8 kV

I35 0.

48 k

VI7 0.48

kV

I8

0.20

8 kV

I9

0.48

kV

I11

0.20

8 kV

I12 0.20

8 kV

I13

0.20

8 kV

I14

0.20

8 kV

I15

0.20

8 kV

I16

0.20

8 kV

I10

0.48

kV

I17

0.48

kV

I19

0.20

8 kV I2

10.

208

kV

I18

0.48

kV

I20

0.20

8 kV

I22

0.48

kV

I32 0.48

kV

I61

0.20

8 kV

I62

0.20

8 kV

I29

0.20

8 kV

I30

0.20

8 kV

I31

0.20

8 kV

I23

0.48

kV

I26

0.20

8 kV

I27

0.20

8 kV

I36

0.20

8 kV

I37

0.20

8 kV

I38

0.20

8 kV

I39

0.20

8 kV

I42

0.20

8 kV

I41

0.20

8 kV

I43 0.20

8 kV

I40

0.20

8 kV

I60

0.20

8 kV

I59 0.20

8 kV

I58 0.

208

kV

I57

0.20

8 kV

I56 0.2

08 k

V

I55 0.

208

kV

I54

0.20

8 kV

I53 0.

208

kV

I52 0.

208

kV

I51 0.2

08 k

V

I45

0.48

kV

I46

0.48

kV

I47

0.48

kV

I48

0.48

kV

I49

0.48

kV

I24

0.20

8 kV

I250.

208

kV

I2

13.8

kV

I1

13.8

kV

I44

0.48

kV

F87

122

Annex B Result of arc flash study (worst case) for 271 bus system

ID kV

(kV) Output

Rpt. Configuration

Total Energy

(cal/cm²)

AFB (ft)

Energy Levels

Final FCT (sec)

Ia at FCT (kA)

Source PD ID

A 13.8 NAFMA

X Normal 5.26 3.1 Level 2 0.12 17.556

NORM SERV

B 13.8 NAFMA

X Normal 3.37 2.5 Level 1 0.077 17.529 FUSE1

BM2D52

0.48 EMAFMAX

EM 1.79 1.8 Level 1 0.15 3.618 CB-104

C 13.8 TCAFM

AX Ties

Closed 3.43 2.5 Level 1 0.079 17.483 FUSE2

D 0.48 NAFMA

X Normal 58.28 10.5

> Level 4

0.625 24.271 CB-1

D1 0.48 EMAFMIN

EM 867.6 82.9 > Level

4 162.127 1.842 CB-101

D1A 0.48 EMAFMIN

EM 874.32 40.5 > Level

4 140.571 1.978 CB-101

D1B 0.48 TCAFM

AX Ties

Closed 3.36 2.5 Level 1 0.026 33.398 CB-3

D1C 0.48 EMAFMIN

EM 874.32 40.5 > Level

4 140.571 1.978 CB-101

D2 0.48 TCAFM

AX Ties

Closed 0.489097 1 Level 0 0.012 11.203 CB-7

D3 0.48 TCAFM

AX Ties

Closed 0.303614 0.6 Level 0 0.011 8.615 CB-8

D4 0.48 TCAFM

AX Ties

Closed 0.801793 1.2 Level 0 0.008 26.582 CB-4

D5 0.48 EMAFMIN

EM 0.275931 0.6 Level 0 0.015 5.735 CB-5

D6 0.48 EMTCA

FMIN EMTC 8.46 4 Level 3 30.279 FUSE5

D7 0.48 EMTCA

FMIN EMTC 10.12 4.4 Level 3 24.952 FUSE5

D8 0.48 EMTCA


D9 0.48 EMTCAFMAX

EMTC 0.25 0.6 Level 0 21.754 FUSE 6

D10 0.20

8 EMTCA


D11 0.20

8 TCAFM

IN Ties

Closed 24.56 9.4 Level 3 2.772 2.94 CB-28

D12 0.20

8 TCAFM

AX Ties

Closed 0.144963 0.4 Level 0 0.017 2.793 CB-26

D13 0.20

8 TCAFM

AX Ties

Closed 0.148789 0.4 Level 0 0.017 2.89 CB-24

D14 0.20

8 TCAFM

AX Ties

Closed 0.171397 0.5 Level 0 0.016 3.536 CB-22

123

D15 0.20

8 TCAFM

IN Ties

Closed 32.24 11.1 Level 4 5.362 2.057 CB-20

D16 0.20

8 TCAFM

AX Ties

Closed 0.136216 0.4 Level 0 0.018 2.513 CB-18

D16A

0.208

TCAFMIN

Ties Closed

32.24 11.1 Level 4 5.362 2.057 CB-13

D17 0.20

8 TCAFM

AX Ties

Closed 0.123088 0.4 Level 0 0.02 2.109 CB-16

D19 0.48 EMTCA


D20 0.48 TCAFM

AX Ties

Closed 0.25 0.6 Level 0 20.869 FUSE 8

D21 0.20

8 EMTCA

FMIN EMTC 31.52 11 Level 4 3.119 FUSE9

D22 0.20

8 TCAFM

AX Ties

Closed 0.173073 0.5 Level 0 0.016 3.534 CB-32

D23 0.20

8 EMAFMIN

EM 0.135164 0.4 Level 0 0.027 1.736 CB-34

D24 0.20

8 TCAFM

AX Ties

Closed 0.123071 0.4 Level 0 0.02 2.108 CB-36

D25 0.20

8 TCAFM

IN Ties

Closed 32.25 11.1 Level 4 5.366 2.056 CB-38

D26 0.20

8 TCAFM

IN Ties

Closed 32.25 11.1 Level 4 5.366 2.056 CB-41

D27 0.48 EMTCA


D28 0.20

8 TCAFM

AX Ties

Closed 0.041196 0.2 Level 0 0.008 1.724 CB-46

D29 0.20

8 TCAFM

AX Ties

Closed 0.024183 0.1 Level 0 0.008 1.053 CB-47

D30 0.20

8 TCAFM

IN Ties

Closed 27.12 10 Level 4 6.185 1.536 FUSE10

D31 0.48 EMTCA


D32 0.48 EMTCA


D33 0.20

8 TCAFM

IN Ties

Closed 50.92 14.7

> Level 4

6.135 2.771 FUSE11

D34 0.20

8 TCAFM

AX Ties

Closed 0.157773 0.4 Level 0 0.017 3.147 CB-51

D35 0.20

8 TCAFM

AX Ties

Closed 0.157773 0.4 Level 0 0.017 3.147 CB-52

D36 0.20

8 EMAFMIN

EM 0.242876 0.6 Level 0 0.06 1.425 CB-53

D37 0.20

8 TCAFM

AX Ties

Closed 0.121254 0.4 Level 0 0.021 2.022 CB-54

D38 0.20

8 TCAFM

IN Ties

Closed 4.39 3.3 Level 2 1.582 1.006 CB-55

D39 0.20

8 TCAFM

AX Ties

Closed 0.110472 0.4 Level 0 0.017 2.187 CB-56

124

D40 0.20

8 EMAFMIN

EM 0.141175 0.4 Level 0 0.034 1.455 CB-57

D41 0.48 TCAFM

AX Ties


D42 0.20

8 TCAFM

IN Ties

Closed 117.37 14.8

> Level 4

16.162 2.29 FUSE13

D43 0.48 EMTCA


D44 0.48 TCAFM

AX Ties


D45 0.20

8 TCAFM

IN Ties

Closed 77.25 19

> Level 4

11.994 2.193 RL2-FS02

D46 0.20

8 TCAFM

IN Ties

Closed 26.77 7.1 Level 4 3.879 2.183 CB-67

D47 0.20

8 TCAFM

AX Ties

Closed 0.123604 0.4 Level 0 0.018 2.388 CB-69

D48 0.20

8 TCAFM

AX Ties

Closed 0.123604 0.4 Level 0 0.018 2.388 CB-71

D49 0.20

8 TCAFM

AX Ties

Closed 0.123604 0.4 Level 0 0.018 2.388 CB-73

D50 0.48 TCAFM

AX Ties

Closed 138.71 16.1

> Level 4

24.991 1.786 FIRE

PUMP BKR N

D51 0.48 TCAFM

AX Ties

Closed 141.9 16.3

> Level 4

26.196 1.746 FIRE

PUMP BKR N

D52 0.48 EMAFMAX

EM 1.54 1.7 Level 1 0.15 3.384 CB-104

D53 0.20

8 EMAFMIN

EM 22.23 8.9 Level 3 6.37 1.238 CB-85

D53A

0.48 TCAFM

AX Ties

Closed 0.182417 0.6 Level 0 0.016 3.46 CB-85

D54 0.20

8 TCAFM

AX Ties

Closed 0.041958 0.2 Level 0 0.008 1.753 CB-87

D55 0.20

8 EMAFMIN

EM 17.37 7.6 Level 3 8.181 0.784 CB-89

D55A

0.48 TCAFM

AX Ties

Closed 0.212192 0.6 Level 0 0.015 4.164 CB-89

D56 0.20

8 EMAFMIN

EM 8.07 4.8 Level 3 3.883 0.767 CB91

D57 0.48 EMAFMAX

EM 1.51 1.7 Level 1 0.15 3.318 CB-104

D58 0.20

8 EMAFMIN

EM 24.34 9.4 Level 3 7.414 1.171 CB-94

D59 0.48 EMAFMAX

EM 1.45 1.7 Level 1 0.15 3.194 CB-104

D60 0.20

8 EMAFMIN

EM 24.6 9.4 Level 3 7.546 1.164 CB-97

D61 0.20

8 NAFMI

N Normal 59.39 16.2

> Level 4

19.508 1.097 CB-290

125

D62 0.20

8 NAFMI

N Normal 60.28 16.3

> Level 4

20.064 1.083 CB-290

D63 0.20

8 NAFMI

N Normal 60.28 16.3

> Level 4

20.064 1.083 CB-290

D64 0.20

8 NAFMI

N Normal 61.17 16.5

> Level 4

20.627 1.07 CB-290

D65 0.48 EMAFMAX

EM 1.89 1.9 Level 1 0.15 3.816 CB-106

D66 0.48 EMAFMAX

EM 1.57 1.8 Level 1 0.15 3.432 CB-106

E 0.48 TCAFM

AX Ties

Closed 75.25 11.9

> Level 4

0.657 29.366 CB-2

E1 0.48 TCAFM

AX Ties

Closed 0.602785 1 Level 0 0.008 21.846 CB-75

E2 0.48 TCAFM

AX Ties

Closed 9.29 5.2 Level 3 0.2 13.639 CB-77

E3 0.48 TCAFM

AX Ties

Closed 5.41 3.2 Level 2 0.1 14.688 CB-79

E4 0.48 TCAFM

AX Ties

Closed 0.619691 1.1 Level 0 0.013 12.768 CB-80

E5 0.48 TCAFM

AX Ties

Closed 2.88 2.3 Level 1 0.051 15.275 CB-81

E6 0.48 TCAFM

AX Ties

Closed 2.78 2.3 Level 1 0.051 14.794 CB-82

E7 0.48 TCAFM

AX Ties

Closed 2.78 2.3 Level 1 0.051 14.794 CB-83

E8 0.48 TCAFM

AX Ties

Closed 0.834716 1.3 Level 0 0.053 4.687 CB-84

F 0.48 EMAFMAX

EM 1392.24 51.1 > Level

4 57.882 6.935 CB-GEN1

F1 0.48 NAFMI

N Normal 56.07 10.3

> Level 4

0.668 21.64 CB115A

F1B 0.48 TCAFM

AX Ties

Closed 5.95 3.3 Level 2 0.1 16.031 CB-115

F1E 0.48 EMAFMIN

EM 221.94 20.4 > Level

4 31.79 2.195 CB-107

F2 0.48 EMAFMIN

EM 115.91 14.7 > Level

4 17.132 2.084 CB-102

F3 0.48 TCAFM

AX Ties

Closed 0.990049 1.4 Level 0 0.008 32.308 CB-113

F4 0.48 EMAFMIN

EM 129.98 15.6 > Level

4 22.107 1.848 CB-102

F5 0.48 EMAFMIN

EM 218.53 35.8 > Level

4 36.025 2.064 CB-107

F6 0.48 EMAFMIN

EM 29.93 10.6 Level 4 6.136 1.664 CB-119

F7 0.20

8 EMAFMIN

EM 24.85 9.5 Level 3 7.674 1.157 CB-116

F8 0.48 EMAFMIN

EM 30.87 10.9 Level 4 6.614 1.602 CB-119

126

F9 0.20

8 EMAFMIN

EM 18.12 7.8 Level 3 8.86 0.758 CB-120

F10 0.48 TCAFM

AX Ties

Closed 0.387487 0.8 Level 0 0.016 7.573 CB-123

F11 0.20

8 EMAFMIN

EM 23.09 9.1 Level 3 6.791 1.209 CB-123A

F12 0.48 TCAFM

AX Ties

Closed 0.334838 0.7 Level 0 0.016 6.343 CB-123

F13 0.20

8 EMAFMIN

EM 17.54 7.7 Level 3 8.334 0.778 CB-127

F14 0.20

8 EMAFMIN

EM 18.87 8 Level 3 4.731 1.398 CB-130

F14A

0.48 TCAFM

AX Ties

Closed 0.313544 0.8 Level 0 0.014 6.306 CB-130

F15 0.20

8 EMAFMIN

EM 15.66 7.2 Level 3 4.075 1.35 CB-131

F16 0.20

8 EMAFMIN

EM 24.56 9.4 Level 3 7.526 1.165 CB-134

F16A

0.48 EMAFMIN

EM 0.13312 0.5 Level 0 0.029 1.511 CB-134

F17 0.20

8 EMAFMIN

EM 19.94 8.3 Level 3 6.287 1.134 CB-135

F18 0.20

8 EMAFMIN

EM 20.37 8.4 Level 3 5.426 1.322 CB-138

F18A

0.48 TCAFM

AX Ties

Closed 0.258585 0.7 Level 0 0.015 5.115 CB-138

F19 0.20

8 EMAFMIN

EM 18.6 8 Level 3 5.557 1.191 CB-139

F20 0.20

8 EMAFMIN

EM 20.72 8.5 Level 3 5.596 1.306 CB-142

F20A

0.48 TCAFM

AX Ties

Closed 0.217701 0.6 Level 0 0.015 4.219 CB-142

F21 0.20

8 EMAFMIN

EM 17.03 7.6 Level 3 7.883 0.797 CB-145

F22 0.48 EMAFMIN

EM 10.02 4.3 Level 3 20.364 FUSE16

F23 0.48 EMAFMIN

EM 11.98 4.7 Level 3 19.782 FUSE16

F24 0.48 EMAFMIN

EM 12.62 4.9 Level 3 19.593 FUSE16

F25 0.48 TCAFM

AX Ties


F26 0.48 TCAFM

AX Ties


F27 0.20

8 NAFMI

N Normal 203.02 34.2

> Level 4

24.453 2.774 FUSE19

F27A

0.48 EMAFMIN

EM 13.24 5 Level 3 19.406 FUSE16

F28 0.20

8 NAFMI

N Normal 37.92 12.3 Level 4 7.904 1.67 CB-151

127

F29 0.20

8 TCAFM

AX Ties

Closed 0.153015 0.4 Level 0 0.017 3.009 CB-153

F30 0.48 TCAFM

AX Ties


F31 0.20

8 NAFMI

N Normal 28.5 10.3 Level 4 4.471 2.172 FUSE21

F32 0.48 EMAFMIN

EM 13.86 5.1 Level 3 19.222 FUSE16

F33 0.20

8 NAFMI


F34 0.48 TCAFM

AX Ties


F35 0.48 EMAFMIN

EM 12.93 4.9 Level 3 19.499 FUSE16

F36 0.48 TCAFM

AX Ties


F37 0.48 TCAFM

AX Ties


F39 0.20

8 NAFMI

N Normal 86.84 20.4

> Level 4

11.677 2.505 FUSE24

F40 0.20

8 TCAFM

AX Ties

Closed 0.150815 0.4 Level 0 0.017 2.947 CB-165

F41 0.20

8 TCAFM

AX Ties

Closed 0.145415 0.4 Level 0 0.017 2.796 CB-166

F42 0.20

8 TCAFM

AX Ties

Closed 0.120826 0.4 Level 0 0.021 2.002 CB-167

F43 0.20

8 NAFMI

N Normal 24.33 6.8 Level 3 3.064 2.487 CB-168

F44 0.48 EMAFMIN

EM 13.86 5.1 Level 3 19.222 FUSE16

F45 0.48 TCAFM

AX Ties


F46 0.20

8 NAFMI

N Normal 2224.39

147.1

> Level 4

194.529 3.73 FUSE28

F46A

0.48 NAFMI

N Normal 0.488862 1 Level 0 0.008 15.821 FUSE28

F47 0.20

8 NAFMI

N Normal 26.69 7.1 Level 4 3.85 2.194 CB-171

F48 0.20

8 TCAFM

AX Ties

Closed 0.245393 0.6 Level 0 0.019 4.086 CB-172

F49 0.20

8 EMAFMIN

EM 0.264776 0.7 Level 0 0.024 3.313 CB-173

F50 0.20

8 TCAFM

AX Ties

Closed 0.195124 0.5 Level 0 0.015 4.11 CB-174

F51 0.20

8 NAFMI

N Normal 24.94 9.5 Level 3 2.864 2.899 CB-177

F52 0.20

8 NAFMI

N Normal 23.87 9.3 Level 3 2.613 3.029 CB-179

F53 0.20

8 TCAFM

AX Ties

Closed 0.128589 0.4 Level 0 0.019 2.278 CB-181

128

F54 0.20

8 NAFMI

N Normal 577.42 64.6

> Level 4

61.2 3.122 FUSE29

F55 0.48 TCAFM

AX Ties

Closed 56.86 10.3

> Level 4

0.532 27.563 CB-115B

F55A

0.48 TCAFM

AX Ties

Closed 0.270585 0.7 Level 0 0.01 7.674 CB-214

F55B

0.48 TCAFM

AX Ties

Closed 0.281695 0.7 Level 0 0.01 8.172 CB-213

F55D

0.48 TCAFM

AX Ties

Closed 0.524466 1 Level 0 0.008 17.949 CB-184

F55E

0.48 TCAFM

AX Ties

Closed 12.22 4.8 Level 3 0.2 16.425 CB-191

F55G

0.48 EMTCA

FMIN EMTC 4.07 2.8 Level 2 0.066 16.451 C-196

F56 0.48 EMAFMIN

EM 115.29 24.2 > Level

4 20.135 1.92 CB-103

F57 0.48 EMAFMIN

EM 30.7 10.8 Level 4 6.528 1.579 CB-185

F58 0.48 EMAFMIN

EM 29.99 10.7 Level 4 6.177 1.618 CB-187

F59 0.48 NAFMI

N Normal 0.289446 0.6 Level 0 0.017 5.349 CB-184

F60 0.48 EMAFMIN

EM 374.79 49.7 > Level

4 63.701 2.007 CB-109

F61 0.48 EMAFMIN

EM 29.91 10.6 Level 4 6.038 1.662 CB-192

F62 0.48 EMAFMIN

EM 185.29 32.3 > Level

4 40.974 1.573 CB-194

F63 0.48 EMAFMIN

EM 501.16 59.3 > Level

4 85.299 2.007 CB-110

F64 0.48 EMAFMIN

EM 165.83 30.2 > Level

4 33.261 1.718 CB-197

F65 0.48 EMAFMIN

EM 282.11 23 > Level

4 43.893 2.032 CB-198

F66 0.48 EMAFMAX

EM 0.298296 0.7 Level 0 0.022 4.051 CB-108

F67 0.48 EMAFMIN

EM 1.01 1.4 Level 0 0.045 6.457 CB-103

F68 0.48 EMAFMIN

EM 211.25 19.9 > Level

4 30.766 2.152 CB-109

F69 0.48 EMAFMIN

EM 506.14 30.8 > Level

4 74.302 2.149 CB-110

F70 0.20

8 TCAFM

IN Ties

Closed 685.12 71.7

> Level 4

57.544 3.872 CB-200

F70A

0.48 TCAFM

AX Ties

Closed 3.05 2.4 Level 1 0.028 28.44 CB-200

F70B

0.208

TCAFMIN

Ties Closed

681.86 35.7 > Level

4 48.564 4.215 CB-200

F71 0.20

8 TCAFM

IN Ties

Closed 65.42 17.1

> Level 4

12.91 1.757 CB202

129

F72 0.20

8 TCAFM

AX Ties

Closed 0.075707 0.3 Level 0 0.018 1.504 CB-205

F73 0.20

8 TCAFM

IN Ties

Closed 105.67 23

> Level 4

10.111 3.432 CB-208

F74 0.20

8 TCAFM

AX Ties

Closed 0.197234 0.6 Level 0 0.018 3.435 CB-211

F75 0.20

8 TCAFM

AX Ties

Closed 0.214888 0.6 Level 0 0.016 4.012 CB-212

F76 0.20

8 TCAFM

IN Ties

Closed 691.39 72.1

> Level 4

58.697 3.834 CB-215

F76A

0.48 EMTCA

FMIN EMTC 3.13 2.4 Level 1 0.044 19.056 CB-215

F76B

0.208

TCAFMIN

Ties Closed

688.52 35.9 > Level

4 49.604 4.17 CB-215

F77 0.20

8 TCAFM

IN Ties

Closed 17.34 7.6 Level 3 5.835 1.072 CB-243

F78 0.20

8 TCAFM

IN Ties

Closed 14.27 6.8 Level 3 4.292 1.19 CB-240

F79 0.20

8 TCAFM

IN Ties

Closed 16.44 7.4 Level 3 5.366 1.103 CB-237

F80 0.20

8 EMTCA

FMIN EMTC 0.128094 0.4 Level 0 0.024 1.814 CB-234

F81 0.20

8 TCAFM

IN Ties

Closed 13.43 6.5 Level 3 3.897 1.229 CB-231

F82 0.20

8 TCAFM

AX Ties

Closed 0.14387 0.4 Level 0 0.017 2.765 CB-228

F83 0.20

8 TCAFM

IN Ties

Closed 13.01 6.4 Level 3 3.708 1.25 CB-225

F84 0.20

8 TCAFM

IN Ties

Closed 38.5 12.4 Level 4 8.149 1.646 CB-222

F85 0.20

8 TCAFM

IN Ties

Closed 31.31 10.9 Level 4 4.991 2.14 CB-218

F86 0.20

8 TCAFM

IN Ties

Closed 37.75 8.4 Level 4 6.6 1.836 CB-217

F87 13.8 NAFMA


F88 13.8 TCAFM

AX Ties


F89 0.48 EMAFMIN

EM 115.91 14.7 > Level

4 17.132 2.084 CB-102

F90 0.48 EMAFMIN

EM 221.94 20.4 > Level

4 31.79 2.195 CB-107

F91 0.48 EMAFMAX

EM 0.371097 0.8 Level 0 0.021 5.201 CB-108

F92 0.48 NAFMI

N Normal 109.91 14.4

> Level 4

15.562 2.214 CB-103

F93 0.48 NAFMI

N Normal 365.18 26.2

> Level 4

51.394 2.239 CB-109

F94 0.48 EMAFMIN

EM 506.14 30.8 > Level

4 74.302 2.149 CB-110

130

F95 0.48 EMAFMAX

EM 1.79 1.8 Level 1 0.15 3.618 CB-104

F96 0.48 EMAFMAX

EM 1.89 1.9 Level 1 0.15 3.816 CB-106

F97 0.48 EMAFMAX

EM 0.762621 1.2 Level 0 0.15 1.647 CB-105

F100 0.48 TCAFM

AX Ties

Closed 0.866543 1.3 Level 0 0.007 32.427 CB-183

G 0.48 EMAFMIN

EM 1173.31 46.9 > Level

4 168.059 2.206 CB-GEN2

H 0.48 EMAFMIN

EM 1198.27 47.4 > Level

4 175.658 2.158 CB-GEN3

I1 13.8 NAFMA


I2 13.8 TCAFM

AX Ties


I3 0.48 EMAFMIN

EM 54.52 10.1 > Level

4 0.654 21.878 CB-246

I4 0.48 EMAFMIN

EM 6.31 3.4 Level 2 21.46 FUSE 32

I5 0.48 EMAFMIN

EM 8.05 3.9 Level 3 20.945 FUSE 32

I6 0.48 EMAFMIN

EM 8.63 4 Level 3 20.774 FUSE 32

I7 0.48 TCAFM

AX Ties

Closed 0.259416 0.6 Level 0 0.004 17.887 FUSE 33

I8 0.20

8 NAFMI


I9 0.48 EMAFMIN

EM 9.21 4.2 Level 3 20.603 FUSE 32

I10 0.48 TCAFM

AX Ties


I11 0.20

8 NAFMI

N Normal 1868.38

132.2

> Level 4

154.796 3.921 FUSE36

I12 0.20

8 TCAFM

AX Ties

Closed 0.251368 0.6 Level 0 0.019 4.267 CB-257

I13 0.20

8 NAFMI

N Normal 29.58 10.6 Level 4 4.339 2.312 CB-258

I14 0.20

8 EMAFMIN

EM 1.71 1.9 Level 1 0.467 1.301 CB-259

I15 0.20

8 NAFMI

N Normal 29.58 10.6 Level 4 4.339 2.312 CB-260

I16 0.20

8 TCAFM

AX Ties

Closed 0.130967 0.4 Level 0 0.019 2.352 CB-261

I17 0.48 EMAFMIN

EM 9.79 4.3 Level 3 20.432 FUSE 32

I18 0.48 EMAFMIN

EM 22.74 9 Level 3 13.369 FUSE 32

I19 0.20

8 NAFMI

N Normal 85.55 20.2

> Level 4

11.448 2.517 FUSE37

131

I20 0.20

8 EMAFMIN

EM 0.149084 0.4 Level 0 0.036 1.45 CB-264

I21 0.20

8 TCAFM

AX Ties

Closed 0.14362 0.4 Level 0 0.017 2.758 CB-266

I22 0.48 EMAFMIN

EM 10.36 4.4 Level 3 20.262 FUSE 32

I23 0.48 TCAFM

AX Ties


I24 0.20

8 TCAFM

AX Ties

Closed 0.251125 0.6 Level 0 0.019 4.26 CB-275

I25 0.20

8 TCAFM

AX Ties

Closed 0.251125 0.6 Level 0 0.019 4.26 CB-274

I26 0.20

8 TCAFM

AX Ties

Closed 0.213309 0.5 Level 0 0.015 4.54 CB-272

I27 0.20

8 TCAFM

AX Ties

Closed 0.149376 0.4 Level 0 0.017 2.907 CB-270

I29 0.20

8 NAFMI

N Normal 25.19 9.6 Level 4 2.923 2.871 CB-277

I30 0.20

8 NAFMI

N Normal 38.87 12.5 Level 4 8.308 1.632 CB-279

I31 0.20

8 NAFMI

N Normal 25.19 9.6 Level 4 2.923 2.871 CB-282

I32 0.48 TCAFM

AX Ties


I33 0.48 EMAFMIN

EM 8.92 4.1 Level 3 20.688 FUSE 32

I34 0.20

8 NAFMI


I35 0.48 TCAFM

AX Ties


I36 0.20

8 NAFMI

N Normal 223.37 36.2

> Level 4

25.639 2.9 CB-287

I36A 0.48 TCAFM

AX Ties

Closed 0.300625 0.8 Level 0 0.009 9.603 CB-287

I37 0.20

8 TCAFM

AX Ties

Closed 0.167476 0.5 Level 0 0.016 3.388 CB-291

I38 0.20

8 TCAFM

AX Ties

Closed 0.157456 0.4 Level 0 0.017 3.12 CB-291

I39 0.20

8 TCAFM

AX Ties

Closed 0.148566 0.4 Level 0 0.017 2.886 CB-291

I40 0.20

8 TCAFM

AX Ties

Closed 0.140999 0.4 Level 0 0.018 2.684 CB-291

I41 0.20

8 NAFMI

N Normal 4.32 3.3 Level 2 1.546 1.013 CB-296

I42 0.20

8 NAFMI

N Normal 4.5 3.4 Level 2 1.643 0.994 CB-296

I43 0.20

8 NAFMI

N Normal 4.74 3.5 Level 2 1.778 0.97 CB-296

I44 0.48 TCAFM

AX Ties

Closed 160.93 17.4

> Level 4

1.559 26.693 FUSE31

132

I44A 0.48 TCAFM

AX Ties

Closed 138.71 16.1

> Level 4

24.991 1.786 FIRE

PUMP BKR N

I45 0.48 NAFMA

X Normal 4.87 3.5 Level 2 0.1 14.247 CB-298

I46 0.48 NAFMA

X Normal 0.642312 1.1 Level 0 0.053 3.678 CB-300

I47 0.48 NAFMA

X Normal 0.775128 1.2 Level 0 0.053 4.377 CB-301

I48 0.48 NAFMA

X Normal 0.406563 0.8 Level 0 0.008 15.122 CB-302

I49 0.48 NAFMA

X Normal 3.24 2.7 Level 1 0.1 9.783 CB-303

I50 0.48 EMTCAFMAX

EMTC 54.24 10.1 > Level

4 0.529 26.536 CB-247

I51 0.20

8 NAFMI

N Normal 62.65 10.8

> Level 4

13.171 1.548 CB-307

I52 0.20

8 NAFMI

N Normal 49.43 9.6

> Level 4

8.5 1.865 CB-308

I53 0.20

8 NAFMI

N Normal 191.45 18.9

> Level 4

20.705 2.864 CB-309

I54 0.20

8 NAFMI

N Normal 191.45 18.9

> Level 4

20.705 2.864 CB-310

I55 0.20

8 NAFMA

X Normal 0.171799 0.6 Level 0 0.018 2.99 CB-311

I56 0.20

8 NAFMI

N Normal 144.82 16.5

> Level 4

12.116 3.631 CB-312

I57 0.20

8 NAFMA

X Normal 0.169491 0.6 Level 0 0.018 2.902 CB-313

I58 0.20

8 NAFMI

N Normal 149.44 16.7

> Level 4

12.843 3.542 CB-314

I59 0.20

8 NAFMI

N Normal 150.66 28.5

> Level 4

14.932 3.322 CB-315

I60 0.20

8 NAFMI

N Normal 983.28

190.1

> Level 4

75.431 6.411 CB-305

I60A 0.48 NAFMA

X Normal 5.27 3.1 Level 2 0.051 26.92 CB-305

I60B 0.20

8 NAFMI

N Normal 1423.97 51.7

> Level 4

53.554 7.608 CB-305

I61 0.20

8 NAFMI

N Normal 1142.84 98

> Level 4

94.851 3.915 FUSE39

I62 0.20

8 NAFMI

N Normal 400.46 51.7

> Level 4

42.234 3.137 FUSE40

133

Appendix C: Result of short circuit study for 271 bus system

Location:

Engineer: Study Case: SC

12.0.0C Page: 1

SN:

Filename:

Project: ETAP

Contract:

Date:

Revision: Base

Config.: Normal

Momentary Duty Summary Report

3-Phase Fault Currents: (Prefault Voltage = 100 % of the Bus Nominal Voltage)

ID kA Peak kA rms kA rms kA Peak kA rms M.F. Ratio kA rms Type ID kV Symm. X/R Asymm. Asymm. Symm. Asymm. Asymm.

Momentary Duty Device Bus Device Capability

34.036 19.828 1.128 3.2 17.572 A 13.800 A Bus 33.968 19.790 1.128 3.2 17.544 B 13.800 B Bus 15.661 10.578 1.002 1.0 10.552 BM2D52 0.480 BM2D52 Bus 33.973 19.793 1.128 3.2 17.546 C 13.800 C Bus

111.511 65.264 1.407 8.8 46.391 D 0.480 D Bus 81.100 65.000 100.554 58.361 1.328 6.5 43.954 D1 0.480 D1 Panelboard

12.468 7.234 1.324 6.4 5.465 D1A 0.480 D1A Bus 105.721 61.572 1.363 7.4 45.165 D1B 0.480 D1B Bus 105.721 61.572 1.363 7.4 45.165 D1C 0.480 D1C Bus 24.141 15.673 1.010 1.4 15.519 D2 0.480 D2 Bus

81.100 65.000 19.132 12.839 1.003 1.1 12.797 D3 0.480 D3 Panelboard 75.832 43.804 1.198 4.1 36.557 D4 0.480 D4 Bus

81.100 65.000 17.431 10.776 1.032 1.8 10.441 D5 0.480 D5 Panelboard 102.142 59.400 1.349 7.0 44.039 D6 0.480 D6 Bus 94.604 54.712 1.279 5.5 42.767 D7 0.480 D7 Bus 93.450 54.016 1.269 5.3 42.556 D8 0.480 D8 Bus

81.100 65.000 64.225 37.909 1.088 2.6 34.828 D9 0.480 D9 Panelboard 15.707 9.121 1.145 3.4 7.967 D10 0.208 D10 Bus

22.400 18.000 13.680 8.039 1.099 2.8 7.315 D11 0.208 D11 Panelboard 22.400 18.000 8.315 5.201 1.025 1.7 5.075 D12 0.208 D12 Panelboard 22.400 18.000 8.305 5.384 1.010 1.4 5.329 D13 0.208 D13 Panelboard 22.400 18.000 12.512 7.506 1.061 2.3 7.075 D14 0.208 D14 Panelboard 22.400 18.000 6.955 4.440 1.015 1.5 4.372 D15 0.208 D15 Panelboard 22.400 18.000 6.955 4.440 1.015 1.5 4.372 D16 0.208 D16 Panelboard 22.400 18.000 6.955 4.440 1.015 1.5 4.372 D16A 0.208 D16A Panelboard 22.400 18.000 4.980 3.418 1.001 0.9 3.415 D17 0.208 D17 Panelboard

91.220 52.687 1.250 5.0 42.135 D19 0.480 D19 Bus 17.500 14.000 55.531 34.014 1.039 1.9 32.736 D20 0.480 D20 * * Panelboard 22.400 18.000 15.678 9.106 1.144 3.4 7.960 D21 0.208 D21 Panelboard 22.400 18.000 12.494 7.497 1.061 2.3 7.069 D22 0.208 D22 Panelboard 22.400 18.000 4.977 3.416 1.001 0.9 3.413 D23 0.208 D23 Panelboard 22.400 18.000 4.977 3.416 1.001 0.9 3.413 D24 0.208 D24 Panelboard 22.400 18.000 6.950 4.437 1.015 1.5 4.369 D25 0.208 D25 Panelboard 22.400 18.000 6.950 4.437 1.015 1.5 4.369 D26 0.208 D26 Panelboard

Location:


12.0.0C Page: 2

SN:

Filename:

Project: ETAP

Contract:

Date:

Revision: Base

Config.: Normal




89.089 51.438 1.233 4.7 41.716 D27 0.480 D27 Bus 12.500 10.000 3.828 2.572 1.003 1.1 2.564 D28 0.208 D28 Panelboard 12.500 10.000 1.807 1.274 1.000 0.5 1.274 D29 0.208 D29 Panelboard 12.500 10.000 4.442 2.901 1.008 1.3 2.877 D30 0.208 D30 Panelboard 17.500 14.000 54.726 33.608 1.037 1.9 32.411 D31 0.480 D31 * * Panelboard

92.322 53.341 1.260 5.1 42.345 D32 0.480 D32 Bus 17.500 14.000 11.857 7.118 1.060 2.3 6.716 D33 0.208 D33 Panelboard 12.500 10.000 9.942 6.178 1.029 1.8 6.005 D34 0.208 D34 Panelboard 12.500 10.000 9.942 6.178 1.029 1.8 6.005 D35 0.208 D35 Panelboard 12.500 10.000 3.709 2.577 1.000 0.8 2.576 D36 0.208 D36 Panelboard 12.500 10.000 4.689 3.220 1.001 0.9 3.217 D37 0.208 D37 Panelboard 12.500 10.000 2.234 1.569 1.000 0.6 1.569 D38 0.208 D38 Panelboard 12.500 10.000 5.287 3.599 1.002 1.0 3.594 D39 0.208 D39 Panelboard 12.500 10.000 3.823 2.653 1.000 0.8 2.652 D40 0.208 D40 Panelboard 17.500 14.000 63.683 37.635 1.086 2.6 34.659 D41 0.480 D41 * * Panelboard

8.187 4.998 1.042 2.0 4.797 D42 0.208 D42 Bus 90.142 52.053 1.242 4.8 41.926 D43 0.480 D43 Bus

17.500 14.000 37.234 25.300 1.002 1.0 25.254 D44 0.480 D44 * * Panelboard 17.500 14.000 8.180 4.994 1.042 2.0 4.794 D45 0.208 D45 Panelboard

7.491 4.635 1.031 1.8 4.495 D46 0.208 D46 Bus 12.500 10.000 6.304 4.105 1.009 1.3 4.068 D47 0.208 D47 Panelboard 12.500 10.000 6.304 4.105 1.009 1.3 4.068 D48 0.208 D48 Panelboard 12.500 10.000 6.304 4.105 1.009 1.3 4.068 D49 0.208 D49 Panelboard

3.505 2.479 1.000 0.3 2.479 D50 0.480 D50 Bus 3.418 2.417 1.000 0.3 2.417 D51 0.480 D51 Bus

81.100 65.000 14.517 9.830 1.002 1.0 9.809 D52 0.480 D52 Panelboard 12.500 10.000 4.314 2.884 1.004 1.1 2.874 D53 0.208 D53 Panelboard

6.145 4.331 1.000 0.5 4.331 D53A 0.480 D53A Bus 12.500 10.000 3.907 2.641 1.002 1.0 2.634 D54 0.208 D54 Panelboard 12.500 10.000 1.952 1.285 1.007 1.3 1.276 D55 0.208 D55 Panelboard

7.565 5.331 1.000 0.6 5.331 D55A 0.480 D55A Bus 12.500 10.000 1.864 1.235 1.005 1.2 1.228 D56 0.208 D56 Panelboard 81.100 65.000 13.708 9.299 1.002 1.0 9.281 D57 0.480 D57 Panelboard 12.500 10.000 3.971 2.616 1.006 1.2 2.600 D58 0.208 D58 Panelboard 81.100 65.000 12.335 8.393 1.002 1.0 8.378 D59 0.480 D59 Panelboard 12.500 10.000 3.916 2.583 1.006 1.2 2.567 D60 0.208 D60 Panelboard

Location:


12.0.0C Page: 3

SN:

Filename:

Project: ETAP

Contract:

Date:

Revision: Base

Config.: Normal




12.500 10.000 2.649 1.778 1.003 1.1 1.772 D61 0.208 D61 Panelboard 12.500 10.000 2.600 1.747 1.003 1.1 1.741 D62 0.208 D62 Panelboard 12.500 10.000 2.600 1.747 1.003 1.1 1.741 D63 0.208 D63 Panelboard 12.500 10.000 2.554 1.717 1.003 1.1 1.711 D64 0.208 D64 Panelboard

17.053 11.370 1.004 1.1 11.323 D65 0.480 D65 Bus 0.000 200.000 13.954 9.345 1.004 1.1 9.312 D66 0.480 D66 * Panelboard

130.041 76.169 1.413 9.0 53.889 E 0.480 E Bus 81.100 65.000 74.556 43.269 1.148 3.4 37.688 E1 0.480 E1 Panelboard 81.100 65.000 41.525 24.401 1.099 2.8 22.197 E2 0.480 E2 Panelboard

38.381 22.954 1.065 2.3 21.549 E3 0.480 E3 Bus 30.367 18.965 1.026 1.7 18.491 E4 0.480 E4 Bus 46.819 27.041 1.202 4.2 22.500 E5 0.480 E5 Bus 45.257 26.138 1.203 4.2 21.727 E6 0.480 E6 Bus 45.257 26.138 1.203 4.2 21.727 E7 0.480 E7 Bus

8.649 6.081 1.000 0.6 6.081 E8 0.480 E8 Bus 15.844 9.411 1.520 14.9 6.190 F 0.480 F Bus

107.622 62.992 1.407 8.8 44.756 F1 0.480 F1 Bus 49.615 29.151 1.100 2.8 26.509 F1B 0.480 F1B Bus 49.615 29.151 1.100 2.8 26.509 F1E 0.480 F1E Bus

107.622 62.992 1.407 8.8 44.756 F2 0.480 F2 Bus 107.622 62.992 1.407 8.8 44.756 F3 0.480 F3 Bus 22.638 13.763 1.046 2.1 13.161 F4 0.480 F4 Bus

81.100 65.000 46.274 27.312 1.089 2.6 25.089 F5 0.480 F5 Panelboard 81.100 65.000 8.437 5.819 1.001 0.9 5.815 F6 0.480 F6 Panelboard 12.500 10.000 3.682 2.442 1.005 1.2 2.430 F7 0.208 F7 Panelboard 81.100 65.000 7.382 5.106 1.001 0.8 5.103 F8 0.480 F8 Panelboard 12.500 10.000 1.738 1.175 1.002 1.0 1.172 F9 0.208 F9 Panelboard 81.100 65.000 16.541 11.084 1.003 1.1 11.046 F10 0.480 F10 Panelboard 12.500 10.000 4.058 2.668 1.007 1.3 2.650 F11 0.208 F11 Panelboard 81.100 65.000 13.339 9.052 1.002 1.0 9.035 F12 0.480 F12 Panelboard 12.500 10.000 1.821 1.228 1.003 1.1 1.224 F13 0.208 F13 Panelboard

0.000 10.000 4.637 3.250 1.000 0.7 3.250 F14 0.208 F14 * Panelboard 11.920 8.378 1.000 0.6 8.378 F14A 0.480 F14A Bus

12.500 10.000 4.312 3.026 1.000 0.6 3.026 F15 0.208 F15 Panelboard 12.500 10.000 3.480 2.396 1.001 0.9 2.394 F16 0.208 F16 Panelboard

3.370 2.382 1.000 0.4 2.382 F16A 0.480 F16A Bus

Location:


12.0.0C Page: 4

SN:

Filename:

Project: ETAP

Contract:

Date:

Revision: Base

Config.: Normal




12.500 10.000 3.296 2.275 1.001 0.9 2.274 F17 0.208 F17 Panelboard 12.500 10.000 4.822 3.171 1.007 1.3 3.150 F18 0.208 F18 Panelboard

9.476 6.639 1.000 0.7 6.639 F18A 0.480 F18A Bus 12.500 10.000 3.736 2.532 1.002 1.0 2.526 F19 0.208 F19 Panelboard 12.500 10.000 4.585 3.058 1.004 1.1 3.045 F20 0.208 F20 Panelboard

7.612 5.374 1.000 0.5 5.374 F20A 0.480 F20A Bus 12.500 10.000 1.900 1.278 1.003 1.1 1.274 F21 0.208 F21 Panelboard

76.659 45.132 1.094 2.7 41.236 F22 0.480 F22 Bus 72.253 42.903 1.077 2.5 39.848 F23 0.480 F23 Bus 70.895 42.221 1.072 2.4 39.399 F24 0.480 F24 Bus 47.309 30.431 1.013 1.4 30.047 F25 0.480 F25 Bus

17.500 14.000 64.263 38.533 1.062 2.3 36.301 F26 0.480 F26 * * Panelboard 17.500 14.000 11.660 7.032 1.054 2.2 6.670 F27 0.208 F27 Panelboard

69.586 41.565 1.067 2.4 38.956 F27A 0.480 F27A Bus 12.500 10.000 4.920 3.250 1.006 1.2 3.231 F28 0.208 F28 Panelboard 12.500 10.000 9.084 5.752 1.019 1.6 5.647 F29 0.208 F29 Panelboard 17.500 14.000 50.892 32.296 1.018 1.6 31.730 F30 0.480 F30 * * Panelboard 12.500 10.000 7.632 4.803 1.022 1.6 4.701 F31 0.208 F31 Panelboard

68.326 40.934 1.063 2.3 38.519 F32 0.480 F32 Bus 12.500 10.000 1.882 1.285 1.001 1.0 1.283 F33 0.208 F33 Panelboard 17.500 14.000 38.454 26.128 1.002 1.0 26.080 F34 0.480 F34 * * Panelboard

70.234 41.890 1.069 2.4 39.176 F35 0.480 F35 Bus 0.000 14.000 45.195 29.934 1.005 1.2 29.774 F36 0.480 F36 * * Panelboard

17.500 14.000 29.525 20.566 1.000 0.8 20.561 F37 0.480 F37 * * Panelboard 9.806 5.998 1.040 2.0 5.766 F38 0.208 F38 Bus

81.100 65.000 9.806 5.998 1.040 2.0 5.766 F39 0.208 F39 Panelboard 12.500 10.000 9.083 5.641 1.029 1.8 5.482 F40 0.208 F40 Panelboard 12.500 10.000 8.181 5.185 1.018 1.6 5.091 F41 0.208 F41 Panelboard 12.500 10.000 4.657 3.179 1.001 1.0 3.174 F42 0.208 F42 Panelboard

8.833 5.489 1.029 1.8 5.336 F43 0.208 F43 Bus 68.326 40.934 1.063 2.3 38.519 F44 0.480 F44 Bus

17.500 14.000 25.586 16.974 1.005 1.2 16.888 F45 0.480 F45 * Panelboard 22.400 18.000 20.116 11.679 1.146 3.4 10.194 F46 0.208 F46 Panelboard

41.510 25.661 1.032 1.8 24.863 F46A 0.480 F46A Bus 6.952 4.540 1.008 1.3 4.502 F47 0.208 F47 Bus

22.400 18.000 15.658 9.318 1.073 2.4 8.685 F48 0.208 F48 Panelboard

Location:


12.0.0C Page: 5

SN:

Filename:

Project: ETAP

Contract:

Date:

Revision: Base

Config.: Normal




13.642 8.262 1.050 2.1 7.872 F49 0.208 F49 Bus 22.400 18.000 15.159 9.187 1.049 2.1 8.758 F50 0.208 F50 Panelboard 12.500 10.000 12.959 7.677 1.081 2.5 7.103 F51 0.208 F51 Panelboard 22.400 18.000 14.268 8.365 1.106 2.9 7.566 F52 0.208 F52 Panelboard 22.400 18.000 5.607 3.817 1.002 1.0 3.811 F53 0.208 F53 Panelboard 22.400 18.000 15.297 8.912 1.128 3.2 7.901 F54 0.208 F54 Panelboard

122.790 71.727 1.390 8.2 51.587 F55 0.480 F55 Bus 15.661 10.578 1.002 1.0 10.552 F55A 0.480 F55A Bus 17.053 11.370 1.004 1.1 11.323 F55B 0.480 F55B Bus 43.458 27.598 1.018 1.6 27.122 F55D 0.480 F55D Bus 54.412 32.066 1.092 2.7 29.362 F55E 0.480 F55E Bus 64.218 37.635 1.107 2.9 34.001 F55G 0.480 F55G Bus

81.100 65.000 39.642 25.441 1.014 1.5 25.101 F56 0.480 F56 Panelboard 81.100 65.000 8.263 5.686 1.001 0.9 5.681 F57 0.480 F57 Panelboard 81.100 65.000 9.121 6.302 1.001 0.8 6.298 F58 0.480 F58 Panelboard 81.100 65.000 13.950 9.541 1.001 0.9 9.529 F59 0.480 F59 Panelboard 81.100 65.000 50.748 30.033 1.083 2.6 27.733 F60 0.480 F60 Panelboard 81.100 65.000 10.257 6.859 1.004 1.1 6.833 F61 0.480 F61 Panelboard 81.100 65.000 11.005 6.828 1.030 1.8 6.631 F62 0.480 F62 Panelboard 81.100 65.000 60.514 35.603 1.096 2.7 32.480 F63 0.480 F63 Panelboard 81.100 65.000 16.417 10.177 1.030 1.8 9.878 F64 0.480 F64 Panelboard

27.913 17.899 1.014 1.5 17.654 F65 0.480 F65 Bus 18.242 12.359 1.002 1.0 12.334 F66 0.480 F66 Bus 43.458 27.598 1.018 1.6 27.122 F67 0.480 F67 Bus 54.412 32.066 1.092 2.7 29.362 F68 0.480 F68 Bus 64.218 37.635 1.107 2.9 34.001 F69 0.480 F69 Bus 22.310 12.892 1.191 4.0 10.826 F70 0.208 F70 Panelboard 97.040 56.052 1.252 5.0 44.755 F70A 0.480 F70A Bus 22.853 13.201 1.199 4.1 11.011 F70B 0.208 F70B Bus

22.400 18.000 5.248 3.493 1.004 1.2 3.478 F71 0.208 F71 Panelboard 12.500 10.000 3.016 2.119 1.000 0.6 2.119 F72 0.208 F72 Panelboard 27.400 22.000 17.788 10.343 1.137 3.3 9.095 F73 0.208 F73 Panelboard

10.343 6.492 1.023 1.7 6.347 F74 0.208 F74 Bus 14.787 8.665 1.107 2.9 7.828 F75 0.208 F75 Bus

22.400 18.000 21.850 12.632 1.184 3.9 10.672 F76 0.208 F76 Panelboard 80.124 46.342 1.177 3.8 39.368 F76A 0.480 F76A Bus

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Revision: Base

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22.372 12.927 1.191 4.0 10.852 F76B 0.208 F76B Bus 22.400 18.000 2.441 1.718 1.000 0.6 1.718 F77 0.208 F77 Panelboard 22.400 18.000 2.834 1.993 1.000 0.6 1.992 F78 0.208 F78 Panelboard 22.400 18.000 2.541 1.788 1.000 0.6 1.788 F79 0.208 F79 Panelboard 22.400 18.000 5.238 3.634 1.000 0.8 3.633 F80 0.208 F80 Panelboard 22.400 18.000 2.971 2.088 1.000 0.6 2.088 F81 0.208 F81 Panelboard 22.400 18.000 7.430 5.047 1.002 1.0 5.037 F82 0.208 F82 Panelboard 22.400 18.000 3.044 2.139 1.000 0.6 2.139 F83 0.208 F83 Panelboard 22.400 18.000 4.756 3.181 1.004 1.1 3.170 F84 0.208 F84 Panelboard 22.400 18.000 7.147 4.655 1.009 1.3 4.614 F85 0.208 F85 Panelboard

5.353 3.558 1.005 1.2 3.541 F86 0.208 F86 Bus 31.917 18.616 1.123 3.1 16.571 F87 13.800 F87 Bus 31.707 18.494 1.123 3.1 16.466 F88 13.800 F88 Bus 15.277 9.020 1.476 11.9 6.111 F89 0.480 F89 Bus 15.562 9.223 1.504 13.6 6.134 F90 0.480 F90 Bus 13.693 7.956 1.340 6.8 5.936 F91 0.480 F91 Bus 14.746 8.661 1.436 9.9 6.033 F92 0.480 F92 Bus 15.802 9.383 1.518 14.7 6.183 F93 0.480 F93 Bus 15.715 9.323 1.511 14.2 6.169 F94 0.480 F94 Bus

7.533 4.476 1.076 2.5 4.162 F95 0.480 F95 Bus 7.711 4.569 1.081 2.5 4.228 F96 0.480 F96 Bus 2.387 1.685 1.000 0.5 1.685 F97 0.480 F97 Bus

122.790 71.727 1.390 8.2 51.587 F100 0.480 F100 Bus 15.912 9.457 1.524 15.2 6.204 G 0.480 G Bus 16.551 9.888 1.561 19.0 6.335 GEN 1 BUS 0.480 GEN 1 BUS Bus 16.551 9.888 1.561 19.0 6.335 GEN 2 BUS 0.480 GEN 2 BUS Bus 16.551 9.888 1.561 19.0 6.335 GEN 3 BUS 0.480 GEN 3 BUS Bus 15.980 9.503 1.528 15.6 6.219 H 0.480 H Bus 31.752 18.521 1.123 3.1 16.493 I1 13.800 I1 Bus 31.548 18.403 1.123 3.1 16.390 I2 13.800 I2 Bus

103.982 60.899 1.413 9.0 43.112 I3 0.480 I3 Bus 99.730 58.211 1.383 8.0 42.076 I4 0.480 I4 Bus 92.573 53.651 1.310 6.1 40.944 I5 0.480 I5 Bus 90.399 52.312 1.289 5.7 40.568 I6 0.480 I6 Bus

17.500 14.000 43.677 28.651 1.007 1.3 28.442 I7 0.480 I7 * * Panelboard 12.500 10.000 1.917 1.290 1.003 1.1 1.286 I8 0.208 I8 Panelboard

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Revision: Base

Config.: Normal




88.319 51.052 1.270 5.3 40.193 I9 0.480 I9 Bus 17.500 14.000 60.285 35.971 1.069 2.4 33.663 I10 0.480 I10 * * Panelboard 22.400 18.000 22.626 13.068 1.201 4.2 10.880 I11 0.208 I11 Panelboard 22.400 18.000 17.146 10.093 1.095 2.7 9.220 I12 0.208 I12 Panelboard 22.400 18.000 8.048 5.187 1.012 1.4 5.125 I13 0.208 I13 Panelboard 22.400 18.000 3.219 2.260 1.000 0.6 2.260 I14 0.208 I14 Panelboard 22.400 18.000 8.048 5.187 1.012 1.4 5.125 I15 0.208 I15 Panelboard 22.400 18.000 5.774 3.990 1.001 0.8 3.988 I16 0.208 I16 Panelboard

86.329 49.865 1.252 5.0 39.819 I17 0.480 I17 Bus 81.100 65.000 42.698 28.088 1.007 1.3 27.900 I18 0.480 I18 Panelboard 81.100 65.000 9.919 6.040 1.044 2.0 5.784 I19 0.208 I19 Panelboard 12.500 10.000 3.819 2.638 1.001 0.8 2.636 I20 0.208 I20 Panelboard 12.500 10.000 7.992 5.076 1.017 1.6 4.989 I21 0.208 I21 Panelboard

84.423 48.745 1.236 4.7 39.447 I22 0.480 I22 Bus 17.500 14.000 52.657 31.492 1.065 2.3 29.565 I23 0.480 I23 * * Panelboard 22.400 18.000 17.079 10.059 1.093 2.7 9.200 I24 0.208 I24 Panelboard 22.400 18.000 17.079 10.059 1.093 2.7 9.200 I25 0.208 I25 Panelboard 22.400 18.000 19.038 11.150 1.109 2.9 10.056 I26 0.208 I26 Panelboard 22.400 18.000 7.987 5.393 1.002 1.0 5.379 I27 0.208 I27 Panelboard 12.500 10.000 12.769 7.558 1.083 2.6 6.979 I29 0.208 I29 Panelboard 22.400 18.000 4.762 3.140 1.006 1.2 3.120 I30 0.208 I30 Panelboard 12.500 10.000 12.769 7.558 1.083 2.6 6.979 I31 0.208 I31 Panelboard 17.500 14.000 50.614 31.973 1.020 1.6 31.351 I32 0.480 I32 * * Panelboard

89.347 51.672 1.280 5.5 40.380 I33 0.480 I33 Bus 12.500 10.000 1.917 1.289 1.003 1.1 1.286 I34 0.208 I34 Panelboard 17.500 14.000 43.428 28.508 1.007 1.3 28.305 I35 0.480 I35 * * Panelboard

0.000 14.000 12.417 7.477 1.056 2.2 7.080 I36 0.208 I36 * Panelboard 21.777 13.460 1.032 1.8 13.040 I36A 0.480 I36A Bus

12.500 10.000 11.279 6.920 1.038 1.9 6.669 I37 0.208 I37 Panelboard 12.500 10.000 9.537 6.046 1.018 1.6 5.938 I38 0.208 I38 Panelboard 12.500 10.000 8.265 5.373 1.010 1.4 5.322 I39 0.208 I39 Panelboard 12.500 10.000 7.294 4.831 1.005 1.2 4.805 I40 0.208 I40 Panelboard

0.000 10.000 2.252 1.583 1.000 0.6 1.583 I41 0.208 I41 * Panelboard 12.500 10.000 2.192 1.541 1.000 0.6 1.541 I42 0.208 I42 Panelboard 12.500 10.000 2.117 1.489 1.000 0.6 1.489 I43 0.208 I43 Panelboard

122.966 71.838 1.391 8.3 51.629 I44 0.480 I44 Bus

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Revision: Base

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3.505 2.479 1.000 0.3 2.479 I44A 0.480 I44A Bus 106.000 85.000 43.136 25.637 1.075 2.5 23.847 I45 0.480 I45 Panelboard

6.607 4.647 1.000 0.6 4.647 I46 0.480 I46 Bus 8.034 5.649 1.000 0.6 5.649 I47 0.480 I47 Bus

81.100 65.000 40.461 25.930 1.014 1.5 25.572 I48 0.480 I48 Panelboard 81.100 65.000 27.033 16.251 1.058 2.2 15.358 I49 0.480 I49 Panelboard

122.966 71.838 1.391 8.3 51.629 I50 0.480 I50 Bus 4.038 2.809 1.000 0.8 2.808 I51 0.208 I51 Bus 5.215 3.615 1.000 0.8 3.613 I52 0.208 I52 Bus 9.508 6.485 1.001 1.0 6.476 I53 0.208 I53 Bus 9.508 6.485 1.001 1.0 6.476 I54 0.208 I54 Bus 7.675 5.274 1.001 0.9 5.269 I55 0.208 I55 Bus

13.428 8.986 1.004 1.1 8.953 I56 0.208 I56 Bus 7.359 5.064 1.001 0.9 5.059 I57 0.208 I57 Bus

12.943 8.683 1.003 1.1 8.654 I58 0.208 I58 Bus 12.943 8.683 1.003 1.1 8.654 I59 0.208 I59 Panelboard

81.100 65.000 54.228 31.360 1.279 5.5 24.527 I60 0.208 I60 Switchboard 94.489 54.588 1.257 5.1 43.419 I60A 0.480 I60A Bus 55.289 31.990 1.287 5.6 24.851 I60B 0.208 I60B Bus

22.400 18.000 22.510 13.003 1.198 4.1 10.855 I61 0.208 I61 Panelboard 22.400 18.000 15.585 9.052 1.144 3.4 7.916 I62 0.208 I62 Panelboard

Method: IEEE - X/R is calculated from separate R & X networks.

* Indicates a device with momentary duty exceeding the device capability

Protective device duty is calculated based on total fault current. The multiplication factors for high voltage circuit-breaker and high voltage bus momentary duty (asymmetrical and crest values) are calculated based on system X/R.

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Interrupting Duty Summary Report


ID Int. PF kV kA rms M.F. Ratio kA rms Type ID kV Symm. X/R Adj. Sym. Test

Interrupting Duty

Int.

Device Bus Device Capability Rated Adjusted

(Cy) CPT

A 13.800 NORM SERV Fuse 17.572 3.2 1.000 17.572 17.000 3.33 40.000 40.000

FUSE1 Fuse 17.572 3.2 1.000 17.572 17.000 3.33 40.000 40.000

FUSE2 Fuse 17.572 3.2 1.000 17.572 17.000 3.33 40.000 40.000

B 13.800 FUSE3 Fuse 17.544 3.2 1.000 17.544 15.500 6.65 29.400 29.400

BM2D52 0.480 10.552 1.0 C 13.800 FUSE4 Fuse 17.546 3.2 1.000 17.546 15.500 6.65 29.400 29.400

D 0.480 CB-3 Molded Case 46.391 8.8 1.128 52.342 0.480 20.00 65.000 65.000

CB-4 Molded Case 46.391 8.8 1.128 52.342 0.480 20.00 65.000 65.000 FUSE5 Fuse 46.391 8.8 1.128 52.342 0.600 20.00 300.000 300.000

CB-5 Molded Case 46.391 8.8 1.128 52.342 0.480 20.00 65.000 65.000

CB-1 InsulUnfuse 46.391 8.8 1.057 49.042 0.480 15.00 100.000 100.000

D1 0.480 CB-6 Molded Case 43.954 6.5 1.065 46.806 0.480 20.00 65.000 65.000

CB-7 Molded Case 43.954 6.5 1.065 46.806 0.480 20.00 65.000 65.000 D1A 0.480 5.465 6.4

D1B 0.480 45.165 7.4

D1C 0.480 45.165 7.4

D2 0.480 CB-8 Molded Case 15.519 1.4 1.000 15.519 0.480 20.00 35.000 35.000 D3 0.480 CB-9 Molded Case 12.797 1.1 1.000 12.797 0.480 20.00 65.000 65.000

D4 0.480 36.557 4.1

D5 0.480 CB-10 Molded Case 10.441 1.8 1.000 10.441 0.480 20.00 65.000 65.000 D6 0.480 44.039 7.0

D7 0.480 42.767 5.5

D8 0.480 FUSE7 Fuse 42.556 5.3 1.018 43.321 0.600 20.00 300.000 300.000

FUSE 6 Fuse 42.556 5.3 1.018 43.321 0.600 20.00 300.000 300.000

D9 0.480 CB-11 Molded Case 34.828 2.6 1.000 34.828 0.480 30.00 14.000 14.000 * D10 0.208 CB-12 Molded Case 7.967 3.4 1.000 7.967 0.240 20.00 65.000 65.000

CB-28 Molded Case 7.967 3.4 1.000 7.967 0.240 20.00 65.000 65.000

CB-26 Molded Case 7.967 3.4 1.000 7.967 0.240 20.00 65.000 65.000 CB-22 Molded Case 7.967 3.4 1.013 8.070 0.240 30.00 18.000 18.000

CB-20 Molded Case 7.967 3.4 1.000 7.967 0.240 20.00 65.000 65.000

CB-18 Molded Case 7.967 3.4 1.013 8.070 0.240 30.00 18.000 18.000

CB-24 Molded Case 7.967 3.4 1.013 8.070 0.240 30.00 18.000 18.000

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Interrupting Duty

Int.


(Cy) CPT

D10 CB-16 Molded Case 7.967 3.4 1.013 8.070 0.240 30.00 18.000 18.000

CB-13 Molded Case 7.967 3.4 1.000 7.967 0.240 20.00 65.000 65.000


D13 0.208 CB-25 Molded Case 5.329 1.4 1.000 5.329 0.240 20.00 22.000 22.000

D14 0.208 CB-23 Molded Case 7.075 2.3 1.000 7.075 0.240 20.00 22.000 22.000


D16A 0.208 CB-14 Molded Case 4.372 1.5 1.000 4.372 0.240 20.00 65.000 65.000

CB-16A Molded Case 4.372 1.5 1.000 4.372 0.240 20.00 22.000 22.000

D17 0.208 CB-17 Molded Case 3.415 0.9 1.000 3.415 0.240 20.00 22.000 22.000 D19 0.480 FUSE9 Fuse 42.135 5.0 1.003 42.256 0.600 20.00 300.000 300.000

FUSE 8 Fuse 42.135 5.0 1.003 42.256 0.600 20.00 300.000 300.000

D20 0.480 CB-30 Molded Case 32.736 1.9 1.000 32.736 0.480 30.00 14.000 14.000 * D21 0.208 CB-31 Molded Case 7.960 3.4 1.000 7.960 0.240 20.00 65.000 65.000

CB-41 Molded Case 7.960 3.4 1.000 7.960 0.240 20.00 65.000 65.000

CB-32 Molded Case 7.960 3.4 1.000 7.960 0.240 20.00 65.000 65.000

CB-34 Molded Case 7.960 3.4 1.000 7.960 0.240 20.00 65.000 65.000


D22 0.208 CB-33 Molded Case 7.069 2.3 1.000 7.069 0.240 20.00 22.000 22.000

D23 0.208 CB-35 Molded Case 3.413 0.9 1.000 3.413 0.240 20.00 22.000 22.000

D24 0.208 CB-36A Molded Case 3.413 0.9 1.000 3.413 0.240 20.00 22.000 22.000 D25 0.208 CB-39 Molded Case 4.369 1.5 1.000 4.369 0.240 20.00 65.000 65.000

CB-40 Molded Case 4.369 1.5 1.000 4.369 0.240 20.00 22.000 22.000

D26 0.208 CB-42 Molded Case 4.369 1.5 1.000 4.369 0.240 20.00 65.000 65.000

CB-43 Molded Case 4.369 1.5 1.000 4.369 0.240 20.00 22.000 22.000 D27 0.480 FUSE10 Fuse 41.716 4.7 1.000 41.716 0.600 20.00 300.000 300.000

D28 0.208 2.564 1.1

D29 0.208 CB-48 Molded Case 1.274 0.5 1.000 1.274 0.240 50.00 10.000 10.000

D30 0.208 CB-44 Molded Case 2.877 1.3 1.000 2.877 0.240 20.00 65.000 65.000 CB-46 Molded Case 2.877 1.3 1.000 2.877 0.240 20.00 22.000 22.000

CB-47 Molded Case 2.877 1.3 1.000 2.877 0.240 20.00 22.000 22.000

D31 0.480 CB-45 Molded Case 32.411 1.9 1.000 32.411 0.480 30.00 14.000 14.000 *

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Interrupting Duty

Int.


(Cy) CPT

D32 0.480 FUSE11 Fuse 42.345 5.1 1.010 42.780 0.600 20.00 300.000 300.000

FUSE13 Fuse 42.345 5.1 1.010 42.780 0.600 20.00 300.000 300.000

FUSE12 Fuse 42.345 5.1 1.010 42.780 0.600 20.00 300.000 300.000 D33 0.208 CB-49 Molded Case 6.716 2.3 1.000 6.716 0.240 20.00 65.000 65.000

CB-51 Molded Case 6.716 2.3 1.000 6.716 0.240 30.00 18.000 18.000

CB-52 Molded Case 6.716 2.3 1.000 6.716 0.240 30.00 18.000 18.000


CB-57 Molded Case 6.716 2.3 1.000 6.716 0.240 30.00 18.000 18.000

CB-55 Molded Case 6.716 2.3 1.000 6.716 0.240 30.00 18.000 18.000

CB-53 Molded Case 6.716 2.3 1.000 6.716 0.240 30.00 18.000 18.000 D34 0.208 CB-58 Molded Case 6.005 1.8 1.002 6.020 0.240 50.00 10.000 10.000

D35 0.208 CB-59 Molded Case 6.005 1.8 1.002 6.020 0.240 50.00 10.000 10.000

D36 0.208 CB-60 Molded Case 2.576 0.8 1.000 2.576 0.240 50.00 10.000 10.000

D37 0.208 CB15 Molded Case 3.217 0.9 1.000 3.217 0.240 20.00 65.000 65.000 CB-61 Molded Case 3.217 0.9 1.000 3.217 0.240 50.00 10.000 10.000

D38 0.208 CB-62 Molded Case 1.569 0.6 1.000 1.569 0.240 50.00 10.000 10.000

D39 0.208 CB-63 Molded Case 3.594 1.0 1.000 3.594 0.240 50.00 10.000 10.000

D40 0.208 CB-64 Molded Case 2.652 0.8 1.000 2.652 0.240 50.00 10.000 10.000 D41 0.480 CB-50 Molded Case 34.659 2.6 1.000 34.659 0.480 30.00 14.000 14.000 * D42 0.208 4.797 2.0

D43 0.480 FUSE14 Fuse 41.926 4.8 1.000 41.926 0.600 20.00 300.000 300.000

RL2-FS02 Fuse 41.926 4.8 1.000 41.926 0.600 20.00 200.000 200.000 D44 0.480 CB-66 Molded Case 25.254 1.0 1.000 25.254 0.480 30.00 14.000 14.000 * D45 0.208 CB-67 Molded Case 4.794 2.0 1.000 4.794 0.240 20.00 65.000 65.000

CB-65 Molded Case 4.794 2.0 1.000 4.794 0.240 20.00 65.000 65.000


CB-73 Molded Case 4.794 2.0 1.000 4.794 0.240 30.00 18.000 18.000

D46 0.208 CB-68 Molded Case 4.495 1.8 1.005 4.517 0.240 50.00 10.000 10.000


D49 0.208 CB-74 Molded Case 4.068 1.3 1.000 4.068 0.240 50.00 10.000 10.000

D50 0.480 2.479 0.3

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Interrupting Duty

Int.


(Cy) CPT

D51 0.480 2.417 0.3

D52 0.480 CB-85 Molded Case 9.809 1.0 1.000 9.809 0.480 20.00 65.000 65.000


CB-87 Molded Case 2.874 1.1 1.000 2.874 0.240 50.00 10.000 10.000

D53A 0.480 4.331 0.5


CB91 Molded Case 1.276 1.3 1.000 1.276 0.240 50.00 10.000 10.000

D55A 0.480 5.331 0.6

D56 0.208 CB-92 Molded Case 1.228 1.2 1.000 1.228 0.240 30.00 18.000 18.000 CB-93 Molded Case 1.228 1.2 1.000 1.228 0.240 50.00 10.000 10.000

D57 0.480 CB-94 Molded Case 9.281 1.0 1.000 9.281 0.480 20.00 65.000 65.000

D58 0.208 CB-95 Molded Case 2.600 1.2 1.000 2.600 0.240 20.00 65.000 65.000


D60 0.208 CB-98 Molded Case 2.567 1.2 1.000 2.567 0.240 20.00 65.000 65.000

CB-99 Molded Case 2.567 1.2 1.000 2.567 0.240 50.00 10.000 10.000

D61 0.208 1.772 1.1 D62 0.208 CB-100 Molded Case 1.741 1.1 1.000 1.741 0.240 50.00 10.000 10.000

D63 0.208 1.741 1.1

D64 0.208 1.711 1.1

D65 0.480 11.323 1.1 D66 0.480 9.312 1.1

E 0.480 CB-75 Molded Case 53.889 9.0 1.134 61.089 0.480 20.00 65.000 65.000

CB-77 Molded Case 53.889 9.0 1.134 61.089 0.480 20.00 65.000 65.000


CB-82 Molded Case 53.889 9.0 1.134 61.089 0.480 20.00 65.000 65.000

CB-83 Molded Case 53.889 9.0 1.134 61.089 0.480 20.00 100.000 100.000

CB-84 Molded Case 53.889 9.0 1.134 61.089 0.480 20.00 65.000 65.000 CB-2 InsulUnfuse 53.889 9.0 1.062 57.237 0.480 15.00 100.000 100.000

E1 0.480 CB-76 Molded Case 37.688 3.4 1.000 37.688 0.480 20.00 65.000 65.000

E2 0.480 CB-78 Molded Case 22.197 2.8 1.000 22.197 0.480 20.00 65.000 65.000

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Interrupting Duty

Int.


(Cy) CPT

E3 0.480 CB-80 Molded Case 21.549 2.3 1.000 21.549 0.480 20.00 65.000 65.000

E4 0.480 18.491 1.7

E5 0.480 22.500 4.2 E6 0.480 21.727 4.2

E7 0.480 21.727 4.2

E8 0.480 6.081 0.6

F 0.480 GEN 1 MAIN InsulUnfuse 6.190 14.9 1.142 7.072 0.480 15.00 65.000 65.000 CB-102 Molded Case 6.190 14.9 1.219 7.548 0.480 20.00 65.000 65.000

CB-103 Molded Case 6.190 14.9 1.219 7.548 0.480 20.00 65.000 65.000

CB-101 Molded Case 6.190 14.9 1.219 7.548 0.480 20.00 65.000 65.000

F1 0.480 FUSE16 Fuse 44.756 8.8 1.129 50.521 0.600 20.00 300.000 300.000 CB-111 Molded Case 44.756 8.8 1.129 50.521 0.480 20.00 65.000 65.000

CB-113 Molded Case 44.756 8.8 1.129 50.521 0.480 20.00 65.000 65.000

CB-115 Molded Case 44.756 8.8 1.129 50.521 0.480 20.00 65.000 65.000

CB115A InsulUnfuse 44.756 8.8 1.058 47.335 0.480 15.00 100.000 100.000 F1B 0.480 26.509 2.8

F1E 0.480 26.509 2.8

F2 0.480 44.756 8.8

F3 0.480 CB-113 Molded Case 44.756 8.8 1.129 50.521 0.480 20.00 65.000 65.000 CB-114 Molded Case 44.756 8.8 1.129 50.521 0.480 20.00 35.000 35.000 *

F4 0.480 CB-112 Molded Case 13.161 2.1 1.000 13.161 0.480 20.00 65.000 65.000

F5 0.480 CB-119 Molded Case 25.089 2.6 1.000 25.089 0.480 20.00 65.000 65.000


CB-134 Molded Case 25.089 2.6 1.000 25.089 0.480 20.00 65.000 65.000

CB-138 Molded Case 25.089 2.6 1.000 25.089 0.480 20.00 65.000 65.000


F6 0.480 CB-116 Molded Case 5.815 0.9 1.000 5.815 0.480 20.00 65.000 65.000

F7 0.208 CB-117 Molded Case 2.430 1.2 1.000 2.430 0.240 20.00 65.000 65.000

CB-118 Molded Case 2.430 1.2 1.000 2.430 0.240 50.00 10.000 10.000 F8 0.480 CB-120 Molded Case 5.103 0.8 1.000 5.103 0.480 20.00 65.000 65.000

F9 0.208 CB-121 Molded Case 1.172 1.0 1.000 1.172 0.240 20.00 65.000 65.000

CB-121A Molded Case 1.172 1.0 1.000 1.172 0.240 50.00 10.000 10.000

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(Cy) CPT

F10 0.480 CB-123A Molded Case 11.046 1.1 1.000 11.046 0.480 20.00 100.000 100.000

F11 0.208 CB-125 Molded Case 2.650 1.3 1.000 2.650 0.240 20.00 65.000 65.000


F13 0.208 CB-128 Molded Case 1.224 1.1 1.000 1.224 0.240 20.00 65.000 65.000

CB-129 Molded Case 1.224 1.1 1.000 1.224 0.240 50.00 10.000 10.000

F14 0.208 CB-131 Molded Case 3.250 0.7 1.000 3.250 0.240 20.00 65.000 65.000 F14A 0.480 8.378 0.6

F15 0.208 CB-132 Molded Case 3.026 0.6 1.000 3.026 0.240 30.00 18.000 18.000

CB-133 Molded Case 3.026 0.6 1.000 3.026 0.240 50.00 10.000 10.000


F17 0.208 CB-136 Molded Case 2.274 0.9 1.000 2.274 0.240 30.00 18.000 18.000

CB-137 Molded Case 2.274 0.9 1.000 2.274 0.240 50.00 10.000 10.000


F19 0.208 CB-140 Molded Case 2.526 1.0 1.000 2.526 0.240 20.00 65.000 65.000

CB-141 Molded Case 2.526 1.0 1.000 2.526 0.240 50.00 10.000 10.000

F20 0.208 CB-143 Molded Case 3.045 1.1 1.000 3.045 0.240 20.00 65.000 65.000 CB-144 Molded Case 3.045 1.1 1.000 3.045 0.240 50.00 10.000 10.000

F20A 0.480 5.374 0.5

F21 0.208 CB-146 Molded Case 1.274 1.1 1.000 1.274 0.240 30.00 18.000 18.000

CB-147 Molded Case 1.274 1.1 1.000 1.274 0.240 50.00 10.000 10.000 F22 0.480 41.236 2.7

F23 0.480 39.848 2.5

F24 0.480 FUSE18 Fuse 39.399 2.4 1.000 39.399 0.600 20.00 200.000 200.000

FUSE17 Fuse 39.399 2.4 1.000 39.399 0.600 20.00 300.000 300.000 FUSE19 Fuse 39.399 2.4 1.000 39.399 0.600 20.00 200.000 200.000

F25 0.480 CB-148 Molded Case 30.047 1.4 1.000 30.047 0.480 30.00 14.000 14.000 * F26 0.480 CB-149 Molded Case 36.301 2.3 1.000 36.301 0.480 30.00 14.000 14.000 * F27 0.208 CB-153 Molded Case 6.670 2.2 1.000 6.670 0.240 20.00 65.000 65.000

CB-150 Molded Case 6.670 2.2 1.000 6.670 0.240 20.00 65.000 65.000

CB-151 Molded Case 6.670 2.2 1.000 6.670 0.240 20.00 65.000 65.000

F27A 0.480 FUSE20 Fuse 38.956 2.4 1.000 38.956 0.600 20.00 300.000 300.000

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(Cy) CPT

F27A FUSE21 Fuse 38.956 2.4 1.000 38.956 0.600 20.00 200.000 200.000

F28 0.208 CB-152 Molded Case 3.231 1.2 1.000 3.231 0.240 50.00 10.000 10.000

F29 0.208 CB-154 Molded Case 5.647 1.6 1.000 5.647 0.240 50.00 10.000 10.000 F30 0.480 CB-155 Molded Case 31.730 1.6 1.000 31.730 0.480 30.00 14.000 14.000 * F31 0.208 CB12 Molded Case 4.701 1.6 1.000 4.701 0.240 20.00 65.000 65.000

CB-156 Molded Case 4.701 1.6 1.000 4.701 0.240 50.00 10.000 10.000

F32 0.480 FUSE22 Fuse 38.519 2.3 1.000 38.519 0.600 20.00 300.000 300.000 FUSE23 Fuse 38.519 2.3 1.000 38.519 0.600 20.00 300.000 300.000

F33 0.208 CB-157 Molded Case 1.283 1.0 1.000 1.283 0.240 50.00 10.000 10.000

CB18 Molded Case 1.283 1.0 1.000 1.283 0.240 30.00 18.000 18.000

F34 0.480 CB-158 Molded Case 26.080 1.0 1.000 26.080 0.480 30.00 14.000 14.000 * F35 0.480 FUSE24 Fuse 39.176 2.4 1.000 39.176 0.600 20.00 300.000 300.000

FUSE25 Fuse 39.176 2.4 1.000 39.176 0.600 20.00 300.000 300.000

FUSE26 Fuse 39.176 2.4 1.000 39.176 0.600 20.00 300.000 300.000

F36 0.480 CB-160 Molded Case 29.774 1.2 1.000 29.774 0.480 30.00 14.000 14.000 * F37 0.480 CB-161 Molded Case 20.561 0.8 1.000 20.561 0.480 30.00 14.000 14.000 * F38 0.208 5.766 2.0

F39 0.208 CB-159 Molded Case 5.766 2.0 1.000 5.766 0.240 20.00 65.000 65.000


CB-167 Molded Case 5.766 2.0 1.000 5.766 0.240 20.00 100.000 100.000

CB-168 Molded Case 5.766 2.0 1.000 5.766 0.240 20.00 100.000 100.000

F40 0.208 CB-162 Molded Case 5.482 1.8 1.003 5.497 0.240 50.00 10.000 10.000 F41 0.208 CB-163 Molded Case 5.091 1.6 1.000 5.091 0.240 50.00 10.000 10.000

F42 0.208 CB8 Molded Case 3.174 1.0 1.000 3.174 0.240 20.00 65.000 65.000

CB-164 Molded Case 3.174 1.0 1.000 3.174 0.240 50.00 10.000 10.000

F43 0.208 5.336 1.8 F44 0.480 FUSE27 Fuse 38.519 2.3 1.000 38.519 0.600 20.00 300.000 300.000

FUSE29 Fuse 38.519 2.3 1.000 38.519 0.600 20.00 300.000 300.000

FUSE28 Fuse 38.519 2.3 1.000 38.519 0.600 20.00 300.000 300.000

F45 0.480 CB-169 Molded Case 16.888 1.2 1.000 16.888 0.480 30.00 14.000 14.000 * F46 0.208 CB-170 Molded Case 10.194 3.4 1.000 10.194 0.240 20.00 65.000 65.000

CB-174 Molded Case 10.194 3.4 1.000 10.194 0.240 20.00 65.000 65.000

CB-173 Molded Case 10.194 3.4 1.000 10.194 0.240 20.00 65.000 65.000

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(Cy) CPT

F46 CB-171 Molded Case 10.194 3.4 1.000 10.194 0.240 20.00 65.000 65.000

CB-172 Molded Case 10.194 3.4 1.000 10.194 0.240 20.00 65.000 65.000

F46A 0.480 24.863 1.8 F47 0.208 4.502 1.3

F48 0.208 8.685 2.4

F49 0.208 7.872 2.1


F52 0.208 CB-180 Molded Case 7.566 2.9 1.000 7.566 0.240 20.00 22.000 22.000

F53 0.208 CB-182 Molded Case 3.811 1.0 1.000 3.811 0.240 20.00 22.000 22.000


CB-179 Molded Case 7.901 3.2 1.000 7.901 0.240 20.00 65.000 65.000

CB-177 Molded Case 7.901 3.2 1.000 7.901 0.240 20.00 65.000 65.000


CB-191 Molded Case 51.587 8.2 1.115 57.526 0.480 20.00 65.000 65.000

C-196 Molded Case 51.587 8.2 1.115 57.526 0.480 20.00 65.000 65.000


CB-214 Molded Case 51.587 8.2 1.115 57.526 0.480 20.00 65.000 65.000

CB-213 Molded Case 51.587 8.2 1.115 57.526 0.480 20.00 65.000 65.000

CB-115B InsulUnfuse 51.587 8.2 1.045 53.899 0.480 15.00 100.000 100.000 F55A 0.480 10.552 1.0

F55B 0.480 11.323 1.1

F55D 0.480 27.122 1.6

F55E 0.480 29.362 2.7 F55G 0.480 34.001 2.9

F56 0.480 CB-185 Molded Case 25.101 1.5 1.000 25.101 0.480 20.00 65.000 65.000

CB-187 Molded Case 25.101 1.5 1.000 25.101 0.480 20.00 65.000 65.000


F58 0.480 CB-188 Molded Case 6.298 0.8 1.000 6.298 0.480 20.00 65.000 65.000

F59 0.480 CB-190 Molded Case 9.529 0.9 1.000 9.529 0.480 20.00 100.000 100.000

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(Cy) CPT

F60 0.480 CB-194 Molded Case 27.733 2.6 1.000 27.733 0.480 20.00 65.000 65.000

CB-192 Molded Case 27.733 2.6 1.000 27.733 0.480 20.00 65.000 65.000


F63 0.480 CB-197 Molded Case 32.480 2.7 1.000 32.480 0.480 20.00 65.000 65.000

CB-198 Molded Case 32.480 2.7 1.000 32.480 0.480 20.00 65.000 65.000

F64 0.480 9.878 1.8 F65 0.480 CB-199 Molded Case 17.654 1.5 1.000 17.654 0.480 20.00 65.000 65.000

F66 0.480 12.334 1.0

F67 0.480 27.122 1.6

F68 0.480 29.362 2.7 F69 0.480 34.001 2.9

F70 0.208 CB-201 Molded Case 10.826 4.0 1.000 10.826 0.240 20.00 65.000 65.000

CB-205 Molded Case 10.826 4.0 1.000 10.826 0.240 20.00 65.000 65.000


CB-212 Molded Case 10.826 4.0 1.000 10.826 0.240 20.00 65.000 65.000

CB202 Molded Case 10.826 4.0 1.000 10.826 0.240 20.00 65.000 65.000

F70A 0.480 44.755 5.0 F70B 0.208 11.011 4.1

F71 0.208 CB-203 Molded Case 3.478 1.2 1.000 3.478 0.240 20.00 65.000 65.000

CB-204 Molded Case 3.478 1.2 1.000 3.478 0.240 20.00 22.000 22.000


F73 0.208 CB-209 Molded Case 9.095 3.3 1.000 9.095 0.240 20.00 65.000 65.000

CB-210 Molded Case 9.095 3.3 1.000 9.095 0.240 20.00 22.000 22.000

F74 0.208 6.347 1.7 F75 0.208 7.828 2.9

F76 0.208 CB-243 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000

CB-240 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000


CB-231 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000

CB-228 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000

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(Cy) CPT

F76 CB-225 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000

CB-222 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000


CB-216 Molded Case 10.672 3.9 1.000 10.672 0.240 20.00 65.000 65.000

F76A 0.480 39.368 3.8

F76B 0.208 10.852 4.0 F77 0.208 CB-244 Molded Case 1.718 0.6 1.000 1.718 0.240 20.00 65.000 65.000

CB-245 Molded Case 1.718 0.6 1.000 1.718 0.240 20.00 22.000 22.000

F78 0.208 CB-241 Molded Case 1.992 0.6 1.000 1.992 0.240 20.00 65.000 65.000


CB-239 Molded Case 1.788 0.6 1.000 1.788 0.240 20.00 22.000 22.000

F80 0.208 CB-235 Molded Case 3.633 0.8 1.000 3.633 0.240 20.00 65.000 65.000


CB-233 Molded Case 2.088 0.6 1.000 2.088 0.240 20.00 22.000 22.000

F82 0.208 CB-229 Molded Case 5.037 1.0 1.000 5.037 0.240 20.00 65.000 65.000


CB-227 Molded Case 2.139 0.6 1.000 2.139 0.240 20.00 22.000 22.000

F84 0.208 CB-223 Molded Case 3.170 1.1 1.000 3.170 0.240 20.00 65.000 65.000

CB-224 Molded Case 3.170 1.1 1.000 3.170 0.240 20.00 22.000 22.000 F85 0.208 CB219 Molded Case 4.614 1.3 1.000 4.614 0.240 20.00 65.000 65.000

CB-220 Molded Case 4.614 1.3 1.000 4.614 0.240 20.00 22.000 22.000

F86 0.208 3.541 1.2

F87 13.800 AL1 HV FUSE A Fuse 16.571 3.1 1.000 16.571 15.500 6.65 29.400 29.400 F88 13.800 AL1 HV FUSE B Fuse 16.466 3.1 1.000 16.466 15.500 6.65 29.400 29.400

F89 0.480 6.111 11.9

F90 0.480 6.134 13.6

F91 0.480 5.936 6.8 F92 0.480 6.033 9.9

F93 0.480 6.183 14.7

F94 0.480 6.169 14.2

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Int.


(Cy) CPT

F95 0.480 4.162 2.5

F96 0.480 4.228 2.5

F97 0.480 1.685 0.5 F100 0.480 51.587 8.2

G 0.480 CB-107 Molded Case 6.204 15.2 1.222 7.585 0.480 20.00 65.000 65.000

CB-108 Molded Case 6.204 15.2 1.222 7.585 0.480 20.00 65.000 65.000


GEN 2 MAIN InsulUnfuse 6.204 15.2 1.145 7.106 0.480 15.00 65.000 65.000

CB-105 Molded Case 6.204 15.2 1.222 7.585 0.480 20.00 65.000 65.000

GEN 1 BUS 0.480 CB-GEN1 Molded Case 6.335 19.0 1.252 7.931 0.480 20.00 85.000 85.000 GEN 2 BUS 0.480 CB-GEN2 Molded Case 6.335 19.0 1.252 7.931 0.480 20.00 85.000 85.000

GEN 3 BUS 0.480 CB-GEN3 Molded Case 6.335 19.0 1.252 7.931 0.480 20.00 85.000 85.000

H 0.480 CB-109 Molded Case 6.219 15.6 1.226 7.622 0.480 20.00 65.000 65.000

CB-110 Molded Case 6.219 15.6 1.226 7.622 0.480 20.00 65.000 65.000 GEN 3 MAIN InsulUnfuse 6.219 15.6 1.148 7.141 0.480 15.00 65.000 65.000

I1 13.800 FUSE30 Fuse 16.493 3.1 1.000 16.493 15.500 6.65 29.400 29.400

I2 13.800 FUSE31 Fuse 16.390 3.1 1.000 16.390 15.500 6.65 29.400 29.400

I3 0.480 FUSE 32 Fuse 43.112 9.0 1.133 48.842 0.600 20.00 300.000 300.000 CB-287 Molded Case 43.112 9.0 1.133 48.842 0.480 20.00 65.000 65.000

CB-246 InsulUnfuse 43.112 9.0 1.061 45.762 0.480 15.00 100.000 100.000

I4 0.480 42.076 8.0

I5 0.480 40.944 6.1 I6 0.480 FUSE34 Fuse 40.568 5.7 1.034 41.955 0.600 20.00 300.000 300.000

FUSE 33 Fuse 40.568 5.7 1.034 41.955 0.600 20.00 300.000 300.000

I7 0.480 CB-248 Molded Case 28.442 1.3 1.000 28.442 0.480 30.00 14.000 14.000 * I8 0.208 CB25 Molded Case 1.286 1.1 1.000 1.286 0.240 30.00 18.000 18.000

CB-249 Molded Case 1.286 1.1 1.000 1.286 0.240 50.00 10.000 10.000

I9 0.480 FUSE35 Fuse 40.193 5.3 1.019 40.944 0.600 20.00 300.000 300.000

FUSE36 Fuse 40.193 5.3 1.019 40.944 0.600 20.00 300.000 300.000

I10 0.480 CB-250 Molded Case 33.663 2.4 1.000 33.663 0.480 30.00 14.000 14.000 * I11 0.208 CB-251 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000

CB-257 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000

CB-258 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000

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Interrupting Duty

Int.


(Cy) CPT

I11 CB-259 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000

CB-260 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000

CB-261 Molded Case 10.880 4.2 1.000 10.880 0.240 20.00 65.000 65.000 I12 0.208 CB-256 Molded Case 9.220 2.7 1.000 9.220 0.240 20.00 22.000 22.000

I13 0.208 CB-255 Molded Case 5.125 1.4 1.000 5.125 0.240 20.00 22.000 22.000

I14 0.208 CB-254 Molded Case 2.260 0.6 1.000 2.260 0.240 20.00 22.000 22.000

I15 0.208 CB-253 Molded Case 5.125 1.4 1.000 5.125 0.240 20.00 22.000 22.000 I16 0.208 CB21 Molded Case 3.988 0.8 1.000 3.988 0.240 20.00 65.000 65.000

CB-252 Molded Case 3.988 0.8 1.000 3.988 0.240 20.00 22.000 22.000

I17 0.480 FUSE37 Fuse 39.819 5.0 1.004 39.993 0.600 20.00 300.000 300.000


CB-263 Molded Case 5.784 2.0 1.000 5.784 0.240 20.00 65.000 65.000

CB-266 Molded Case 5.784 2.0 1.000 5.784 0.240 20.00 100.000 100.000

I20 0.208 CB-265 Molded Case 2.636 0.8 1.000 2.636 0.240 50.00 10.000 10.000 I21 0.208 CB-267 Molded Case 4.989 1.6 1.000 4.989 0.240 50.00 10.000 10.000

I22 0.480 FUSE41 Fuse 39.447 4.7 1.000 39.447 0.600 20.00 300.000 300.000

FUSE38 Fuse 39.447 4.7 1.000 39.447 0.600 20.00 200.000 200.000

FUSE39 Fuse 39.447 4.7 1.000 39.447 0.600 20.00 200.000 200.000 FUSE40 Fuse 39.447 4.7 1.000 39.447 0.600 20.00 200.000 200.000

I23 0.480 CB-268 Molded Case 29.565 2.3 1.000 29.565 0.480 30.00 14.000 14.000 * I24 0.208 9.200 2.7

I25 0.208 9.200 2.7 I26 0.208 CB-273 Molded Case 10.056 2.9 1.000 10.056 0.240 20.00 22.000 22.000

I27 0.208 CB-271 Molded Case 5.379 1.0 1.000 5.379 0.240 20.00 22.000 22.000

I29 0.208 CB-278 Molded Case 6.979 2.6 1.055 7.364 0.240 50.00 10.000 10.000

I30 0.208 CB-280 Molded Case 3.120 1.2 1.000 3.120 0.240 20.00 65.000 65.000 CB-281 Molded Case 3.120 1.2 1.000 3.120 0.240 20.00 22.000 22.000

I31 0.208 CB-283 Molded Case 6.979 2.6 1.055 7.364 0.240 50.00 10.000 10.000

I32 0.480 CB-276A Molded Case 31.351 1.6 1.000 31.351 0.480 30.00 14.000 14.000 * I33 0.480 FUSE42 Fuse 40.380 5.5 1.026 41.442 0.600 20.00 300.000 300.000

FUSE43 Fuse 40.380 5.5 1.026 41.442 0.600 20.00 300.000 300.000

I34 0.208 CB284 Molded Case 1.286 1.1 1.000 1.286 0.240 30.00 18.000 18.000

CB-285 Molded Case 1.286 1.1 1.000 1.286 0.240 50.00 10.000 10.000

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Interrupting Duty

Int.


(Cy) CPT



CB-290 Molded Case 7.080 2.2 1.000 7.080 0.240 20.00 65.000 65.000

I36A 0.480 CB-288 Molded Case 13.040 1.8 1.000 13.040 0.480 20.00 65.000 65.000

I37 0.208 CB-292 Molded Case 6.669 1.9 1.011 6.743 0.240 50.00 10.000 10.000 I38 0.208 CB-293 Molded Case 5.938 1.6 1.000 5.938 0.240 50.00 10.000 10.000

I39 0.208 CB-294 Molded Case 5.322 1.4 1.000 5.322 0.240 50.00 10.000 10.000

I40 0.208 CB-295 Molded Case 4.805 1.2 1.000 4.805 0.240 50.00 10.000 10.000

I41 0.208 1.583 0.6 I42 0.208 1.541 0.6

I43 0.208 CB-297 Molded Case 1.489 0.6 1.000 1.489 0.240 50.00 10.000 10.000

I44 0.480 CB-247 InsulUnfuse 51.629 8.3 1.046 53.982 0.480 15.00 100.000 100.000

FIRE PUMP BKR N Molded Case 51.629 8.3 1.116 57.615 0.480 20.00 65.000 65.000 I44A 0.480 2.479 0.3

I45 0.480 CB-299 Molded Case 23.847 2.5 1.000 23.847 0.480 20.00 65.000 65.000

I46 0.480 4.647 0.6

I47 0.480 5.649 0.6 I48 0.480 25.572 1.5

I49 0.480 CB-304 Molded Case 15.358 2.2 1.000 15.358 0.480 20.00 65.000 65.000

I50 0.480 CB-303 Molded Case 51.629 8.3 1.116 57.615 0.480 20.00 65.000 65.000


CB-300 Molded Case 51.629 8.3 1.116 57.615 0.480 20.00 65.000 65.000

CB-298 Molded Case 51.629 8.3 1.116 57.615 0.480 20.00 65.000 65.000

CB-305 Molded Case 51.629 8.3 1.116 57.615 0.480 20.00 65.000 65.000 CB-247 InsulUnfuse 51.629 8.3 1.046 53.982 0.480 15.00 100.000 100.000

I51 0.208 2.808 0.8

I52 0.208 3.613 0.8

I53 0.208 6.476 1.0 I54 0.208 6.476 1.0

I55 0.208 5.269 0.9

I56 0.208 8.953 1.1

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Int.


(Cy) CPT

I57 0.208 5.059 0.9

I58 0.208 8.654 1.1

I59 0.208 8.654 1.1 I60 0.208 CB-307 Molded Case 24.527 5.5 1.025 25.151 0.240 20.00 65.000 65.000

CB-314 Molded Case 24.527 5.5 1.025 25.151 0.240 20.00 65.000 65.000

CB-312 Molded Case 24.527 5.5 1.025 25.151 0.240 20.00 65.000 65.000


CB-311 Molded Case 24.527 5.5 1.025 25.151 0.240 20.00 65.000 65.000

CB-309 Molded Case 24.527 5.5 1.025 25.151 0.240 20.00 65.000 65.000


CB-306 InsulUnfuse 24.527 5.5 1.000 24.527 0.240 15.00 100.000 100.000

I60A 0.480 43.419 5.1

I60B 0.208 24.851 5.6 I61 0.208 CB-269 Molded Case 10.855 4.1 1.000 10.855 0.240 20.00 65.000 65.000

CB-272 Molded Case 10.855 4.1 1.000 10.855 0.240 20.00 65.000 65.000

CB-274 Molded Case 10.855 4.1 1.000 10.855 0.240 20.00 65.000 65.000


I62 0.208 CB-279 Molded Case 7.916 3.4 1.000 7.916 0.240 20.00 65.000 65.000

CB-282 Molded Case 7.916 3.4 1.000 7.916 0.240 20.00 65.000 65.000


Method: IEEE - X/R is calculated from separate R & X networks. HV CB interrupting capability is adjusted based on bus nominal voltage

Generator protective device duty is calculated based on maximum through fault current. Other protective device duty is calculated based on total fault current. Short-circuit multiplying factor for LV Molded Case and Insulated Case Circuit Breakers is calculated based on asymmetrical current.

* Indicates a device with interrupting duty exceeding the device capability ** Indicates that the circuit breaker has been flagged as a generator circuit breaker. However, ETAP could not detect a single path, without a transformer, to the specified generator. Therefore, this circuit breaker is treated as a regular circuit breaker in short-circuit calculations. + The prefault voltage exceeds the rated maximum kV limit of the circuit breaker - The rated interrupting kA must be derated.

134

Appendix D: Coordination curves

CB-6Cutler-HammerHMDLSize = 800 AmpsThermal Trip = FixedMagnetic Trip = 5

CBL-51 - P

CB-7Cutler-HammerHKDSize = 400 AmpsThermal Trip = FixedMagnetic Trip = 6.25

CBL-52 - P

CB-8Cutler-HammerJDSize = 150 AmpsThermal Trip = FixedMagnetic Trip = 10

CB-9Cutler-HammerHFD (2,3,4P)Size = 30 AmpsThermal Trip = Fixed

CBL-6 - P

D3 D1

CB-8 - 3P

CB-9 - 3P

CB-7 - 3P

CB-6 - 3P

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 10 D3 (Nom. kV=0.48, Plot Ref. kV=0.48)

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 10 D3 (Nom. kV=0.48, Plot Ref. kV=0.48)

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Sec

onds

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Seconds

ETAP Star 12.0.0C

D1

D2

D3

CB-9

CBL-52

3-1/C 1/0

CB-8

CBL-51

6-1/C 3/0

CB-7

CB-6

CBL-6

9-1/C 300

ATS-D1

CB-115BCutler-Hammer RMS 510 Series SPBSensor = 4000 Plug = 4000 AmpsLT Pickup = 1 (4000 Amps)LT Band = 24ST Pickup = 2 (8000 Amps)ST Band = .3 (I^x)t = INOverride = 65000 Amps

C-196Cutler-Hammer RMS 310 N (LSIG)Frame = 800 Plug = 800 AmpsLT Pickup = Fixed (800 Amps)LT Band = FixedST Pickup = 7X (5600 Amps)ST Band = 200Override = 14000 Amps

CB-115B - 3PC-196 - 3P

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 100 F55 (Nom. kV=0.48, Plot Ref. kV=0.48)

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 100 F55 (Nom. kV=0.48, Plot Ref. kV=0.48)

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Sec

onds

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Seconds

ETAP Star 12.0.0C

F55

CB-115B

C-196

CBL-168 - PCB-217Cutler-HammerFD (2,3,4P)Size = 225 AmpsThermal Trip = FixedMagnetic Trip = Fixed

CBL-169 - P

CB-216Cutler-Hammer RMS 310 N (LSG)Frame = 1250 Plug = 1000 AmpsLT Pickup = Fixed (1000 Amps)LT Band = FixedST Pickup = 5X (5000 Amps)ST Band = Fixed (I^x)t = INOverride = 14000 Amps

CB-215Cutler-Hammer RMS 310 N (LSIG)Frame = 800 Plug = 600 AmpsLT Pickup = Fixed (600 Amps)LT Band = FixedST Pickup = 8X (4800 Amps)ST Band = 200Override = 14000 Amps

TRANS 32Inrush

TRANS 32FLA F76

TRANS 32

CB-216 - 3PCB-217 - 3P CB-215 - 3P

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 100 F76A (Nom. kV=0.48, Plot Ref. kV=0.48)

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K


1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Sec

onds

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Seconds

ETAP Star 12.0.0C

F55

F76

CB-217

CB-216

CBL-169

9-1/C 400

CB-215

CBL-168

3-1/C 350

TRANS 32

300 kVA

TRANS 35

TRANS 35Inrush

CB-263Cutler-HammerLDSize = 350 AmpsThermal Trip = FixedMagnetic Trip = 6.25

CB-267Cutler-HammerQuicklag LowMag (1P)Size = 20 AmpsThermal Trip = FixedMagnetic Trip = Fixed

CB-266Cutler-HammerHFD (2,3,4P)Size = 150 AmpsThermal Trip = Fixed

CBL-77 - P

I21 I19

FUSE37

FUSE37 - 3P

TRANS 35FLA

CB-267 - 3P

CB-266 - 3P

FUSE37 - 3P

CB-263 - 3P

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 10 I21 (Nom. kV=0.208, Plot Ref. kV=0.208)

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K

Amps X 10 I21 (Nom. kV=0.208, Plot Ref. kV=0.208)

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Sec

onds

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Seconds

ETAP Star 12.0.0C

I21

I19

FUSE37

TRANS 35113 kVA

CB-263

CB-266

CBL-77

3-1/C 1/0

CB-267

TRANS 31FLA

CBL-180 - P

CB-201Cutler-HammerLDSize = 500 AmpsThermal Trip = FixedMagnetic Trip = 10

TRANS 31

TRANS 31Inrush

CBL-181 - P

CB-211Cutler-HammerJDSize = 225 AmpsThermal Trip = FixedMagnetic Trip = 10

CBL-184 - P

CB-200Cutler-Hammer RMS 310 N (LSIG)Frame = 800 Plug = 600 AmpsLT Pickup = Fixed (600 Amps)LT Band = FixedST Pickup = 8X (4800 Amps)ST Band = 200Override = 14000 Amps

F70

CB-200 - 3P

CB-211 - 3P

CB-201 - 3P

10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K


10K.5 1 10 100 1K3 5 30 50 300 500 3K 5K


1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Sec

onds

1K

.01

.1

1

10

100

.03

.05

.3

.5

3

5

30

50

300

500

Seconds

ETAP Star 12.0.0C

F74

F70

CB-200

CBL-180

6-1/C 350

TRANS 31

300 kVA

CBL-181

9-1/C 400

CB-201

CB-211

CBL-184

3-1/C 4/0

Applying optimization methods to reduce arc flash in low voltage ...

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