B4 - NEMA device Numbers

Protection SkillsFor Electricians

Electrical Industry Training Centre

TABLE OF CONTENTS

Introduction ...................................................................................................2

Learning Tasks

1-Explain the Importance of the Device Identification Number ...........................32 -Read the BC Hydro Device Identification Number ..........................................43-Select Device Identification Numbers Applicable to Local Area Needs ...........8

Self Tests

Self Test Questions ...............................................................................................9Self Test Answers ..................................................................................................10

Performance Activities

1-Identify and Interpret Selected Components ......................................................11

Resources

1-List of NEMA Numbers and their Complete Description .................................132 -Protection Information Sheet for a Substation ..................................................153-Schematic for Performance Activity ..................................................................174-List of Relays Commonly Used by BC Hydro with Device Designation ..........195-Systems Operations and Maintenance Standard (Protection and Control) ........23


Unit B-4 Use NEMA Device Numbers

INTRODUCTION

BC Hydro's device identification system allows you to identify the type, location and function of devices on schematics and wiring diagrams. Being able to quickly identify devices will enhance your troubleshooting skills.

Page 4 BC hWdro

L E A R N I N G T A S K 1

EXPLAIN THE IMPORTANCE OF THE DEVICE IDENTIFICATIONNUMBER

The device identification number is a numbering system that identifies devices on BC Hydro schematics and wiring diagrams. Figure 1 shows a typical example of a complete device identification number as you would see it on a BC Hydro drawing. We have added the shading and labels to show that the number is a composite of a NEMA number (North American. Electrical Manufacturer's Association) and BC Hydro designation extensions.

Fig. 1 BC Hydro's device identification number is acomposite of a NEMA number and BC Hydro extensions

Although all BC Hydro drawings use the above device identification system, be aware that manufacturers often use ISO (International Standards Organization) standards on their schematics and wiring diagrams.

NORTH AMERICAN STANDARD

NEMA numbers are the standards from the North American Electrical Manufacturer's Association. These standards have superseded the WEE (Institute of Electrical and Electronic Engineers) standards.

Importance to Electricians

It is important that you be able to read BC Hydro device identification numbers in order to correctly identify electrical devices. This numbering system gives complete information as to the device's location, it's type and the item number on the bill of materials.


LEARNING TASK 2

READ THE BC HYDRO DEVICE IDENTIFICATION NUMBER

The device identification number is made up of four parts (See Fig. 1). With this information you can access other drawings, and locate the device in the field.

Fig. I The four parts of a device identification number.

DEVICE DESIGNATION

The device designation is made up of two parts: the NEMA number and an extension.

NEMA Number

In the example in Figure 2, "85" is the NEMA number. This number is part of a standard numbering system that goes from 1 to 99 (See Table 1 on page 7).

Common NEMA numbers that pertain to protection and control in substations and generating stations are:

1 Master element3 Checking or interlocking relay

21 Distance relay27 Undervoltage relay43 Manual transfer or selector device50 Instantaneous overcurrent or rate-of-rise relay


51 AC timed overcurrent relay52 AC circuit breaker63 Pressure switch70 Rheostat81 Frequency relay86 Locking-out relay87 Differential protective relay89 Line switch90 Regulating device

Resource B4-1 contains a complete description of all 99 NEMA numbers.

Extension

After the NEMA number, BC Hydro adds letter and number extensions to further identify and locate the device. For example, numbering the protection device "85LTTXS" provides a complete description of the relay, its function and what type of equipment it protects. Table 2 on page 8 gives a complete breakdown of the device designation number.

ITEM NUMBER ON THE BILL OF MATERIALS

The item number refers to the item number on the bill of materials. During the original construction, a bill of materials was compiled that identified all components, devices and equipment. The item number can be enclosed in a half moon, rectangle, square, or it can be simply be the number by itself.

In the example in Figure 2, the device is number 35 on the bill of materials.

Device Location

The device location number tells you in which panel this device is located; whether in the front (F) or in the rear (R). In the example in Figure 2, the device is located on the front of panel 12.

DEVICE TYPE

The device type is the manufacturer's make or model number. This allows you to identify each device type, make, and model.


Table 1 List of NEMA Numbers

1. Master element2. Time-Delay starting or closing relay3. Checking or interlocking relay4. Master Contractor5. Stopping device6. Starting circuit breaker7. Anode Circuit Breaker8. Control power disconnecting device9. Reversing device10. Unit sequence switch11. Reserved for future application12. Over-speed drive13. Synchronous-speed device14. Under-speed device15. Speed or frequency matching device16. Reserved for future application17. Shunting or discharge switch18. Accelerating or decelerating switch19. Starting-to-running transition contactor20. Electrically operated valve21. Distance relay22. Equalizer circuit breaker23. Temperature control device24. Reserved for future application 25. Synchronizing or synchronism-check device26. Apparatus thermal device27. Undervoltage relay28. Flame detector29. Isolating contractor 30. Annunciator Relay 31. Separate excitation device32. Directional power relay

33. Position switch34. Master sequence device35. Brush-operating or slip-ring shirt-circuiting device36. Polarity or polarizing voltage device37. Undercurrent or underpower relay38. Bearing protective device39. Mechanical condition motor40. Field relay41. Field circuit breaker42. Running circuit breaker43. Manual transfer or selector device44. Unit sequence starting relay 45. Atmospheric condition monitor46. Reverse-phase or phase-balance current relay47. Phase-sequence voltage relay 48. Incomplete sequence relay 49. Machine or transformer thermal relay50. Instantaneous overcurrent or rate-of-rise relay51. AC time overcurrent relay52. AC circuit breaker53. Exciter or DC generator relay 54. Reserved for future application55. Power factor relay56.Field application relay 57.Short-circuiting or grounding device58. Rectification failure relay59. Overvoltage relay 60. Voltage or current balance relay 61. Reserved for future application62. Time-delay stopping or opening relay63. Pressure switch

64. Ground protective relay65. Governor66. Notching or jogging device67. AC directional overcurrent relay 68. Blocking relay69. Permissive control device70. Rheostat71. Level switch72. DC circuit breaker73. Load-resistor contractor74. Alarm relay 75. Position changing machine 76. DC overcurrent relay77. Pulse transmitter78. Phase-angle measuring or out-of-step protective relay79. AC reclosing relay 80. Flow switch81. Frequency relay82. DC reclosing relay 83. Automatic selective control or transfer relay84. Operating mechanism85. Carrier or pilot-wire receiver relay86. Locking-out relay 87. Differential protective relay 88. Auxiliary motor or motor generator89. Line switch90. Regulating device91. Voltage directional relay92. Voltage and power directional relay93. Field-changing 94. Tripping or trip-free relay


Table 2 BC Hydro Device Designation System

A B

C D E


This extension indicates the type of equipment that the device protects of controls.

B BusBF Breaker FailureC Capacitor (not CX)G GeneratorGT Grounding L Line M Motor NR Neutral reactor (not NRX)R Reactor (not RX)SS Station service transformerT TransformerVR Voltage regulator TC Tap changerHF Harmonic Filters (DC)ET Exciter Transformer

This extension further clarif ies the equipment’s operation by indicating the phase, zone or transfer trip, medium/phase.-mult i -phase, mult i -zone, mult i function.

A A phaseB B phaseC C phaseN Neutral (residual ground)G Ground (51TG, formerly 151TN) or gas (63TG)1 Zone 1 ( less than 100%of l ine)2 Zone 2 ( greater than 100% of the l ine 3 Zone 3 (greater than zone 2 of some protection)TT transfer tripQ QualitrolQA Oil 71TQA on A phase s imilar for B, C and N phasesGA Gas 63TGA on A phase s imilar for B, C and N phasesOS out of stepSP Spl i t phaseFF Field fai lure F Fire

This extension indicates the type of function served by the relay, whether as a t imer, reverse direct ional relay, auxi l iary, or a blocking relay.

T Timer (t ime delay relay, e .g .21L3R-T)R reverse (e .g . 21L3R is a distance, l ine, third zone, reverse relay)X Auxil iary (e .g. 85LTTXis a permissive, l ine, transfer trip, auxi l iary relay)B Blocking (e .g. 79LB is a reclosing, l ine, blocking relay

This extension designates the devices as primary or standby device is used as a backup for the primary device. (There is no added extension used i f the device primary)

- Primary (e .g. 21L2 is a forward distance, l ine relay, zone 2, primary protection relay)S Standby (e .g. 21L2Sis a forward distance, l ine relay, zone 2, standby protection relay)

This extension is used as a “catch al l” . The l ist wil l be reduced when the HZ relay is replaced.

-T Timed element (e .g.51TS-T CO-9 t imed element f lag)-I Instantaneous element (e .g. 32LNS-ICYL instantaneous direction)-D Direction element (e .g. 32Ln-D SRG2H)-P Permissive trip f lag (e .g. 85L-P)

LEARNING TASK 3

SELECT DEVICE IDENTIFICATION NUMBERS APPLICABLE TOLOCAL AREA NEEDS

Substations and generating stations have a list of protection devices used at the specific substation or generating station. This list, called the Protection Information Sheet, is a resource for identifying protective relay targets.

Resource B4-2 contains a sample Protection Information Sheet for a substation.


SELF TEST QUESTIONS

1. Identify the five parts of BC Hydro's device identification system.

2. What is the name for NEMA number 53?

3. What is the name for a 21L3R?

4. Give a complete description of the following device.


SELF TEST ANSWERS

1.

a. NEMA numberb. Device designationc. Item number on bill of materialsd. Device locatione. Device type

2. Exciter or DC generator relay

3. Distance, line, third zone, reverse relay

4. Reclosing, line, blocking relay Type 100Item number 25 on bill of materials Located in the rear of panel 7.


PERFORMANCE ACTIVITY 1

IDENTIFY AND INTERPRET SELECTED COMPONENTS

Using a schematic from your station, or the schematic in Resource B4-3, identify and interpret the selected components. Give a full description of the complete device identification number.

Protection Skills for Electricians Page 13

Unit 8 4 Use NEMA Device Numbers

RESOURCE B4-1

List of NEMA Numbers and their Complete Description


RESOURCE B4-2

Protection Information Sheet for a Substation


RESOURCE B4-3

Schematic for Performance Activity


RESOURCE B4-4

List of relays commonly used by BC Hydro with device designation



COMMONLY USED RELAYS WITH DEVICE DESIGNATIONS

21. Distance relay

25. Synchronizing or synchronism check relay

27. Undervoltage relay

30. Annunciator relay

32. Directional relay or directional relay with instantaneous overcurrent

element 40. Field relay

46. Unbalance (negative sequence) current relay

50. Instantaneous overcurrent relay

51. Time overcurrent relay

59. Overvoltage relay

63. Gas relay

67. Directional relay with time overcurrent element

71. Low level detector

81. Frequency relay

86. Lock-out relay

87. Differential relay

95. Trip relay


B4 - NEMA device Numbers

Documents

selector device

device identificationnumber

item number

bc hydro schematics

nema number north american

bc hydro extensions

bc hydro drawings

list of nema numbers