Overcurrent protection, SCCR and a new VFD UL Standard...• UL 61800-5-1 (old UL 508C), UL61800-5-2, UL1741 & UL62109-1, UL508A • NEMA 1IS SC7 - Adjustable Speed Drives • IEC

•usa.siemens.com/lv-drives•Unrestricted © Siemens 2020

Overcurrent protection, SCCR and a new VFD UL StandardPresented by Nikunj Shah (Mar 2020)

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Presenter

Presentation Notes

Hello everyone Thanks you for sparing time to attend this webinar on a very important topic of overcurrent protection, short-circuit current rating and a new UL standard for VFD – UL 61800-5-1

Unrestricted © Siemens 2020Page 2

A little about Nikunj Shah

•Responsibilities•R&D and product certification •Product management•Standardization• UL Standards Technical Panel (STP)

• UL 61800-5-1 (old UL 508C), UL61800-5-2, UL1741 & UL62109-1, UL508A

• NEMA 1IS SC7 - Adjustable Speed Drives• IEC USNC SC22G TAG - NEMA appointed US Expert of

IEC 61800-5-1, IEC 61800-5-2, IEC 61800-9-1 & -9-2, IEC 62477-1• Member of IEEE Standards Association

and in the Working Group of IEEE 519 & 519.1• NFPA 70 (NEC), NFPA 79, CSA standards for drives

(C22.2 No 274, C22.2 No 14)

Presenter

Presentation Notes

Good morning/Good afternoon My name is Nikunj Shah and I am responsible for the development & certification of drive products. I also get to involve in development & maintenance of various national & international stds such as UL, NEMA, IEEE IEC etc and represent Siemens & our LV & GMC drive segments in various UL’s standards technical panel such as UL508C, UL508A, UL61800-5-1 etc. and also various IEC & NEMA technical committees and IEEE standards association.


Disclaimer of liability

•The illustrations and text included in this presentation are selected as examples, and there is no claim as to their completeness in regard to conceivable configurations and applications. These are meant to give an orientation to accomplishing typical tasks.

•The application of the standards and directives is based upon the interpretation of Siemens Industry, Inc. Siemens assumes no liability and responsibility for the correctness and completeness of their interpretation. Users of these standards and directives (equipment builders and owners) are responsible for checking whether their equipment (e.g. industrial control panel, motor control center etc. ) and its application comply with the applicable standards and directives. Also, equipment builders and/or owners are responsible for its safe and proper installation and for making its safe commissioning, use and maintenance.

•The tables and texts in this presentation have been used from the relevant standards and technical datasheets when the presentation was created. The standards & technical datasheets are subject to regular revisions. For this reason, each user of this presentation should check the cited passages for the correctness and latest revision.

•Siemens Industry, Inc. reserves the right to make changes to this presentation at any time and without prior notice. Reproduction and distribution of this presentation or any of its content to third parties are not permitted.

Presenter

Presentation Notes

Please note this presentation has been created based on the interpretation of the standards and directives by Siemens and Siemens claims no liability and responsibility for the completeness of their interpretation. Users, equipment owners and equipment builders are responsible for checking whether their equipment and application comply with applicable local standards & directives ensuring safety in installation, operation and maintenance as well as service. Siemens reserves the right to make changes to this presentation at any time without prior notice. Reproduction and distribution of this presentation or any of its content to third parties are not permitted


Overcurrent protection, SCCR and a new VFD UL StandardIntroduction

•For LV drives, there is frequent confusion about topics related to• SCCR (Short circuit current rating)• Short circuit protection - what devices are needed• Compliance with the UL and NEC / NFPA70• Compliance with IEC standards• UL listing

•Sometimes incomplete information in the available product documentation from product manufacturers also contributes to this confusion

The intent here is to explain the fundamental concepts and requirements to clarify this topic better and to hopefully eliminate any confusion

Presenter

Presentation Notes

Overcurrent protection using appropriate type of protective devices and determination of the short-circuit current rating of an electrical equipment according to codes’ and standards’ requirements has always been somewhat challenging & confusing topic! For the LV drives, I have frequently noticed confusion about SCCR SC protection – which type of devices can be used? Compliance with NEC Compliance with IEC Overall UL listing etc Sometimes incomplete information in the available product documentation from the product manufacturers also contributes to this confusion. Therefore, this presentation is a genuine attempt to clarify the topic better & to hopefully eliminate this confusion.


Definitions

Protective devices concept

NEC, UL and IEC requirements of motor circuits

Short-circuit current rating

UL 61800-5-1: A New UL Standard for Drives

SCCR of Siemens VFDs

Overcurrent protection, SCCR and a new VFD UL Standard

Presenter

Presentation Notes

The presentation is divided into these 6 sections At the end of the presentation you would know What is the difference between overcurrent, overload & short circuit protection? What are different types of protective devices mainly popular in North America, their behavior & difference among them? What are the requirements of motor branch circuit protection according to NEC, UL & IEC and differences among them? What is SCCR & how to determine SCCR of an electrical equipment such as panel or enclosed drive to comply with NEC & UL? And very importantly about the new VFD UL standard UL 61800-5-1 and the impact of withdrawal of old VFD standard UL 508C on the industry And last but not least another important section showing what Siemens VFDs offer to you? What is the SCCR or Siemens VFDs (Sinamics products) and what are the various types of OCPDs used to achieve this SCCR? along with TONNES of value adds that these SINAMICS VFDs bring to you


Overcurrent protection, SCCR & A New VFD UL Standard

Definitions






Presenter

Presentation Notes

Now let’s start with few basic definitions related to protection of an electrical equipment


Overcurrent protection and SCCRDefinitions

•What is Overcurrent (OC)?•Any current in excess of the rated current of equipment or the ampacity of a conductor • The excessive current may result from overload, short-circuit or ground fault

•What is Overcurrent (OC) protection?A protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit over the full range of overcurrents between its rated currents and its interrupting rating – includes overload (OL) and short-circuit (SC) protection• Non-motor circuit: A single device can provide the overcurrent

protection, i.e. SC and OL protection• Motor circuit: Separate devices are required for the

SC and OL protectionException: a very small motor

Presenter

Presentation Notes

What is overcurrent? According to NEC, it is a current flowing through an electric circuit or an equipment in excess of its rated current or a current greater than the ampacity of a conductor. This excess current may be due to overload or short-circuit or ground fault. What is OC protection? Per NEC, a protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit over the full range of overcurrents between its rated currents and its interrupting rating. Includes overload (OL) & short-circuit (SC) protection For a non-motor circuit the OC protection i.e. SC & OL protection can be provided by a single device whereas for a Motor circuit: separate devices are required for the SC & OL protection. Except for a very small motor less than 1 hp



•What is Overload (OL)?

•An operation or operating condition of any equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating• Represented by inverse time curve• Typically up to 6 (or 10) times rated current• A fault, such as a short circuit or ground fault is not an overload• Overload condition for motor circuit:

• Failure to start• Running overload

Presenter

Presentation Notes

Now, what is overload? According to NEC, it is an equipment operation or operating condition in excess of normal full load rating or it is an operating condition of a conductor in excess of its rated ampacity which may cause damage to the equipment or conductor or cause dangerous overheating if persists for a sufficient duration. The overload condition is represented by an inverse time-current curve as shown here. The current greater than full load current and up to 6 (or sometimes even 10) times its rated current as shown in this curve here represents the overload condition Overload is not a short circuit or ground fault In a motor, the overload condition can arise due to either failure to start the motor or due to running overload.



•What is Overload (OL) protection?

•A protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit to prevent excessive heating when a current in the circuit exceeds a predetermined value above the rated current for a specified duration

•Sometimes OL condition is desirable for certain applications for a short period within the thermal limit of a component/conductor

•Effects• Excessive heating may cause “Slow burn” • Damaged conductors and components, deteriorated insulation

causing risk of SC and/or electric shock and/or fire

•Designed for → Slow current rise - Long duration - Slow response time (Slow operating speed)

Presenter

Presentation Notes

What is overload protection? A protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit to prevent excessive heating when a current in the circuit exceeds a predetermined value above the rated current for a specified duration. As you can see during OL condition only thermal effects (i2t) on the circuit/conductor are predominant Some times OL condition is desirable for certain applications for a short period within the thermal limit of a component or a conductor Now what are the effects of overload? Overload causes obviously excessive heating if it is beyond the specified max i2t limit of a component or conductor of an electric circuit which can cause slow burning of the associated part or conductor And therefore, cause damage to the component or conductor and its associated insulation system. Which can cause short circuit and/or electric shock and/or arc flash or fire. Therefore, OL protective devices are designed for a slow current rise, long duration with a slow response time or slow speed of operation to differentiate for example the motor starting or transformer inrush and actual overload condition Examples of OL protective devices are UL listed non-semiconductor time delay class fuses, inverse time circuit beaker and overload relays


•What is a Short-Circuit (SC)?

•An abnormal connection (including arc) of relative low impedance, whether made accidentally or intentionally, between two points of different potentials

•Symmetrical or Asymmetrical•Typically >10-20 times the rated current


Presenter

Presentation Notes

What is short-circuit? According to IEEE short-circuit is an intentional or unintentional low impedance connection between two points of different potentials. A simple example will be an intentional short across 9V battery using a wire or an unintentional short across line & neutral like this! By the way, I believe everybody knows that this is dangerous and none of this should be tried by yourself! In case of a three phase system, a bolted fault creates an exponentially decaying sinusoidal phase current waveform. Such as shown in this image. The short circuit current can be represented either by asymmetrical or symmetrical rms values. What is asymmetrical component? Exponentially decaying DC component responsible for shifting of the sinusoidal current waveform around X - axis. What is symmetrical component? Sinusoidal component in steady state condition showing equal division (equal positive and negative peak values) around X-axis. Typically depending upon the impedance of the fault current path this short circuit current is typically greater that 10 to 20 times and for a stiff source such as a large transformer or several MVA it can be >50-100 times or even more.



•What is Short-Circuit (SC) protection?•A protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit against short-circuit currents by interrupting them•Effects• Very high fault currents lead to

• Electromagnetic forces deform or break conductors and supports• Rapid and extreme overheating causing damages to the insulation, wires,

busbars, components, supports etc.• Saturate core of reactor or transformer leading to further overheating

and damages• Create resonance by interaction with other power system components • High risk of electric shock or fire

•Designed for → Fast current rise - Short duration - Quick response time (Fast operating speed)

Presenter

Presentation Notes

A short circuit protection is a protection provided by a device which is intended to protect an electric circuit or parts of an electric circuit against short-circuit currents by interrupting them Effects: Very high currents lead to: Electromagnetic forces deform or break the conductors or supports Rapid & extreme overheating which cause damages to the insulation & deform busbars, components or their supports May saturate the core of reactors or transformers leading further overheating & damages. May create resonance by interaction with other system components High risk of electric shock or fire So as we have seen, for SC protection, both the thermal (i2t) effects as well as mechanical (ip) effect on the circuit/component/conductor are of interest Typical SCPD are the non-semiconductor & semiconductor fuses, inverse time & instantaneous trip circuit breakers, combination motor controllers etc. Typically SCPDs only provide SC protection and is not for protection against OL, For e.g. Instantaneous trip CB, semiconductor fuses etc. However full range fuses or TM CB or Type E CMC provide both -OL & SC protection Therefore, SCPD are designed to detect the fast current rise and operate very quickly to isolate the faulty circuit to prevent the consequential damages due to SC.



Definitions






Presenter

Presentation Notes

Now let us understand different types of protective devices & their behavior


Protective devices conceptCharacteristics of Over Current Protective Devices (OCPD)

Represented by tripping (or time-current) and let-through characteristics

Performance is determined by comparison of peak let-through current (IP in Ampere) and let-through thermal energy (I2t in A2 sec)

Overload

Short-circuit

Overload

Short-circuit

Presenter

Presentation Notes

The behavior or characteristics of the OCPD is represented by a time-current curve or a tripping characteristic and a let-through characteristic which is a curve between the available short-circuit current versus peak let through current (Ip) and let-thru energy (i2t). The performance of OPCD is determined by comparison of peak let-thru current (Ip) and let-thru thermal energy (i2t). Smaller the peak let thru current and I2t for the same interrupting current better is the OCPD type. Typically class CC or J fuses or high speed fuses are some of the examples of the OCPDs which exhibit the lower Ip & I2t Here is a typical trip curve of non-semiconductor fuse. It is approximately a straight line with a negative slope. This is a trip curve of the breaker which is contrary to a fuse trip curve & shows a distinct inverse time OL region and short circuit region. Out of these two trip curve comparison which OCPD type appears sluggish in fault clearing? A let thru characteristic of a current limiting breaker is shown in this image which depicts peak let through current on Y axis and available short circuit current on X axis. It exhibits, the distinct current limiting and non-current limiting regions. And here is the characteristic showing available SC current vs let-through thermal energy (i2t) for the same current limiting breaker. In both these let through characteristics you may notice that as the supply voltage goes up the let through current & energy both goes up!


NEC and UL requirements of motor circuitsUL – fundamental differences among OCPD types

Non-semiconductor fuse

Semiconductor fuse

Circuit Breaker

Manual Motor Controller &Type E CMC

UL standards UL248 UL248 Part 13 UL489UL508 / UL60947-4-1

Has standard physical size? Yes No No No

Available with standard characteristic?

Yes No No No

Max IP & Max I2t defined for each type?

Yes No No No

Is substitution allowed for UL? Yes 1) No No No

1) Same class fuse from any manufacturer only if UL certification is done using UL umbrella (test limiter) fuse

Presenter

Presentation Notes

Here is a chart summarizing the fundamental differences among the different types of overcurrent protective devices prevalent in the North America for the motor circuit branch circuit protection i.e. non-semiconductor or Class fuses, semiconductor fuses, circuit breakers & motor controllers (either manual or Type E combination motor controllers) As you can see, since non-semiconductor fuses have standard defined max ip & i2t and physical size & characteristic in UL 248 based on the class of the fuse, except these type of fuses substitution is not allowed for any other types of OCPDs. Moreover, substitution is allowed for non-semiconductor fuses with the same or better class from any fuse manufacturer only if the drive or equipment is tested using a special type of for a chosen class known as the UL umbrella fuses or test limiter. There are UL umbrella fuses available for each class such as class CC, J, T, L, RK5 etc. So for example if testing of the drive is done using 30A Class J test limiter, then a Class J or CC fuse from any fuse manufacturer can be used with the VFD for UL compliance.



Definitions






Presenter

Presentation Notes

Now let us talk about the requirements for motor branch circuit & its protection according to NEC, UL & IEC


NEC, UL and IEC requirements of motor circuitsNEC Article 430•…specifies requirements for motors, motor branch / feeder / control circuits, conductors & their protection, motor overload & over temperature protection, and motor controllers

•Feeder Circuit: Conductors and circuitry on the supply side of the branch circuit overcurrent protective device

•Branch Circuit: Conductors and components following the last overcurrent protective device protecting a load

•Per the NEC the motor is the device being protected – the presence of a motor controller (e.g. a ASD) for OC protection was largely irrelevant few code cycles back Now can be sized per input current of ASD (430.128 & .130)

Main disconnect

Motor branch circuit protection

Motor controller

Motor overload protection

Motor

Encl

osur

eASD – Adjustable Speed Drive

Presenter

Presentation Notes

NEC Article 430 specifies requirements for motors, motor branch-circuit & feeder conductors and their protection, motor overload protection, motor control circuits, motor controllers, which have been trickled down to many UL standards such as UL508/ UL60947, 508A & 508C/UL61800-5-1, UL 845, UL 1995 etc. This single line diagram shows the control and protection components required for a motor circuit According to NEC & UL: The motor branch circuit is - Conductors & components following the last overcurrent protective device protecting a load. And the motor feeder Circuit is – the Conductors & circuitry on the supply side of the branch circuit overcurrent protective device Therefore, few codes cycles back, according to NEC & hence UL, the branch circuit protection & main disconnect were required to be sized based on the motor current since motor is the device/load that is being protected. The presence of the motor controller or VFD was largely irrelevant except for the motor OL & over temperature protection. However, from few code cycles back, it is now allowed to size the motor disconnect and branch circuit protection based on the input current of the ASD according not NEC article 430.128 & 430.130.


NEC, UL and IEC requirements of motor circuitsNEC requirements − Motor branch circuits

NEC Article 430.109 permits use of OCPDs such as Circuit breakers, Self-Protected Combination Controller, non-semiconductor fuses with fuse disconnects as main disconnect

Note: Typically standalone UL recognized IEC fuses are NOT suitable for for use as a main motor circuit disconnect

NEC Article 430.110 specifies minimum rating of main disconnect as 115% of motor FLA and per NEC Article 430.128 115% of input current of ASD•NEC Article 430.52 specifies maximum ratings or settings of motor branch circuit short-circuit and ground fault protective devices, for different types of power supply and motors e.g. Inverse time (thermal magnetic) circuit breaker max. 250% of FLA of a typical squirrel cage induction motor

NEC Article 430.130 − Maximum rating shall not exceed ASD manufacturer’s specified value for a given & approved OCPD type

•NEC Article 210.20(A) requires the motor branch circuit short-circuit and ground fault protective devices shall be rated or set at minimum 125% of the FLA

ASD – Adjustable Speed Drive

Presenter

Presentation Notes

Now focusing only on the requirements of motor branch circuit short circuit and ground fault protection, NEC article 430.109 permits the use of OCPDs such as UL listed Circuit breakers, Self-Protected Combination Controller, non-semiconductor fuses with fuse disconnects as a main motor disconnect to comply with OSHA’s Lock Out Tag Out (LOTO) requirements It is important to note here that, the UL recognized IEC style (square body for example) semiconductor fuses are not permitted to be used as a main motor disconnect! NEC article 430.110 provides a minimum rating of main disconnect as 115% of motor FLA and per NEC article 430.128 115% of the input current of ASD, {unless those are full range fuses and used with VFD i.e. providing overload & short circuit protection, (most of those are only partial range and can provide only short circuit of semiconductors and not for the conductors or other components in the motor branch circuit) and tested & certified for the protection of a motor branch circuit which includes a drive or a solid state motor controller. These fuses & associated fuse disconnect also do not meet the NEC requirement of main motor circuit disconnect for LOTO and therefore, a separate UL98 listed disconnect or listed circuit breaker is required to comply with NEC for LOTO.} Now for sizing the branch circuit protection or OCPD, the NEC article 430.52 specifies the max ratings of different types of motor branch circuit protective devices. For example, the max rating of inverse time breaker is 250% of FLA of a typical sq cage ind motor. However, is ASD is used to control the motor, the OCPD max size is determined according to NEC article 430.130 and its max rating is dependent on the drive’s manufacture’s specified value which depends on the UL certification of the ASD using particular size and type of the OCPD. Similarly, article 210.20(A) specifies that the motor branch circuit protective devices shall be rated or set at least 125% of the FLA


NEC, UL and IEC requirements of motor circuitsUL requirements − Motor branch circuits

End product UL standards for ASD e.g. UL 508A, UL 845, UL 1995 etc. follows NEC requirements, for e.g. sizing and selection of main disconnect, OCPD, field wiring conductors, connectors etc.

UL 508A Cl. 30.1 also permits use of OCPDs e.g. Circuit breakers, Self-Protected Combination Controller, non-semiconductor fuses with fuse disconnects as main disconnect

Note: Like NEC, UL 508A does not permit use of UL recognized IEC fuses as a main motor circuit disconnect

UL 508A Cl. 30.2 specifies minimum rating of main disconnect (& OCPD) as 115% of motor FLA or ASD input current. Exceptions: Allows breakers marked for 100% continuous use, and also self protected combination motor controller sized at 100% of motor FLA or ASD input current

•UL 508A Cl. 31 & Table 31.2 specifies maximum ratings of motor branch circuit protective devices very similar to NEC article 430.52


Presenter

Presentation Notes

These NEC requirements about the motor branch and feeder circuit and associated components have been included in to many end product standards of UL. The most used end product standard for drive is UL 508A which is UL standard for safety of Industrial control Panels. The other end product UL standards for drives are UL 845 for the MCC, UL 1995 for the Heating & Cooling Equipment etc. In addition to the article 430 of NEC, article 409 of NEC specifies requirements for industrial control panels. The NEC requirements that we saw in the previous slide on sizing and selection of motor branch circuit disconnect or main disconnect, branch circuit short circuit protection are also specified in UL 508A. That is, for the use of OCPD as a motor main disconnect, the requirements are specified in the clause 30.1 of UL 508A. Clause 30.2 specifies the requirements of sizing of the disconnect including minimum rating of the main disconnect and hence minimum rating of OCPD if the UL listed OCPD is also used as main disconnect. Since UL 508A is a safety standard for industrial control panels, this cl 30.2 also allows few exceptions to the NEC’s minimum size requirement of main disconnect i.e. 115% of motor FLA. For example, UL 508A allows the size of a UL 489 or UL 1066 listed breaker as a main disconnect with a rating 100% of motor FLA if the breakers are listed & marked for 100% continuous use. Similarly, a UL 508/60947-4-1 listed MSP or self protected combination motor controller are also allowed to be sized at 100% of the motor FLA or input current rating of a drive. However, UL 508A also does not permit the use of UL recognized IEC style (square body for example) semiconductor fuses in their appropriate fuse disconnect as a main motor disconnect! Similar to NEC Article 430.52, clause 31 and Table 31.1 specifies the requirements of max rating of the motor branch circuit protection. So over all you can see that pretty much all the requirements related to selection of types of devices as well as their sizing are trickle down from NEC to UL except only few exceptions are allowed in sizing of the main disconnect and branch circuit protection in UL 508A being a product safety standard.


NEC, UL and IEC requirements of motor circuitsNEC & UL 508A

Fuse & Fuse Disconnect Circuit Breaker

Manual Motor ControllerType E CMC

Overload Relay

Yes 1) Yes Yes No

Yes Yes Yes No

Yes 1/2) Yes 2) Yes 2) No

Yes Yes Yes Yes

1) When used with UL98 fusible switch2) Additional contactor with overload relay typically require

Main disconnect


Motor controller


Motor

Presenter

Presentation Notes

So in summary according to NEC as well as UL, a UL listed full range OCPD or branch circuit protective devices such as non-semiconductor fuses with fuse disconnect or inverse time circuit breakers or type E combination motor controllers are permitted to be used as main disconnect to comply with OSHA’s LOTO requirements, also as motor branch circuit short circuit protection and moreover, as a motor controller (if drive is not present) typically when used with contactor and overload relay


NEC, UL and IEC requirements of motor circuitsIEC approach − Motor branch circuit

•Line side protection is selected based on the device that is connected to the supply, in this case a ASD

•A circuit breaker and/or fuses and fuse holders are selected on the basis of max. continuous nominal input current

Overload currents must also be considered with respect to characteristics of OCPD (i.e. Time-current and I2t) to appropriately size the OCPD and prevent its false operation

•The fact that a motor is connected to the output of the ASD is largely irrelevant; since there is no circuitry that would allow the motor to be started across the line, the across the line inrush current is not considered

Main disconnect and protection

VFD

Motor


Presenter

Presentation Notes

In the IEC world, The branch circuit short circuit protection for the motor circuit containing a motor controller such as VFD has always been selected based on the input rating of the VFD and to provide SC & OL protection to the VFD considering the temporary OL and i2t of the semiconductor modules, and not the motor! The OCPD selection is done by the system designer/installer based on the recommendation of the drive’s manufacturer and based on the characteristic of the protective devices. The fact that a motor is connected to the output of the drive is largely irrelevant; since there is no circuitry that would allow the motor to be started across the line, the inrush current is not considered. --------------------------------------------------------- Why NEC does not recognize presence of motor controller or VFD although VFD protects the o/p ckt from OL & SC? NEC is formed of number of experts from many industry and has high presence of people from switchgear & protective device industry and therefore there has always been a requirement of control and isolation of hazardous energy by physical separation i.e. creating air gap using reliable (i.e. listed) protective device such as fuse or circuit breaker in the NEC, and therefore, code forming panel does not recognize use of VFD as a reliable protective device in lieu of fuse or breaker. therefore, according to NEC presence of VFD with solid state OL & SC protection circuitry for protection of conductors & motor, does not eliminate the use of reliable listed BCPD for the protection of load i.e. motor. In last few code cycles ASD NEMA committee has proposed that the VFD can be used for electronic protection of conductors & even motor however all time the proposal has been rejected by Code forming panel stating that VFD does not include OL & SC testing on selected samples similar to CB or fuses and therefore cannot used in place of CB or fuse and the motor and conductors still needs to be protected by CB or fuse. Whereas IEC has already recognized the use of VFD as an electronic means to control the hazardous energy due to fault or OL and therefore does not care for protection of motor, and requires OCPD only for VFD (not for motor) which is selected by a system designer or installer by review of protective device characteristics considering the application of the VFD. Moreover, the health of protective device i.e. the automatic disconnection of the circuit in the even of fault, is checked for every new installation and repeated every two years where as in North America this is not done typically.



Definitions






Presenter

Presentation Notes

Now let us see what is short-circuit current rating and how to determine it?


What is Short-Circuit Current Rating (SCCR)?NEC and UL508A definition

•The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria

•Equipment SCCR ≥ Available SC current from a supply source

•SCCR requirements effective NEC 2005

•NEC Articles 409 and UL508A state the requirements of ICP – Article 409.110 → SCCR marking on ICP

ICP – Industrial Control Panel

Presenter

Presentation Notes

According to NEC & UL508A – SCCR is the prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria and the acceptance criteria is given by the equipment mfr In general, SCCR is a marking requirement for an electrical equipment such as panel, drive, contactors, switch boards, MCC etc. The short-circuit current rating is marked on the equipment nameplate such as panelboards, switchboards, switchgear, busways, contactors, starters, industrial control panels etc, same as shown in this image. This value must not be exceeded. Otherwise, the equipment can be damaged by short circuit currents, posing a hazard to personnel and property For industrial control panels, the installation & construction requirements are stated in Article 409 and in UL508A


What is Short-Circuit Current Rating (SCCR)?SCCR per UL 508A Supplement SB

•Step 1 Determine marked SCCR of each UL certified component

•Step 2 Use SCCR from the testedcomponent combinations (e.g. for fuse/CB + contactor +OL Relay combo)

•Step 3 Consider SCCR from TableSB4.1 for a UL listed componentfor which no SCCR informationis available from its nameplate orproduct documentation

Presenter

Presentation Notes

According to UL508A, Supplement SB, the SCCR of an industrial control panel comprised of UL certified components can be determined using a three step process. Step 1 is to determine marked SCCR of each UL listed component. The key point here is that each component in the panel must be UL certified i.e UL listed or UL recognized as allowed per supplement SA of UL508A. Step 2 – Use SCCR from the tested component combinations for e.g. fuse/CB + contactor + OL Relay combination or particularly in case of Sinamics VFD a specified OCPD. Step-3 – If the SCCR of UL listed component is unknown then use standard SCCR values from Table 4.1 for that component. The key point here is the component must be UL listed! So for example, if we are constructing a panel using a drive controller, and using a breaker as a main disconnect and OCPD, then can we use this std value for a drive controller? The answer is yes as long as the drive controller is UL listed and an OCPD specified by drive controller mfr is used! (New revision to UL508A done last year now allows the use of any UL listed breaker or fuse sized per input current of UL listed VFD if the OCPDs are not specified by the VFD mfr but only with std SCCR)! Please NOTE, the values of std SCCR specified in this table SB4.1 are not generic values, which means those cannot be applied to “NON-UL listed” components!! However, these values are std sccr values that every UL listed component or PCE or VFD requires to be tested with using appropriate OCPD to meet the applicable UL std (such as UL508C or UL61800-5-1 for drive, UL508 or UL60947-4-1 for contactor, OL relay or RVSS or terminal block according to UL1059 or UL486) requirement and so if the HIGH SCCR is not known for any drive then this STD SCCR can be used however only when using the same OCPD that is described in the UL listed component UL file & manual for UL compliance.


•= Smallest SCCR of all power circuit componentsand control circuit OCPDs

•Standard SCCR of unmarked motor controllers

Main disconnect


Motor controller


Motor

Encl

osur

e

What is Short-Circuit Current Rating (SCCR)?Overall SCCR of ICP – example

Motor Controller RatingHp (kW) SCCR, kA0 – 50 (0 – 37.3) 5

51 – 200 (38 – 149) 10

201 – 400 (150 – 298) 18

401 – 600 (299 – 447) 30

601 – 900 (448 – 671) 42

901 – 1600 (672 – 1193) 85

•Ic = 65kA, 480V

•Ic = 100kA, 480V

•SCCR = 10kA

•SCCR = ?

•Overall •SCCR = ?

•40hp•SCCR = 5kA

•Overall •SCCR = 5kA

Presenter

Presentation Notes

Now let us see this in an example here Overall SCCR of an ICP = smallest short circuit current rating of all power circuit components on the load side of a branch circuit protective device and the control circuit overcurrent protection We have an industrial control panel here which is comprised of UL listed circuit breaker as a main disconnect , branch circuit protection fuses, UL listed motor controller, and motor OL protection. If a UL listed VFD is used with integral solid state SC & OL protection then a motor controller and OL protection are merged in VFD. However, the branch circuit protection must be provided by the same type of OCPD which was used for testing the VFD and if it is semicond fuse then use of listed breaker will satisfy the dual function 1 – as a UL listed motor disconnect and the other as a UL listed branch circuit protection for motor. If the SCCR of motor controller or VFD are unknown then based on it hp rating say if it is 40hp we can determine the std sccr of the vfd or motor controller as 5kA. So the weakest link here is the VFD with SCCR of 5kA and therefore the overall SCCR of the panel is 5kA!


•Standard SCCR - Minimum UL Shot-circuit current test requirements (per UL)•High SCCR - High fault current at which equipment are additionally tested (per Manufacturer)

•So what is the significance of the standard SCCR values?• Can we use the standard SCCR for a non- UL listed (or untested) device?• OCPDs which were used for a drive UL certification & specified by a drive manufacturer, are

required only when we would like to use high SCCR (Correct or Incorrect?)

What is Short-Circuit Current Rating (SCCR)?“Standard” and “High” SCCR Values

Output Power of the Electric Drive “Motor Controller”

Hp (kW)Standard SCCR per UL508A [kA]

UL Approved High SCCR [kA]

0 – 50 (0 – 37.3) 5 65

51 – 200 (38 – 149) 10 65

201 – 400 (150 – 298) 18 65

401 – 600 (299 – 447) 30 65

601 – 900 (448 – 671) 42 84

901 – 1600 (672 – 1193) 85 100

Presenter

Presentation Notes

Now let us see the difference between the standard and high fault sccr and those of our Sinamics products This table is taken for the SINAMICS large drives chassis and enclosed drives and as you can see that the std sccr values according to UL 61800-5-1 or UL508 or UL508A or depending upon the rating of the Sinamics products and also it shows the high SCCR values based on the UL testing & description in the UL file So what is the significance of the standard SCCR values? Is the standard SCCR the value that can be used for a non-listed (or untested) device? If the VFD is used without the short-circuit protective device which was used to determine the “high” SCCR, does the standard SCCR apply?


What is Short-Circuit Current Rating (SCCR)?“Standard” and “high” SCCR Values, cont’d

•Those are common misconceptions

•Basically, the standard SCCR is the minimum value that UL would expect a particular type and rating of device to be tested at

•For that reason, when determining the SCCR of a circuit, the standard SCCR can be used if the “high” SCCR of a UL listed device or component is unknown

•So in summary:• If the actual SCCR value of a listed device is known, the standard SCCR is of

no significance• Standard as well as high SCCR − The value is only valid in combination with

specific OCPDs which are listed in the operating manualAnd if those protective devices are not listed for motor branch circuit protection, then additional devices are needed to comply with NEC!

Presenter

Presentation Notes

The answer to the previous questions is NO! There are some common misconceptions! So in addition to its high sccr of the device, every device such as drive must be tested at the std sccr for UL listing and therefore, if the high sccr of UL listed VFD is unknown then this std sccr can be safely applied if the VFD is used in conjunction with an appropriate protective device complying with its UL508C or UL61800-5-1 requirements So in summary: if the actual SCCR value of a listed device is known, the standard SCCR is of no significance. the SCCR value is only valid in combination with specific short circuit protection devices, which should be listed in the operating manual.�And if those protective devices are not listed for motor branch circuit protection (such as if drive controller was tested using semiconductor fuses), then additional full range OCPD such as UL listed inverse time breaker or fuses, are needed to satisfy the NEC!


•Until Ed 2.1 which was published in Mar 2017 as a result of NEMA, UL and IEC harmonization efforts, IEC std did not have any SCCR marking requirement, nor did they use or define the term SCCR

•However, previous editions of IEC 61800-5-1 before Ed 2.1 did require short-circuit tests as part of type testing of a drive product, to confirm the maximum permissible short circuit current the device may be exposed to

•Now the short-circuit test requirements of IEC 61800-5-1 Ed 2.1 and UL 61800-5-1 (or its predecessor UL508C) are very similar, and hence now, the SCCR (per UL) and max. short circuit current (per IEC) are the same

•Values published for IEC drives (CE mark) actually use the results from the UL short -circuit tests

•SINAMICS OCPD & SCCR information sheet specifies list of European OCPDs for IEC applications

Short-circuit current rating per IEC

IECNEMA

Presenter

Presentation Notes

Now let us see IEC perspective of SCCR. There was no definition of SCCR in IEC and hence there were no requirements in the IEC world to mark the product with SC current value, until Ed 2.1 which was published in Mar 2017 as a result of NEMA, UL and IEC harmonization efforts However, the product std such as IEC 61800-5-1 for the VFD did & does specify the requirement of SC testing of the drive which is similar to those in UL508C or UL61800-5-1. Therefore, there wasn’t any separate SC testing done on any of our drive products certified for CE marking according to IEC. And hence, all our Sinamics products and enclosed drive products also get the same SC current values at the nominal voltage since those have been determined by UL testing.


•Overcurrent protective devices (OCPD) need to protect equipment from• High short circuit currents• Overload currents applied for too long a duration

•However, they must allow typical duty cycle overloads• OCPDs have a current vs. time characteristic which is

used to select them• If the supply system is weak (high source impedance)

fault currents (short circuit current) will be lower than expected, and in extreme cases the fault current may be too low to cause the fuse or circuit breaker to trip

•Therefore, to ensure that the OCPD will function in normal operating condition and isolate the drive circuit as expected during over current condition within an acceptable time period, minimum available short circuit current values are provided •Rule of thumb: ISC min ≈ IN x 15

Short-circuit current rating per IEC

Presenter

Presentation Notes

According to IEC, Overcurrent protective devices (OCPD) need to protect equipment from High short circuit currents Overload currents applied for too long a duration However, they must allow normal duty cycle overloads, OCPDs have a current vs. time characteristic which is used to select them If the supply system is weak (high source impedance) fault currents (short circuit current) will be lower than expected, and in extreme cases the fault current may be too low to cause the fuse or circuit breaker to trip. Therefore, to ensure that the OCPD will trip as expected within an acceptable time period, the minimum available short circuit current values are also required to be specified by the drive manufacture. And the installer and the customer/equipment owner must make sure that the available SC current from the supply sources is equal to or higher than this min available SCCR for a faithful operation of the SCPD in the even of fault.



Definitions






Presenter

Presentation Notes

Now let us go over the most important section of this presentation that is UL 61800-5-1 – a new UL standard for drives and what you need to know - if you are a user or panel builder or MCC builder or OEM especially since now the old UL standard of drives - UL 508C has been obsolete and withdrawn by UL as of Feb 1 2020. This withdrawal UL 508C has greatly impacted the industry


UL 61800-5-1: NEW UL Standard for DrivesBackground

•Motivation:• Create a single global set of requirements for the design of low voltage (LV) drive products

• Reduce design, testing & certification burden for drives which otherwise would require compliance with at least two different sets of requirements i.e. UL 508C (for UL marking typically in North America) and EN / IEC 61800-5-1 (for CE marking typically in Europe and rest of the world)

• Help create a single design of LV drive products which can be used globally•Requirements:• Develop a new global UL standard for LV drives by bringing UL 508C & IEC 61800-5-1 closer together

through harmonization of their requirements• UL 508C + IEC 61800-5-1 + Additional UL requirements (incl. CSA C22.2 No. 274) = UL 61800-5-1

• Most rigorous construction & performance requirements to ensure improved product safety•Development:• Standard harmonization and development efforts are on going• 1st harmonized version UL 61800-5-1 Ed 1.0 was published on Jun 8, 2012• UL 508C has been withdrawn and replaced by UL 61800-5-1 as of Feb 1, 2020

Presenter

Presentation Notes

First let us see background information and motivation. The main motivating factors behind development of this new standard UL 61800-5-1 are: Create a single global set of requirements for the design of low voltage (LV) drive products Reduce design, testing & certification burden for drives which otherwise would require compliance with at least two different sets of requirements i.e. one according to UL 508C (for UL marking typically in North America) & the other according to EN / IEC 61800-5-1 (for CE marking typically in Europe and rest of the world) – and both were vastly different And ultimately to help create a single design of LV drive products which can be used globally without requiring to additionally go through another certification based on the geographical location where drive is installed and used. Requirements: The requirements were to develop a NEW global drive standard by harmonization of the requirements from UL 508C and IEC 61800-5-1. Therefore NEW standard contains the requirements from UL 508C plus requirements from IEC 61800-5-1 and also additional NEW requirements that were created to fill the gaps or holes which existed in both the UL & the IEC standards as well as CSA standard for drives CSA C22.2 No. 274. The result is UL 61800-5-1 - the MOST stringent drive safety standard on the globe ensuring improved safety of the adjustable speed drive products Development: Continuous maintenance & further development of this new UL standard is on going process like any other industry standard and will help bring both the IEC & UL versions of 61800-5-1 together eliminating national differences. This ultimately helps create a single global product using single set of design requirements as envisioned originally. The 1st edition of UL 61800-5-1 was published in Jun 2012 that is almost 8 years ago and was introduced in parallel with UL 508C which was active old drive UL standard at that time. Now UL 508C has been completely withdrawn by UL as of Feb 1, 2020 and replaced with new UL 61800-5-1 as I mentioned before.


UL 61800-5-1: NEW UL Standard for DrivesMajor differences: UL 61800-5-1 (New) vs UL 508C (Old)

•UL 508C has been obsolete & withdrawn by UL as of Feb 1, 2020 and replaced by UL 61800-5-1•UL 61800-5-1 is now the only valid UL standard available for UL certification of the low voltage drives

• A reference to obsolete UL 508C is being replaced with NEW UL 61800-5-1 in ALL UL standards including UL 508A (Panels), UL 845 (MCC), UL 1995 (Heating & Cooling equipment) & others

•UL 61800-5-1 has more stringent construction and performance (testing) requirements than UL 508C

•UL 61800-5-1 requires short-circuit tests at: • Standard (e.g. 5kA, 10kA, etc.) as well as • High-fault currents (e.g. 65kA, 100kA, etc.) • On ALL output terminals (including DC terminals)

Click here

Click here

Note: This is only a list of most significant differences between UL 61800-5-1 and UL 508C and not a complete list.

Presenter

Presentation Notes

So now let us understand what are the major differences between new UL 61800-5-1 and old UL 508C. There are plenty of other differences between these two standards but the ones I have included here are the major ones responsible for making the drive product more safe using UL 61800-5-1 for design, testing & certification. As I have mentioned previously, UL 508C was the old UL standard for drives and withdrawn by UL on Feb 1, 2020 and currently, UL 61800-5-1 is the only (again repeat – is the only) available UL standard for the LV drives up to 1500V ac or dc. Since 508C was scheduled to be withdrawn it was not maintained to meet the latest technology safety requirements and changing NEC code requirements. Moreover, following a withdrawal of UL 508C from Feb 1, 2020, UL has started a process of removal of references to old UL 508C from ALL active UL standards. There are about 80 UL documents where old UL 508C has been referenced. These references are being replaced with the new UL 61800-5-1. You may see this from the UL notifications and letter on the UL and LinkedIn links here. Also, as I mentioned earlier, the NEW UL 61800-5-1 contains the most stringent construction and performance or testing requirements for the drive compliance. According to new construction requirements of UL 61800-5-1 major design changes within the drive to comply with new clearance and spacings requirements is required as compared to UL 508C. So for an existing drive designed & certified according to UL 508C a major overhaul of the design is required to comply with new construction requirements of UL 61800-5-1, and to improve safety. In addition, the drive has to comply with NEW rigorous performance or testing requirements. For example, according to UL 61800-5-1, the SC tests are required to be performed at the standard or low fault level as well as high fault level currents and these SC tests are required at ALL the output terminals of the drive, which also now include the DC terminals if provided for customer connections! This was not the requirement before when old UL 508C was used for drives. So naturally, according to new UL 61800-5-1, more destructive testing and more number of test samples are required.

https://collateral-library-production.s3.amazonaws.com/uploads/nfp/nfp_asset/attachment/1373/UL_508C_WD.pdf

https://www.linkedin.com/posts/nikunjmshah_powerconversion-standards-activity-6639223369294196737-Dme_


UL 61800-5-1: NEW UL Standard for DrivesMajor differences: UL 61800-5-1 (New) vs UL 508C (Old), cont’d

UL 61800-5-1 also requires Breakdown of Component (BoC) tests at:• Standard (e.g. 5kA, 10kA, etc.) as well as • High-fault currents (e.g. 65kA, 100kA, etc.) • Contrary to the tests in withdrawn UL 508C, the internal components of a

drive are truly experiencing the actual let-through current at these fault currents

•Overall UL 61800-5-1 requires more number of rigorous destructive tests on more number of test samples representing real life drive operations / applications in contrast with obsolete & withdrawn UL 508C•Contrary to UL 508C, UL 61800-5-1 has been maintained and kept up-to-date with the changes in the National Electrical Code (NEC/NFPA 70) as well as through the updates of existing requirements and addition of new requirements with new emerging technologies and drive applications•Ultimately UL 61800-5-1 ensures a safer and more robust product

UL live webinar on March 26 at 10:00am CST (11:00am EST)

Note: This is only a list of most significant differences between UL 61800-5-1 and UL 508C and not a complete list.

Click here Click here

Webinar Recording

Presenter

Presentation Notes

Similar to SC test, NOW with UL 61800-5-1, the breakdown of component tests are also required to be performed at a standard or low as well as high fault level currents i.e. 5 or 10kA as well as 65 or 100kA that is whatever high SCCR that manufacturer wants to assign to the drive. For those of you who don’t know, the breakdown of component test is the test which includes identification of the components of a drive through circuit analysis, which pose a risk of electric shock, fire or operator injury when fails, that is when component shorts or opens and then by testing the drive while it is running and creating this failure mode at a standard fault current level that is 5 or 10kA as well as high fault current level that is 65 or 100kA. Such breakdown of component tests are repeated for each component which exhibits risks of shock, fire or operator injury. Whereas, in UL 508C this test was only required to be performed at the whatever available plant SCCR level ONLY which could be 5kA or less. So Contrary to the tests in withdrawn UL 508C, the internal components of a drive are truly experiencing the actual let-through current at these fault currents This means once again, per requirements of new UL 61800-5-1 more number of destructive tests are required on more number of test samples. This shows, ultimately the drive gets heavily beaten up to ensure safety and the drive which inherently has robust & reliable design can only pass such rigorous tests using the requirements per new UL 61800-5-1 to ensure that in addition to normal operating conditions, in all the possible failure modes, abnormal conditions, and fault conditions, the drive still does not pose any risks to operator or property! Moreover, after introduction of UL 61800-5-1, the old UL 508C was not maintained to cover the design changes due to the latest technology products as well as changes to the national Electirc codes. So now from the product safety point of view, any products that have undergone design, testing and certification according to UL 508C after publication of UL 61800-5-1, will not mee the same enhanced safety level given by products certified according to UL 61800-5-1. Hence Ultimately UL 61800-5-1 ensures a more safer and more robust drive product than the products certified according to Ul 508C.

https://connect.ul.com/Webinar-UL-Motor-Drive-Standards-Reg.html

https://www.linkedin.com/posts/cayetano-siete-919742b5_ul-508c-for-motor-drives-has-been-withdrawn-activity-6638080207905402880-ogqj

https://connect.ul.com/Webinar-508C-MotorDriveStandard-OnDemand_TY.html?utm_source=single-email-send&utm_term=ept&utm_medium=email&utm_campaign=ept_glo_wb_200326_distribution_automation_ul_motordrivestandard


UL 61800-5-1: NEW UL Standard for DrivesMajor differences: UL 61800-5-1 (New) vs UL 508C (Old), cont’d

Additional technical information on major differences available on UL and NEMA websites

Click here Click here Click hereClick here

Presenter

Presentation Notes

You can find more technical details and information on the major differences between the new UL 61800-5-1 and old UL 508C on UL & NEMA website links shown here. I would highly encourage you to refer to this material and also standards to see some serious and major differences in requirements.

https://ifs.ul.com/ifr/ifr.nsf/0/94794D8D496054B748257D940036A718/$FILE/UL%20508C%20-%20Bulletin.docx?OpenElement

https://www.ul.com/sites/g/files/qbfpbp306/files/2019-06/UL61800-5-1_FAQs_071513.pdf

https://www.nema.org/Standards/Pages/New-UL-Variable-Frequency-Drive-Standard-and-Its-Effects-on-Unit-Short-Circuit-Rating.aspx

https://lms.ulknowledgeservices.com/catalog/display.resource.aspx?ClassID=455803&ResourceID=582901


UL 61800-5-1: NEW UL Standard for DrivesUL 508C to UL 61800-5-1 transition timeline

2012 2013 2014 2015 2016 2017 2018 2019 2020

UL 61800-5-1 Ed. 1.0 Published Jun 8, 2012

UL 61800-5-1 is MUST for NEW drive products

Feb 1, 2016

UL 508C ONLY for legacy/existing drive products

UL 508C WITHDRAWN & replaced with UL 61800-5-1 Feb 1, 2020

UL 508CManufacture’s choice – can be used for existing or NEW drive products

UL 61800-5-1MUST for NEW drive products

UL 61800-5-1 MUST for ALL drive

products

UL 61800-5-1 Manufacture’s choice – can be used for existing or NEW drive

products

•UL process of withdrawal of UL 508C and implementation of NEW UL 61800-5-1 for drives

Presenter

Presentation Notes

UL & STP of UL 61800-5-1 agreed the following timeline for transition from old UL 508C to new UL 61800-5-1 which allowed almost 8 years to manufacturers and system builders to convert the design and certification of their products to UL 61800-5-1.


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – To drive end users/customers, cont’d

Many industrial customers/equipment owners/users (e.g. in automobile, water / waste water, infrastructure, construction, oil & gas, metals, pulp & paper etc.)

• already have been specifying UL 61800-5-1 listed drives in their requirement / bid specifications,

• DO NOT allow use of UL 508C certified drives anymore

•Customer specifications have already started demanding the OEMs/system builders & consequently, the drive manufacturers to supply UL 61800-5-1 listed drives

•What does this UL change mean to the drive end customers / users?

Presenter

Presentation Notes

What does this UL change mean to the drive end customers / users? Many end customers/equipment owners/drive users (e.g. in automobile, water / waste water, infrastructure, construction, oil & gas, power plants, buildings, metals, pulp & paper etc. industries) have already been specifying the new & latest technology UL 61800-5-1 listed drives in their requirement / bid specifications and DO NOT allow use of obsolete and old technology UL 508C certified drive products anymore! These customer specs have now started demanding the OEMs/system builders & consequently, the drive manufacturers to start supplying UL 61800-5-1 listed drives


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – To drive end customers / users

UL 508C is withdrawn & UL 61800-5-1 is the only UL standard for drives, and UL announced removal of references to UL 508C & their replacement with UL 61800-5-1 in ALL UL standards e.g. UL 508A, UL 845, UL 1995 etc.

•It becomes prudent to use latest technology drives in equipment (i.e. panel, MCC or chiller etc.) which are designed with the latest & most rigorous safety requirements according to UL 61800-5-1

• DO NOT want to use obsolete & outdated technology drive product that is designed with safety requirements that have not been up to date with NEC/NFPA 70

AHJ / electrical inspectors in many counties and cities have already been increasingly demanding UL 61800-5-1 listed drives in equipment or panels at the end customers’ / users’ or equipment owners’ sites

AHJ – Authority Having Jurisdiction

•What does this UL change mean to the drive end customers / users? [Cont’d]

Presenter

Presentation Notes

What does this UL change mean to the drive end customers / users? UL 508C is withdrawn & UL 61800-5-1 is the only UL standard for drives, and UL announced removal of references to UL 508C & their replacement with UL 61800-5-1 in ALL UL standards e.g. UL 508A, UL 845, UL 1995 etc. It is prudent to use latest technology drives in equipment (i.e. panel, MCC or chiller etc.) which are designed with the latest & most rigorous safety requirements according to UL 61800-5-1 to ensure process continuity and personnel safety, and DO NOT want to use obsolete & outdated technology drive product that is designed with safety requirements that have not been up to date with NEC/NFPA 70 AHJ / electrical inspectors in many counties and cities have already been increasingly demanding UL 61800-5-1 listed drives in equipment or panels at the end customers’ / users’ or equipment owners’ sites Authority Having Jurisdiction (AHJ) means the organization, office, or individual responsible for approving layout drawings, equipment, an installation or a procedure. Usually the AHJ is the building and/or fire official of the city or county in which the job site is located.


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – To OEMs and system/panel builders

•What does this UL change mean to OEMs & system / panel builders?•Following the UL withdrawal of old UL 508C, although, OEMs and system or panel builders using drives (e.g. Panels, MCC, HVAC, Chiller etc.) will have some time to change design of their products and switch to UL 61800-5-1 listed drives in their equipment,

• Due to specifications from industrial users / customers demanding the latest & new technology UL 61800-5-1 listed drives, the OEMs and system or panel builders will have to adapt to this change sooner than later, and

• Need to start modifying their equipment design to use UL 61800-5-1 listed drives to become ahead of the curve and hence ahead of their competition

Which means, demand from OEMs and system or panel builders for latest & new technology UL 61800-5-1 listed drives will increase for use in their equipment (e.g. Panels, MCC, HVAC, Chillers etc.)

Presenter

Presentation Notes

What does this UL change mean to OEMs & manufactures of equipment comprised of drives e.g. Panels, MCC, HVAC, Chiller etc.? Following the UL withdrawal of old UL 508C, although, OEMs and system or panel builders using drives (e.g. Panels, MCC, HVAC, Chiller etc.) will have some time to change design of their products and switch to UL 61800-5-1 listed drives in their equipment, Due to specifications from industrial users / customers demanding the latest & new technology UL 61800-5-1 listed drives, the OEMs and system or panel builders will have to adapt to this change sooner than later, and Need to start modifying their equipment design to use UL 61800-5-1 listed drives to become ahead of the curve and hence ahead of their competition Which means, manufacturers/OEMs/system builders of the drive end products (such as Panels, MCC, HVAC, Chiller etc.) will mandate the drive manufacturers to supply the replacement drives with the latest & new technology UL 61800-5-1 listing for their equipment!


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – To drive manufacturers

•What does this UL change mean to drive manufacturers?According to UL test & certification group within UL LLC, any drive products which are listed according to UL 508C will remain UL listed until those will be modified (i.e. typically requiring changes to construction or design of a drive)

•However, following the UL withdrawal of old UL 508C, the drive manufactures are now expected to supply UL 61800-5-1 listed drives ONLY, and will face extreme difficulty in convincing customers, system or panel builders, OEMs to use drives certified according to outdated, obsolete technology & already withdrawn UL 508C in their equipment

•Ultimately, drive manufactures who have not followed the UL process of transition from UL 508C to UL 61800-5-1 within last almost 8 years timeline allowed by UL, and if are significantly behind in modifying & certifying their drive products according to UL 61800-5-1 will face great challenges now to respond to the market requirements & demand

Presenter

Presentation Notes

What does this UL change mean to drive manufacturers? According to UL 508C/UL 61800-5-1 certification group within UL LLC, any drive products which are listed according to UL 508C will remain UL listed until those will be modified (i.e. typically requiring changes to the construction or design of a drive). Which means if an end user or customer or OEM or panel builder is using such outdated technology & old UL 508C listed product and if drive manufacturer has to undergo replacement of component due to supply chain issue such as shortage or discontinuation or obsolescence of capacitor or diode or igbt then they don’t have any choice but to redesign the complete drive and hence potentially of end product and needless to say will take a long time before the UL approval is received means the processes & business will face very high risk of discontinuity! However, following the UL withdrawal of old UL 508C, the drive manufactures are now expected to supply UL 61800-5-1 listed drives ONLY, and will face extreme difficulty in convincing customers, system or panel builders, OEMs to use drives certified according to outdated, obsolete technology & already withdrawn UL 508C in their equipment Considering all of these, ultimately, the drive manufactures who have not followed the UL process of transition from old UL 508C to new UL 61800-5-1 by modifying their drive product design to comply with latest technology safety requirements and also meet NEC/NFPA 70 in last almost 8 years allowed by UL, will face extreme challenges now to respond to the market requirements & demand


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – To retrofit or repair projects

Retrofit or repair of equipment comprised of UL 508C listed drives •UL compliance of an electrical system / equipment after retrofit or repair at the end customer / equipment owner site does not fall under UL’s responsibility / jurisdiction unless being specified in equipment retrofit or repair specifications

• UL field inspection group (or any other NRTL) needs to be engaged to carry out field inspection and approval of the finished equipment after retrofit or repair

• In such cases, whether to use the same old UL 508C listed drive or its UL 61800-5-1 listed successor is solely at discretion of end customer / equipment owner

• However, following UL announcement of UL 508C withdrawal, AHJs / electrical inspectors and hence, end customers / equipment owners have already started specifying UL 61800-5-1 listed drives for a retrofit or repair of their equipment / panel

• OEMs / system or panel builders already ahead of the curve and adapted to this UL change by modifying their equipment design using UL 61800-5-1 listed drives & ready to offer replacement in the field per customer specs, will certainly have better chances of winning such retrofit or repair opportunities

Presenter

Presentation Notes

Retrofit or repair of equipment comprised of UL 508C listed drives UL compliance of a system/equipment after retrofit or repair at the end customer/equipment owner site does not fall under UL’s responsibility / jurisdiction unless being specified in equipment retrofit or repair specs by an equipment owner or end customer In such cases, a field inspection group of UL (or any other NRTL) needs to be engaged to carry out the field inspection and approval of the finished equipment after retrofit or repair Moreover, in such cases, whether to use the same old UL 508C certified drive or to use its UL 61800-5-1 certified successor is solely at discretion of end customer / equipment owner However, following UL announcement of withdrawal of UL 508C, the AHJ / electrical inspector and hence end customers / equipment owners demanding UL 61800-5-1 listed drives in general, for a retrofit or repair of an equipment or a panel also a use of UL 61800-5-1 listed drive is highly anticipated reality. In such situations also the OEMs / system or panel builders who are already ahead of the curve, adapted to this UL change by modifying their equipment design using UL 61800-5-1 listed drives & ready to offer replacement in the field per customer specs, will certainly have better chances of winning such retrofit or repair opportunities


UL 61800-5-1: NEW UL Standard for DrivesImpact to industry – Key takeawaysUL 61800-5-1 has more stringent construction and performance (testing) requirements• Requires more number of destructive tests → Represent real life drive operation / applications • Requires more rigorous testing of more number of drive test samples as compared to old & withdrawn

UL508CUL 61800-5-1 is the ONLY valid UL standard for low voltage drives as UL 508C has been obsolete & withdrawn from Feb 1, 2020 • References to old & withdrawn UL 508C are being replaced with NEW UL 61800-5-1 in ALL UL

standards including UL 508A (Panels), UL 845 (MCC), UL 1995 (HVAC/R) End customers have already started specifying use of UL 61800-5-1 listed drivesOEMs / System or Panel Builders:• Need to adapt this UL change (UL 61800-5-1 listed drives) sooner than later• Should be proactive and start modifying the design of your equipment / panel quickly to replace old

UL 508C listed drives with their equivalent UL 61800-5-1 listed drives • Faster implementation of such design change will help address the new customer requirements more

effectively & get better market exposureUltimately end customers will get the latest technology, safer & more robust drive products



Definitions






Presenter

Presentation Notes

Now let us see the comparison of SCCRs offered by a typical non-Siemens VFD and Siemens VFDs and their corresponding protective devices for UL compliance


•UL Testing and Certification mostly with specific fuses

•And according to old standard, UL508C

•Fuse type and rating used for testing is required to achieve SCCR, and is therefore mandatory for UL listing

•Without this fuse the UL listing is invalid, and SCCR = 0

•UL 508C has been withdrawn by UL from Feb 1, 2020 – Click here

SCCR of typical non-Siemens VFDs

VFD SCCR Prevalent in North America65kA or 100kA @ 480VUL 508C Listed

Circuit breaker or MSP

Special fuse

+or

or

Class J Semiconductor

A typical non-Siemens VFD

Presenter

Presentation Notes

For a majority of non-Siemens drives available in the market, First of all, it is very hard to find the SCCR and OCPD information for UL / CSA application. And if you are lucky and find this information then most of this information is confusing, incomplete, and many times non-compliant with UL/NEC. I am not sure as to how these manufacturers get away providing such an incomplete information non-compliant with UL!!! Moreover, for these non siemens drives, the UL testing and certification is done according to obsolete UL 508C using either specific semiconductor fuses or a specific class J or class T fuses from a specific fuse manufacturer that is either Bussmann or Ferraz/Mersen. This specific fuse is always required in the panel or equipment construction to protect these non-Siemens drives to achieve panel or equipment UL listing and also SCCR as specified by the VFD manufacturer. Without the use of this specific fuse the UL listing of VFD and hence panel or equipment is no more valid and SCCR is 0! Moreover, due to the use of this specific fuse, a separate UL 98 listed fuse disconnect or an a breaker or MSP upstream of this fuse is required to comply with motor disconnect and LOTO requirements of OSHA. Moreover, since, UL has already started removing the references to UL 508C from all UL standards (there are about 80+ UL documents where this reference was shown) and UL started replacing them with new UL 61800-5-1, it is prudent for a panel or equipment manufacturer to change their panel or equipment design using UL 61800-5-1 certified VFDs.

https://ul.org/library

https://collateral-library-production.s3.amazonaws.com/uploads/nfp/nfp_asset/attachment/1373/UL_508C_WD.pdf


•UL applications: No other option for OC protection of a non-Siemens VFD

•Specific fuse always required – No flexibility in panel design & construction, & also in the field

•“Semiconductor” fuse can’t be used as main BCP for enclosed panels, hence additional main BCP (CB or MSP) with disconnect function is required for Lock-Out Tag-Out (LOTO) per OSHA → Redundant OCPD• If “semiconductor fuse“ then single supply

chain can interrupt process / plant continuityin case of no spares and unavailability of fuses from manufacturer

•Class J or T fuse can be used as main BCP however, an additional fuse disconnect is required for disconnect function → typically larger and more expensive than equivalent CB or MSP

•Requires more cabinet space, i.e. bigger enclosure

•Increased product cost

•Makes the panel / end product non-competitive andunsuitable

•Requires fuses in spare stock to maintain process continuity

•Increases overall cost of ownership

SCCR of typical (non-Siemens) VFDsConsequences of UL certification using a specific fuse


Non-Siemens VFD

Class J semicond.

SCCR of Siemens VFDsExample: SINAMICS G120/G120C/G120X

•Determined by testing with many different types of Over Current Protective Device (OCPD) – i.e. breakers, MSPs and fuses•UL Testing and Certification according to new standard UL61800-5-1

SINAMICS G120 VFD SCCRUp to 100kA 1) @ 240V, 480V

and 600VUL61800-5-1 listed

Circuit breaker or MSP

Special fuse

SINAMICS

or

+or

Class J, CC, T, CF

SIEMENS

1) SCCR of 100kA can be achieved using Siemens SENTRON current limiting breakers, certain types of NEW 3VA breakers and fuses (Class J, CC, CF, T, etc.)

Any OCPD from a wide variety of Siemens breakers or MSPs or fuses (non-semiconductor or semiconductor) may be used to achieve thedesired SCCR


SCCR of Siemens VFDsAdvantages of more OCPD choices with Siemens VFDs

•Wide choice of UL approved Over Current Protective Devices (OCPD)• Almost all types of UL-listed Siemens circuit breakers and motor starter protectors

(e.g. 3RV type) for US market• Significantly increases flexibility of panel design & construction, & also in the field• Easy retrofit possible → Existing Siemens circuit breaker or MSP or non-

semiconductor fuses may be used • Eliminates need for redundant OCPDs and improves protective device coordination• Reduces overall product (panel) & manufacturing costs

•High SCCR up to 100kA according to UL 61800-5-1• Improves product safety from destructive fault currents• Provides better protection and reduces risks of property damage & personnel injury• Helps mitigate or eliminate incidents and hence OSHA non-conformances• Potentially helps reduce insurance costs, PPE requirements• Reduces overall cost of ownership


SINAMICS V20SINAMICS G120X / G120 / G120C / G120D

SINAMICS S120 Booksize Line Module SINAMICS S210

up to 100kA1) up to 100kA1) up to 100kA1) up to 65kA1)

SIOS Link SIOS Link – G120XSIOS Link – G120

SIOS Link SIOS Link

SCCR of Siemens VFDsSCCR of UL Open Type SINAMICS Drives

1) SCCR lower than shown here is possible depending upon the drive rating, type of OCPD used

Product information on Siemens Industry

Online Support (SIOS)

SINAMICS G120

SINAMICS G120X

Presenter

Presentation Notes

This slide shows the high SCCR of the Sinamics drives. The slide also shows the SIOS (Siemens Industry Online Support web) links where this SCCR and OCPD information for each Siemens drive product is available. Siemens is the ONLY drive manufacturer currently in the industry which offers very wide choices of overcurrent protective devices such as various classes of non-semiconductor fuses, semiconductor fuses, breakers and MSPs with SCCR up to 100kA and that is also according to the most stringent and new UL 61800-5-1 design. Here is the example of SCCR and OPCD information sheet of SINAMICS G120X. As you can see Siemens offers 27 pages of different types of OCPDs complying with IEC as well as UL 61800-5-1 requirements and sccr up to 100kA. No one else in the market is even remotely close to Siemens offering currently. That is all from my side and now I would like to turn this over to John.

https://support.industry.siemens.com/cs/ww/en/view/109755266






Overcurrent protection, SCCR and a new VFD UL StandardThank you for attending today’s presentation!

•Nikunj ShahDevelopment and Certification Manager

•Siemens Industry, Inc.Digital Factory — Motion Control5300 Triangle Parkway, Suite 100Norcross, GA 30092

•[email protected]

•usa.siemens.com/lv-drives

mailto:[email protected]

Overcurrent protection, SCCR and a new VFD UL Standard...• UL 61800-5-1 (old UL 508C), UL61800-5-2, UL1741 & UL62109-1, UL508A • NEMA 1IS SC7 - Adjustable Speed Drives • IEC

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