Short Circuit Current Ratings and AC Drives

Transcription

1 Short Circuit Current Ratings and AC Drives Ivan Spronk, Product Marketing AC Drives Schneider Electric Industry NOW Express

2 Goal of this session Understand Importance of proper SCCRs Hot button points and confusion about SCCRs Be able to articulate the various aspects of SCCRs Understand The information Schneider Electric provides The information most competitors provide Be able to position yourself to help your customers Know what documents to use to find SCCR for the Altivar product line 2

3 Why are these ratings important? 3

4 Why are these ratings important to you? Applying SCCRs properly can: Enhance personnel safety Limit equipment damage Reduce lost production time Provide the most cost effective solution 4

5 Hot Buttons & Points of Confusion Recent changes to NEC and UL508 Control panels are now required to have a SCCR Increased industry attention to SCCRs UL 508C: test standard for AC Drives Lacks specific test method for short circuit testing Leads to different interpretations by manufacturers Not all manufacturers publish the same info Allows for a higher must be better mentality Who is impacted the most? Those not performing tests on each design: System integrators Panel builders OEMs 5

6 Aspects of SCCRs Circuit breakers and fuses Designed to operate at some level of short circuit current Designed to interrupt current Common values: 1k, 5k, 10k, 22k, 42k, 65k 100k These are overcurrent protective devices (OCPD) Has an AIR rating: ampere interrupting rating Other electric equipment panels and products UL requirement: Have a maximum short circuit current rating Designed to operate at some level of short circuit current Common values: 1k, 5k, 10k, 22k, 42k, 65k 100k Rating can be no higher than lowest rated product Equipment and panel need to safely withstand the level 6

7 Aspects of SCCRs and AC Drives Input section Available short circuit current has a thermal impact True for any device converting AC power to DC power Internal section Internal of an AC Drive has many current paths AC Drives should not be tested like starters Output section Have IGBTs that turn off at high current level Many suppliers provide SCCRs based on testing the output 7

8 Aspects of SCCRs and AC Drives: Schneider Electric Position Input section Customers need to know the level of available short circuit current the drive was designed to handle Internal section Short circuit testing should test the most vulnerable part Output section A SCCR should not be based on the output 8

9 Information provided by Schneider Electric: Input Section Input Section: The input current increases as AFC increases AFC = amount of available fault or short circuit current True for any devise converting power The input AFC rating reflects: Available short-circuit current at input terminals that the drive was designed to operate both thermally and electrically How much effect do various levels have? See Data Bulletin 8800DB0801 for more info Schneider Electric designs to UL recommended levels Schneider Electric provides this input AFC rating If the available prospective short circuit current exceeds the level the drive was designed for, use externally mounted impedance to reduce level Line reactors are commonly used DC chokes 9

10 Information provided by Schneider Electric: Internal Section Internal Section: AC Drives contain many power components Diodes Capacitors IGBTs There are multiple paths for a short circuit Internal components may short across the power circuit. To obtain a SCCR, Schneider Electric performs A breakdown of components test Testing the most vulnerable parts At the marked SCCR value Why do other manufacturers only test and provide a SCCR based on shorting the out put of the drive? 10

11 Information provided by Schneider Electric: Internal Section Electric Company / Distribution Panel Why do other manufacturers only test and provide a SCCR based on shorting the output of the drive? Left over from the legacy test method for a motor starter For a starter or contactor Shorting the output tests this entire device Many drive manufactures are currently providing a SCCR based on only testing by shorting the output Schneider Electric has taken an industry leadership position Providing SCCR ratings based on internal breakdown tests Leading UL 508C to mandate an internal breakdown tests Load 11

12 Information provided by Schneider Electric Internal Section: Schneider Electric SCCR parameters validated during Breakdown of Components testing Contain a breakdown within its enclosure based on the Available Fault Current (AFC) and its listed Overcurrent Protective Device (OCPD) Should not create shock, flame, fire or expulsion hazard outside the enclosure Schneider Electric provides a rating for a wall mounted AC Drive AC drive with optional conduit entrance Housing of the unit must contain the hazard Schneider Electric provides a rating for an AC drive mounted in an enclosure Enclosure around the drive must contain the hazard See ANNEX document 12

13 Information provided by Schneider Electric: Output Section Output Section: Today s IGBT technology used by most manufactures Will turn off well before fault current builds to dangerous levels Interrupting 100kA on the output is no issue Drive input does not see fault current Available input short-circuit current and output interruption rating are unrelated Schneider Electric provides this information only to show our product can obtain the same rating on the output Testing the output does not help construct a robust solution 13

14 Aspects of SCCRs and AC Drives: our position Input section Customers need to know the level of available short circuit current the drive was designed to handle Internal section Short circuit testing should test the most vulnerable part Output section A SCCR should not be based on the output 14

15 What information do competitors provide? ABB provides: Input currents with and without line reactors with no explanation Specifying expensive Class T fuses only No circuit breaker ratings Schneider Electric provides: Multiple ratings with circuit breakers and GV2 Ratings with Class J fuses 25-50% less expensive than Class T fuses 15

16 What information do competitors provide? ABB Claiming maximum 200k SCCR rating Clearing relying on testing only the output of the drive Claiming actual rating is based on OCPD Providing no information about thermal impact of various levels of available fault current Schneider Electric provides information about: Thermal impact of various levels of available fault current Multiple ratings with circuit breakers and GV2 Ratings with Class J fuses 16

17 What can you do with this information? Assist customers to build equipment that can Enhance personnel safety with ratings on product match installation Limit equipment damage Properly rated to contain a short circuit Reduce lost production time Properly rated to contain a short circuit Provide the most cost effective solution Install just what is needed Control panel cost is proportional to specified SCCR Schneider Electric is leading the industry in this effort by challenging the information being supplied by others 17

18 Resources Know which Codes & Standards apply to your customer s equipment NEC2011 Article and Requires that industrial control panels be marked with (SCCR) Requires AC Drives be rated with a SCCR UL508A points to UL508C for power conversion controllers i.e. AC & DC power converters or drive controllers UL 1995 Standard for Air Conditioning and Refrigeration Equipment UL508C Provides a method of establishing SCCR for Drives Provides a SCC rating that satisfies NEC requirements. Issues being worked with UL508C The standard lags technology changes. As such the test methods have room for interpretation. Most are publishing only an output short circuit rating 18

19 Resources SCCR ratings for each Altivar product line Each product line has a document listing SCCRs The Effects of Available Short Circuit Current on AC Drives Data Bulletin 8800DB0801 Variable Frequency Drives and Short Circuit Current Ratings Data Bulletin 8800DB1203 coming soon Control Panel Technical Guide How to ensure trouble free approval of your UL complaint control panels CPTG005_EN 19

20 Summary Short-circuit ratings allow to: Have safer installations Minimize equipment damage Improve up-time in the most cost effective way 20

21 A 5HP AC drive. 5 ka Isc, without Line Reactor, Ipeak=

22 A 5HP AC drive. 22 ka Isc, without Line Reactor, Ipeak=

23 A 5HP AC drive. 100 ka Isc, without Line Reactor, Ipeak=

24 Altivar 61 Annex 24

25 ABB ACS355 specifying expensive Class T fuses 25

26 ABB ACH550 UH 26

27 ABB ACH850 now providing Input current with and without line choke Class T fuses 27

28 AB PowerFlex 40P actual SCCR = AIC of installed fuse / circuit breaker claiming 100k SCCR 28

29 AB PowerFlex 700 actual SCCR = AIC of installed fuse / circuit breaker claiming 200k SCCR 29

30 Internal Break Down of Components Tests 30

31 Typical available fault current at various points and appropriate SCCR rating 31

32 Codes and Standards: UL508C says: 47 Short Circuit Test High Fault Currents 47.1 When any models within a drive series are intended to be rated with high fault current values in excess of the standard current values required by Table 45.1, then one representative model from those intended to be rated with high fault current values shall be used for testing. This representative model shall be subjected to only one high fault current short circuit test. Exception: A drive series complies with the High Fault Current Short Circuit Test in this section without additional testing when: a) The drive series uses solid state short circuit protection circuitry for compliance with the Short Circuit Test, Section 45; and b) The solid state short circuit protection circuitry is used in accordance with Most Drives Manufactures take this exception! Schneider Electric does NOT Schneider Electric conducts short circuit testing at the marked short circuit current rating 32

33 UL 508 C: Minimum Short Circuit Test Values 33

34 Thank You! 34