1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a
2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): NITWStandard Number: UL 508AStandard Title: Standard for Industrial Control PanelsEdition Date: December 20, 2013Edition Number: 2Section / Paragraph Referen
3、ce: Table SB4.4Subject: Three phase transformer secondary available short circuit currentsDECISION:Table SB4.4 revised as noted below.Table SB4.4Three phase transformer secondary available short circuit currents (Amps)aColumn 1 Column 2Transformer Minimum Transformer Secondary Voltage (V)Max kVA 208
4、Y/120b208 240 480Y/277b480 600Y/347b6005 1,160 A 930 A 810 A 510 A 410 A 410 A 330 A10 2,320 A 1,860 A 1,610 A 1,010 A 810 A 810 A 650 A15 3,470 A 2,780 A 2,410 A 1, 510 A 1,210 A 1,210 A 970 A20 4,630 A 3,710 A 3,210 A 2,010 A 1,610 A 1,610 A 1,290 A25 5,790 A 4,630 A 4,010 A 2,510 A 2,010 A 2,010
5、A 1,610 A30 6,940 A 5,560 A 4,820 A 3,010 A 2,410 A 2,410 A 1,930 A45 10,410 A 8,330 A 7,220 A 4,520 A 3,610 A 3,610 A 2,890 A75 17,350 A 13,880 A 12,030 A 7,520 A 6,020 A 6,020 A 4,820 A100 23,140 A 18,510 A 16,040 A 10,030 A 8,020 A 8,020 A 6,420 AaZ assumed to be 2.1%.bShort-circuit current shown
6、 is line-to-neutral.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULTable SB4.4Three phase transformer secondary available short circuit currents (Amps)aColumn 1 Column 2Transformer Minimum Transformer Secondary Voltage (V)Max kVA 208Y/120b208
7、 240 480Y/277b480 600Y/347b6005 840 A 670 A 580 A 360 A 290 A 230 A 230 A10 1,660 A 1,330 A 1,150 A 730 A 580 A 460 A 460 A15 2,490 A 1,990 A 1,730 A 1,090 A 870 A 690 A 690 A20 3,310 A 2,650 A 2,300 A 1,440 A 1,150 A 920 A 920 A25 4,140 A 3,310 A 2,870 A 1,800 A 1,440 A 1,150 A 1,150 A30 4,980 A 3,
8、980 A 3,450 A 2,160 A 1,730 A 1,380 A 1,380 A45 7,450 A 5,960 A 5,170 A 3,240 A 2,590 A 2,070 A 2,070 A75 12,410 A 9,930 A 8,610 A 5,390 A 4,310 A 3,450 A 3,450 A100 16,550 A 13,240 A 11,470 A 7,180 A 5,740 A 4,590 A 4,590 AaZ assumed to be 2.1%.bShort-circuit current shown is line-to-neutral.RATION
9、ALE FOR DECISION:Table SB4.4 indicates the available secondary short circuit currents for three phase transformers. Thesevalues are based on a transformer with an impedance of 2.1%. Based on the formula in paragraphSB4.3.1 a), the values in the table are in error. The correct values are less than th
10、e published values, area relaxation of current requirements, and therefore are effective upon publication of this decision.Copyright 2015 Underwriters Laboratories Inc.UL, in performing its functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Req
11、uirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of Underwriters Laboratories Inc. inpractically applying the requirements of the standard. They do not represent formal interpretations of thestandard under Americ
12、an National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use of or reliance upon Certification Requirement Decisions by anyone. UL shall not incurany obligation or liability for damages, including consequential damages, arising out of or in connectionwith the use or reliance upon Certification Requirement Decisions. The electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersSTANDARD NUMBER: UL 508A -2-
