1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared by UL LLC. It is normative for the applicable ULProduct Certification Program(
2、s); however, it is currently not part of the UL Standard(s) referencedbelow.Product Category (CCN): NITWStandard Number: UL 508AStandard Title: Standard for Industrial Control PanelsEdition Date: April 24, 2018Edition Number: 3Section / Paragraph Reference: 42.2.3/42.2.3.1Subject: Sizing Power Suppl
3、ies Complying with UL 61010-2-201DECISION:42.2.3 Sizing of power supply42.2.3.1 A power supply or bridge rectifier shall be loaded at not more than 50 percent of the ampererating of the device. Where the power supply has multiple secondaries, each secondary shall be loadedat not more than 50 percent
4、 of the secondary ampere rating.Exception No. 1: An enclosed power supply having provisions for connection to conduit is able to be usedfor loading to 100 percent of the ampere rating of the power supply.Exception No. 2: A power supply that complies with the Temperature Test in the Standard for Indu
5、strialControl Equipment, UL 508, is able to be used for loading to 100 percent of the ampere rating of the powersupply.Exception No. 3: A power supply that complies with the Temperature Test in the Standard for SafetyRequirements for Electrical Equipment for Measurement, Control, and Laboratory Use
6、Part 2-201:Particular Requirements for Control Equipment, UL 61010-2-201, is able to be used for loading to 100percent of the ampere rating of the power supply.RATIONALE FOR DECISION:As permitted by the existing “Exception No. 2”, power supplies that comply with the Temperature Test inthe Standard f
7、or Industrial Control Equipment, UL 508, are suitable for loading to 100 percent of theampere rating of the power supply based on being evaluated for use in a 40C ambient. The sameperformance criteria for the Temperature Test detailed in UL 508 is also specified in the Standard forSafety Requirement
8、s for Electrical Equipment for Measurement, Control, and Laboratory Use Part2-201: Particular Requirements for Control Equipment, UL 61010-2-201. Therefore, this CertificationRequirement Decision extends the same provision, as a new “Exception No. 3”, to those power suppliesevaluated using UL 61010-
9、2-201.The standard is being revised to reflect these permissions.Copyright 2018 UL LLCUL LLC, in performing its functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby a
10、nyone. Certification Requirement Decisions are the opinion of UL LLC. in practically applying therequirements of the standard. They do not represent formal interpretations of the standard underUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULAm
11、erican National Standards Institute (ANSI) processes. UL LLC shall not be responsible to anyone forthe use of or reliance upon Certification Requirement Decisions by anyone. UL LLC shall not incur anyobligation or liability for damages, including consequential damages, arising out of or in connection withthe use or reliance upon Certification Requirement Decisions. The electronic version of the CertificationRequirement 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-
