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): PRGY, PRHZ, PRHJ, XDNW, XDNZStandard Number: UL 1004-1Standard Title: Standard for Rotating Electrical Machines - General RequirementsEdition Date: September 19, 2012Edition Number: 2Section / Paragra
3、ph Reference: 44.9Subject: Requirements for ECMs with electronic protection intended for fieldinstallationDECISION:REVISED44.9 For field installed motors, an alternating-current motor rated 1/2 horsepower (373 W output) or moreshall be marked with a code letter to indicate the locked-rotor amperes i
4、n accordance with the NationalElectrical Code, NFPA 70.Exception: Motors requiring a drive to operate as intended, where the in-rush current is limited, may havethe locked rotor amperes (KVA) code letter omitted.RATIONALE FOR DECISION:The intent of the marking (and NEC requirement) is to assist inst
5、allers to select compatible motor startersand properly sized circuit breakers to allow proper operation (prevent nuisance tripping) after the motor isinstalled.The current marking requirement is ambiguous for constructions where a drive provides power to themotor (either integrally mounted or from s
6、upply leads) and limits the in-rush current.This Certification Requirement Decision (CRD) clarifies when it is permissible to omit the locked rotoramperes (KVA) code letter.When a motor uses a drive that:1) provides the motor with a generated AC signal, instead of a standard sinuosity waveform,and2)
7、 limits the current inrush (often referred to as a “soft-start” to minimize strain on the windingsand other components),the locked rotor amperes (KVA) code letter is not required to be marked on the motor.The requirement in the NEC was specifically written to address standard induction motors.While
8、motors operated from drives do not actually use a sinusoidal AC current wave-form, this alonewould not exempt a motor with a drive from needing to provide a KVA code.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThe more critical aspect of t
9、his relates to the concern that high currents observed during start-up andlocked-rotor conditions (from standard induction motors) and properly sizing motor starter and circuitbreakers for proper functioning.This part is addressed by only allowing a drive with a limited in-rush current feature to be
10、 exempt from themarking requirement.This CRD is intended to document present practice.Copyright 2017 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 reco
11、gnized or adoptedby anyone. 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 underAmerican National Standards Institute (ANSI) processes. UL LLC shall not be responsibl
12、e 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 1004-1 -2-
