1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories (UL). Itis normative for the applicable
2、UL Product Certification Program(s); however, it is currently not part ofthe UL Standard(s) referenced below.Product Category (CCN): AAAKStandard Number: UL 991Edition Date: October 22, 2004Edition Number: 3Section / Paragraph Reference: Section 18DECISION:The Composite Operational and Cycling test
3、in Section 16 represents the Thermal Cycling test of Section18 and the Overvoltage and Undervoltage test of Section 10.RATIONALE FOR DECISION:The Composite Operational and Thermal Cycling test evaluates the controls robustness to cumulativevariations in temperature and voltage without compromising a
4、ny of the protective functions. Thesevariations are introduced while the control is operating/cycling through its operational modes; thus,electrically and thermally stressing the electronic components.When the Thermal Cycling test and Overvoltage and Undervoltage tests are done separately, theelectr
5、onics are independently subjected to the particular stresses and the cumulative affect of thesestresses on the electronics are not realized. It is these cumulative stresses that may cause the solid-statecomponents to behave differently.Copyright 2007 Underwriters Laboratories Inc.UL, in performing i
6、ts 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 anyone. Certification Requirement Decisions are the opinion of Underwriters Laboratories Inc. inpractically ap
7、plying the requirements of the standard. They do not represent formal interpretations of thestandard under American 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
8、 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electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSTANDARD NUMBER: UL 991 -2-No Text on This Page
