UL 873 CRD-2012 UL Standard for Safety Temperature-Indicating and-Regulating Equipment - Section Paragraph Reference 47A Subject Abnormal Switching Test - Requirements for controlsa.pdf

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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): XAPX, SDFYStandard Number: UL 873Edition Date: November 16, 2007Edition Number: 12Section / Paragraph Reference: 47ASubject: Abnormal Switching Test - Requir

3、ements for controls using electronictriggering techniques, such as zero-crossing switching, to control the controlsoutput switching deviceDECISION:47A Abnormal Operation Tests47A.1 General - The abnormal conditions described in 47A shall be imposed and maintained until ultimateresults are obtained.4

4、7A.2 Abnormal Switching Test47A.2.1 Controls incorporating electronic circuitry to trigger the controls output switching device in orderto achieve switching of contacts during more advantageous electrical conditions such as at zero crossing,shall be subjected to this abnormal switching test. This te

5、st is applicable when:a) Loads and circuits are only non-safety.b) Switching device components are used beyond their ratings47A.2.2 Two test samples shall be prepared and connected as follows:a) The driver circuit to the switching device is to be removed or modified to allow randomswitching.b) A gro

6、und arc fault indicating fuse is connected to accessible dead metal of the control. Thisfuse shall be 3-ampere maximum, non-time delay type fuse rated not less than the workingvoltage.c) The control is supported on a tissue paper covered softwood surface, and is covered with adouble layer of cheesec

7、loth conforming to the outline of the control. The cheesecloth is inaccordance with 63.1.2.d) The rated supply circuit is connected through a branch circuit protection device sizedaccording to installation requirements.e) The control is connected to its rated electrical load.UL COPYRIGHTED MATERIAL

8、NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL47A.2.3 The prepared test samples shall be operated in accordance with the endurance test requirementsin section 46, including the number of operating cycles and on/off periods, using random switching. Thetest samples s

9、hall be operated until either the required number of endurance test cycles are achieved oruntil ultimate results are demonstrated for 1h stabilized duration.47A.2.4 Immediately after each abnormal switching test, each control shall be subjected to the dielectricwithstand test in 47.1.47A.2.5 The con

10、trol shall either operate as intended in accordance with the endurance test specifications,or demonstrate an end-of-life fail safe condition with no evidence of an imminent electrical shock, fire orinjury to persons hazard. There shall be:a) no opening of the ground arc fault detection fuse,b) no bu

11、rning of the cheese cloth,c) no opening of the branch circuit protection device, andd) no breakdown during the post-abnormal switching dielectric withstand testingRATIONALE FOR DECISION:This Certification Requirement Decision is intended to establish requirements for controls using electronictrigger

12、ing techniques, such as zero-crossing switching, to control the output switching device in order toachieve switching of contacts during more favorable electrical conditions. To demonstrate capability andalso demonstrate required evaluation of the electronic control with zero-crossing switching techn

13、iques, thecontrol / switching device shall be subjected to an investigation that examines both normal and abnormalcontact switching conditions. Normal operating conditions are already evaluated under the existingtemperature, overload, endurance, and dielectric withstand tests. Abnormal contact switc

14、hing operatingconditions need to be evaluated under this Abnormal Switching Test. The Abnormal Switching Test is notapplicable if the electronic control with zero-crossing switching circuitry has been subjected to a UL 991and UL1998 (if applicable) investigation, or a UL 60730-1 investigation, since

15、 the control has demonstratereliability and production repeatability of the zero-crossing switching circuitry. In general the triggeringcircuitry is relied on to provide optimum switching operation of the contacts. Zero-crossing algorithms aretypical examples but there may be other methods that are

16、permitted. This CRD reflects current practice.This testing method can be applied provide the following conditions are met:- The circuit is NOT a safety circuit.- The switching component is being used outside of its certified rating.- The control has acceptably completed overload, endurance and diele

17、ctric withstand testing.Copyright 2012 Underwriters Laboratories Inc.UL, 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 anyone. Certification

18、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 American National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use

19、of or reliance upon Certification Requirement Decisions by anyone. UL shall not incurSTANDARD NUMBER: UL 873 -2-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULany obligation or liability for damages, including consequential damages, arising o

20、ut 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 873 -3-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSTANDARD NUMBER: UL 873 -4-No Text on This Page