UL 746B-2018 UL Standard for Safety Polymeric Materials - Long Term Property Evaluations (Fifth Edition).pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 746B Polymeric Materials Long Term Property Evaluations STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRI

2、GHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Polymeric Materials Long Term Property Evaluations, UL 746B Fifth Edition, Dated August 15, 2018 SUMMARY OF TOPICS This new Fifth Edition of ANSI/UL 746B was issued tto Update

3、 Default Correlation Time for RTI Determination from 100,000 Hours to 60,000 Hours The requirements are substantially in accordance with Proposal(s) on this subject dated May 11, 2018. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in

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7、st any loss, expense, liability, damage, claim, or judgment (including reasonable attorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronic Standard on the purchasers computer system. AUGUST 15, 2018 UL 746B tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FO

8、R FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL AUGUST 15, 2018 UL 746B tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL AUGUST 15, 2018 1 UL 746B Standard for Polymeric Materials Long Term Property E

9、valuations First Edition September, 1975 Second Edition June, 1979 Third Edition August, 1996 Fourth Edition April, 2013 Fifth Edition August 15, 2018 This ANSI/UL Standard for Safety consists of the Fifth Edition. The most recent designation of ANSI/UL 746B as an American National Standard (ANSI) o

10、ccurred on August 15, 2018. ANSI approval for a standard does not include the Cover Page, Transmittal Pages, and Title Page. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line Collabo

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12、 exclusive property of UL. COPYRIGHT 2018 UNDERWRITERS LABORATORIES INC. ANSI/UL 746B-2018UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 2 No Text on This PageUL C

13、OPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .5 2 References .5 3 Supplementary Test Procedures 5 4 Characteristics of Polymeric Materials .6 5 Use of Polymeric Materials .6 DETERMINATION OF THE RELATIVE THERMAL

14、INDICES OF POLYMERIC MATERIALS 6 General 7 7 Relative Thermal Index Based Upon Historical Record .8 8 Relative Thermal Index Based Upon Long-Term Thermal-Aging Programs 10 9 Apparatus .11 9.1 Ovens .11 10 Scope of Test Programs .12 10.1 Selection of test properties 12 11 Property-Evaluation Tests 13

15、 11.1 General .13 11.2 Choice of end-point .14 12 Sampling Programs .14 13 Selection of Oven Temperatures 15 14 Selection of Control Material .16 15 Specimens .17 16 Thermal Aging 17 17 End-of-Life .19 17.1 Primary properties 19 17.2 Secondary properties .20 18 Proof Testing .20 19 Analysis and Eval

16、uation .21 20 Related Material Coverage of Variations in Material Composition .27 20.1 General .27 20.2 Thermoplastic materials .27 20.3 Thermosetting molded materials .32 21 Aging, Specimen, and Check-Test Schedules 33 21.1 General .33 21.2 Polypropylene .33 21.3 Coating powders .34 22 Fixed Time S

17、ampling Method 40 22.1 General .40 22.2 Screening procedure .41 22.3 Remainder of Fixed Time sampling method .42 RELATIVE THERMAL INDEX CLASS 23 Assignment of Temperature Classications 42 MARKING 24 General 42 AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 3UL COPYRIGHT

18、ED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL SUPPLEMENT SA - FOLLOW-UP INSPECTION INSTRUCTIONS INTRODUCTION SA1 Scope SA1 SA2 Glossary SA1 SA3 Responsibility of the Manufacturer .SA2 SA4 Responsibility of the Field Representative SA3 SA5 Selection of

19、 Samples for Follow-Up Testing .SA3 SA6 Follow-Up Test Program SA3 AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements cove

20、r long-term test procedures to be used for the evaluation of materials used for parts intended for specic applications in end products. 1.2 Together with the Standards mentioned in Supplementary Test Procedures, Section 3, these investigations provide data with respect to the physical, electrical, a

21、mmability, thermal, and other properties of the materials under consideration and are intended to provide guidance for the material manufacturer, the molder, the end-product manufacturer, safety engineers, and other interested parties. 2 References 2.1 Any undated reference to a code or standard app

22、earing in the requirements of this standard shall be interpreted as referring to the latest edition of that code or standard. 3 Supplementary Test Procedures 3.1 The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94, covers ammability of polymeric ma

23、terials used for parts in devices and appliances. The Standard for Polymeric Materials Short Term Property Evaluations, UL 746A, contains short-term test procedures to be used for the evaluation of materials used for parts intended for specic applications in electrical end products. The Standard for

24、 Polymeric Materials Fabricated Parts, UL 746D, contains requirements for traceability and performance of parts molded and fabricated from polymeric materials. 3.2 Programs for the investigation of material part modications, such as the plating of plastics or the use of ame-retardant paints, are con

25、tained in the Standard for Polymeric Materials Use in Electrical Equipment Evaluations, UL 746C. 3.3 Data concerning the effect of various environments and contaminants upon the properties of materials can also be obtained through standard test procedures. The more commonly used procedures are briey

26、 described in the Standard for Polymeric Materials Short Term Evaluations, UL 746A. 3.4 Test procedures are provided in the Standard for Polymeric Materials Use in Electrical Equipment Evaluation, UL 746C, for the evaluation of polymeric materials in specic applications in end products. These test p

27、rocedures include references to the data obtained from the standard property tests as well as other practical means of evaluation. 3.5 Requirements for materials that have been modied to match the requirements of a specic application, including the use of recycled and regrind materials, the use of a

28、dditives and colorants, and the blending of two or more materials, are described in the Standard for Polymeric Materials Fabricated Parts, UL 746D. AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIB

29、UTION WITHOUT PERMISSION FROM UL 4 Characteristics of Polymeric Materials 4.1 Polymeric materials include thermoplastic, thermosetting, and elastomeric materials. A thermoplastic material can be easily softened and resoftened by repeated heating. A thermosetting material cures by chemical reaction a

30、nd, when cured, cannot be resoftened. An elastomeric material is capable of being stretched at room temperature to at least twice its length under low stress and recovers to its original length when released from the stress. 4.2 Characteristics of polymeric materials that necessitate additional cons

31、ideration include: a) Mold stresses b) Insulating quality c) Resistance to ignition d) Extinguishing characteristics e) Production of smoke and gases f) Mechanical Strength g) Compatibility with solvents h) Melting or distortion i) Cold ow, if under stress j) Fuel contribution k) Dimensional stabili

32、ty 5 Use of Polymeric Materials 5.1 The reduction to an acceptable level of the risks of electric shock, re, and personal injury from electrical equipment depends upon the selection of materials, design, and processing of parts as well as the assembly, mounting, and relative positions of these parts

33、. 5.2 The properties needed by individual parts are dened by the function or functions of the part. An enclosure, for example, must ordinarily be designed to withstand mechanical abuse. Accordingly, a material known to have substantial impact strength would normally be used although a material that

34、has a lower impact strength, but is reinforced, might also be acceptable. 5.3 Electrical equipment of necessity employs many materials that usually have divergent properties. The ability to match the demands of the application with the characteristics of a material as well as the ability to compare

35、the properties of one material with those of another can lead to an acceptable selection of materials. AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 5.4 The info

36、rmation gained from the data obtained from these tests can be used as an aid in the evaluation of electrical equipment using parts made of polymeric materials. Knowledge of materials can be obtained from an analysis of data from standard tests conducted on small specimens. DETERMINATION OF THE RELAT

37、IVE THERMAL INDICES OF POLYMERIC MATERIALS 6 General 6.1 A relative thermal index of a material is an indication of the materials ability to retain a particular property (physical, electrical, etc.) when exposed to elevated temperatures for an extended period of time. It is a measure of the material

38、s thermal endurance. For each material, a number of relative thermal indices can be established, each index related to a specic property and a specic thickness of the material. 6.2 In determining the relative thermal index of a material, the basic concepts to be followed are stated in the Institute

39、of Electrical and Electronics Engineers Specications No. 1, General Principles for Temperature Limits in the Rating of Electrical Equipment; No. 98, Guide for the Preparation of Test procedures for the Thermal Evaluation of Electrical Insulating Materials; No. 101, Guide for the Statistical Analysis

40、 of Thermal Life Test Data. 6.3 The relative thermal index of a material is to be based upon an evaluation of long-term thermal-aging data obtained under the program described in Relative Thermal Index Based Upon Long-Term Thermal-Aging Programs, Section 8. Thermal indices on a generic basis have be

41、en established through knowledge of extensive eld-service records, as outlined in Relative Thermal Index Based Upon Historical Record, Section 7. Relative thermal indices may also be established based upon a study and evaluation of the interrelationship of all of the data mentioned in Supplementary

42、Test Procedures, Section 3, which can also be coupled with knowledge concerning the materials performance in insulating systems gained through experience or long-term aging tests. 6.4 A comparison of the thermal-aging characteristics of one material of proven eld service at a particular temperature

43、level with the thermal-aging characteristics of another material with no eld service history provides a means for estimating the relative thermal index level at which the second material might also provide acceptable eld service. 6.5 Another explanation of a relative thermal index is the maximum tem

44、perature below which a material maintains its characteristics over a reasonable period. This relative thermal index serves the very great need to evaluate materials that are exposed to heat sources in electrical products in which they are not used as part of an insulating system and in which they ar

45、e not subjected to other major degradation inuences. It is to be assumed that neither excessively long nor excessively short duty cycles are involved. 6.6 To be valid for use in a specic application, a relative thermal index of a material must be established by a study of the degradation rates of al

46、l properties that are relied upon in that application. As a corollary to this principle, more than one relative thermal index can be assigned to a material depending on the relative degradation rates of the properties of the material and depending on which of these properties are considered in estab

47、lishing the indices. AUGUST 15, 2018 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 7 Relative Thermal Index Based Upon Historical Record 7.1 Table 7.1 presents a list of materia

48、ls, each of which is assigned a relative thermal index based on acceptable service experience, the chemical structure of the material, and a knowledge of the performance of the material in tests of insulating systems and electrical equipment. The assigned relative thermal index is applicable to each

49、 member of the generic material class. 7.2 Unless otherwise indicated in Table 7.1, the generic thermal index of a material is to be considered 50C (122F). 7.3 Unless otherwise indicated in Table 7.1, the generic thermal index of a material is independent of thickness and pigmentation. Table 7.1 Relative thermal indices based upon past eld-test performance and chemical structure a Material ISO designation Generic thermal index,C Polyamide b PA 65 Polycarbonate b