1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA LI 6-1993 (R2005)Relative Temperature Indices of Industrial Thermosetting LaminatesNEMA Standards Publication LI 6-1993 (R1999, R2005)Relative Temperature Indices of Industrial Thermosetting LaminatesPublished by:National El
2、ectrical Manufacturers Association1300 North 17th Street, Suite 1847Rosslyn, VA 22209 Copyright by the National Electrical Manufacturers Association. All rights including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of L
3、iterary and Artistic Works, and the International and Pan American Copyright Conventions.NOTICE AND DISCLAIMERThe information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consens
4、us does not necessarily mean that there is unanimous agreement among every person participating in the development of this document.The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a vo
5、luntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus,
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8、ny information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this stan
9、dard or guide.In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely
10、on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the us
11、er may wish to consult for additional views or information not covered by this publication.NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health pur
12、poses. Any certification or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement.Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7
13、Appendix A NEMA LI*b 93 6470247 0509652 93T W LI 6-1993 Page i Table of Contents Foreward . ii Referenced Standatds 1 Introduction . 3 History 5 Relative Tmperatme indices 7 Theory 11 Testprocedures . 13 ArrheniusCurves 19 Determination of Relative Temperaim index . 15 NEMA LI*b 93 b470247 0507653 A
14、76 M LI 6-1993 Page i Foreword The industriai Laminate Section of the National Electrical Manufacturers Association represents the major manufacturers of industrial laminated plastics. It is an industry group which conducts activities of interest not only to customers and manufacturers, but also to
15、the general public which ultimately benefits in safay, economy, and convenience, through such programs as standardization, safety and en- gineering, statistics and marketing, and other projects of mutual intenst. Industrial laminates consist of fibrous materiais such as cellulose paper, cotton, glas
16、s, or asbestos fabric; or a mat of random-laid glass or other fibers impregnated or coated with a thermoSetting resin binder and laminated under pressure and high temperature into hard, solid products. These products have useful properties of high mechanical strength, good electrical insulating prop
17、erties and service- ability at elevated temperatures when used within the range of temperatures indicated in Table 4-1 of this publication. The Industrial Laminate Section has supported applied research and development at the Johns Hop- kins University, the University of Delaware, and at the Univers
18、ity of Cincinnati for the following rea- sons: a. The need for an unbiased source of professional quality work on test method development b. The testing of industry offerings of industrial laminates for the purpose of guiding NEMA standards c. Special studies of technology related to industrial lami
19、nates Much of the work at these university laboratories has been directed at obtaining data for industrial laminates under the special environmental and test conditions of the Underwriters Labomtories Inc. Representatives of UL have cooperated with these NEMA-sponsored iabomries through interlabora-
20、 tory correlations of test methods, and, as in the case of the publication at hand, have developed relative temperature indices of the laminates. for these products Comments and suggested revisions should he sent to: Vice President, Engineering Department National Electrical Manufacturers Associatio
21、n 2101 L Street, N.W., Suite 300 Washington, D.C. 20037-1526 NEMA LI*b 93 = 6470247 0509654 702 = LI 6-1993 Page 1 Section 1 REFERENCED STANDARDS In this publication, reference is made to the standards listed below. Copies are available from the indicated sources. International Eiectrotechnical Comm
22、ission 1, rue de Varembe Geneva, Switzerland American National Standards Institute, Inc. 11 West 42nd Street New York, NY 10036 Pub. No. 216-1 Guide for the Determination of Thermal Endurance Properties of Electrical Insulating Muterials Also available in other countries hm their National Committees
23、 for IEC. The Institute of Electrical and Electronic Engineers, Inc. 445 Hoes Lane Piscataway. NJ 08854-1331 Pub. NO. 1-1986 Pub. NO. 98-1984 Pub. NO. 99-1980 Pub. NO. 101-1987 Pub. No. D2034 Standard 746B-1992 Standard 746C General Principles Upon which Temperature Limits Are Based in the Rating of
24、 Electric Equipment Guide for the Preparation of Test Procedures for the Thermal Evaluation and Estab- lishment of Temperature Indexes of Solid Electrical Insulating Materials Guide for the Preparation of Test Procedures for the Thermal Evaluation of Insulation Systems for Electric Equipment Guide f
25、or the Statistical Analysis of Thermal Life Test Data American Society for Testing and Materiais 1916 Race Street Philadelphia, PA 19103-1187 Standard Method for Thermal Evaluation of Rigid Electrical Insulating Materials Underwriters Laboratories, Inc. 333 Pfingsten Road Northbrook, IL 60062 Polyme
26、ric Material+ but with the advances in polymer chemistry, insulating materials were being produced that were so complex that simple chemical description became aimost meaningless. Beginning with the June 1957 edition of AIEE (now IEEE) Publication No. 1, the method of establishing temperature classi
27、fication was changed to one based on operating life as detennined by test or actual experience. This concept of thermal classification of insulating materiais by test is described in the current editions of IEEE Publications No. 1 and 98 and ASTM D-2304. A pint project between Underwriters iabomfies
28、, Inc., the University of Delaware, and NEMA was estab- lished to obtain long time thermal degradation data of industrial laminates in order to provide a guide to their selection in insulation systems and products. NEMA LI+b 93 6470247 0509659 294 = LI 6-1993 Page 6 NENA LI*b 93 m 6470247 0509660 TO
29、b m LI 6-1993 Page 7 Section 4 RELATIVE TEMPERATURE INDICES 4.1 DEFINITION Relative Temperature Index is defined as an index that allows relative comparisons of the tempexatuxe capabil- ity, of insulating materials or insulation systems based on specife, controlled test conditions. The temperature i
30、ndex is used to provide a temperature “designation“ for insulating materials, and is related to the temperature at which the material will provide a specified life as deter- mined by test or service experience. (IEC Publication No. 216-1.) This indexing method effectively separam the temperature cap
31、abilities of individual insulating materi- als from the temperature classification of insulation sys- tems. (IEEE Publication No. 1.) From the data obtained in these test programs, the Relative Temperature Indices were developed as shown in Table 4-1. which lists a maximum continuous use temperature
32、 for each materiai. (Data for Grades CEM-1 and CEM-3 were obtained by a different program, as expiained in 3.2) These indices were established, as discussed in detail later, by comparing the degradation of properties of industriai laminates under controlled test procedures with the degradation of NE
33、MA Grade Xxxpc. This grade was chosen because of its long history as a grade capable of continuous use at 1ZC. Table 3- 1 can be interpreted in the following manner: 1/6 inch (1.588 mm) Grade A. for example, will retain its mechanid and electricai propeais 0.062 inch (1.6 rmn) * Based on a refe- aan
34、dard for Xxxpc. t Not nconmiended for eledcal application at elevated temperanires. NENA LI*b 93 = 6470247 O509662 9 LI 6-1993 Page 9 Table 4-1 (continu 0.062 inch (1.6 mm) Based on a reference standard for xXXPC. NOL recommended for electrical application at elevated temperatures. Maximum continuou
35、s use temperature assigned by Underwriters Laboratories, inc in UL Standard 74C. The maximum continuous use uxnperature recognized by L for the generic types GPO-2 and GPO-3 is 105. Most brands of GPO-2 and GPO-3 have he indices of 130 and 120 shown here, established by actual thermal aging. NEMA LI
36、*b 93 m 6470247 O509663 715 m LI 6-1993 Page 10 NENA LI*b 93 6470247 050bb4 651 m L16-1993 Page 11 Section 5 THEORY The test program was based on the assumption that heat is the chief cause of insulation deterioration. Other factors being quai, th in the case of this investigation, Grade Xxxpc indus
37、trial laminate has been established by experience as being capable of con- tinuous use at 125C, and its endurance curve provides a basis for comparison with the thermal capabilities of other grades of industrial laminates. The thermal endur- ance curves are used to establish a relative temperature r
38、ating or index which provides a simple nominal number for comparing the thermal capability of other industriai thermosetting laminates. Arrhenius curves for ail grades mted are given in the Appendix. NOTES 1. The “confidence Limits of the Mean“ shown on the Arrhenius cwea in the apgendix. express th
39、e faa that repe9ted testa would prove that 99.7% of the mean of all tes vaiuea in he specified grade would fall within the 95% limit selected based on a nod distribution. 2 The 95% confidence imiU of the mean for several g and, therefore, the temperature capability of 0.062 inch (1.6 mm) material is
40、 conservative for thicker material. Five test specimens of each grade tested were selected at random from the following companies, ail of whom supplied at least one tested grade: a. b. C. d. e. f. g. h. i. j. k. 1. The Budd Company Polychem Division Formica Corporation (A wholly owned subsidiary of
41、American Cyanamid) General Electric Company The Glastic Company Oak Materials Group, Inc. The Item Fibre Company NVF Company UOP Norplex Division Panelyte Industrial Division Thiokol Chemical The Richardson Company Insurok Division Spaulding Fibre Co., Inc. Synthane-Taylor Corp. (An Aico Standard co
42、rp. Company) m. Westinghouse Electric Corporation 6.2 TEST TEMPERATURE AU specimens were tested under standard laboratory conditions after aging. Experience has shown that the long-term degradation rate, as determined by change in either mechanical strength or electric strength, is inde- pendent of
43、the temperature at which the property is measured. Since it is more convenient to measure these properties at room temperature than at elevated tempera- ture, only room temperature measurements are specified. It should be cautioned, however, that a material that is Table 6-1 MATERIALS TESTED Other G
44、rades Grades Tested Represented XP x, XFC FR-2 - FR-3 - CE C, L, LE FR-4 G-10 A AA G-9 G-5 G-7 - G-3 - G-11 FR-5 GPO-2 - GPO-3 - CEM-1 CEM-3 (Electric Strength) CEM3 - judged to have acceptable thermal degradation charac- teristics for a given use temperature may not be suitable in a given applicati
45、on at that temperature because of insufficient initiai properties strength at this use tempera- ture (as per ASTM D 2304.) Curves of property values measure at aging tempera- ture and at room temperature after aging and that are plotted against hours of exposure parallel each other after long-time a
46、ging; it is necessary only to select an end- point far enough out on the curve. An end-pint thus suitably chosen gives a point on the Arrhenius curve. (See curves in Appendix.) 6.3 AGING TEMPERATURES Industrial laminates were aged at the temperatures shown in Table 6-2. 6.4 TESTS AND TEST METHODS Fe
47、xurai strength was selected as representing me- chanical characteristics. Electric strength was selected as representing electrid characteristics. NENA LIU6 93 6470247 0509667 360 LI 6-1993 Page 14 The test methods and number of specimens for each Specimens test were as follows. Number of Specimens
48、Eact Test Performed Method ConditionA* Aged Test Tgt Flexural ASTM D-790 10 5 strength Electric ASIUD-149 10 5 Strength 6x6hch (152.4 x 152.4 mm)spBcimen tested in aK, perpaidicular to laminations; short-time test; voltage increase 500 vlsecl Specimens were placed in forced-air-circulating ovens mai
49、ntained at the constant aging temperature. Peri- odically the number of specimens required for the test were removed from the oven, conditioned at 23C and 50% relative humidity for a minimum of 48 hours and then subjected to the required test. The procedure fol- lowed the program recommended in IEEE Publications No. 1,98,99 and 101. * Condition A means “as received. no special conditioning.“ Table 6-2 THERMAL AGING TEMPERATURES Aging Temperature-Degrees C Grade 90 120 130 140 150 160 165 170 180 190 200 210 220 230 270 280 XP- x- xx- x - - -
