1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA RE 2-1999Electrical Insulating Varnish- STDmNEMA RE 2-ENGL 1999 b470247 0527818 555 NEMA Standards Publication No. RE 2-1999 Electrical Insulating Varnish Published by National Electrical Manufacturers Association 1300 North
2、 17th Street, Suite 1847 Rosslyn, VA 22209 O Copyright 1999 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 Literary and Artistic Works, and the
3、International and Pan American Copyright Conventions. STD-NEMA RE 2-ENGL 1797 U 6470247 0527839 493 111 RE 2-1999 Page i Table of Contents Page Section 1 REFERENCED STANDARDS AND DEFINITIONS 1 1.1 Referenced Standards . 1 1.2 Definitions 2 Section 2 GENERAL 5 2.1 General Information . 5 2.2 Safety P
4、recautions . 5 2.3 Packaging Specifications Military Markings . 6 Section 3 PRODUCT PROPERTIES . 7 3.1 Required 7 3.2 Additional . 7 3.3 Military 7 3.4 Disclaimer Paragraph 7 Section 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.1 1 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 TEST METHODS
5、9 Bond Strength-Helical Coil Method 9 Bond-Strength-Twisted Coil Method 11 Chemical Strength of Electrical Insulating Varnish 14 Dissipation Factor-Varnish Magnet Wire . 18 Drying Time . 19 Film Build . 19 Flash Point . 20 Gel Time 21 Refrigerant Resistance/Extractables . 22 Monomer Content 24 Nonvo
6、latile Matter-Solvent Varnishes 25 Permittivity (Dielectric Constant) and Dissipation Factor . 26 Specific Gravity 27 Thermal Aging-Helical Coil 32 Thermal Aging-Non-Enameled Rectangular Insulated Magnet Wire 33 Thermal Aging-Twisted Pairs 36 Varnish Adjustment Procedure 37 Varnish Compatibility . 3
7、8 Dielectric Breakdown Voltage 15 Dielectric Strength of Solvent or Solventless Varnishes 17 Thermal Aging-Curved Electrode 28 . Viscosity, Brookfield 38 Annex A NEMA RE-2 Specification Sheets 41 RE 2-1 999 Page iii FOREWORD This Standards Publication is intended to assist those responsible for the
8、design of new and the repair of existing electrical equipment. This Standards Publication was developed by the Electrical Insulating Resins Section of the National Electrical Manufacturers Association. In the preparation of this Standards Publication input of users and other interested patties has b
9、een sought and evaluated. Inquiries, comments, and proposed or recommended revisions should be submitted to the concerned NEMA product subdivision by contacting the: Vice President, Engineering Department National Electrical Manufacturers Association 1300 N. 17th Street, Suite 1847 Rosslyn, VA 22209
10、 At the time it was approved, the Section was composed of the following members: Arnoco Polymers, Inc.-Alpharetta, GA Bentley-Harris Manufacturing Co.-Mon, PA EI Dupont De Nemours environmental chamber for elevated temperature 4.1.3 Required Specimen The test specimen shall consist of helical coils
11、which have been dipped and cured with the varnish being tested. 4.1.4 a. b. C. d. 4.1 .!i Req u red Procedure Five coils, 3 inches in length, are prepared by winding 18 AWG magnet wire on a 0.250 inch mandrel. The coils are dipped in solventless, or solvent type varnish which has been previously adj
12、usted in accordance with 4.0. The coils are withdrawn from the varnish at a rate of 4 inches per minute, drained for 10 minutes and then baked according to the manufacturers recommendation. The coils treated with solvent varnish are then reversed, dipped, and baked, using the above procedure. Coils
13、treated with solventless varnish are only single dipped. The 3 inch helical coil shall be placed in the test fixture (see Figure 4-1 with regard to all dimensions shown). The fixture shall be attached to a machine equipped with a drive which has a crosshead speed of 2 inches per minute and a suitabl
14、e instrument for measuring the force used in breaking the specimen. Bond strengths shall be detemined at any temperature mutually agreed upon between buyer and seller. Elevated Temperature Bond Strength When bond strengths are measured at elevated temperatures, the environmental chamber shall enclos
15、e the test fixture without inhibiting the movement of the measuring device. The temperature in the chamber shall be maintained within f 2C of the desired temperature. The specimens shall be exposed for 6 minutes (I 1 minute) at the desired temperature prior to breaking, in accordance with the proced
16、ures in 4.1.4. Previous page is blank. RE 2-1 999 Page 10 4.1.6 Required Report The following shall be reported: a. Varnish b. Magnet wire type and manufacturer c. Cure time and temperature d. Test temperature e. Average bond strength Wo V Block Radius at Apex is -_ Figure 4-1 TEST FIXTURES FOR BOND
17、 STRENGTH STD-NEMA RE 2-ENGL 1777 II b470247 0527832 925 RE 2-1999 Page 11 4.2 BOND STRENGTH-TWISTED COIL METHOD 4.2.1 General The Twisted Coil Method is used in evaluating bond strength of solventless insulating varnishes. 4.2.2 Required Apparatus The following apparatus shall be used: a. Varnish t
18、o be tested b. Enameled wire, 28 AWG heavy build c. Coil winding jig, as shown in Figure 4-2 d. Coil twister, as shown in Figure 4-3 e. Dipping apparatus “Dip Coater-Fisher Payne or equivalent f. Forced draft oven g. Test fixture and machine, environmental chamber for elevated temperature 4.2.3 Requ
19、ired Specimen The test specimens shall consist of five twisted coils which have been dipped and cured with the vamich be- ing tested. 4.2.4 Required Procedure The following procedure shall be followed: a. b. C. d. e. f. 9. h. 4.2.5 Individual twisted coils are formed using 100 loops of 28 AWG enamel
20、ed wire. The 100 loops are made by using wire from two spools wrapped 50 times or one spool wrapped 1 O0 times around the mandrel as shown in Figure 4-2. Pull the double strands of wire from the center mandrel through one of the slots and secure the ends around one of the wing nuts on the front plat
21、e. Wind 1 O0 turns of wire around the mandrel. After winding, cut the strands leaving about 6 inches of unwound wire. Use this extra length to secure one side of the coil by making four or five loops around the coil. Use the strands from the wing nut to secure the opposite side of the coil by making
22、 four or five loops around the coil. Remove the front plate and then remove the coil. By hand, elongate the coil until an elliptically shaped coil is formed. Using a coil twister, as shown in Figure 4-3, twist the elliptical coil two and one half complete turns to produce a tight twisted coil. If th
23、e loops are loose, do not use the coil. Required Dipping and Curing Single dip the coils as follows: Submerge the coil horizontally and hold until bubbling stops. Withdraw at a rate of 4 inches per minute. Let the coil drain for 10 minutes in the horizontal position and then cure in accordance with
24、the manufacturers instructions. Vacuum Pressure Impregnation (VPI) treatment shall be permitted for some products. STD.NEMA RE 2-ENGL L997 6470247 0527833 861 RE 2-1 999 Page 12 4.2.6 Testing Bond Strength Test the coil in the same manner and on the same test assembly as prescribed in 4.1 (see Figur
25、e 5-1) 4.2.7 Required Report The following factors shall be reported: a. Varnish b. Magnet wire type and manufacturer c. Cure time and temperature; VPI processing conditions (if used) d. Test temperature e. Average bond strength COIL WINDER-SIDE VIEW 1 mm COIL WINDER-FRONT VIEW Figure 4-2 COIL WINDE
26、R STD-NEMA RE 2-ENGL 1799 W 6470247 0527834 iT8 RE 2-1 999 Page 13 Figure Ma OVAL SHAPED COIL Fixed End I OriginalGap9mm f 3mm c Wied Gap 8mm 3mm _)1 il Rotating End lnsion L Figure 43b COIL TWISTER STD-NEMA RE 2-ENGL 1999 6470247 0527835 b34 RE 2-1 999 Page 14 4.3 CHEMICAL RESISTANCE OF ELECTRICAL
27、INSULATING VARNISH 4.3.7 General This method evaluates effects of chemicals on the bond strength of cured varnish films. 4.3.2 Required Apparatus The following apparatus shall be used: a. Varnish to be tested b. Enameled wire, 18 AWG heavy build c. Dipping apparatus “Dip Coater“-Fisher Payne or equi
28、valent d. 800 cc heat resistant glass beaker and 150 mm widewatch glass e. Forced draft oven f. Apparatus for testing bond strength as described in the Helical Coil Method (4.1) and as shown in Figure 5-1 4.3.3 Required Test Specimen Test specimens shall consist of 10 helical coils, as prescribed in
29、 5.1, which have been dipped and cured with the varnish being tested and prepared in the following manner: a. Adjust solvent varnish to be tested to give a double film thickness of 2 mils. Use solventless varnish as received. b. Immerse helical coil in varnish and hold until bubbling stops. Withdraw
30、 at a rate of 4 inches per minute and drain for 10 minutes. In the case of thixotropic, solventless varnishes, the drain time shall be in accordance with the manufacturers recommendations. Prepare 1 O coils for each test. Cure according to manufactureh recommendations. c. For solvent varnish, revers
31、e the coil and repeat step 2 4.3.4 Required Procedure The procedure shall be as follows: a. Suspend 5 helical coils in the 800 cc beaker and cover the coils with the specified chemical. b. Cover the beaker with a watch glass and age at the required temperature for 168 hours. c. Remove coils and blot
32、 residual liquid with absorbent material. Test bond strength immediately using the apparatus and procedure in Helical Coil Method. Also test the five remaining coils which were unaged in the same manner. 4.3.5 Required Report The following shall be reported: a. Varnish b. Type of wire and manufactur
33、er c. Cure time and temperature STD-NEMA RE 2-ENGL 1979 e 6470247 0527836 570 111 RE 2-1 999 Page 15 d. Chemical and concentration of chemical used e. Exposure temperature and bond strength test temperature f. Average bond strength readings of aged and unaged coils 4.4 DIELECTRIC BREAKDOWN VOLTAGE 4
34、.4.1 General This method determines the dielectric breakdown voltage of twisted pairs of magnet wire coated with a cured varnish film. 4.4.2 Required Apparatus The following apparatus shall be used: a. Varnish to be tested b. Enameled wire, 18 AWG heavy build c. Apparatus to form the twisted pairs a
35、ccording to NEMA MW 1000 d. Dipping apparatus “Dip Coater-Fisher Payne or equivalent e. Forced draft oven f. Voltage source and meter 4.4.3 Required Procedure The procedure shall be as follows: a. A specimen of wire shall be formed into a U shape and the two legs shall be twisted together for a dist
36、ance of approximately 4.75 inches. The total tension on the two legs while being twisted and the number of twists shall be as shown in Table 4-1. The loop shall be cut and the ends shall be carefully and adequately separated. There shall be no sharp bends in the specimen or damage to the insulation.
37、 b. Prepare 1 O hivisted pairs of specimens as follows: five specimens are dipped in solventless varnish or solvent type varnish, which has been adjusted, according to 4.0. They shall be withdrawn from the varnished at the rate of 4 inches per minute, drained for 1 O minutes, and then baked accordin
38、g the manufacturers instructions. c. Solvent varnish specimens are then reverse dipped and baked using the above procedure. Carefully snip the ends of one pair of the legs which will then become the electrical contacts. d. Apply a 60 Hertz variable voltage source between the legs. e. The test transf
39、ormer shall have a rating of 20 kVA or more and shall provide an essentially un- distorted wave form under test conditions. The voltage shall start at zero and increase uniformly at the rate of approximately 500 volts per second until breakdown occurs. In the event that breakdown occurs in less than
40、 5 seconds, the rate of increase in voltage shall be reduced to approximately 100 volts per second. The trip current of the circuit breaker shall be between 15 and 50 rniliiamps. The breakdown voltage shall be measured with a meter calibrated in rms (root mean square) volts in accordance with one of
41、 the methods described in ANWIEEE No. 4. STDeNEMA RE 2-ENGL 11997 b470247 0527837 407 8-9* 10-1 1 12-1 4 RE 2-1 999 Page 16 24 Pounds (107N) 3 24 Pounds (107N) 3 12 Pounds ( 53N) 4 4.4.4 Required Report 18-20 21-23 24-26 27-29 The following shall be reported: 3 Pounds ( 13N) 8 1.5 Pounds ( 7N) 12 17
42、0 Grams (1.7N) 20 340 Grams ( 3.3N) 16 a. Varnish b. Magnet wire type and manufacturer c. Cure time and temperature d. Average dielectric strength of the varnished and unvarnished magnet wire tested 30-32 33-35 36-38 39-41 Table 4-1 WIRE TENSION REQUIREMENTS 85 Grams ( 0.8N) 25 40 Grams ( 0.4N) 31 2
43、0 Grams ( 0.2N) 36 10 Grams (0.lN) 41 AWG SIZE 42-44 5 Grams (0.05N) 1 TOTAL TENSION 1 TOTALNUMBER ON SPECIMEN TWISTS 46 15-1 7 I 6 Pounds ( 27N) I 6 *Aluminum only STD-NEMA RE 2-ENGL 1777 m 6470247 0527838 343 H RE 2-1 999 Page 17 4.5 4.5.1 General This method is used to detemine the dielectric str
44、ength of a cured vamish film that is coated on a metallic substrate. 4.5.2 Required Apparatus The following apparatus shall be used: DIELECTRIC STRENGTH OF SOLVENT OR SOLVENTLESS VARNISHES a. Varnish to be tested b. 8 inch x 4 inch metal panels c. Dipping apparatus “Dip Coater“-Fisher Payne or equiv
45、alent d. Forced draft oven e. Voltage source, meter, and electrodes 4.5.3 Required Procedure The procedure shall be as follows: a. b. C. d. e. Solvent varnishes shall be adjusted in accordance with 4.0. Solventless varnishes shall be tested as received. Using a suitable micrometer, at 1 O points, me
46、asure the thickness of the metal substrate to determine the average thickness of the metal. Where variations are noted, mark the reverse side of the panel. The test specimens shall be prepared by placing two 8 inch x 4 inch metal panels together and sealing the edges so that a vamish film is obtaine
47、d on one side of the panel only. The specimens are then dipped in the varnish. They shall be withdrawn at the rate of 4 inches per minute, allowed to drain in a vertical position for 1 O minutes, and cured in accordance with the manufacturers recommendations. Solvent varnishes shall be reverse dippe
48、d and cured. Solventless varnishes shall be single dipped and cured. After the proper cure cycle, the strips shall be separated without bending and conditioned as follows: 0 0 0 Other conditions as specified Breakdown voltage measurements shall be made using an electrode 0.25 inch in diameter with e
49、dges rounded to a radius of 0.032 inch. Circular gaskets shall be permitted to be placed over the end of each electrode to prevent flashover. After carefully placing the test specimens between the electrodes connected to a suitable test ap- paratus, increase the voltage from zero to breakdown at a rate of 500 volts per second. Make a minimum of ten voltage breakdown determinations. Using a suitable micrometer, measure the thickness at ten test points. Subtract the thickness of the metal to determine the thickness of the film. Divide the b
