This test method is used to determine the effect of exposure to elevated temperatures on the bond strength of combinations of magnet wire insulations and electrical insulating varnishes. The results are used as a guide for the comparison and selection of varnishes and combinations of varnishes and magnet wire insulation for specific applications. Test Methods D 1932, D 3251, and D 3850 describe additional tests for determining the thermal endurance of insulating varnishes. A comprehensive evaluation of thermal characteristics includes a comparison of the thermal endurance determined in these different ways.

This test method is useful for research and product qualifications purposes.

1. Scope

1.1 This test method covers the determination of the thermal endurance of electrical insulating varnishes alone or in combinations with magnet wire insulation. Changes in the helical coil bond strength are used as the test criteria. The coils are made from bare aluminum or copper wire, or from film- or fiber-insulated magnet wire.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific precautionary statement, see Section 7.

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

Note 1—There is no similar or equivalent IEC standard.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D1711 Terminology Relating to Electrical Insulation

D1932 Test Method for Thermal Endurance of Flexible Electrical Insulating Varnishes

D2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet Wire

D2519 Test Method for Bond Strength of Electrical Insulating Varnishes by the Helical Coil Test

D3251 Test Method for Thermal Endurance Characteristics of Electrical Insulating Varnishes Applied Over Film-Insulated Magnet Wire

D3850 Test Method for Rapid Thermal Degradation of Solid Electrical Insulating Materials By Thermogravimetric Method (TGA)

D5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation

D6054 Practice for Conditioning Electrical Insulating Materials for Testing

International Electrotechnical Commission Publications

Keywords

electrical insulating; helical coil; magnet wire; thermal endurance; varnish; Electrical insulating varnishes; Flexural testing--electrical insulating materials; Helical coil method; Thermal endurance--electrical insulating materials;

ICS Code

ICS Number Code 29.035.60 (Varnished fabrics)

Citing ASTM Standards

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