ASTM D902-12 - 1.4.2012
 
Significance and Use

The electrical properties of resin-coated glass fabrics are affected by their temperature and moisture content. For this reason it is necessary to control these properties for a specified time immediately prior to testing in order to attain reasonably good reproducibility of test values. The time of exposure to the conditioning atmosphere must be long enough to permit the test specimen to reach a relatively stable value. Usually the moisture content of these materials has little effect on the mechanical properties.

 
1. Scope

1.1 These test methods cover procedures for the testing of resin-coated glass fabrics and glass fabric tapes (Note 1) to be used as electrical insulation.

Note 1—Methods of testing varnished cloths and tapes are given in Methods D295.

1.2 The warp threads in fabrics are the threads that are parallel with the length dimension as manufactured.

1.3 The procedures appear as follows:


Procedure


Section

ASTM Test
Method Reference

Breaking Strength

22-28

D828

Conditioning

6-8

...

Dielectric Breakdown Voltage and Di-
electric Strength

29-38

D149, D295

Dissipation Factor and Relative Permit-
tivity

52-60

D150, E104, D5032

Effect of Elevated Temperature

39-45

D1830

Resistance to Oil

46-51

D3487

Sampling

3-5

...

Thermal Endurance

68

D1830

Thickness

16-21

D374

Thread Count

12-15

...

Weight

9-11

...

Weight Loss at Elevated Temperature

61-67

D5423

1.4 The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are for information only.

1.5 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. Specific warning statement are given in 35.1.1 and 58.1.

 
2. Referenced Documents

D295-12

Standard Test Methods for Varnished Cotton Fabrics Used for Electrical Insulation (Withdrawn 2020)

D828-22

Standard Test Method for Tensile Properties of Paper and Paperboard Using Constant-Rate-of-Elongation Apparatus

E104-20a

Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions (Includes all amendments and changes 12/21/2020).

IEEE No. 1

General Principles for Temperature Limits in the Rating of Electrical Equipment Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.

D149-25

Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies

D150-22

Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation

D374-99

Standard Test Methods for Thickness of Solid Electrical Insulation

D1711-25a

Standard Terminology Relating to Electrical Insulation (Includes all amendments and changes 12/12/2025).

D1830-17(2024)

Standard Test Method for Thermal Endurance of Flexible Sheet Materials Used for Electrical Insulation by the Curved Electrode Method

D3487-25

Standard Specification for Mineral Insulating Liquid Used in Electrical Apparatus

D5032-19

Standard Practice for Maintaining Constant Relative Humidity by Means of Aqueous Glycerin Solutions

D5423-23

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