Standard Test Method for Thermal Endurance of Flexible Electrical Insulating Varnishes

Importancia y uso:

5.1 A major factor affecting the long term performance of insulating materials is thermal degradation. It is possible that factors, such as moisture and vibration, will cause failures after the material has been weakened by thermal degradation.

5.2 An electrical insulating varnish is effective in protecting electrical equipment only as long as it retains its physical and electrical integrity.

5.3 The thermal degradation of the varnish results in weight loss, porosity, crazing, and generally a reduction in flexibility. Degradation of the varnish can be detected by a decrease in dielectric strength, which is therefore used as the failure criterion for this test method.

5.4 Electrical insulating varnishes undergo flexing in service due to vibration and thermal expansion. For this reason, this functional test includes flexing and elongation of the insulation. The electrodes used in this test method are designed to elongate the outer surface of the specimen 2 % with respect to the neutral axis of the base fiber while being tested for dielectric breakdown.

Subcomité:

D09.01

Referida por:

D2756-07R17, D3145-20, D0115-17R24

Volúmen:

10.01

Número ICS:

29.035.60 (Varnished fabrics)

Palabras clave:

dielectric strength; glass fiber fabric; thermal endurance; varnish;