New Test Method for Determination of the Electric Tangential Interfacial Surface Discharge of Solid Dielectric Materials in a Liquid
1. Scope
1.1 This test method covers the determination of the tangential interfacial surface breakdown
voltage, also known as interfacial surface creep breakdown, of solid insulation materials in an
insulating liquid. The test procedures will include:
• AC line frequency
• Full-wave impulse defined as 1.2 x 50 µs
• Chopped-wave impulse defined as a 1.2 x 50 µs wave chopped after 1 µs and/or 3 µs
• Switching impulse wave defined as a 100 x 1000 µs and/or 250 x 2500 µs wave
1.2 The testing will determine the influence of combining solid and liquid dielectric insulation materials on the tangential interfacial surface breakdown. The solid insulation can either be impregnated or conditioned with the liquid insulation. The test procedure should include a sufficient number of determinations to provide a mean breakdown using a 50 % Gaussian distribution and a 1 % or 2 % probability of breakdown using either a two or three parameter Weibull distribution.
Keywords
Creep; Surface discharge
Rationale
The proposed testing method has been used by various entities and would be helpful to have an industry approved standard. Users will be manufacturing facilities where the creep strength of the materials used is of particular interest.
