Comparative Analysis on Insulation Degradation Characteristics of Two Commercial Silicone Gels

Silicone gels have been widely used as an encapsulation for power electronics modules, and their own insulation performance directly determines the voltage resistance reliability of electronic devices such as IGBT devices. Electrical treeing in two different silicone gels has been investigated using a typical pin-plane geometry. The purpose of this study was to investigate the difference in the electrical tree growth characteristics of two different commercial silicone gels under AC voltage. The bifurcation voltage is defined in this paper, and the electrical tree in each silicone gel grows at its respective bifurcation voltage. Combined with the data results of electrical tree growth rate, expansion coefficient, fractal dimension and accumulated damage, the insulation degradation characteristics of two silicone gels can be compared and analyzed.