Dependence of the Shape of Electric Trees in Silicone-based Encapsulants on the Frequency of the Applied Voltage

Abstract

Silicone gels have been used as an encapsulant of power electronics modules. We investigated electric treeing in silicone gel under AC voltage. The growth patterns of the trees depended on the frequency of the applied voltage. At low frequencies (10mHz to 10Hz), a bubble appeared at the tip of needle electrode, and a simple tree grew at 10Hz. Trees had many small branches at 350 and 400Hz and did not appear at frequencies over 450Hz.