Electrical treeing failure in silicone gel insulation for encapsulation under high frequency bipolar square-wave voltage

 

Abstract:

Silicone gel protection has been broadly utilized in power electronic gadgets, filling in as the exemplification material. Its dielectric strength under high-recurrence voltage decides the dependable activity of the gadgets. Electrical tree is a run of the mill disappointment of strong protecting materials, and the electrical tree proliferation in silicone gel under bipolar square-wave voltage are explored in this paper. The outcomes show that electrical trees are pearl-line like, shrub like and air pocket like under differed voltage conditions. After the fast development period, the electrical trees deteriorate under recurrence lower than 20 kHz while grow consistently when the voltage recurrence is higher than 25 kHz. The quantity of tree limb, fractal aspect and aggregated harm increment with the voltage recurrence. In examination, the electrical trees spread gradually under sinusoidal-wave voltage. The fractional release and photograph corruption comparing to the fluorescence are found in primary tree channel, which are connected with voltage waveform and lead to various electrical tree conduct. The infusion and transportation of room charge speeds up the electrical tree spread, particularly at the rising/falling edge of bipolar square-wave field because of extremity inversion. Furthermore, the shapeless carbon kept close to the needle tip and the air pockets in tree channels loaded up with hydrogen and carbon monoxide are undeniably related with the electrical tree proliferation.

Keywords

Bipolar square-wave voltage

Silicone gel

Electrical tree

Encapsulating insulation

 

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