Investigation of tracking phenomena in outdoor polymeric insulation material under DC voltages using wavelets

In the present study, it is observed that the tracking time of silicone rubber insulation under negative dc is less compared to positive dc voltage. It is noticed that the current flow during tracking studies is highly intermittent under the positive dc voltage compared to the negative dc voltage. It is realized that the energy content of the surface discharge current (wavelet transformed current signal) measured under the negative dc voltage is high compared to positive dc voltage. It is realized from wavelet transform study that the tracking resistance of the material and the discharge energy level of the current signal measured during tracking studies shows an inverse relationship.