Influence of frequency on electrical tree growth of Nylon 6 under nanosecond pulses

After a long in-service period, the electrical aging phenomenon of Nylon 6 may cause insulation degradation. Most of the researches focus on AC/DC or room temperature conditions. Less attention is paid to the nanosecond pulses conditions. In this paper, frequency effect on the electrical tree growth of nylon 6 was investigated. A solid-state pulse generator MPC50D was used to export nanosecond pulses. The output voltage had a rise time of 30 ns and the full width at half maximum of 70 ns. Temperature and humidity tester chamber SP-80U was used to control the experiment temperature. The range of temperature was set to -40 ~ 60 degree and the range of frequency was set to 20 ~ 1000 Hz. The shape of the electrical tree in Nylon 6 was investigated in this paper. The influence of the electrical tree shape on the electrical tree growing speed was also discussed. The experimental results showed that if the frequency was under 200 Hz, the growing speed of electrical tree increases with the frequency increases; if the frequency was above 200 Hz, the growing speed of electrical tree decreases with the frequency increases.