Effect of Electric Field Frequency on the AC Electrical Treeing Phenomena in an Epoxy/Layered Silicate Nanocomposite

The effects of electric field frequency on the AC electrical treeing phenomena in an epoxy/layered silicate (1.5wt%) were investigated in a needle-plate electrode arrangement. A layered silicate was exfoliated in an epoxy-baseresin with AC electric field apparatus. To measure the treeing initiation and propagation- and the breakdown rate,a constant alternating current (AC) of 10 kV with three different electric field frequencies (60, 500, and 1,000 Hz)was applied to the specimen in the needle-plate electrode specimen in an insulating oil bath at130℃. At 60 Hz, thetreeing initiation time was 12 min, the propagation rate was 0.24 × 10-3 mm/min, and the morphology was a densebranch type. As the electric field frequency increased, the treeing initiation time decreased and the propagation rateincreased. At 1,000 Hz, the treeing initiation time was 5 min, the propagation rate was 0.30 × 10-3 mm/min, and themorphology was a dense bush type