Dielectric behavior and electric strength of polymer films in varying thermal conditions for 5 Hz to 1 MHz frequency range

Dielectric behavior and electric strength of polymer films are dependent on various factors. In this paper, an experimental study is presented on the dielectric behavior of polymer films under high frequency voltages and thermal stresses. The AC electric breakdown strength of thin polymer films as a function of sample thickness with the sphere-plane electrode configuration was investigated at various temperature. The electric strength of the polymer film is reduced with increasing thickness of the film and temperature. The relative permittivity of polyester under thermal stress decreases with increasing frequency, especially at high frequencies and low temperatures. At low frequencies, the loss factor of polyester is very low. At high frequencies and in high temperatures it increase rapidly