Frequency spectrum of dielectric strength of PET

It is a well-known fact that the breakdown voltage of a dielectric at the same thickness depends on a rate of increase of the applied voltage. At some rate of increase of voltage a minimum of either the voltage-time characteristic or the dielectric strength are usually observed. This effect is very important from the practice for the choice of the optimal frequency range of dielectrics being used in HV designs. In this work the testing results of the voltage-time characteristic study for PET film are represented. PET is usually used as HV insulation of various electrical engineering equipment. The role of the frequency dispersion of the complex permittivity in the appearance of minimum in the voltage-time characteristic or the dielectric strength of PET films was discussed.