Correlation between volume effect and lifetime effect of solid dielectrics on nanosecond time scale

Theoretical analysis for the volume (V) effect on electric breakdown strength (E_BD) and the operating field (E_op) effect on lifetime (NL) of solid dielectrics on a nanosecond time scale is presented in the perspective of the Weibull distribution. It is derived that the general formula for the volume effect is E_BD=kV^-1/m and the formula for the lifetime effect is N_L=(E_BD/E_op)^m, where m is a parameter which is determined by the dielectric quality and influenced by the dielectric types. Besides that, it is found that the volume effect and the lifetime effect correlate with each other via m. By summarizing the experimental results, it is concluded that m is averaged to be 8 for polymers with a normal quality under short pulses and that m will be larger (or smaller) than 8 when polymers are with better (or poor) quality. It is suggested that m can be defined as a parameter to describe the dielectric´s quality and m of 8 can be regarded as a criterion to choose polymers as insulation materials.