Breakdown characteristics of MV distribution and electric traction lines insulators stressed by standard and short tail lightning impulses

The paper presents the results of experimental tests performed with impulse voltage with short tail (STLI: 1.2/4 mus) on composite insulators in use in the MV distribution lines and electric traction lines. The voltage-time to breakdown characteristics under 1.2/4 mus waves are presented and compared with the characteristics under standard lightning impulse (LI: 1.2/50 mus). Models based on the disruptive effect, as proposed by Kind [9], and modified by Chowdhuri [13], are also considered and applied in order to predict the Volt-time characteristics under standard and non standard lightning voltages. The viability of the application of these models to the tested insulators is considered and discussed.