Conical insulator
DC dielectric strength The breakdown characteristics of conical insulators are tested at 3.5kg/cm2 abs. for DC, lightning impulse, switching impulse and AC voltage.
The results are given in Table 1. The negative DC breakdown voltage of conical insulators is unexpectedly higher than that of the coaxial cylinder gap alone by about 10 percent, while the positive DC breakdown voltage is lower than that of the coaxial cylinder gap alone