Study on electrical strength of suspension insulators in steep impulse voltage range

High and steep lightning surge voltages sometimes cause electrical punctures of suspension insulators. Microscopic analysis clarifies electrical breakdown mechanism of ceramic material. V-t characteristics of the insulators are closely examined Chance of the puncture depends on the dnnensions of the insulators, steepness of the mpulse voltages and the number of impulse occurrences. Empirical equations relating to these parameters has been established based on laboratory test results. Calculation shows no risk of puncture on the quality insulators for the impulse voltages of 250OkVlfis steepness which is required by the standards.