Inception time delay for internal partial discharges

Partial discharge measurement is a well-established method for testing the quality of solid insulation systems. Multiple standards for different assets and types of insulation are known. The testing time for partial discharge measurement of different assets varies from as little as 30 seconds up to 1 hour. In order for partial discharges to start, a free starting electron is needed. In absence of light, photoionization cannot create the first starting electron, but cosmic and terrestrial background radiation. The likelihood of a partial discharge to happen underlies the statistical probability of background radiation to create the first starting electron. At the same time, the electrical field must be high enough to accelerate the free electron sufficiently to start an ionisation avalanche…