Partial discharge measurement´s over the frequency range 0.1 Hz to 50 Hz

The need for partial discharge (corona) measurements at very low frequencies is explained and the results of tests on epoxy resin samples are given for the frequency range 0.1 Hz to 50 Hz. As no suitable commercial generator was available, a new type of low-frequency low-noise generator has been developed and this is described. The discharge detection system is also explained in the paper. This includes a pulse discrimination system for eliminating unwanted pulses from outside the test component. This was particularly useful when measuring discharges in a short length of cross-linked polyethylene cable, in the presence of discharges over its ends.