Recognition of electrical discharges in SF6 and atmospheric air by RFI measurements

An RF spectrum analyzer equipped with suitable antennas proved to be a useful device in discharge type identification. Different kinds of corona and gap discharges in SF₆ and atmospheric air can be identified by measuring the time domain representation of the discharges relative to the power frequency voltage wave with a spectrum analyzer. The diagnosis can be confirmed by measuring the spectrum of the interference. The sensitivity of a spectrum analyzer can be improved by using a wider measurement bandwidth. The results indicate that the harmfulness of the discharge can be evaluated by measuring the frequency spectrum and the time domain representation of the discharge. Different modes of corona discharge are identified, and the existence of streamer pulses is found to be a sign of a harmful discharge