Abstract
The smallest discharge which may be detected during partial discharge tests on electrical equipment is usually determined by the levels of background interference. To improve the signal/noise ratio the real-time computational technique known as signal recovery has been used. This has the additional advantage that the end result is a permanent record which will allow the user to reliably compare discharge characteristics throughout a component's life.While the approach is applicable to any component, the experimental evaluation programme was based on 11 kV polymer-insulated cable. This was tested in various situations, namely, as a short length in the laboratory, as drum lengths in several factories, and lengths (together with associated switchgear) installed in a number of power stations. In these conditions, discharges of 1 pC and less could be detected, even where the noise levels on conventional display-only equipment were tens of picocoulombs.

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