Contact discharge test cell: a means of generating signals for sensitivity verification of UHF PD detection in GIS

A novel test cell is described, which is capable of providing a consistent level of partial discharge (PD) for generating UHF signals in GIS. The cell can be used to determine the sensitivity of UHF PD detection equipment. SF₆ gas is not required and the device can operate from a low-current DC supply at less than 1 kV. Its use is demonstrated in the testing of a new method for coupling UHF signals using a sensor designed to fit the test injection loop terminals of current transformers. The experiments demonstrate that contact discharges in the cell generate suitably broadband signals and show that the coupler is capable of achieving a PD detection sensitivity of <5 pC.