A partial discharge monitor for the measurement of partial discharges in a high voltage plant by the transient earth voltage technique

Several proprietary discharge detectors are available that are suitable for measuring the magnitudes of the partial discharges in plants such as high voltage metalclad switchgear. Their main disadvantages are the high capital cost of the test equipment and the complexity of the testing procedure. When performing such tests, the plant must be switched out, connections must be made to the high voltage conductors of the plant under test and high voltages applied from a test set. A `sanction for test´ is therefore required. This overhead may be acceptable when testing primary or grid substations. However, for discharge measurements to be widely applicable it is essential that the tests can be made with the plant live and under load. The Transient Earth Voltage or TEV measurement technique has been developed to fulfil this requirement