Checking HV cable insulation - is performed by applying short duration HV pulses to excite partial discharges by ionisation

摘要

During manufacture a HV cable the insulation are checked by a test in which short high voltage pulses are used to provoke partial discharges by ionisation. A cable (1) from an extruder (2) travels at high speed through processing areas (3, 4) which include cooling. An electrode (5) conducts to ground. A group of electrodes (6, 7, 8, 9) form a test station where test pulses from a high voltage generator (14) are applied (6, 9) for detection (7, 8) of faults. Detected signals are applied via differential input amplifier (15) to coupling circuit (16) which isolates high voltages from detected signal. The signal is amplified (17) and applied to oscilloscope (18) and recording instruments (20). Faults are indicated by marking on cable or by an audible warning indicator (19).