First, after the line is connected by multiple pulse method, it is normal to apply the impact high voltage for the first time if the test waveform is not relatively ideal. Because the distance of the fault is not known in advance, the anti-electric strength of the fault point is not clear. If the impulse voltage is not high enough and the fault point is not broken down by the impulse high voltage, the fault echo cannot be collected. You can only see the open terminal waveform. The impulse voltage must be increased until the fault echo is seen.
Second, sometimes the fault point is far from the test end, the echo is weak, it must adjust the "length selection", in order to get a stronger fault echo. Cable fault tester with "short distance", "medium distance", "long distance" three states. Short range is suitable for testing faults within 1km, medium range is suitable for testing faults within 1 to 3km, and long range is suitable for testing faults within 3 to 16km.
3. In order to ensure the full breakdown of the fault point and enough arc duration, it is recommended to use 2μF withstand voltage over 35kV energy storage capacitor.
Four, in the multiple pulse method test process, there is a "pulse generator" between the high voltage equipment and the fault cable, the actual impact high voltage added to the cable fault phase voltage is lower than the high voltage generator output voltage. If the output voltage of the high voltage generator has reached 35 ~ 42kV and the fault point has not broken down, then the impact high voltage flashover current sampling method should be replaced for testing.
