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Precautions for partial discharge detection test

time:2020/11/29   source:华天电力  reading:613 time

The partial discharge detector is used to detect the partial discharge source in medium and high voltage (MV/HV) equipment. If no discharge is detected, it does not mean that the medium and high voltage equipment has no discharge activity. The discharge source often has a latency period, and the insulation performance may also fail due to reasons other than partial discharge. If a considerable discharge is detected in the equipment connected to the medium and high voltage power system, the equipment maintenance department should be notified immediately. Partial discharge is an electrical discharge that does not completely short-circuit the electrodes. The amplitude of this discharge is usually very small. But they do cause the continuous degradation of the insulating layer performance and ultimately lead to the failure of electrical equipment.

Partial Discharge Detector.png

Note for partial discharge detection test:

1. Before the test starts to pressurize, the test personnel must check the circuit in detail and comprehensively to avoid wrong wiring. Test whether the grounding wire of the instrument is firmly connected to the grounding body. If the connection is not firm or the wire is kicked off when the head is pinched and the tail is being prepared for work, this may cause personal and equipment accidents.

2. For the connecting wire, avoid exposing the tip to prevent corona discharge at the tip, especially for partial discharge tests with higher voltage levels. If necessary, thicken the high-voltage connecting wire and install an anti-corona cover to reduce the field strength. Corona discharge caused by too high. The shielding cover should not be in contact with the porcelain skirt of the sample.

3. Under normal circumstances, during the test, the partial discharge of the test product during the withstand voltage and pre-boost is much larger than the normal value. At this time, the instrument will inevitably exceed the full scale. In order to prevent damage to the instrument, the coarse gain adjustment knob of the instrument should be turned counterclockwise by one or more steps, with the standard not exceeding the full scale. When the voltage drops to the measured voltage, turn the coarse gain adjustment switch clockwise for one or more gears to record the measured value.

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