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Detection Technology

Common interference in partial discharge test

time:2020/5/20   source:华天电力  reading:785 time

1) the filter in the power supply can suppress the interference from the power supply. The filter shall be able to reject all frequencies on the detector bandwidth but allow low-frequency test voltages to pass.

2) interference from the grounding system can be eliminated by connecting the test circuit through a separate connection to the appropriate grounding site.

Partial Discharge Detector

3) the discharge test circuit will be coupled with external interference sources, such as high voltage test, nearby switch operation, radio transmission, etc., electrostatic or magnetic induction and electromagnetic radiation, and will be mistaken for discharge pulse. If these interference sources cannot be eliminated, the test circuit should be shielded. A thin metal, metal or iron steel shield layer is required, and sometimes the metal shell of the sample will be used as a shield. Conditional construction of shielding laboratory.

4) external discharge caused by the test voltage. If the ground in the test area is not well grounded or the suspended part is charged by the test voltage, discharge will occur. It can be distinguished from the internal discharge by judging the waveform. An ultrasonic detector can be used to locate the discharge. During the test, all test materials and instruments shall be reliably grounded. The connection point of the equipment shall not be rusty or painted and shall be tightly grounded.

5) most discharge detectors can detect the discharge in the test circuit, such as the discharge in the high-voltage test transformer. In these cases, a test transformer without discharge is required. Otherwise, a balance detector or filter can be inserted into the high voltage line to suppress the discharge pulse from the transformer.

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