What interferences should be considered in partial discharge testing?

Partial discharge interference can be divided into two types of interference, namely:
(1) There is interference when the test circuit is not powered on. Usually there are welding, radio waves, high voltage testing nearby, rectification equipment, and electric brushes for motors.
(2) Interference that only occurs when powered on. The characteristic is that it increases with the increase of test voltage, such as lead corona, discharge caused by suspended potential in conductors, spark discharge due to poor contact between conductors, etc.
Common interferences in measurement include:
(1) High voltage measurement circuit interference.
(2) Interference from power side intrusion.
(3) Interference caused by poor contact of high-voltage charged parts.
(4) Metal objects within the range of the high-voltage electric field in the test area are subject to interference from suspended potential or poor grounding.
(5) Space electromagnetic wave interference, including interference from radio stations, high-frequency equipment, etc.
(6) The interference caused by the zero sequence current entering the partial discharge measuring instrument from the grounding end.