Partial discharge refers to the discharge that occurs between electrodes but does not run through the electrodes. It is caused by the weakness inside the insulation of the equipment or the defects in the production process. Under the action of high electric field intensity, repeated breakdown and extinction phenomenon occur.

The ability to discharge is small, so its short duration does not affect the insulation strength of electrical equipment. However, if the electrical equipment continuously appears partial discharges under the operating voltage, these weak discharges will have a cumulative effect, which will gradually deteriorate the dielectric performance of the insulation and enlarge the local defects, finally leading to the breakdown of the whole insulation. Although partial discharge will make the insulation deteriorate and lead to damage, its development needs a certain time, so it is necessary to use the partial discharge tester to measure the partial discharge regularly.

The purpose of partial discharge tester test is to find defects in equipment structure and manufacturing process. For example, the local electric field intensity inside the insulation is too high; Metal parts with sharp corners; The partial discharge test is used to eliminate these defects and prevent the damage caused by partial discharge multi-insulation.