It refers to a kind of partial discharge that occurs between the electrodes but does not pass through the discharge electrodes. This is due to the defects or shortcomings in the production process that cause the insulation breakdown of the internal equipment to repeat and fall off. The effect of higher electric field strength occurs, and it manifests In order to carry out the breakdown of the gas in the insulation, the local breakdown using solid or liquid as the medium in a small area or the field strength of the edges and sharp corners of the metal material surface can be centralized to manage the local breakdown discharge caused by the local breakdown.

Hazard 1: This discharge is very small, so its existence does not affect the short-term dielectric strength of the electrical equipment, but if the electrical engineering equipment continues to develop a partial discharge under the operating voltage, these weak discharges A cumulative effect will result in the gradual deterioration of the dielectric properties of the insulation and the expansion of local defects, which will eventually lead to the breakdown of the entire insulation of the enterprise.

Hazard 2: Under the action of heat, the surface of the medium is 5×10-17 meters near the local volume due to the occurrence of partial discharge, and the temperature of the medium rises to 170℃ within 10-7 seconds, sometimes even as high as 1000℃ by the discharge action. High temperature, and therefore may cause thermal melting or decomposition of chemical media.

Hazard 3: Chemical, or through the action of secondary products in the medium, can withstand corrosion, due to the higher partial discharge of excited molecules than electrothermal effects.