Partial discharge mainly refers to high-voltage electrical equipment. According to the statistics of the power grid, partial discharge is an important cause of insulation breakdown in high-voltage electrical equipment and also an important indicator of insulation degradation. The partial discharge is that occurs in the insulation of power equipment under the action of a sufficiently strong electric field. This discharge is limited to only causing partial short circuit of insulation between conductors without forming conductive channels. Each partial discharge has some impact on the insulation medium, with slight partial discharges having a smaller impact on the insulation of power equipment and a slower decrease in insulation strength; but strong partial discharge can quickly reduce the insulation strength. This is an important factor that causes insulation damage to high-voltage power equipment. Therefore, when designing insulation for high-voltage power equipment, it is necessary to consider that under the long-term working voltage, strong partial discharge is not allowed to occur within the insulation structure. The power grid should strengthen monitoring the equipment in operation. When partial discharge exceeds a certain level, the equipment should be taken out of operation for maintenance or replacement. In a solid dielectric medium containing gas or liquid, when the local field strength of the gas or liquid with breakdown field strength reaches its breakdown field strength, this part of the gas or liquid begins to discharge. The partial discharge is generally caused by a particularly concentrated local electric field inside the insulation or on the insulation surface. Usually, this discharge is characterized by a pulse duration of less than 1 μs . When partial discharge occurs in insulation, it will affect the insulation life. Each discharge, the impact of high-energy electrons or accelerated electrons, especially the long-term partial discharge, will cause various forms of physical effects and chemical reactions. For example, when charged particles hit the outer wall of the bubble, they may break the Chemical bond of the insulation and cause cracking, damage the sub structure of the insulation, cause insulation degradation, and accelerate the insulation damage process.

1. Partial discharge is a precursor to local overheating and aging of electrical and mechanical components;

2. The trend of partial discharge is the exponential increase of partial discharge over time, which is a tortuous process. At a certain stage, it may decrease, but at a certain stage, it increases;

3. When partial discharge is generated in the insulation structure, it will be accompanied by the generation of electrical pulses, ultrasound, electromagnetic radiation, light, chemical reactions, and cause local heating and other phenomena;

Due to the above characteristics of partial discharge, how to avoid and remove partial discharge in electrical equipment, so as to ensure normal and safe operation of the equipment, has become the most important consideration for power equipment maintenance personnel. In order to eliminate this latent fault phenomenon, many online detection methods of partial discharge phenomenon have been derived for electric pulse, ultrasonic, electromagnetic radiation and other signals generated with partial discharge.

The LDS800 handheld partial discharge tester developed by our company is a multi-functional handheld instrument, which detects partial discharge of equipment based on transient ground voltage, ultrasonic, Ultra high frequency and high-frequency current detection methods; Suitable for partial discharge detection of electrical equipment such as cables, GIS, switchgear, and transformers.