Partial Discharge Causes and Handling Methods of Switchgear

Partial discharge causes and handling methods of switch cabinets Partial discharge of switch cabinets means that in the switchgear cabinet, once the electric field strength of the area reaches the breakdown field strength, discharge occurs in this area, but the two conductors that apply the voltage Between the entire discharge process does not penetrate, that is, discharge does not break through the insulation system, this phenomenon is partial discharge. Partial discharge will promote the deterioration of the insulation of the switchgear cabinet and accelerate the aging of the switchgear cabinet. Therefore, it is very important to understand the principle and processing method of the partial discharge of the switchgear cabinet.

The reason for the partial discharge of the switchgear is that the high-voltage electrical terminals of the high-voltage electrical equipment are exposed to air, so the probability of corona discharge is relatively large. Corona discharge shows the characteristics of a typical, extremely inhomogeneous electric field, and is also a characteristic self-sustained discharge under extremely inhomogeneous electric fields. It is also possible that once the strength of the internal electric field of the medium is lower than the electric field strength of the electrode edge air gap, and the dielectric breakdown voltage is relatively low along the surface, the creeping discharge occurs on the surface of the insulating medium. Usually the voltage waveform, the distribution of the electric field, the air quality, the surface state of the medium, and the climatic conditions all affect the creeping discharge voltage, so the creeping discharge shows unstable characteristics.

At the same time, the production and processing of insulating media inevitably have problems with material and process defects, resulting in internal defects in the insulation medium, such as the incorporation of a small amount of air or impurities. Once the insulation is subjected to high voltage, there is the possibility of partial breakdown or repetitive breakdown of internal defects. Usually, the characteristics of the medium itself, the size of the air gap, the position and shape of the defect, and the type of air gap gas have an influence on the occurrence conditions of the internal discharge.

If you want to know if there is partial discharge in the switch cabinet, you can test it. When partial discharge occurs in the insulating layer of the high voltage switch cabinet, electromagnetic waves will be generated. The metal shell of the switch cabinet will block this electromagnetic wave. In part, there is still a small part that propagates through the seam of the metal shell or the gas-insulated switch pad, and it also generates a ground wave that passes underground through the outer surface of the device's metal shell. The range of ground waves is usually in the range of a few millivolts up to several volts, and there are several nanoseconds in the rise time. The probe can be set on the outer surface of the switchgear in the operating state to detect partial discharge activity.

The switchgear plays an important role in the application of the power system, and the partial discharge of the switchgear will have a huge impact on its service life. Therefore, the switchgear cabinet should be tested in time to detect the problem as soon as possible and be solved as soon as possible to improve the switch. The service life of the cabinet.