Reasons for local discharge of switching cabinets
2022-11-11
In the switch cabinet insulation system, there are differences in the strength of the electric field in each part. Once the strength of the electric field in a certain area reaches its breakdown, the area will occur. The entire discharge process, that is, the discharge undistributed insulation system, this phenomenon is local discharge. The electrical field distribution of the insulation medium and the electrical physical properties of insulation determine the conditions for local discharge. Generally, local discharge is prone to occur under the conditions of high electric field strength and low electrical strength. Although local discharge usually does not penetrate insulation, it may be localized to damage the electrical medium. If there is a phenomenon of local discharge for a long time, the electrical strength of the insulating medium is reduced based on specific conditions. It can be seen that local discharge is a hidden danger in electrical equipment, and its destruction process reflects the characteristics of chronic and long -term. Generally, the characteristics of local discharge can be better confirmed by the insulation defect, and the degree of local damage of the insulation can be analyzed through the characteristics of local discharge. To largely measure the various local discharge characteristics, it can objectively evaluate the insulation level of the product.
2 Types of local discharge
2.1 Electric discharge
Electric discharge discharge around the high -voltage conductor surrounded by gases, such as high -voltage transmission lines or high -voltage transformers, etc. The high -voltage wire terminals of these high -voltage electrical equipment are exposed to the air, so the chance of discharge discharge is relatively large. Electric discharge discharge reflects the characteristics of typical, extremely uneven electric field, and is also a self -control discharge form unique to the extremely uneven electric field. Many external factors will affect the starting voltage of electromotive halo, such as the shape of the electrode, the exterior voltage, the gas density, the distance between the pole, and the air humidity and flow speed.
2.2 Discharge along the surface
The phenomenon of discharge along the surface on the surface of the insulation medium is usually discharged. This form of local discharge belongs to a special gas discharge phenomenon. Power cable, motor winding, and the end of the insulation sleeve are more commonly discharged along the surface. Once the intensity of the internal electric field of the medium is lower than the power field strength of the electrode edge gap, and the breakdown voltage along the surface is relatively low, the discharge along the surface will occur on the surface of the insulation medium. Generally, the distribution of voltage waveforms, electric fields, air quality, surface state of the medium, climate conditions, etc. will affect the discharge voltage along the surface, so discharge along the surface reflects the characteristics of unstable.
2.3 Internal discharge
The internal discharge of solid insulation medium is relatively common internal discharge. In the production and processing insulation medium, there are inevitable problems with material and process defects, resulting in internal defects inside the insulation medium, such as a small amount of air or impurities mixed with people. Once the insulation is high -pressure, internal defects are likely to occur or duplicate. Generally, the characteristics of the medium itself, the size of the air gap, the position and shape of the defect, the type of air gap gas will affect the conditions of the internal discharge.
2.4 Suspension potential discharge
This form of local discharge refers to a structural design defect in a conductor component in a high -voltage device, or other reasons that cause poor contact to disconnect, which eventually causes the component to get between the high -voltage electrode and the low -voltage electrode and obtain a score based on the impedance ratio of its position. The voltage is discharged, and the ground potential on the conductor is called a suspension potential. When the conductor has a suspension potential, usually the nearby field strength will be more concentrated, and it will destroy the formation of the surrounding insulating medium. Suspension potential discharge is prone to suspended potentials on the high potential of the electrical equipment or the metal components at the ground potential.
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