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The hazard of partial discharge

time:2020/6/29   source:华天电力  reading:294 time

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. It is manifested as the breakdown of gas in the insulation, partial breakdown of solid or liquid medium in a small range, or partial breakdown discharge caused by the concentrated field intensity at the edge and sharp Angle of the metal surface.


Partial discharge detector


Hazard 1: The role of electricity This discharge capacity is very small, so its short-term presence 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. If partial discharge exists for a long time, it will lead to insulation deterioration and even breakdown. Partial discharge test on power equipment can not only understand the insulation condition of equipment, but also find out many problems related to manufacturing and installation in time to determine the cause and severity of insulation fault.


Hazard 2: The effect of heat, in the local volume of 5×10-17 meters near the surface of the medium due to a partial discharge, the temperature of the medium can rise to 170℃ in 10-7 seconds, and sometimes even reach 1000℃ due to the effect of discharge, so it may cause the thermal fusion or chemical decomposition of the medium.


Besides the action of heat, the light action that partial discharge produces (basically be in ultraviolet ray range), still can make plastic organic medium produces the phenomenon such as photoageing, crack.


Hazard 3: Chemical action, due to the partial discharge generated by the stimulated molecules or secondary products, the medium may be subjected to more erosion than electricity, heat action results


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