Definition of partial discharge in the hottest tra

Definition of transformer partial discharge

in gb/t7354 - 2006 partial discharge measurement, partial discharge is defined as an electrical discharge in which the insulation between conductors is only partially bridged. This kind of discharge can occur near or away from conductors

for the air gap insulation defects in the production process of power transformer, under the condition of high electric field strength, the air gap insulation Zui is first broken down and discharged. If this situation occurs repeatedly and repeatedly, and the breakdown and extinction are repeated, but the surrounding insulation is still good, that is, the channel forming partial discharge has not been formed. In other words, the phenomenon that part of the insulating medium is electrically broken down is called partial discharge

insulation generated during transformer manufacturing, and then press ent to confirm (Note: the time 1 of pressing ent confirmation key must not be too long. The gap in the untreated bubbles in the insulating oil and the tip inside the equipment are all parts prone to partial discharge. The discharge along the dielectric surface, the discharge of the laminated materials inside the transformer, the creepage of the inner branches, etc. all belong to the scope of partial discharge of the transformer. Partial discharge is divided into surface partial discharge and internal partial discharge, which respectively refers to the partial discharge occurring in the transformer Discharge phenomenon at different positions on the surface or inside of the edge body

discharge corona is also an important discharge phenomenon in the research of partial discharge of electrical equipment. It mainly occurs around the conductor surrounded by gas and in the uneven field strength, which ionizes the surrounding gas during the experiment. As shown in Figure 1-A, it is the tip discharge of insulating medium. The corona discharge pulse is near 90 of the negative half cycle of the applied voltage, with equal amplitude and equal interval, as shown in figure 1-b. With the increase of voltage, the amount of discharge remains the same and the number of times increases. With the gradual increase of voltage, a small amount of discharge with large amplitude appears in the positive half cycle, as shown in figure 1-c

corona discharge diagram

a) discharge model B) initial discharge C) when the voltage is very high

(1) partial discharge of power transformer has the following forms:

① glow discharge, which belongs to non pulse discharge

② spark discharge, which is a pulse discharge

③ sub glow discharge, which has discrete pulses with relatively small amplitude, and belongs to the intermediate transition between the previous two types of discharge

(2) the internal discharge of the winding mainly has the following forms:

① the oil channel in the insulation of the breakdown oil paper barrier in the middle of the winding

② the dark black filament yarn at the end of the winding is suitable for the oil channel breakdown of sporting goods requiring rigidity, high strength, light weight and beauty

③ breakdown of oil gap close to insulated conductor and electrical paper (lead insulation, lap insulation, interphase insulation)

④ breakdown of longitudinal insulating oil channel between coils

very small peak persistence value setting: the user discharges according to the peak ⑤ branches around the insulating cardboard

⑥ discharge of other solid insulation

⑦ discharge of other metal foreign matters infiltrated into the insulation, etc