Partial discharge

About: Partial discharge is a research topic. Over the lifetime, 13997 publications have been published within this topic receiving 102058 citations. The topic is also known as: PD.

Insulation optimization by electrode contour modification based on breakdown area/volume effects

Abstract: This paper shows how to determine the electrode contour with the best insulation performance on the basis of an area effect and a volume effect in the breakdown field strength. Previous electric field optimization techniques have provided us only with an optimum electric field distribution, For the design of power apparatus insulation, we have to consider the dielectric breakdown characteristics rather than the electric field distribution. As a first step, we developed a new optimization technique which enables us to obtain an optimum electrode contour with the highest breakdown strength while taking into account the area and volume effects of breakdown strength of insulating media. From the results, we have confirmed that the proposed optimization method improved the breakdown voltage more than did the electric field optimization. This leads to an effective insulation design of electric power apparatus.

Partial discharge resistant enameled wire

Abstract: Accompanied with the prevalence of motors controlled by the inverter, the problem of surge voltage arising from the inverter has become intensified. The high frequency components of the inverter switching pulse voltage lead to the overvoltages due to the impedance of the cable between the inverter and the motor, and the insulating materials have been damaged by the partial discharges. In this study, we prepared an wire enamel hybridized with nano-scale inorganic particles, and investigated the properties of the enameled wire. By the uniform hybridization of a small amount of nano-scale inorganic particles to the wire enamel, the insulation breakdown time was improved by some ten times compared with that of the standard enameled wire, and it showed a good partial discharge resistance.

The Law of Corona and the Dielectric Strength of Air-IV The Mechanism of Corona Formation and Loss

Abstract: The mechanisms of corona and corona loss have been studied with the cathode-ray oscillograph. High voltage power of the order of 0.1 watt can be measured with an accuracy of 1 per cent with this instrument. The measurements show that the loss follows the quadratic law above the visual critical voltage. On polished wires there is no loss until the visual critical voltage is reached. The loss then starts quite suddenly and takes a finite value on the quadratic curve. On cables and imperfect conductors there is a loss below the visual critical voltage on brushes at local ``rough'' spots. The loss due to these irregularities can be represented by the probability law. This is quite in accord with former work. In practise it is important not to mutilate the conductors in stringing. The really important factor in design is the irregularity factor, m e , for weathered conductors. No line should be operated with a corona loss under fair weather conditions. It is not necessary from the economic stand point since large diameters can be obtained with special types of conductors. The visual critical corona voltage can be calculated with great accuracy. As the applied a-c. voltage is increased above the visual critical value, the instantaneous critical voltage becomes lower and lower until finally corona starts at the zero point of the wave. This occurs when the applied voltage is twice the visual critical voltage. At still higher voltage, corona starts below zero or on the falling wave.

UHF detection of leader discharges in SF/sub 6/

Abstract: The ultra-high frequency (UHF) technique of partial discharge detection has been used to study the partial discharges produced by electrode protrusions and surface contamination in a gas insulated substation (GIS). The paper describes the stages of discharge development from inception to breakdown. The work has shown that the UHF technique may be used to identify distinct phases of discharge activity corresponding to discharge inception and a prebreakdown condition. The prebreakdown activity is detected as an increase in the UHF signal magnitude which has been attributed to the formation of leader-type discharges. These discharges form an essential part of the breakdown process, and their detection can be used to identify when the system is close to breakdown. The paper describes a filtering technique that may be employed to optimize the sensitivity of UHF leader detection. >