Druckabhängigkeit des Teilentladungsverhaltens in Hermetiktransformatoren

authored by

M. Kuhnke, P. Werle

Abstract

Hermetically sealed power transformers have several advantages compared with conventional transformers with conservator. They are more compact and do not require air drying equipment, which need regular maintenance. Therefore, hermetically sealed transformers are common choice for wind power plants. In recent years there have been many reports of transformer failures in these wind power plants. Most of them related to partial discharges in the transformers. The thermal expansion of the insulating liquid can lead to a severe change of the internal pressure. Therefore, the pressure dependent PD inception for five different insulating liquids is investigated with different electrode configurations. A transformer model with two special electrodes resembling high voltage windings and aramid paper is used inside a test vessel with temperature and pressure control. With this model the PD inception can be measured at different pressures and temperatures. The electrodes can be replaced with standard needle-sphere electrodes. To investigate the influence of the dissolved gas in the liquid, the liquids are dried and degassed and then saturated with different gasses prior to the measurement. To compare these model results with a real transformer, the PD inception voltage is measured on a hermetically sealed 160 kVA transformer with varying internal pressure.

Organisation(s)

High Voltage Engineering and Asset Management Section (Schering Institute)
Institute of Electric Power Systems

Type

Conference contribution

Pages

231-235

No. of pages

5

Publication date

2018

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Energy Engineering and Power Technology, Electrical and Electronic Engineering