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Transformer oil is an important part in a high voltage transformer. Under excessive condition, electric arc may occur in the transformer oil. The electric arc may reduce the performance of the transformer oil. This paper explains the experimental results on the effects of electric arc on the partial discharge (PD) inception and patterns in mineral transformer oil. In the experiment, electric arc was...
Identifying partial discharge (PD) phenomena in power transformers is the key to achieve proper maintenance actions. In order to tag a recorded PD pattern obtained from either on site testing or monitoring as, e.g., internal, surface or corona discharges, a diagnostic database has to be built first. This database would contain patterns and relevant statistic parameters recorded in the lab under controlled...
In this paper, we present the most recent test of the multigap gas switches which are one of the key elements of the fast LTD stages with oil insulation. Inside these switches, the charge voltage is distributed between the multiple gaps with the use of a corona discharge. The evident advantages of this technique are low cost and extreme compactness of the voltage divider because it just consists of...
This paper describes the experimental results on the creeping streamer progressing the surface of a bakelite board immersed in transformer oil under the application of a standard lightning impulse voltage with peak values of plusmn100~350 kV. The growth of streamers is significantly affected by the thickness of bakelite board and the streamers are extended longer exponentially for the applied voltage...
Studies were carried out for needle-plane gaps with a comparatively long separation in transformer oil. Relations between needle voltages and space charge quantities due to coronas by lightning impulse and AC voltages were obtained. It was found that the charge quantities for AC voltages were larger by 1.2 times and 6 times than that for the positive and the negative impulse voltages respectively...
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