Online DGA for partial discharge investigation at various PDIV levels and mineral oil temperatures

Summary

The aim of this paper is to study the behaviour of gases caused by partial discharge (PD) in the mineral oil at different temperatures and test voltage levels. Firstly, partial discharge inception voltage (PDIV) of the mineral oil was investigated with the needle-plane electrode. The PDIV test circuit was set up according to IEC 60270: the test experiment was performed in accordance with IEC 61294. Then, the test cell was equipped with the online dissolved gas analysis (DGA), Calisto 9, for detection the gases generated by PD in the mineral oil. The electrode system for investigation was the same as the electrode used in the PDIV experiment. In the investigation procedure, the mineral oil was heated until its temperature was 40 degree Celsius. After that, the test voltage was applied to the test cell at PDIV test level for 12 hours. The concentration of gases in the mineral oil was detected and recorded every hour. Moreover, the gas generation was also examined at 1.5PDIV and 1.7PDIV levels. To study the influence of mineral oil temperatures on the gas generation, the mineral oil was heated to 50 and 60 degree Celsius as well.From the test results, a small amount of hydrogen was found due to corona discharge in the mineral oil with the temperature of 40 and 50 degree Celsius testing at PDIV level. Furthermore, acetylene and ethylene were found at 1.5PDIV level. In addition,at1.7PDIV test levelacetylene and ethylene carbon monoxide was detected. When the mineral oil temperature was increased to 50 degree Celsius, all mentioned gases, namely hydrogen, acetylene, ethylene and carbon monoxide were detected at the PDIV, 1.5PDIV and 1.7PDIV levels, thereby more gas concentration was directly proportional to the higher PDIV level. At 50degree Celsius, increase of gas generation was markedly found compared with the generation of dissolved gases at 40degree Celsius tested at PDIV levels.

Additional informations

Authors

TOTZAUER, HORNAK, PIHERA, PIRKER

Keywords

Dissolved gas analysis, Partial discharge, Monitoring, Transformer