Investigation of the Breakdown Voltage of Insulation Oil in a Frequency Range between 50 Hz and 10 kHz

Conference: VDE-Hochspannungstechnik 2018 - ETG-Fachtagung
11/12/2018 - 11/14/2018 at Berlin, Deutschland

Proceedings: ETG-Fb. 157: VDE-Hochspannungstechnik

Pages: 6Language: englishTyp: PDF

Personal VDE Members are entitled to a 10% discount on this title

Authors:
Moeller, Robert; Puffer, Ralf (Institute for High Voltage Technology, RWTH Aachen University, Aachen, Germany)

Abstract:
AC/DC converters can be included into medium voltage grids due to the increase of semiconductor┬┤s power and voltage capability. These converters are built of a rectifier, an inverter, a transformer and another rectifier. A reduction of converter size and an increased efficiency can be reached by using a medium frequent voltage in the range between 1 and 10 kHz in the intermediate circuit of the converter. Liquid immersed transformers are commonly used in medium voltage level. Due to higher loss densities of the transformer at increased frequency, liquid insulation might be used in the medium frequent (MF) range. The breakdown voltage of insulation oil is unknown in the medium frequent range and has to be investigated. In contrast to 50 Hz, dielectric losses might increase and thermal heating occur. Therefore, the breakdown voltage of mineral oil, silicon oil and synthetic ester is investigated in the range between 1 and 10 kHz. Additionally, the breakdown voltage is measured at 50 Hz, for comparison of breakdown voltage in MF range and at power frequency.