Investigation on the Accelerated Ageing Behaviour of an Oil-Paper-Insulation Using Different Weight Ratios

authored by

T. Münster, T. Kinkeldey, P. Werle, K. Hämel, J. Preusel

Abstract

This research presents a comparative study of the ageing process of an oil-paper-insulation using Kraft paper. The main goal of this research is the comparison of the ageing behaviour of the insulation with different weight ratios and the influence on pertinent ageing markers, which are used to estimate the remaining lifetime of an oil-paper insulated transformer. Therefore, an investigation has been conducted to measure different parameters of a non-inhibited insulating oil during a long-term thermal stress over 15 weeks at a temperature of 130 ℃ to examine the influence of the ratio on the formation of these markers. The higher temperature compared to the normal operation temperature of a transformer is used to accelerate the thermal ageing of the insulation material in order to simulate the lifetime of a transformer. In addition to the ageing of pure paper and pure insulating oil, the paper-oil weight ratios 1:5, 1:10 and 1:20 will be investigated. The aim is to study how the respective insulating medium ages individually and to determine the ageing behaviour of the insulating materials when used together as a mixed dielectric, as it can be found in real transformers. Therefore, a typically used uninhibited liquid based on mineral oil is used as insulating liquid. Ageing markers such as water content, acidity as well as DGA analyses and other parameters are investigated. Furthermore, the DP-value of the paper samples is also measured. For this, an open system is reproduced, so that a permanent contact with the ambient air is given to simulate a free breathing transformer. The main aim of this study is to investigate the influence of the various weight ratios and how it influences the possibility of indirectly determining the condition of the insulating paper. For this purpose, ageing markers are to be investigated. The obtained results showed that the weight ratio has no influence on the ageing rate of paper but on some ageing markers.

Organisation(s)

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

External Organisation(s)

GRIDINSPECT GmbH

Type

Conference contribution

Volume

1

Pages

788-798

No. of pages

11

Publication date

2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Industrial and Manufacturing Engineering

Electronic version(s)

https://doi.org/10.1007/978-3-030-31676-1_74 (Access: Closed)