Experimental model of aging mechanisms of on-load tap changer contacts

Conference paper (2008)

Authors

JJ Erbrink Old - EWI Sect. High-Voltage Techn. and Management
PP Seitz External organisation
R Leich External organisation
Research Group
Old - EWI Sect. High-Voltage Techn. and Management
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Published Date

2008

Language

Undefined/Unknown

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Research Group

Old - EWI Sect. High-Voltage Techn. and Management

Abstract

It is known that most failure of power transformers are related to aging effects of the on-load tap changer contacts. To understand the aging mechanisms and to develop knowledge rules to interpret different failure mechanisms a test model has been developed. In particular, the effect of the several aging stages of tap changer change-over selector contacts on dynamic resistance measurements (DRM) has been considered, by several measurements with aged tap changer contacts. These aging phases include clean contacts, contacts with an oil film layer, contacts with coking and contacts with pitting. Based on these experiments it is shown that the DRM method is very sensitive to aged change-over selector contacts of an on-load tap changer. In addition to laboratory experiments, the same measurements are performed on naturally aged change-over selector contacts at a Dutch utility.