Self-Organized Classification of On-load Tap Changers Acoustic Signatures

On-load Tap Changers (OLTC) are widely used for voltage regulation in electricity networks. A set of electrical contacts (taps) is used to change the transformer input/output ratio as the input voltage varies. Non-invasive acoustic methods for condition monitoring of internal electrical contacts have been recently proposed in the literature. A limitation of these analysis is that there is no information on gradual degradation of the equipment condition. In this work a classifier system using Self-organizing Maps (SOM) is developed in order to identify different levels of electrical contacts wear. The method proposed here was able to separate the available signatures into four distinct operation conditions: post-maintenance (no-wear out), low, intermediate and severe wear out.