Practical Experiences with State-of-the-Art Surge Arrester Monitoring Devices

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

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Authors:
Raschke, Philipp (Tridelta Meidensha GmbH, Hermsdorf, Germany)

Abstract:
In the past 30 Years, numerous devices with different technologies for surge arrester monitoring were introduced to the market. Today, leakage current monitoring is a prevalent method for assessing the condition of surge arresters and most importantly for estimating their remaining life span. Nevertheless there are effects on the arrester leakage current, which lead to measurement errors, false interpretations and finally to unnecessary replacement or even to unexpected breakdown of an arrester. Utilizing leakage current for surge arrester monitoring often causes confusion since diverse leakage current behavior phenomena must be understood. This paper is based on the first experiences with a state-of-the-art Surge Arrester Monitoring System examined in the test lab and in an extensive international field test in numerous countries with different HV Systems, climates and environmental conditions. The paper gives new insights into effects on the surge arrester leakage current and may be used as a guideline for interpretation of measurement results and accurate decision making in surge arrester maintenance. In order to build up an adequate knowledge base for users of surge arrester monitors, different effects on surge arrester leakage current, which may lead to misunderstanding the measured data were investigated. Temperature and grid related influences like harmonics in the system voltage play a minor role since there are existing methods for rough compensation of them. Weather and pollution still influence the arrester current by adding surface currents and hence errors to the measured values. A humidity ingress or successive degradation of MOV blocks are the most common reasons for surge arrester failure and need to be detected early. Only proper understanding of measured leakage current values, preferably available as periodically logged long term data, guarantees early failure recognition and the making of a correct decision for replacing a surge arrester. Thus, the most frequent cases of leakage current behavior are explained and set in relation to the according practical scenario. Side effects and their impact on the measurement results are discussed and recommendations for a proper condition assessment of surge arrester are given.