ABB Excount II User Manual
Also see for EXCOUNT-II: User manual
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Contents
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52 1HSA 801 080-15en EXCOUNT-II Users Manual6. Surge arrester monitoring theory6.1 IntroductionThe rising demands for improved reliability of power supply andreduced maintenance costs have increased the attention on condi-tion monitoring of equipment in HV substations. As far as metal-oxidesurge arresters are concerned, there are two important aspects whichare related to the reliability of the arresters:• The stress on the arrester in terms of the intensityand frequency of impulse currents• The condition of the arrester in terms of its insulatingproperties in normal serviceThe first aspect is addressed by performing continuous surge coun-ting and the second by leakage current measurements on regularbasis.The EXCOUNT-II is designed to handle both surge counting andleakage current measurements in a single monitoring system. TheEXCOUNT-II system comprises a sensor, permanently mounted at thebase of the arrester, a transceiver for wireless communication with thesensor, and proprietary software installed on a personal computer.In the following, the bases for surge counting and leakage currentmeasurements are described, and the corresponding functions of theEXCOUNT-II are presented. For general information on various diag-nostic methods for metal-oxide arresters, please refer to IEC 60099-5.6.2 Surge countingGeneralThe primary aim of a surge counter is to give an indication of thestress on the arrester from impulse currents caused by overvoltages.In addition, surge counters may be helpful in analysing the occur-rences of overvoltages on the system, provided the surge countinginformation is sufficiently detailed.Surge counting with EXCOUNT-IISurge counters operate at impulse currents above a certain ampli-tude. The EXCOUNT-II sensor is equipped with an impulse current |
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