LA.pdf - In-Service Testing and Diagnosis of Gapless Metal Oxide Surge Arresters According to IEC60099-5 Overview of presentation • Motivation for

LA.pdf - In-Service Testing and Diagnosis of Gapless Metal...

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In-Service Testing and Diagnosis of Gapless Metal Oxide Surge Arresters According to IEC60099-5
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Title 2 2 Overview of presentation Motivation for condition monitoring of metal oxide surge arresters (MOSA) “The Surge arrester life” Service experience Examples of arrester failures Characteristic properties of MOSA (ZnO)- arrester Aging and causes of failure Consequences of failure transformer failures
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Title 3 3 Overview of presentation contd. Surge arrester condition assessment IEC 60099- 5 about “Diagnostic indicators of metal oxide surge arresters in service” Monitoring equipment and field application for third harmonic analysis with compensation Testing strategy and risk assessment Case studies
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Title 4 4 Background and Motivation The Metal Oxide Surge Arrester (MOSA) is a cheap and passive component, but protecting crucial apparatus. Overlooked despite severe consequences if it fails. MOSAs can age and fail due for a number of different reasons. May offer inadequate overvoltage protection, especially if the rated voltage is selected too low. Diagnostic indicator: Resistive leakage current increases with time increasing risk for failure.
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Title 5 5 Power System Overview Typical Location of Surge Arresters Typical location of surge arresters: In substations At the end of transmission lines At cable ends At transformers, generators, capacitors etc Location depending on voltage level, equipment and local conditions
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Title 6 6 The Surge Arrester Life The normal destiny of the surge arrester is to be: specified, purchased, installed - and forgotten… Most common maintenance practice: No testing of surge arresters Only replacement after breakdown. “surge arresters are inexpensive no big deal to replace !!!” Is this really an acceptable practice?
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