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Comparison of circuit breaker stress related to the first pole to clear factor. Helmut Heiermeier 14. October 2007. Background. A circuit breaker experiences different stresses depending on the grounding condition of the network
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Comparison of circuit breaker stress related to the first pole to clear factor Helmut Heiermeier 14. October 2007
Background A circuit breaker experiences different stresses depending on the grounding condition of the network TRV for the circuitbreaker depending on first,second or third clearing phase Necessary arcing time window A comparison of the stresses is given
Not covered if tested for ungrounded condition
Conclusion If a test is performed at undgrounded condition Short arcing times are tested with higher TRV Medium arcing times are tested with lower TRV Long arcing times are not tested testing under ungrounded condition if the majority of the faults are grounded leaves some major stresses untested and lowers confidence