Testing of high voltage circuit breakers can be a hazardous task due to the risk of induced high electric potential. Safety in high voltage substations is the highest priority for all personnel involved. Regulations require all objects to be grounded on both sides before any maintenance work is performed. However, conventional testing methods require removing the grounding cable from one side of the circuit breaker in order to allow test equipment to conduct measurement and get correct results. In this case, there is a danger of induced high electric potential at the side with removed grounding cable.
Is it possible to perform testing of the circuit breaker with both sides grounded? How can the resistance of the circuit breaker main circuit be measured if there is a parallel low-resistance circuit through the grounding cables and grounding network?
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June 10, 2019