Moral of the story: don't under-rate the permanently installed ground switch.Īnd 1916, I don't know if this is possible, but perhaps you could modify your OP so it has a subject line you might get more responses that way. In a breaker and a half switchyard, the sequence is: open the two diameter breakers for said circuit, open the outside disconnects for both, have Station Maintenance apply a set of working grounds between one of the breakers and its outside disconnect, close the line disconnect, close the breaker with the working grounds on its outside to create a parallel path to ground, open, check open and lock the permanently installed ground switch, open the closed breaker to unground the circuit, have temporary grounds removed, return all equipment to service in the normal manner. The operators were left with no choice but to close that ground switch back in, then go through the process of what we call "ungrounding through a breaker" to get that ground switch open. I recall one instance where the permanently installed ground switch was closed in with no issues in order to de-energize the line / prove isolation for work.but at the conclusion of the outage, when all working grounds had been removed and the only grounding of the circuit was via that single handwheel-driven ground switch and the operator cranked it open, it drew an arc that never broke the switch was fully open and the arc just buzzed and snapped away steadily. How to rate that switch will depend on a number of factors length, voltage, number and spacing of parallel circuits, conductor transpositions, and so on come to mind. I can't answer the technical side of the question, but within my utility a permanently installed grounding switch is required on such circuits in order to prove isolation for Work Protection purposes.
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