Working on trying to provide a solution to implement installing GFI protection on a 600V 3ph Delta feeder for a welder being used underground in wet conditions.
Feeder ampacity being asked for is 100A.
Anyone had experience in designing any similar installs?
Not exactly. Your 600V system is ungrounded delta? Does it have ground fault detection? Shouldn't that protect against ground fault on this (branch) feeder?
Or when you say delta do you just mean the feeder is 3 phase 3 wire, though the 600V system is grounded? If so, a 100A MCCB (or fused switch) w/ GFI trip should do though I would guess the cost between one thousand and several thousand dollars.
If your system is ungrounded delta then a breaker with GFI doesn't sound like the correct animal for you. You should speak with the service outfit who does servicing on whatever brand of gear you have, they may be able to recommend something. Maybe a shunt trip breaker and some residual current sensing / relaying would get you what you want. What happens, at present, if one ground fault occurs somewhere on your 600V system? Warning buzzer / lights?
I should mention that I seem to recall that there is an important difference between a breaker rated 600V 3P (suitable for ungrounded delta as each pole is rated for 600V from ground) and a breaker rated
347/600V 3P (not suitable for ungrounded delta as poles are rated for
347V from ground).
That sounds like a heck of a welder at 600V 3P 100A. Or is the feeder just extremely long.
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