Cold Fusion
Senior Member
- Location
- way north
That is an example of poor design and poorly selected equipment, and maybe even poor commissioning. An 150kva/208V gen can only put out 2ka - 3ka SSC. An 208V, 800A, 5%Z utility can deliver maybe 16ka. I would hope that the designer could deal with that pretty easily.I have seen what happens when both the utility and the generator thinks its supplying the load. Well, I waw it once the "discussion" had. The switchgear was the loser in this discussion. Arc F'd. But not arc flash. A big mess. ...
Normally one uses a second check relay in addition to the dead buss relay. So it takes two failures to close into a live buss out of sync. But it can happen. The equipment has to handle it with no extraneous energy escape. There may be a damaged CB, but usually that is considered acceptable after two failures.
cf