We recently had a Shut-down in a local factory, to upgrade the 11kV/400V tranny, after the work was done and the transformer was re-energised, I had the task of throwing the Main Isolator,(a heap of remedial work, had been done in the factory),and as I went to throw the switch, (a 1000A ACB), it got stuck half-way,resulting in a flash and a bang!. How do you guys feel about throwing High current Isolators?, personally they give me the Willies. Your thoughts please?.
Sparky, After I had replaced(Hooked Up), the DDO fuses, with all of the Isolators OFF, there was still a spark at the top terminal of the DDO's,(Xformer load), but we had a lot of new 400V gear, installed during the Shut-Down period, by other firms as well, I had to make sure that the people where ready for the power, to be connected, as it was not Locked Out, at their Isolator, as is required by law. But Sparky, I feel more comfortable, replacing a DDO fuse, than throwing a 1000A Main Switch, at least you've got a certain amount of Manual control over a DDO fuse, if it blows.