Once repaired/overhauled a small 3 phase motor for a guy with a wood shop where he made windows/doors etc.
Done the repairs and tested it fully, sent it back and thought nothing about it. Next day motor comes back with terminal block blown to bits and box full of carbon dust. Checks everything over, cleans up terminal box, fit new block, re-test and send back. Motor comes back late afternoon same problem. Strange! Goes through it all again, had witness check when I tested it and sent it back following morning confident I wouldn't see it again.
It was back in the afternoon with a VERY annoyed chippie asking what the f*%k I was playing at nearly killing him when ever he tried to switch his machine on. So, being humble and apologetic explained I couldn't understand what was happening as it always tested ok on our test bed. Repaired it AGAIN! and this time took it back myself to check his wiring. Isolator with correct motor fuses in it etc so said ok let your spark connect it up and I'll see what happens. "Oh I do all the sparking around here, I'm a one man outfit so have to do everything myself."
"CLANG, CLANG. CLANG, CLANG!!!
Alarm bells start to ring.
"Right," said I, "connect up but DO NOT switch on till I have done a few checks."
So he proceeds to connect 3 phase leads.....................
TO THE STAR POINT!!!
swore blind thats the way they were connected when he dis-connected it originally!
I connected it correctly and he stepped back when I switched on.
SUCCESS!
Needless to say he was billed for all my wasted time!
Done the repairs and tested it fully, sent it back and thought nothing about it. Next day motor comes back with terminal block blown to bits and box full of carbon dust. Checks everything over, cleans up terminal box, fit new block, re-test and send back. Motor comes back late afternoon same problem. Strange! Goes through it all again, had witness check when I tested it and sent it back following morning confident I wouldn't see it again.
It was back in the afternoon with a VERY annoyed chippie asking what the f*%k I was playing at nearly killing him when ever he tried to switch his machine on. So, being humble and apologetic explained I couldn't understand what was happening as it always tested ok on our test bed. Repaired it AGAIN! and this time took it back myself to check his wiring. Isolator with correct motor fuses in it etc so said ok let your spark connect it up and I'll see what happens. "Oh I do all the sparking around here, I'm a one man outfit so have to do everything myself."
"CLANG, CLANG. CLANG, CLANG!!!
Alarm bells start to ring.
"Right," said I, "connect up but DO NOT switch on till I have done a few checks."
So he proceeds to connect 3 phase leads.....................
TO THE STAR POINT!!!
swore blind thats the way they were connected when he dis-connected it originally!
I connected it correctly and he stepped back when I switched on.
SUCCESS!
Needless to say he was billed for all my wasted time!