Loss of One Phase

Additional information from Bussman to add to Jr's post

See this link for detail:

http://www.progress-energy.com/custservice/carcig/resourcectr/presentations/MotorProtection_VoltageUnbalance.pdf

- MS

you would be running at a single phase state which later on burn-out your motor's winding..this is another scenario of unbalanced system..it occured in our factory where our gantry crane motor drive winding shifted colors from insulated red to burnt black..

Damn that color shift problem... happens all too often. Someone needs to invent wire that doesn't change color like that...

In a correctly-installed system, either another of the supply fuses would rupture, stopping the motor, or the motor overload device woudl operate, doing the same.

There is no excuse for burnt-out motors these days.

..the incident occured at the CB terminals, the ones that supplies it...another reason for this was because that system existed longer than i am here...so all i could do is to correct it..

No, the other phase won't carry 450A each.

What will happen is that the load connected to the feeder with a blown fuse won't have electricity to pass through to the load, but the current will be flowing up until the point of the fuse and will ultimately reach infinity (maximum), and if not attended to timeously, it will cause a big damage to the cable that might lead to an explosion.

So to correct this, the fuse should be replaced asap because there is no earth fault as well.By earth fault I am under the impression that you are talking about earth fault relay.