B
brizospark
We have been involved in the installation of a dust extraction system which is powered by a fairly large 3 phase motor (18A).
The motor was pre-wire to a control box on the side of the extraction housing and the star/delta starter was also pre-wired. The only wiring that was required was the 2 sets of cables from the extraction junction box to the star delta starter. These cables were to be connected to the main contactor and the star contactor, anyway we followed the drawing to a t.
The overload was set at 22a and we have used a 32 TP type C MCB at the DB.
The motor was first operated yesterday, it ran for a few hours and then the MCB tripped. I couldn't understand why this would trip before the O/L but anyway it did.
So I had a look at the motor and it was red hot, couldn't even touch it for any period of time so we waited a bit and checked everything, our wiring was spot to drawing and everything in the starter looked ok. I took the cover off the motor when it was cool enough and checked the resistance across the set of windings and one set was Open circuit.
Any ideas what could have caused this apart from a faulty motor?
The motor was pre-wire to a control box on the side of the extraction housing and the star/delta starter was also pre-wired. The only wiring that was required was the 2 sets of cables from the extraction junction box to the star delta starter. These cables were to be connected to the main contactor and the star contactor, anyway we followed the drawing to a t.
The overload was set at 22a and we have used a 32 TP type C MCB at the DB.
The motor was first operated yesterday, it ran for a few hours and then the MCB tripped. I couldn't understand why this would trip before the O/L but anyway it did.
So I had a look at the motor and it was red hot, couldn't even touch it for any period of time so we waited a bit and checked everything, our wiring was spot to drawing and everything in the starter looked ok. I took the cover off the motor when it was cool enough and checked the resistance across the set of windings and one set was Open circuit.
Any ideas what could have caused this apart from a faulty motor?
