3 phase motor.

[ukracer]

If the full load current of the motor is 6 amps and your having to adjust the overload to 10 amps then there is something wrong, I'd suggest a clamp meter as above. No need for anything fancy, most cheapies will read close enough. Also what's the load on the motor, if it's got a lot of inertia then you can be limited by the number of starts (the windings get hot due to the starting current) , unlikely on a small motor but I've had overloads trip on large fans with a couple of starts in a row.

This is a 3kw motor. ..

 

[daleyd]

This is a 3kw motor. ..

So full load current is around 6-7 amps per phase at 415 volts? If your having to turn up the overload to 10 then your masking a problem.

The overload should be set at or just above full load current, else your going to run the risk of burning the windings out in the event of a problem.

 

[daleyd]

Without a clamp meter you won't know if the overload is faulty or the motor is genuinely pulling too much current. If you were closer I would borrow you one, but as said above you can pick them up from Toolstation or similar for not much money - an invaluable tool for stuff like this.

 

[ukracer]

Cheers for all the info. I am pretty happy my initial guesses are more or less confirmed more of less by your replies and the solution to finding the source of the problem is as cheap as chips.

My mate wanted to just take out the switch and try without that but as I said if that takes out the converter that's 50 quid down the spout.

There is a Toolstation just 500 yards from his unit. So its a no brainer.

Thanks again. ..will update you all on solution but my guess is come Monday he will buy a new single phase motor. ...as it would make his operating the blasting booth much more simple.