Film-Tech Forum ARCHIVE: Monee motor start resistor problem

This is topic Monee motor start resistor problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Matthew Taylor (Member # 2310) on 01-01-2007, 06:11 AM:

I have just acquired a Monee MA with base. I have got it running really nice but after a few minutes, the big wirewound start resistor in the base starts smoking. It's really hot.

What could be wrong with the wiring to cause this? The motor runs great.

Posted by Marin Zorica (Member # 1716) on 01-01-2007, 06:19 AM:

Try to look contactor or starting electronic (relay and similar) because when You start projector, first the motor runs thrue that resistor (to get easy start) and then (after second or two) motor get connected directly to mains....so resistor get short-circuted!

Posted by Mark Gulbrandsen (Member # 72) on 01-01-2007, 11:14 AM:

Check the centrifugal switch in the motor(if there is one) and also be sure its wired correctly. The resistor you mention is normally in series with the start winding of the motor and limits current though that winding. The start switch should disconnect after a second or so or when the motor is up to a percentage of its normal speed. If your motor does not have a start switch built in then you need to fit in a time delay off contactor to do the job.

Mark

Posted by Matthew Taylor (Member # 2310) on 01-01-2007, 12:56 PM:

I can hear the centrifugal switch activate - I don't know whether it works electrically or not.

I simply have a live and neutral supply to the motor via the resistor and double pole switch. Could it be that the supply live and neutral are wired the wrong way round?

I forgot to mention, it's a single phase motor.

Posted by Bob Koch (Member # 1062) on 01-01-2007, 01:37 PM:

Maybe this resistor has been inserted in the line to dampen the rapid start, as is sometimes done. If so it should be 2 ohms or less, not the higher value that would be used in the starting winding which would be switched by the centrifugal switch within the motor.