motor starter help

Discussion in 'General Electronics Chat' started by jax444, May 18, 2009.

  1. jax444

    Thread Starter New Member

    May 18, 2009
    I have an AC 3 ph motor that does not stay running. If I manually push in the contactor on the motor starter it runs, but when I let go it stops. There is a motor starter with an thermal overload circuit (bi -metal). it has a two wire aux. to to the coil on the starter. i have proper voltage to the supply and secondary side. Could the contacts on the thermal overload device be bad? I would appreciate any input thanks.Or any ideas on how someone might approach the problem.

  2. DonQ

    Active Member

    May 6, 2009
    Manually pushing does the same thing as the coil being energized, so it seems that the coil is not getting energized. If the coil itself is good, then something in the circuit that activates it is open. Things like interlocks, the aux contacts on the MS, or anything else in the chain of contacts that are in series with the coil. You just have to backtrack this chain with a voltmeter to find what is open.