AC motor control problems

[jderrico]

have (a hopefully) simple question about how to proceed:

I'm setting up a simple motor control circuit w/ a momentary SPST-NC button, momentary SPST-NO button, and single pole contactor (rated at 30amps). The start button is in parallel to the contactor, the stop button in series. The control circuit seems to function properly: start button engages contactor, remains on when start button released and until stop button pressed. The problem is that the motor I'm trying to control no longer starts up. Previously it was controlled by a simple, two-pole continuous switch (that worked fine).

Details on the motor: it's a G.E. 3hp single phase 220V motor. Has start capacitors. Draws 17 amps if memory serves. The switch and now motor control is switching a single 120V leg.

I'm wondering what to try next.. is this a timing issue? Is the contactor stealing current? Do I need a contactor rated for a higher current? Bigger start caps? Any suggestions on what to try next?

I apologize for any stupid questions. My area of expertise lies elsewhere...

 

[jbartos]

Suggestions:
1. Check the voltage across the motor terminals after you press start push button. If there is 220V, then it is probably the motor problem. If not, trace the line upstream to find out where is the voltage blocked. It may be a bad connection only at some terminal.
2. Check the contactor rating. It should be rated for the motor hp, at least.
3. If the contactor is not clicking, the contactor coil may be burned.
4. Etc.