troubleshoot 120v reversible motor

[brantmacga]

had a call about a reversible motor not working.

only had a few min to look at it, but what i found is that i had 120v on both motor leads.

discharged and checked capacitor; reading was normal.

disconnected motor from control board and manually opened/closed relays, and found the board to be sending voltage to the correct terminals for each direction.

so the backfeed is coming from inside the motor.

what causes this?

thanks

 

[ptonsparky]

I can't quite grasp how younare checking this motor. Is it reversed via a switch or relay frequently?

Single pole start stop switch? If so reverse the polarity of the incoming lines and check again. Checking voltage reference to EG?

 

[ActionDave]

Is the motor not reversing or not running?

 

[hurk27]

had a call about a reversible motor not working.

only had a few min to look at it, but what i found is that i had 120v on both motor leads.

discharged and checked capacitor; reading was normal.

disconnected motor from control board and manually opened/closed relays, and found the board to be sending voltage to the correct terminals for each direction.

so the backfeed is coming from inside the motor.

what causes this?

thanks

Check the common (neutral conductor) at the motor, if you have 120 volts to this conductor at the motor you have lost it internally in the motor, this will cause one winding to back feed the other winding on a 3-lead reversible motor.

Same problem as a 240 volt dryer heating element back feeding a lost phase

 

[brantmacga]

Check the common (neutral conductor) at the motor, if you have 120 volts to this conductor at the motor you have lost it internally in the motor, this will cause one winding to back feed the other winding on a 3-lead reversible motor.

Same problem as a 240 volt dryer heating element back feeding a lost phase

i'm trying to think back; it seems like I did but I can't remember for sure. That makes sense though; I just couldn't figure out where inside the motor it was backfeeding but i believe you've probably nailed it.



as for the other questions; the motor is not running. It has a screw drive to open/close relays that I can manipulate manually to check the control board voltage.

When I disconnect the motor, the board voltage works as it should based on the position of the relay switch.