phasing an a.c. motor before startup

[electricguru]

If I know high and low legs from 3-phase 480vac transformer secondary to motor starter, can I determine phase angle of motor before startup?

 

[jbartos]

Suggestion: Please, clarify the "phase angle". If you mean a phase sequence ABC or ACB to establish a proper motor rotation, then an appropriate and consistent lead identification and a motor direction of rotation meter are recommended.

 

[rhatcher]

If your concern is proper roation on startup of an AC motor, try an Amprobe Model PRM-1 "phase sequence and motor rotation testor". It costs about $60 and will allow you to determine the phase sequence (rotation) of your line and then phase the leads of the motor for proper rotation before startup.