Pull-up Torque Not Consistent

[lanier]

While testing a line of motors with the required pumps, we noticed that the pull-up torques varied. The motors were designed as 208-230V, 3515 rpm, TENV, 1 Phase. The required minimum pull-up torque was set at 90 oz-ft. This motor was designed with at a minumum of 99 oz-ft of torque. While testing this motor with the application, we recorded the pull-up torques and most were at 90 oz-ft, but there were a few motors around 45 oz-ft. That is the part that concerns us. With the pump combination used, the required pull-up torque for some applications were only 62 oz-ft and occasionally a motor would fail to pull-up. Any ideas.

 

[jbartos]

Suggestions: There may be several causes:
1. Improperly wound coils
2. Interturn shorts
3. Bad connections of winding conductors
4. Etc.