Electric Motor Torque
Electric Motor Torque
(OP)
Taking a sample of 10 electric motors (2Hp, 208/230V, 3600rpm, single phase, capacitor start)and coupling them to a pump we tried to find the Pull/Up Torque of each motor. The motors were designed to have a minimum Pull/Up Torque of 90 oz-ft. All of the motors are from the same batch off the production line ( i.e same date codes). Eight of the motors produced approx. 90 oz-ft of torque +/- 2. Two of the motors, however, developed 43 oz-ft of torque. All of the motors were tested under the same conditions and with the same pump. Initial analysis has not indicated any differences between the motors. Any ideas on what it could be?





RE: Electric Motor Torque
You've probably checked this already, but is there any possibility of undersized/defective start capacitors in the two weak units?
RE: Electric Motor Torque
i have already checked the capacitors and they checked out fine. i have also checked the resistances of the start windings as well and took measurements of the rotor and bearings. everything appears to check out.
RE: Electric Motor Torque
Is the condition reproduceable? ie the same two motors always test lower than the others. If so then of course you'll look closely at those motors. It sounds like you have looked at stator pretty closely. Maybe a close look at stator connections. Rotor might also cause those symptoms.
If the condition is not reproduceable then of course you look at test conditions:
Next time you run the test you might want to measure voltage directly at the motor terminals to make sure there isn't something in the supply system creating a problem. Intermittent open circuit or loose connection, contactor problem etc.
Are you sure you can trust your torque measurement equipment. Is there a redundant indication avialable?
RE: Electric Motor Torque
RE: Electric Motor Torque
Mark Empson
http://www.lmphotonics.com
RE: Electric Motor Torque
RE: Electric Motor Torque
RE: Electric Motor Torque
RE: Electric Motor Torque
RE: Electric Motor Torque
3b2
RE: Electric Motor Torque