Minimum RPM for TEFC motor
Minimum RPM for TEFC motor
(OP)
We are using a VFD to control a 3/4 HP, TEFC, 1800 RPM, 1.15 SF motor with rolled steel frame. The Application is constant torque (positive displacement pump). The actual HP (at full speed) is only about 1/4 HP. Is there any way to estimate the minimum RPM for the motor without overheating. We want to operate at 12Hz. If we test this using trial and error, what should the max. frame temperature be? Are there other issues besides temperature that we should be concerned about?





RE: Minimum RPM for TEFC motor
I would think you should have no temperature problem at 12HZ and 33% load.
Caution: if the motor has overbolts, sometimes they complete a circuit and overheat. If so, Change to non-magnetic SS bolts.
RE: Minimum RPM for TEFC motor
Manufacturer lists speed range at which motor may operate at full torque without overheating and committing thermal suicide.
1800RPM/360RPM = 5:1 speed range. Should be okay if motor is rated for inverter duty.
I esitmated you are operating at 360RPM with the assumption the motor is rated is for 60Hz operation, and your listed 1800 RPM specification.
RE: Minimum RPM for TEFC motor