What would make a 1 hp single phase motor increase in rpm by 25%
#1
11-11-19, 02:56 PM
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What would make a 1 hp single phase motor increase in rpm by 25%
120v -Single phase- no VFD- after years it simply turning substantially faster that if was last week
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#3
11-12-19, 09:56 AM
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It could be a resistive neutral at the utility..., do you notice lights getting unusually brighter at times ? Or a resistive neutral on that motor circuit. Check the neutral splices at every switch and junction box all the way back to the panel, including the panel. A resistive ( corroded or slightly loose ) neutral connection can sometimes cause unusually high voltage when another circuit is drawing amperage. It could also be a winding issue within the motor. Depending on how old the motor is, the frequency of use, etc.
#7
11-13-19, 08:10 AM
Electric induction motor's rotor synchronous speed is determined by the voltage frequency and the number of magnetic poles formed by the stator's run coil windings. If the induction motor is a non-synchronous design, the motor's rotor speed will be less than synchronous due to something called slip. Slip is not a constant and can result in a small RPM change (not 25%). Operating the non-synchronous motor beyond design torque will also cause motor rotor RPM to decrease. What does the motor nameplate state for RPM?
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