Over load capability of Permanent Split Capacitor Motor 1

[Mbrooke]

I have an application where at times a motor needs to spin a centrifuge partly filled with water which will place a much greater strain on the motor to the point it may slow down a little. How much over load an a PSC motor take before it over heats? Motor in question is 1/2 HP.

 

[jraef]

I don't think that a PSC motor has any more or less OL capability than any other motor. At 1/2HP it most likely has an embedded thermal protector ("Klixon") in the windings which, typically, is going to be set for around the thermal equivalent of between 125 to 140% of FLA.

But that's still likely based on an I²t curve, probably following a NEMA Class 20 OL curve (125% indefinitely, 600% for 20 seconds).

the more relevant issue for a centrifuge application would be, in my mind, the issue of torque capability. PSC motors are not known for good starting torque without adding the 'hard start" capacitor option, which then can lead to earlier motor failure. You may want to read this report.

https://goodsonengineering.com/wp-content/uploads/2017/08/Analysis-of-the-PSC-Motor.pdf

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