Pool pump motor

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nizak

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Got a call from a customer who tells me that his 2 hp 2 speed pool pump motor will run on high speed, but when he switches to low speed it shuts off after 10 seconds or so. It will continue to run on high speed but the motor gets extremely hot. I am only assuming that it is tripping the thermal cut out.But then how can it still operate if the element is open? Tells me that he can't read the pump info except that it's 2 hp 230V. Will go over in the A.M and look at it, any thoughts? Thanks.
 

ActionDave

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Sounds like it is the motor. Put an amp meter on it. Check all the usual stuff....connections, voltage.

Pool pumps lead an unhappy existence in a harsh environment. Bearings, pump seals, centrifugal switches can all go bad. Unless you are handy with motors, once they start acting up it is easier to replace them.
 

Dennis Alwon

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I agree it's the motor. I am not sure but perhaps the motor has 2 overload protections built in the motor, one for each speed. That would explain why it continues to run on high speed.
 

GoldDigger

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A motor that has full speed and half speed will often have a separate run winding with twice the number of poles, so separate overloads would make sense too.
 

kwired

Electron manager
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NE Nebraska
A motor that has full speed and half speed will often have a separate run winding with twice the number of poles, so separate overloads would make sense too.
But it shouldn't continue to run on a different speed after failing at the first speed without some interaction to change to the second speed. May at least want to make sure it is not trying to run at both speeds simultaneously, and finally has some success once one winding is taken out of the circuit.
 

ActionDave

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But it shouldn't continue to run on a different speed after failing at the first speed without some interaction to change to the second speed. May at least want to make sure it is not trying to run at both speeds simultaneously, and finally has some success once one winding is taken out of the circuit.
A lot of those little two speed motors are PSC and they have a centrifugal switch just like a starting switch but instead of dropping out the starting winding it goes to the low speed winding, or the high speed I can't remember, anyway the motor can start on either speed.

If the switch gets stuck or one of the windings goes bad the motor will only work on one speed or it will alternate back and forth between the two. It can often be an easy fix, but once you get the endbell off, see what's going on, try it you could have replaced the motor.
 

kwired

Electron manager
Location
NE Nebraska
A lot of those little two speed motors are PSC and they have a centrifugal switch just like a starting switch but instead of dropping out the starting winding it goes to the low speed winding, or the high speed I can't remember, anyway the motor can start on either speed.

If the switch gets stuck or one of the windings goes bad the motor will only work on one speed or it will alternate back and forth between the two. It can often be an easy fix, but once you get the endbell off, see what's going on, try it you could have replaced the motor.

I can't seem to picture how that works, other then maybe it is designed same as a single speed motor but they don't leave the capacitor in the circuit for low speed (other then maybe for torque boosting during starting) and this causes less torque and more slip which essentially makes it run at a lower speed - if there is a load, at little or no load it still would likely reach same/similar speed as high speed. Just a guess of what could be going on there - I never seen such a critter.
 
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