Pool motor not starting - extremely hot

[gbrenham]

My main pool motor is not working. After Harvey and the electrical surges throughout the neighborhood, I figured it got the motor even though my booster pump continues to work.

I went out today to get the specs off of it (A.O. Smith Century Centurion / Model: B230SE / Serial: 007113M / Type: CX / FR: Y56J / HP: 2.0) and the thing tried to start but failed. I touched it and it was extremely hot. I'm guessing it has some thermal safety switch so it won't burn itself up.

I replaced the diffuser (Part#: SP3021-B) and impeller (Part#: SP3016-C) in 9/16.

What could be wrong and how should I go about fixing it?

 

[Ted527]

Check and make sure impellor spins freely. After that Start capacitor would be my first choice.

 

[gbrenham]

Ok...pulled off the motor from the pump. The motor will start and spin for approximately 15 seconds and then I hear a slight pop and it stops spinning. After about 5 minutes, I hear the pop again and I can restart the motor. The impeller spins, but I don't know if I would call it spinning freely. If I spin it hard, I can get 2 revolutions.

 

[gbrenham]

Removed the impeller and the same results...motor starts and spins for 15 seconds and then trips what I'm assuming is the thermal cut off switch.

 

[Ted527]

Could be The centrifugal switch in the back of the motor not dropping out the start winding causing it to trip thermal safety.
Pop back off motor and try some wd-40 on switch.

 

[gbrenham]

No joy on the centrifugal switch. If I'm reading the serial number (007113M) correctly, this motor was built in 2011. Should I assume the motor needs to be replaced?

 

[Ted527]

I would try a new start capacitor before giving up on it.
May not be coming up to speed and cutting off on thermal safety.

 

[FletchMan]

I agree with Ted527 - Replace the starter cap and give it another try. Starter caps are wearable items and often need replacing after a couple of years.

 

[gbrenham]

Ok..any recommended places to purchase a starter capacitor for this motor? Can someone confirm this is the part --> http://amzn.to/2xbbfh0
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Motor Capacitor 25 MFD 370VAC RD-25-370[/h]More buying choices for[h=1][COLOR=#555555 !important][/COLOR]
Motor Capacitor 25 MFD 370VAC RD-25-370[/h]More buying choices for[h=1][COLOR=#555555 !important][/COLOR]
Motor Capacitor 25 MFD 370VAC RD-25-370[/h][/FONT][/COLOR][FONT=&quot]More buying choices for[/FONT][h=1][COLOR=#555555 !important][/COLOR]
Motor Capacitor 25 MFD 370VAC RD-25-370[/h][FONT=&quot]More buying choices for[/FONT][h=1][COLOR=#555555 !important][/COLOR]
Motor Capacitor 25 MFD 370VAC RD-25-370[/h]

 

[Ted527]

Did you open motor and pull old capacitor out? Should have size printed on it.

 

[mas985]

If it was the start capacitor, the motor would not spin up and would just sit there and hum.

More than likely the bearings are bad creating a higher than normal load which creates excess heat in the motor and then trips the thermal limiter.

 

[Ted527]

If it was the start capacitor, the motor would not spin up and would just sit there and hum.

More than likely the bearings are bad creating a higher than normal load which creates excess heat in the motor and then trips the thermal limiter.

That is a PSC motor with a run capacitor after looking it up.
Symptoms he described point to bad capacitor.

 

[mas985]

There are several modes of failure for an capacitor.

1) An open would not allow the motor to start so that cannot be a cause.

2) A change in capacitance change is very rare (<2%) and is also accompanied by a change in the capacitor can volume so that is usually noticeable. The capacitance can only decrease but it would have to change by a lot for the motor to over current that much so the expansion of the can would be very noticeable if not catastrophic.

3) Current leakage is another possibility but if it is small, it won't usually affect the motor that much and if it is large, the heat caused by that will usually cause dielectric expansion if not complete enclosure failure so again, very noticeable.

4) A capacitor short may allow the motor to start and would draw excess current but the motor would also start slow, run slow and run very rough so it would be very noticeable. I did not read that as a symptom but perhaps it just wasn't mentioned. Plus, because of the excess heat in the capacitor, most of the time these end up as opens or expanded cans.

But anyone that is working on a motor should have an ohm meter in their tool kit. Opens, shorts and leakage are easily diagnosed with an ohm meter if you know what to look for.

 

[Ted527]

Capacitance decreasing in a run capacitor is very common. A drop of 10%-15% will be enough to affect the operation of the motor.
Not something you will detect with a regular ohm meter, a capacitance meter will readily show it though.
I did HVAC for 45 years, dealt with PSC motors on a daily basis. A bad capacitor can cause the motor to do some really strange things.

 

[mas985]

Any change in capacitance large enough (well above the capacitor tolerance) that would affect the motor performance and trip the thermal limiter would also increase the slip of the motor so it will run slower and hesitate which should be fairly obvious. That is the missing piece for me.

 

[gbrenham]

Well...I ordered a new capacitor. Will let everyone know...thanks for everyone's input.

 

[gbrenham]

Recieved and installed new capacitor and same symptoms. Runs until thermal switch is tripped. Any other suggestions before I pay for another motor?

 

[mas985]

I think your best bet is a new motor.

 

[Ted527]

New motor or take old motor to a shop for diagnosis at this point.

 

[gbrenham]

So should I replace with another 2HP A.O. Smith Century Centurion Model B230SE? or something else? suggestions?