Swimming Pool Single Phase Motor/Pump Tripping

Thread Starter

johnnysneds

Joined May 7, 2017
5
Hi

I have an issue with my pump/motor for my swimming pool. I have checked the winding resistance and also to Earth, all good. The start capacitor is ok however I replaced it just to be sure and same issue. The issue is the pump/motor will start then struggle and eventually trip the thermal switch on top of the motor. I believe the start circuit should disconnect after it winds up and then the main windings take over. However when I opened the motor I did not notice any centrifugal disconnect switch. I have attached a simple diagram. Hopefully someone can understand it and help he out to whatbthe issue is. I have heard something clicking after the motor trips approx 10 seconds afterwards so it sounds like something is electrically connect/disconnecting. I also have to reset the thermal switch every time it trips obviously. I have attached photos of some of the components. Just to add the windings and armature looks good and clean and rotates freely.

Any thoughts with this would be gratefully appreciated

Rgds
JohnnyIMG_2986.JPGIMG_2982.JPGIMG_2983.JPGIMG_2970.JPG
 

MaxHeadRoom

Joined Jul 18, 2013
20,022
If just one capacitor and no starting switch, either centrifugal or separate current relay then it is a PSC (permanent start cap) motor where the cap is in permanently.
Are you sure the motor is free enough to turn?
Max.
 

Thread Starter

johnnysneds

Joined May 7, 2017
5
Yes 100%, I had the motor apart, removed the shaft and rebuilt it. Both bearings are in excellent condition and the shaft can be rotated easily and it feels smooth with no play. The assembly is only 3 years old and should be good for 10. Inside as per the photo everything looks nice and clean i.e. no corrosion. Only test I haven't done is meggered it to Earth as I don't have a megger. However multimeter was indicating over 20meg. I have ordered a megger online and will test it at 250v, maybe the leak to Earth is only under load. I have to agree with you that the start cap must be permanent, however this would make it inefficient and high electricity cost not to mention extra heat it might cause.
For reference the three wires leading into the motor windings - red, yellow and green the resistance was Yel-Grn=8.8Ohms, Yel-Red=5.8Ohms and Grn-Red=3.3Ohms. I assume these three wires are Start, Run and Common. What I have read the Start to Common should be higher than the Run to Common so the above reading I recorded look ok?!?
I have also checked the motor with another power source and no difference.
It may be indeed that the winding resistance is not good. I have ordered a new pump/motor ($500) and will cross check against that when it arrives. It is annoying though that all avenues lead to a dead end. Would love to know what the problem is.
 

MaxHeadRoom

Joined Jul 18, 2013
20,022
I have to agree with you that the start cap must be permanent, however this would make it inefficient and high electricity cost not to mention extra heat it might cause.
.
Why would that be and be different from every other PSC motor up to 1/2hp?
Yellow-green would be windings in series according to your readings.
Yellow red = start, Grn Red= run.
Max.
 

Thread Starter

johnnysneds

Joined May 7, 2017
5
Just noticed what you were saying with regards to the windings in series i.e. the way the ohms readings adds up. I think I may have my diagram (motor part) incorrect.
 

Thread Starter

johnnysneds

Joined May 7, 2017
5
So I have now the-arranged my diagram as per the resistance results putting the windings in series. This now puts the capacitor between the Start and Run windings. Now makes it a PSC motor, however for a 1.5hp motor is this feasible. Sorry for so many questions just trying to understand how it all works. For me it's pretty difficult without a proper diagram. I've attached my updated diagram does this now look correct?

IMG_2999.JPG
 
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