Odd electric motor behavior -- pool pump


Sometimes, when I start my pool pump motor, it turns for a few revolutions, then pops the circuit breaker. Other times, it starts and runs normally. This is not a case of clogged skimmers. Before the breaker pops, I can run the electric light in the pool shed--the breaker only pops when I switch the motor on.
The motor is ju-u-u-st out of warranty --installed May '09. Before I spend $370 replacing it I want to be sure it's the motor and not some electrical glitch in my wiring, or a problem with the pool pump. Any suggestions?
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Ivan wrote:

You could check the voltage to the motor at startup. I would take the motor apart and see if the.... don't know what it's called... the centrifugal switch and contacts are working properly. It is what powers the start winding then with speed it switches to the run winding.
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Is it old it could be worn and drawing excess amps on startup, a clamp on anp meter will show its amp draw, a short is possible, test everything
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wrote:

Is it old...........
=========== Reading problems, eh? He clearly answered that question in his original message.
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short answer Probably the centrifugal switch..........
explanation....... I've been confronted with this situation twice; once about 40 years ago and a couple years ago.
Different motors, different pools (thus completely) different setups.
The first case a lizard had crawled into the motor at night and his tail got into the swtich.
The second time it was just that the contacts were a bit burn & pitted. I showed my neighbor how to dis-assemble the motor and run some crocus cloth over the contacts. Blow the mechanism and re-assemble.....been working fine for a couple years now.
You only have to expose the switch, you don't have to remove it from the motor rotor. The contacts can be easily tuned up in place. The switch is spring loaded so I recommend against messing with the switch assembly. Just open the contacts slighty to get the point file or some crocus cloth between them.
Your motor is new so that adds a bit to the mystery. But I've had new motors be problematic too (case misalignment that caused excessive starting torque)
I'd try some compressed air into the end of the motor before a complete R&R.
Let us know how it works out.
cheers Bob
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wrote:

Or the starting capacitor. I'd suspect either as a possibility.
Also, you could have a weak breaker. Try another breaker if there is one to swap to (or just buy a spare, they're usually $5 or less)
Is the wiring heavy enough?
Of course there could be crud in the motor causing it to bind up a little.
Did you oil the bearings? (unless they are the oilless type).
PS. A motor shop can test capacitors....
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*Is your pool pump motor on a GFI circuit breaker? Is this an above ground pool?
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Does it have a starting capacitor? If so that could be bad. WW
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wrote:

Turn off the disconnect/unplug the pump Take the bell off the end of the motor and make sure it isn't just full of ants.
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Ivan wrote:

Take it back. Sure, it's out of warranty, but a reputable supplier isn't going to insist on the fine print for a few weeks either way.
All they can do is say "No!" Maybe beat you, but that's unlikely.
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Don;t know how many hp this motor is, but a typical 1 hp pool pump motor should cost about 1/2 that price. Besides the suggestions already made, you could take the motor to a local electric motor repair shop.
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snipped-for-privacy@optonline.net wrote:

I often see good prices in surplus electronics catalogs. This is old, don't know if it's still available. They may have other different ones now also.
3/4hp explosion proof motor $99.99 (A.O. Smith) # 420-0368 1-800-344-4465
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Ivan wrote:

I have a 220V compressor that would cycle well for awhile, then randomly trip the breaker. It finally quit starting. Turn on the breaker, and it would just buzz loudly. I cleaned the starter switch contacts - no help. Tracked down the bad starter capacitor and replaced that, both problems seem to be solved. $13 at Grainger for the part.
You can check the capacitors with an ohmmeter. A good one will show a gradual reading rise from when you touch the leads to the capacitor. Reverse the leads, and the reading goes negative, then gradually climbs into the positive readings, until it finally reaches the bleed resister value, or off scale if no resister. A bad Cap will change quickly if open, it not at all is shorted.
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