Pumps Tripping Breaker After Startup

[1poolguy]

I have two 3hp pumps for my vanishing wall system. I was putting the system back in service today and when I turn the pumps on after about ten seconds the breaker trips. The pumps are turning freely so I don't think it is a motor bearing. Could it be a capacitor? It is not a dead short so I am not sure how to troubleshoot this. They are Whisperflow pumps.

 

[Bama Rambler]

Are these single speed pumps?

Are the pumps on the same breaker? If so what happens if you just start one pump?

Can you tell if they sound like they're getting up to full speed?

Is this the first time you've tried to run them after de-winterizing?

 

[1poolguy]

Are these single speed pumps? They are single speed pumps.

Are the pumps on the same breaker? If so what happens if you just start one pump? The pumps are on the same breaker. I have not tried to start just one pump. I would have to disconnect the wiring and I will try that next.

Can you tell if they sound like they're getting up to full speed? They sound like they are running full speed but it is hard to tell since they are both running at the same time.

Is this the first time you've tried to run them after de-winterizing? This is the first time running them this season. They were not fully primed so they were surging a little.

 

[Bama Rambler]

Them surging due to not being primed could cause the breaker to trip if the combined full load amps are close to the breaker rating. Especially since both pumps are on the same breaker and start at the same time.

 

[racket]

Them surging due to not being primed could cause the breaker to trip if the combined full load amps are close to the breaker rating. Especially since both pumps are on the same breaker and start at the same time.

Pumps will pull less amperage if they are not pumping water.

If you have 2 3hp pumps on the same breaker you would need a 40amp breaker. It seems really strange that to pumps that pull 15amps each would not have their own dedicated breakers.

When you start the motors do they spin, or buzz or do anything. Typically when a capacitor goes the pump tries to start but dies on it's internal thermal limit.

If you hear a *POP* and then the breaker trips the windings in the motor are trashed.

 

[1poolguy]

The motors start and run for about ten seconds and then the breaker trips. They ran fine last season so the breaker should be sized correctly. I am going to try to disconnect one pump at a time and see if I can isolate the bad motor.

 

[Bama Rambler]

It's true that they won't draw much current when pumping air, but when they surge trying to prime the current draw will go up dramatically, and if it happens to both at the same time it could cause the inrush to trip the breaker.

What size breaker are they connected to?

It also could be a breaker getting weak.

 

[Poolguy1]

Are you absolutely sure both pumps are running?

 

[1poolguy]

I checked them out and one of the pumps has a bad bearing. I took the motor shaft cover off and the shaft was a little hard to turn and it had some grease in the cap. I worked the shaft back and forth until it loosened up a little. I started the motors again and they did not trip the breaker. Funny thing during this whole process the bearings did not make any noise. Does anyone know what bearing number I need for the 3hp whisperflow? I am going to go ahead and change them before it burns up the motor.

 

[pooldv]

Alright, good deal! I know nothing about the bearing number.

Did notice that poolguy1 and 1poolguy talking in a forum is kinda funny.