Irrigation Pump Trips Breaker!

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Seagiant

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Hi,
Wifey noticed Irrigation Sprinklers not working.

Went to Breaker Panel and Beaker tripped.

Put breaker back on started system at control box no pump running.

Checked Breaker and Tripped.

Put in new Breaker to test, new breaker trips also.

Went to newly rebuilt pump to visual wiring all good.

Pulled Motor Capacitor and tested with VOM and tested BAD.

Have ordered new Capacitor.

Question, can bad Capacitor trip Motor?

Tested Capacitor from terminal to case, all good, but...

Capacitor would not come up to rated Farads!

Thanks!
 

WorthFlorida

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When it comes to a tripped breaker, anything can cause because it. A bad starter cap will not allow the pump to run but the motor will still draw current. Since the rotor is stationary there is less resistance, therefore, the motor will heat up but most if the time the breaker will usually will not trip. All motors have a lock rotor rating and a safety requirement is the motor should not burn and catch fire but it can get very hot.

It's not uncommon that a new start cap can be bad in a short time, I've had it happen but you mention "newly rebuilt" pump. If you bought it as a rebuilt its unknown why it was rebuilt. It is possible the motor rotor or stator winding(s) were damages.

The rated cap specs is at line voltage, not using a test meter with a 9v battery.
 

Seagiant

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Hi,
Thanks, the rebuild was about a year ago and has run great up to this time.

Just trying to check the easy stuff first and the cap tested bad.

If the new one does not fix it, I'll go to the pump relay and see if there is good power to there.

Could be the relay I guess, but something is tripping the panel breaker!

I'm going to find it just do not want to throw parts at it if I can keep from it!
 

WorthFlorida

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Pump relay works on 24vac from the controller. The contacts can be burned out or even welded (one side) and the motor will not run, unless there is short (doubful), it cannot trip the breaker.
 

Reach4

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Is the breaker a GFCI breaker by chance? Seems unlikely.

How long after you reset the breaker back on does the breaker trip take to trip? 4 seconds maybe?

I like your start cap measurement idea. But Is this a 115 volt motor, or 230? And is the capacitance range 200µF or 20µF? If the cap has more capacity than the meter can measure, it might make the cap look bad.

But discharging the cap, then using a high range resistance setting will work. Resistance should slowly climb on a good cap. Then reverse polarity, and go again. Resistance should kick down to zero or lower, and then slowly rise.
 

Seagiant

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Hi,
It is 220V Motor.

The cap is a 35 uf and it only builds to a 1 or 2 on my Fluke.

The breaker is fine when cold until you start the pump then trips...

After that will trip when you try to reset it in a few sec.

What ever it is is a HARD Short!

The Cap is cheap and did not come up to it's rating when tested so have another coming will see.

Thanks!
 

Reach4

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I like your replacing the cap.

If the start cap is the only problem, I would expect the breaker to take over a second (not sure how much over) to trip. A hard short to ground would be quicker.

Another check would be a resistance measurement to ground on either of the hot lines. Normal resistance is over 1 Meg. It would take something really low to trip an non-GFCI breaker.
 

Seagiant

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Hi,
Thanks!

Received the new cap, no difference, still trips breaker.

Went to Relay Box pulled Relay, reset breaker with wires loose at Relay Box, no trip and 120V at each wire to ground.

Took Relay to bench tore it down, heavy rust on contacts but was free to move.

Cleaned up Relay and put it back together and will reinstall today and test???
 

Reach4

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Don't forget to check resistance to ground.

Also, if easy, measure new capacitor with VOM. Maybe the capacitance scale is not working right.
 

Seagiant

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Hi,
Thanks, the new Cap tested like the old?

Thought it should run up to it's rating and stop, but niether one would do that?
 

Reach4

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What meter?

I was thinking the way those work is to act as an AC ohmmeter, in a way. I don't know why that would be a problem with your start caps. Meter could be damaged for capacitance mode. It should be a fast measurement-- no runup. However https://en.wikipedia.org/wiki/Capacitance_meter says "Many DVMs (digital volt meters) have a capacitance-measuring function. These usually operate by charging and discharging the capacitor under test with a known current and measuring the rate of rise of the resulting voltage; the slower the rate of rise, the larger the capacitance.". So that is different than what I was thinking.

The other way of qualitatively checking the cap is to use the ohms mode, and look for that slow runup.
 
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WorthFlorida

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With the motor wires disconnected at the relay, operate the relay from the controller with the 240v connected and hot. Check the voltage on the contact side of motor connection. If it tests OK then connect the motor wires (power removed of course). Turn power back on and test. If it trips, looks like a bad motor.
 

Seagiant

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Hi,
I ran a OHM Test with a jumper at the motor back to relay box and got abut 2.5 OHM Reading, call that good for a 30yd. run.

Then just by passed Relay and connected hot wires straight to pump with wire nuts.

Pump tripped so going to pull that and look.

Any ideas on where the short might be?

Centrifigal switch?

Maybe can see something on the bench, will see...

Thanks again, not happy Pump and motor rebuilt a year ago!!!
 

Seagiant

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Hi,
Pulled Motor and called Shop that rebuilt it.

Going to take it in Monday to see what we can find.

May need to just get a new Motor this one is 18 years old???

Thanks again!
 

Fitter30

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If motor has a start cap 90 mfd + and not a run cap 5 mfd? It has a centrifugal switch back side of motor that switches from start to run. Put end of motor to check windings and switch.
 

Seagiant

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Hi,
Thanks, took motor in to test and windings are shot. (18 yrs. old!)

Just ordered a 3 HP. Leeson motor for $200

Best deal I could find,

A Baldor is $700!

See what happens!
 

Seagiant

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Hi,
Well, installed new motor to pump using old seal...

Hooked everything up and breaker tripped again with the old cleaned relay.

Wired the 240 straight and pump kicked on and pumped water.

Ordered new relay and will go from there.

Good news is everything replaced so far is 18 yrs. old so not worried about it.

If circuit blows with new relay have to start looking at control box next?
 

Seagiant

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Hi,
Well, installed new Relay and everything working now!

New Motor rebuilt Flint-Walling Pump, and new Relay...

About $300 for an almost new irrigation system...

Cheaper than calling a Service Tech!

Big THANK YOU to everyone that helped!!!
 
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