A sump pump (1 hp) control panel has two capacitors wired in series inside it. When power is applied the pump contactor closes for 5 or 6 seconds prior to tripping the circuit breaker. The capacitors seem to be alright. The pump motor megger tests great (50 meg-ohms). Any ideas?
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Capacitor Testing
- Thread starter electric1
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Ed MacLaren
Senior Member
Re: Capacitor Testing
More questions-
Is this a single phase motor?
Did you mean that the two capacitors are in series with the motor winding?
It is unlikely that the two capacitors were originally connected in series with each other. That simply isn't done in engineered equipment.
Ed
[ June 15, 2004, 06:26 PM: Message edited by: Ed MacLaren ]
Does that mean they have been tested?The capacitors seem to be alright
More questions-
Is this a single phase motor?
Did you mean that the two capacitors are in series with the motor winding?
It is unlikely that the two capacitors were originally connected in series with each other. That simply isn't done in engineered equipment.
Ed
[ June 15, 2004, 06:26 PM: Message edited by: Ed MacLaren ]
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Capacitor Testing
Ed I just did a lift station that had the pumps wired just like that. each pump (3hp) had it's starting caps in series they were 105uf 125 VAC rated each but were on a 240 volt motor. ether cap went bad the motor will not start or draw a very high starting current. I never seen it before, but this system came directly from the factory that way.
I'll bet he has a bad cap. or a bad start/run switch/relay
Ed I just did a lift station that had the pumps wired just like that. each pump (3hp) had it's starting caps in series they were 105uf 125 VAC rated each but were on a 240 volt motor. ether cap went bad the motor will not start or draw a very high starting current. I never seen it before, but this system came directly from the factory that way.
I'll bet he has a bad cap. or a bad start/run switch/relay
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Capacitor Testing
Also check the line voltage if this is a 240 volt motor and you have a 208/120 volt service the motor will draw about 15% more current. but shouldn't trip the breaker that fast? I still suspect the starting circuit. bad caps or incorrect wiring to motor.
Also check the line voltage if this is a 240 volt motor and you have a 208/120 volt service the motor will draw about 15% more current. but shouldn't trip the breaker that fast? I still suspect the starting circuit. bad caps or incorrect wiring to motor.
Re: Capacitor Testing
The pump motor is a 240 VAC 1-ph motor with the caps wired in series from the factory. Using a fluke we got deflection and then a swing to about 2 megohms ( not near infinity) so we replaced both caps and the pump is running fine.
Thanks for your input on this topic.
The pump motor is a 240 VAC 1-ph motor with the caps wired in series from the factory. Using a fluke we got deflection and then a swing to about 2 megohms ( not near infinity) so we replaced both caps and the pump is running fine.
Thanks for your input on this topic.
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