Separate loads on multipole breakers.
Separate loads on multipole breakers.
(OP)
I have a couple of reagent pumps in a water filtration plant. I don't really want one running while a second isn't running so I'd like to run them on individual poles of a ganged breaker in my control panel. They're both about 2A 1ph 120V pumps. I can't think of any proscription on this. Anyone else?
Keith Cress
kcress - http://www.flaminsystems.com





RE: Separate loads on multipole breakers.
RE: Separate loads on multipole breakers.
Yes, though being 1/3hp 1ph motors I think they have internal thermal protection anyway. I'm thinking a tripped breaker is less puzzling than a "sporadic motor".
Keith Cress
kcress - http://www.flaminsystems.com
RE: Separate loads on multipole breakers.
SceneryDriver
RE: Separate loads on multipole breakers.
Nothing prevents me from putting both motors on a single(pole) breaker. I absolutely could place them on one breaker. However a two pole 2A breaker will provide some motor OVERload protection. Without it a motor might thermal itself off leaving the other motor running. Instead of jamming in a bunch of unreacted chlorine or ferric chloride because the other motor continues, the two-pole trips, stopping the 'other' reagent. This provides a bit of protection from making bad water.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Separate loads on multipole breakers.
I would use an individual overload relay for each motor but use a common contactor for both motors. If either motor trips, both stop and the tripped O/L will indicate the source of the trip.
The "Cadillac" system would monitor the flow from each motor/pump but we all don't drive Cadillacs.
Bill
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"Why not the best?"
Jimmy Carter
RE: Separate loads on multipole breakers.
That makes a tremendous amount of sense. "Unreacted chlorine" is a very good reason to get things shut down.
Are you planning on using a 2-pole 2A breaker, and feeding both sides from one hot leg? Just curious.
SceneryDriver
RE: Separate loads on multipole breakers.
Scenery; When making water you aren't supposed to get over about 1ppm chlorine. When injecting ferric chloride the chlorine reacts with it. You have to increase the chlorine to something like 5ppm so once reacted you still have the 1ppm. If the ferric chloride stopped you'd find yourself delivering 5ppm water which can cause burns.
Normally you'd be monitoring the individual flows and arrest the system at a loss of any reactant flow. Unfortunately there doesn't appear to be any sensors capable of monitoring the flows we have to work at.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Separate loads on multipole breakers.
Bill
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"Why not the best?"
Jimmy Carter
RE: Separate loads on multipole breakers.
You could put a aux contact on the circuit breakers, have this going to a controller to open a contactor above both circuit breakers. I think Bill is right for a different reason, even if its more expensive.
RE: Separate loads on multipole breakers.
Bill
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"Why not the best?"
Jimmy Carter
RE: Separate loads on multipole breakers.
Bill; They're reagents that you need to independently set so I don't think so.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Separate loads on multipole breakers.
Mike Halloran
Pembroke Pines, FL, USA
RE: Separate loads on multipole breakers.
Bill
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"Why not the best?"
Jimmy Carter
RE: Separate loads on multipole breakers.
So what does a three pole ganged MCB do if one of the phases has an overcurrent? How does a three phase breaker feeding three different boards decide that the other two phases are OK?
It trips.
RE: Separate loads on multipole breakers.
RE: Separate loads on multipole breakers.
Two single pole breakers with a handle tie may not trip both poles.
Many breaker are trip free. That is the breaker will trip even if the handle is held in the closed position. So with two single breakers ganged, there may not be enough force exerted by the handle of one pole to trip the other pole before the "trip free" feature kicks in.
Moral; If you want to be sure use a two pole breaker, not two single pole breakers with a handle tie.
Bill
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"Why not the best?"
Jimmy Carter
RE: Separate loads on multipole breakers.