AC Bus breaker tripping

Jan 12, 2011
930
Hunter 410 full time cruiser
I tried to run my AC for the first time the other day off my portable 2200W generator and the panel breaker tripped. Now I'm run the generator on the other on the other bus and the bus breaker doesn't trip even though the reverse polarity light does come on (think this is normal for using an inverter generator). On the attached diagram

Bus B supplies the Air Conditioning and I had the generator connected to the Shore Power Outlet 2

On the load breakers:
The 25A breaker is for the forward AC
The next 15A is for the Aft AC
The next 10A is for the seawater pump

With the air conditioner off, the generator running, I had power to Bus B. I shut the Bus B breaker (trip pack) and the 10A relay breaker and everything was fine. But if I shut the breaker for either the forward or aft air conditioner the Bus B trip breaker would trip (the air conditioners were off so it isn't any start current etc). I never saw any amps display on the Bus B amp meter.

I have never run the air conditioners the past 5 years. The generator runs things on Bus A if plugged into that bus just fine.

I'm thinking the problem is the Bus B breaker. I don't understand why it doesn't trip with the Relay breaker shut, but maybe that doesn't even power up till the air conditioner signals it.

I took out the trip breaker to look for a replacement and it is a rare expense thing for the same breaker. I did find a replacement, but is says it will trip on reverse polarity so now I'm confused as maybe is is suppose to trip on reverse polarity, in which an inverter generator can not be used.

Any other thoughts?
 
Jun 2, 2004
241
Hunter 410 Charlevoix, MI
Does the AC run on shore power? If you haven't tried that yet, I would lean toward a failure of some sort with AC gear...
 
Jan 12, 2011
930
Hunter 410 full time cruiser
I've looked at the electrical diagram for hours now. Near as I tell from the breaker the trip part of the Bus B pack trips at 65 VAC. I'm not sure if that is a capacitor or a resistor between the neutral breaker pole and the trip pole.

But regardless other than total current I don't see what effect shutting an Air Conditioner breaker should have on the Bus B main breaker.
 

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Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
I've looked at the electrical diagram for hours now. Near as I tell from the breaker the trip part of the Bus B pack trips at 65 VAC. I'm not sure if that is a capacitor or a resistor between the neutral breaker pole and the trip pole.

But regardless other than total current I don't see what effect shutting an Air Conditioner breaker should have on the Bus B main breaker.
Breakers trip on current (amps), not voltage. The 65 VAC is the max voltage the breaker is rated for.
 
Jan 12, 2011
930
Hunter 410 full time cruiser
Breakers trip on current (amps), not voltage. The 65 VAC is the max voltage the breaker is rated for.
Yes if you get down to it current trips it. There lots of breakers with a high voltage trip that use a capacitor to charge up and discharge to trip the breaker. Says ring on the breaker for FLA: * Trip Voltage : 65
 
Sep 28, 2008
922
Canadian Sailcraft CS27 Victoria B.C.
Yes if you get down to it current trips it. There lots of breakers with a high voltage trip that use a capacitor to charge up and discharge to trip the breaker. Says ring on the breaker for FLA: * Trip Voltage : 65
I'm not sure what breaker type you are referring to. Below are the specifications of a typical breaker from Blue Seas rated at 10 amps AC or DC. There is no capacitor involved.
 

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