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Disconnect Boxes and Breakers => Disconnect Boxes and Breaker FAQ'S => Topic started by: kibi on February 20, 2013, 05:53:43 PM

Title: DC Breakers with Inverter / Charger combo devices.
Post by: kibi on February 20, 2013, 05:53:43 PM
I just need some clarification with regard to wiring my Victron MuliPlus Inverter / Charger via an MNEDC250 breaker.
I have it in my head that the + of the breaker goes to the battery + and the - goes to the inverter's + terminal. This is correct as the current flows from the battery to the inverter.
What happens if the inverter is in charge mode and charging the battery? The current is now flowing in the opposite direction (from the inverter / charger to the battery). Will the breaker still operate correctly?
I'm guessing it will because if there was a failure with the inverter / charger it'd most likely short it's terminals and then the high fault current would flow in the correct direction through the breaker again.
It seems obvious, but I just want to be sure that's all.

Many thanks.
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: dbcollen on February 20, 2013, 07:01:30 PM
You are correct.
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: kibi on February 21, 2013, 11:33:37 AM
Thanks very much for the confirmation. One les thing to worry about, I have many. :)
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: Robin on March 12, 2013, 09:30:02 PM
The panel mount breakers we have are all non-polarized. This confused me for yuears too since the current flow flips directions depending on mode of operation. The breakers are marked line and load, but that is for AC stuff only. Carling Technologies says these MNEDC breakers are non-polarized on DC circuits.
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: kibi on April 13, 2013, 05:14:31 AM
Thanks for that information Robin. I thought i was starting to lose my mind a bit on that one. I'm going to wire my 250A inverter breaker with the battery+ coming in on the bottom terminal.
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: vtmaps on April 13, 2013, 10:31:59 PM
Quote from: Robin on March 12, 2013, 09:30:02 PM
The panel mount breakers we have are all non-polarized. This confused me for years too since the current flow flips directions depending on mode of operation. The breakers are marked line and load, but that is for AC stuff only. Carling Technologies says these MNEDC breakers are non-polarized on DC circuits.

I'm glad that you're not confused any longer, but now I am confused.  If the polarity markings are not for DC, that means they are for AC ?!?!?  How is it that AC is polarized?  What would happen if I were to use those breakers for AC and reverse the line and load?

--vtMaps
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: Westbranch on April 13, 2013, 11:07:57 PM
Yes, is there such a thing as an Alternating Arc that needs suppression?  :(
Title: Re: DC Breakers with Inverter / Charger combo devices.
Post by: Vic on April 14, 2013, 11:30:04 AM
But,  in reading Robin's post above,  he mentions that these breakers are marked Line and Load,  NOT with polarity,  and such markings apply only to AC circuits and NOT DC.   Seems clear to me.

Have some Airpax DC breakers that lack any marking as to polarity or line/load,  FWIW.   Vic