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Is this 2pole dc breaker polarized or non-polarized? Also is this connection safe?

zedconnor

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This breaker is going to be put between battery and inverter. (I havent assembled it yet. And nothing is turned on or plugged in)

(Battery + and - is into the bottom of breaker. The top of breaker will go into inverter.)
I have it installed reversed as you can see in the picture and wondering if this is ok?

Battery : 25.6V / 51.2V LFP (i got several systems.)

Thank you.
 

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The +/- markings on it seem to indicate polarization.

I don't know what the consensus is on using polarized breakers between a charge and discharge source though.

I would think you primarily want to protect from battery to inverter power flow, in which case it would be wired as in your picture, with the battery on the bottom wires.
 
I tried to ask chat gpt. How reliable do you think this answer is?
 

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Certainly not reliable, doesn't understand the issue. (How could it, when most people don't?)
Also failed to address AIC.

We know how to get a polarized breaker to function both ways, most of the time. But also how to induce failure.
 
Certainly not reliable, doesn't understand the issue. (How could it, when most people don't?)
Also failed to address AIC.

We know how to get a polarized breaker to function both ways, most of the time. But also how to induce failure.
But I have read that if wired incorrectly(probably meaning inverter as the Source and Battery as the Load connection) , the breaker can catch on fire if it is opened under load from battery.
If I wire it so battery is SOURCE and Inverter is LOAD, will there still be a chance for fire if breaker is Opened while inverter is charging the battery?
 
This is where it is written.
 

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Wired either direction, I think it will successfully open circuit while charging because voltage difference is low. Discharging direction, at least if there is a short, I think it is a problem.

ChatGPT said protects regardless of direction of current flow, charging or charging.

The polarized breaker interrupts current when contacts open and uses a magnet to push arc, but that only works for one direction of current flow. Low voltage or current, probably works either way. Higher voltage and current it is likely to fail with current going the wrong direction.

If wired so correct direction is when battery discharges into inverter, if there is a short at the inverter, breaker trips and has to interrupt full battery voltage and short-circuit current. If within ratings, that should be successful.

Inverter charging battery, the current isn't like to be enough to trip, unless wrong value. If it does, or if you open the breaker, it carries at most rated charging current, and voltage across breaker is Vcharger - Vbattery, not very much. So it should work even though current flows the "wrong" way.

A short of Bat+ to Bat- between battery and breaker, then breaker sees full Vcharger, probably doesn't trip anyway because current from charger isn't too high but if you manually open it, then full Vcharger and breaker may burn. However, unprotected cable from battery Bat+ and Bat- is going to burn regardless of breaker. So put breaker or fuse close enough to battery that there is no opportunity for cables to short (and don't drop a wrench on battery terminals; keep them covered.)

The biggest problem seems to be polarized breakers for multiple PV strings in parallel. A short could be made in wires on either side of breaker, and in the wrong direction of current flow, breaker is likely to burn.
 
Thanks for the explanation, so it is still ok to use this Polarized breaker in between Battery and Inverter. (But wired correctly so Battery is the SOURCE and Inv is the LOAD)

In the case of someone accidentally or unknowingly opening the Breaker during Charging, the breaker may not burn due to low current and voltage.(Unless Inverter is charging with like 125+ Amps)

But there should be no dire consequences if someone open the Breaker during discharging period, since it is wirely correctly and it should be fine as long as the current is within the rated current of the breaker. (125A in this case.)


Is my understanding of your reply correct sir?
 
Yes, and if opened during charging, the voltage it has to interrupt is quite low. Battery remains at 48V or so, and inverter output is what, 60V regulation? Only 12V across the breaker? Way below the 125V/pole rating.

"Icu 10kA" on breaker. 60,000A ultimate on data sheet? Not sure the difference.
Probably good for lithium battery, I think they might deliver 20kA but not sure, just a calculation not a measurement. That's one reason we recommend class T fuses.
 
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