Complete protection of circuit between LiFePO4 battery bank and MultiPlus-II

[Sheergium]

Hello DIYers

I'm thinking about putting a DC MCCB as a disconnector (and load/short circuit protection for the MultiPluses) between my LiFePO4 battery bank and (a set of 3) Victron MultiPlus-II. I'm not that confident with DC as I'm with AC, therefore the following question might be stupid...

With a 3p AC circuit breaker one can protect 3 live wires.

Wiring diagrams of 3p DC MCCBs instead show such wirings:


Thus I can't use it in the following way?


Many thanks.

 

[740GLE]

Why not use 3 single pole breakers? Thus you could isolate individual Multiplus for any maintenance needs.

If you are set on using a 3 pole, I’d be curious if the breaker would need to have balanced load in all 3 poles to trip. Say one unit is down for maintenance (zero current) would the other two trip the same current levels?

 

[HRTKD]

I have a battery disconnect switch (600 amp, I believe) downstream of my Class T fuse. That allows me to turn off all DC power to the system.

Battery -> Class T Fuse -> Disconnect Switch (Positive) -> Positive Bus Bar -> Mega Fuse -> Multiplus

 

[740GLE]

How do you size the class T fuse and mega fuse in series? Same amp rating? Or class T slightly larger?

 

[HRTKD]

How do you size the class T fuse and mega fuse in series? Same amp rating? Or class T slightly larger?

My Class T is higher. The MEGA fuse is only for the inverter. The Class T covers the entire system.