Can I use a AC circuit breaker in a DC circuit?

[Mithun_K_Das]

Can I use an AC circuit breaker in a DC circuit? DC current is 62A and 48V operating voltage. If it is possible then how?

 

[Raza]

Hi,
Yes you can use. But:
Normally DC voltage is 1/5 of the AC rated voltage of the Breaker. So it means if you have 220 volts rated breaker then 44 volts (round up 48) of DC. Because in AC will go every 10 mS (milli Seconds) to Zero in 50 Hz but in DC no break, so in DC the arc on contacts will go to a long distance as compared to DC which may melt more quickly the contacts than AC. At the same time, better, that the breaker specifications mention DC too.
Find here two images just for reference.

 

[SherpaDoug]

For a home project you can use a thermal breaker. A magnetic breaker may trip at the wrong level for DC, but you could test it. Also the contact life may be shorter for DC than AC. Using a 120VAC breaker for 48V DC I would not expect arcover problems. But beware if you try it at 120DC, as the built in arc suppression may not work as well for DC.

 

[FvM]

Standard AC circuit breakers are not guaranteed to work correctly with 48 V DC. You get circuit breakers specified for 250 V DC from major manufacturers, e.g. ABB.

 

[Mithun_K_Das]

Hi Reza,

Your information is helpful, but how can I select an AC Circuit Breaker in this DC circuit (rated 48V/62A)? How can I calculate the current rating? Will it be 5times than AC?

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---------- Post added at 18:05 ---------- Previous post was at 18:05 ----------

Hi FvM,
ABB products are not so available in my country. So I've to replace that DC CB with an AC CB. also I've to guarantee its reliability. in this case I'm also using a set of DC fuses up to 40*3=120A. But i need another protection for user friendly.