MCB Current and Voltage rating

[Girishh]

Hiii friends,,,Iam facing a problem regarding the use of MCB in DC circuit....please give your views friends ...can i use the MCB for AC as well as DC supply both 16 Ampere...Is MCB rating differ for DC Supply than the AC supply pleasee comments...

 

[betwixt]

I would be cautious about using MCBs on DC voltages, the contacts could arc and burn out as it opens. An AC arc extinguishes by the time zero crossing point has occurred but a DC arc can run continuously.

Brian.

 

[Girishh]

Thanks for replying ...Can u please explain the working of MCB ...i searcjed the google but i am not able to understand ...and MCB for 16Ampere AC can be used for 16A DC voltage ....

 

[betwixt]

Lots more information here: https://en.wikipedia.org/wiki/Miniature_circuit_breaker

They will work on AC or DC but the voltage rating on DC may be much lower than AC because of the arc problem I mentioned earlier.

Brian.

 

[isurunalaka]

Lots more information here: https://en.wikipedia.org/wiki/Miniature_circuit_breaker

They will work on AC or DC but the voltage rating on DC may be much lower than AC because of the arc problem I mentioned earlier.

Brian.

could you pls clarify why DC Voltage should be a lower value than AC Voltage value?

 

[betwixt]

An arc will extinguish when the voltage is low enough. With AC, that happens twice per cycle as the polarity reverses so the arc will stop within half a cycle. A DC arc will be continuous if the voltage is high enough. As the damage caused by arcs is mostly due to their high temperature, there is a potential for a DC arc to do much more damage because it can last much longer.

Brian.

 

[FvM]

and MCB for 16Ampere AC can be used for 16A DC voltage ....

You didn't yet talk about voltage rating. A standard 250 AC MCB is typically rated for 60 or 75 V DC. Major manufacturers also offer MCB with e.g. 220 DC rating. They have a different design, able to extinguish a DC arc without relying on zero crossing. E.g. ABB series S 280 UC. **broken link removed**