AC circuit breakers and DC circuit breakers are not universal. The main reason is because the arcing problem, the DC breaker because arc generated so large DC arc extinguishing properties do better than AC breaker, if instead of using AC CB DC open space, it will show up as the arc performance requirements or contact produces burned burned open space of incidents.
For high-volume open space; DC few specific products are generally replaced AC CB. To choose the selection of well-known ones, we must have data and current breaking test parameters. Its protection can only use electromagnetic blurted way, can not use electronic protection. Further main breaking capacity of the switch is determined, he is able to switch OFF and the current size of the product of the rated voltage of a different nature.
Such marked: 220 volts AC. 1A, 48 volts DC 0.5A, different properties of the same sub-current contact, breaking capacity is different, the relay contact is not known in advance through DC or AC, once used in the 48 volt DC circuit, and that its breaking capacity is 48 volts DC 0.5A, then the DC voltage, then the corresponding current value can be larger. Back to the open space that is the case.
Now the most open space at the rated voltage of about AC 690V, as used in the above low DC 48 volts, although the voltage across the switch is DC, but the value of the DC voltage than the rated voltage of the AC, it will not have practical use a big problem on electrical; not that we used DC power distribution fuse is also commonly used to communicate it! I wonder if you look at the capacity of relay contacts have not seen it?
Generally the same grade DC breaker can be temporarily used for AC, but the AC CB is best not just for the current situation, when a short-circuit prone to large spark. So when there is no AC circuit breaker can we have on hand to temporarily fill the seats with DC circuit breaker, but can not have been used because the DC breaker arcing high capacity requirements.