... AC: up to 63A, AC230/400V, AC50/60Hz; b. DC: up to 63A, DC110V/1P, DC125V/2P; Application: for protection ... protection of circuits against short-circuit currents,protection of circuits against overload currents, switch,isolation NB1 circuit-breakers are used in ... point considered: the earthing systems(TNS,TNC),short-circuit current at the circuit-breaker installation point, which must always be less ...