The 5SM3745-6 with RCD breaker, manufactured by Siemens, is a 3-pole + neutral molded-case, circuit-breaker with I-t characteristic and for actuating and indicating auxiliary devices. It has a rated current of 125 A, a residual operating current of 500mA, and is rated for a voltage of 230/400VAC. It features a DIN-rail mount and provides protection in case of overvoltage, overload, short-circuit, earth-fault and insulation-fault. Additionally, the circuit breaker has adjustable performance for optimal protection.