The Siemens 3RB2383-4AC1 is a SIRIUS solid-state overload relay rated for 630 A operational current — that is the continuous motor full-load current it can protect, not a short-time withstand. The adjustable trip class (CLASS 5, 10, 20 and 30) lets you match the thermal memory to the motor's starting profile: Class 5 for submersible pumps or low-inertia loads that accelerate quickly, Class 20 or 30 for high-inertia fans or crushers that need a longer start without nuisance tripping. The 3-pole main circuit and 2 NO + 2 NC auxiliary contacts (spring-loaded terminals for the control circuit) cover the standard motor feeder wiring scheme — one NC in the contactor coil loop, one for a remote fault signal.
Mounts in any position — stand-alone installation, not clip-on to a contactor. The 45 mm width and 95 mm depth fit a standard 45 mm DIN-rail pitch; the 111 mm height leaves clearance under a typical 200 mm enclosure depth. Side clearance of 6 mm to adjacent devices is specified. Surge voltage resistance rated at 4 kV (IEC 60947-1 overvoltage category III).