Motor protection circuit breaker for 25 A motor circuits
The Siemens 3RV1021-4DA10-ZW96 is a SIRIUS motor protection circuit breaker with a rated continuous current of 25 A and CLASS 10 trip class. Rated for a motor output of 11 kW at 400 V AC, this 3-pole breaker handles the starting and running protection for a range of three-phase motor loads — pumps, fans, conveyors — in industrial control panels. The CLASS 10 curve is the most common choice for standard squirrel-cage motors; it coordinates well with contactors in a motor starter assembly. Mounts via screw and snap-on onto 35 mm standard mounting rail per DIN EN 50022. The 45 mm width matches the standard SIRIUS contactor footprint.
Breaking capacity and fault clearing
The interrupting ratings are voltage-dependent: 100 kA at 240 V AC, 50 kA at 400 V AC, 10 kA at 500 V AC, and 4 kA at 690 V AC. At 400 V — the most common industrial supply — the 50 kA SCCR means this breaker can safely clear a bolted fault up to that level without external fusing, provided the upstream transformer can deliver that current. At 690 V the rating drops to 4 kA, so verify the available fault current if used on a 690 V system. Phase failure detection is built in (yes), so the breaker will trip if one phase is lost — protecting the motor from single-phasing. Ground fault detection is not included (no); that requires an external module or a separate ground-fault relay.
Terminal capacity and wiring
Screw-type terminals on both main and auxiliary circuits. Each pole accepts 2 conductors: solid or stranded 1 … 2.5 mm², plus a second pair of 2.5 … 6 mm². For AWG, that's 2x (14 … 10) for the main contacts. The dual-terminal design allows daisy-chaining power through the breaker without extra terminal blocks — common in motor starter wiring where the line side feeds the contactor coil.
Environmental and compliance
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. The IP20 protection on the front means it is finger-safe but not sealed against moisture — suitable for indoor panel installation, not washdown environments. Shock resistance is rated at 25 g for 11 ms, typical for industrial vibration environments.