Motor protection circuit breaker, Trip Class 10, 25 kA at 400 V
The Siemens 3RV2021-4CA40 is a SIRIUS motor protection circuit breaker designed for motor protection, with Trip Class 10 and phase failure detection. It provides a breaking capacity of 25 kA at 400 V, meaning it can safely interrupt fault currents up to that level without cascading upstream — a key figure for coordination studies. The 45 mm width and screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715 make it a direct fit into standard motor control center panels.
Breaking capacity and selectivity
The 25 kA at 400 V rating is the short-circuit breaking capacity that governs selectivity with upstream fuses or breakers. At 240 V it reaches 100 kA, and at 690 V it drops to 2 kA. For the main current circuit, the connection uses ring cable lug with M4 screw terminals. The rated value range spans 20 to 690 V, covering most low-voltage motor applications.
Mounting and clearances
Mounting position is any. Required clearances: 50 mm upwards, 50 mm downwards, 30 mm at the side, 0 mm forwards, 0 mm backwards. The 97 mm depth and 97 mm height fit standard enclosure depths. Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C.