The Siemens 3RV2021-1KA10-ZW96 is a SIRIUS motor protection circuit breaker designed for protecting induction motors against overload, short-circuit, and phase failure. It carries a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2x the thermal setting — fast enough to protect a standard motor during a locked-rotor event. The unit is rated for 100 kA breaking capacity at 400 V AC, so it can interrupt a fault up to that level without upstream fuses needing to clear first.
Mounting and integration
Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715. The 45 mm width matches the standard SIRIUS compact frame — it slots into a panel alongside contactors and relays without wasting rail space. Clearance requirements: 50 mm above and below, 30 mm to the side, zero forward or backward. Any mounting position is permitted.
Termination and wiring
Main circuit terminals are M4 screw-type, accepting 2x (1 to 2.5 mm²) or 2x (2.5 to 10 mm²) solid or stranded copper. The dual-wire capacity is useful for daisy-chaining power through the breaker to a downstream contactor without an extra terminal block.