Motor protection circuit breaker for Class 10 trip curve
The Siemens 3RV2021-4DA10-ZW97 is a SIRIUS motor protection circuit breaker designed for motor protection, with a Trip Class 10 characteristic that clears a stalled-rotor overload within 10 seconds at 7.2× rated current — matching the thermal curve of standard IEC induction motors up to 15 hp at 460/480 V. It includes phase failure detection, which trips the breaker on loss of one phase to prevent single-phasing damage on delta-connected loads.
Breaking capacity and back-up fuse coordination
Rated short-circuit breaking capacity varies with line voltage: 100 kA at 240 V, 25 kA at 400 V, 5 kA at 500 V, and 2 kA at 690 V. For installations requiring higher fault-current withstand, the evidence specifies maximum back-up fuse ratings: gL/gG 63 A at 400 V, gL/gG 50 A at 500 V, and gL/gG 50 A at 690 V. These fuse values define the upstream coordination limit — select a fuse at or below these ratings to maintain the breaker's listed SCCR.
Integration: panel footprint and wiring
The breaker occupies a 45 mm wide DIN-rail footprint, with depth of 97 mm and height of 97 mm. Clearance requirements: 50 mm upwards, 50 mm downwards, 30 mm at the sides, zero forwards and zero backwards. Main circuit connections use screw-type terminals, accepting 2× (1 to 2.5 mm²) or 2× (2.5 to 10 mm²) solid or stranded copper; the main contact terminal screw size is M4.