SIRIUS motor protection circuit breaker, 3RV2021-4CA15-ZX95
The Siemens 3RV2021-4CA15-ZX95 is a SIRIUS-branded circuit breaker designed for motor protection, with a Class 10 trip characteristic that matches standard induction motor starting profiles — it holds through a 10-second locked-rotor event without nuisance tripping, then clears on sustained overload. Rated breaking capacity reaches 25 kA at 400 V and 100 kA at 240 V, so it handles moderate fault-current levels typical of industrial distribution panels; at 690 V the capacity drops to 2 kA, which limits its use on 690 V systems to points with low available fault current. Phase failure detection is built in — the breaker trips on loss of any one phase, preventing single-phasing damage to motor windings.
Mounting and integration
Mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, in any orientation — no derating for side or vertical installation. Dimensions are 97 mm deep, 45 mm wide, and 97 mm tall, with 50 mm clearance required above and below and 30 mm at the sides for heat dissipation and wiring access. Main contact terminals accept M4 screws; wire capacity is 2x 0.5 to 1.5 mm² solid or stranded, or 2x 0.75 to 2.5 mm² — sized for standard motor branch-circuit conductors.
Auxiliary ratings and backup fusing
Auxiliary contact ratings: 1 A at 24 V, 0.5 A at 120/125/230 V, and 0.15 A at 60 V — sufficient for signaling to a PLC or relay interface. For high-fault applications, the breaker coordinates with upstream gL/gG fuses: 63 A at 400 V, 50 A at 500 V, and 50 A at 690 V.