The Siemens SIRIUS 3RV2921-2M is a signaling switch designed as a bolt-on accessory for 3RV2 motor-protective circuit breakers. It provides a separate tripped signal and short-circuit alarm through one NO and one NC instantaneous contact each, giving the panel a clean way to distinguish a thermal overload trip from a short-circuit event without adding a separate monitoring relay.
Mounts via plug-in fixing directly onto 3RV2 breakers in frame sizes S00, S0, S2, and S3 — no DIN rail space consumed beyond the breaker itself. Spring-loaded terminals accept 0.5 to 2.5 mm² solid or stranded, or 2x (0.5 to 1.5 mm²) with ferruled ends. The 18 mm width keeps the assembly tight on the rail.
Contact ratings span the control-voltage range you'd expect on a motor branch: 2 A at 24 V, 0.5 A at 110 V, 0.25 A at 220/250 V, 4 A at 230 V, 3 A at 400 V, and 10 A at 690 V. The AC-12 maximum rating of 10 A covers resistive loads on the auxiliary circuit. These are the values that govern whether the signaling switch can handle the PLC input or indicator lamp load on your specific control voltage.
RoHS compliance date of October 1, 2009, covers EU substance restrictions.