Active production, direct-mount to SIRIUS contactor
The 3RU2126-4DB0 is a current-production SIRIUS thermal overload relay in the S0 frame size. It mounts directly onto the matching SIRIUS contactor — no separate DIN-rail footprint, which saves a slot in the panel and keeps the power wiring between contactor and relay as short as possible. That is the standard class for general-purpose motor starting — it lets the motor accelerate through inrush without nuisance tripping while still protecting against a locked-rotor condition.
Auxiliary contact ratings and diagnostic signal
These are the make/break capacities for the signal circuit — the 690 V rating means it can switch the control voltage directly without an interposing relay in higher-voltage control schemes. Power dissipation is 2.7 W per pole. For a three-phase motor circuit that is 8.1 W total heat into the enclosure — factor this into the panel thermal calculation, especially in a sealed cabinet with multiple relays stacked.
Environmental range and compliance documentation
The compensation ensures the trip curve stays accurate across the ambient range — important for outdoor or unheated enclosure installations where the relay sees the same temperature swings as the motor. RoHS compliance date is 10/01/2009. The relay carries the standard Siemens substance prohibitance documentation for EU markets. MTTF at high demand rate is 2,280 years — a reliability figure relevant for safety circuit assessments where the relay is used in a monitored protective function.
Sourcing and panel fit
The width is the critical dimension for side-by-side mounting on a row of SIRIUS contactors — 45 mm per relay matches the S0 contactor width, so a row of contactor-plus-relay pairs stacks without gaps. Screwdriver requirement is Pozidriv PZ2 with a 5-6 mm shaft diameter — standard electrician's tool, no special bit needed.