What it is and what it does
The Siemens 3RU2116-0DB0 is a SIRIUS thermal overload relay, size S00, designed to protect motors against overload and phase failure by monitoring the motor current and tripping the associated contactor when the current exceeds the set threshold for a time defined by its CLASS 10 trip characteristic. It mounts directly onto a contactor (contactor mounting), uses screw-type terminals for the main circuit, and includes an integrated auxiliary switch that provides a "Tripped" signal for the control system.
Key ratings and what they mean for fit
The CLASS 10 trip class means the relay will trip within 10 seconds at 7.2× the current setting — this is the standard for standard-duty motor starts (pumps, fans, compressors) where the start-up transient is brief; it is not intended for high-inertia loads that require a longer acceleration ramp. Rated insulation voltage is 690 V, covering 400 V and 480 V systems with headroom, and the relay carries motor power ratings at those voltages: 0.09 kW at 400 V, 0.12 kW at 500 V, and 0.12 kW at 690 V. The auxiliary contact ratings span multiple control voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V, and 0.75 A at 690 V — these are the switching capacities for the signal circuit, not the motor circuit. Temperature compensation is active from -40 °C to +60 °C, meaning the trip curve stays accurate across that ambient range without manual adjustment.
Where it fits in the panel
The S00 frame size (76 mm high, 45 mm wide, 70 mm deep) is the smallest SIRIUS overload relay footprint, designed to snap onto the matching S00 contactor (e.g., 3RT6015 or 3RT6017 series) without additional wiring between the relay and contactor — the power connections pass through the relay. Terminals accept 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded wire; screwdriver tip is Pozidriv PZ2 with a 5 to 6 mm shaft diameter. Mounting position is any orientation, and the relay can be installed in any ambient position within the enclosure.
Lifecycle and sourcing reality
Substance prohibitance per the manufacturer's declaration dates to 10/01/2009, indicating RoHS compliance for that cutoff.