What it is and what it does
The Siemens 3RU2116-1GC0 is a SIRIUS thermal overload relay in the S00 frame size, Trip Class 10, that mounts directly to a contactor.
Key ratings and what they mean for fit
The auxiliary contact block is integrated and carries ratings across multiple control voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V. For a 24 VDC PLC output driving the contactor coil, the 2 A rating is ample — the relay's own signal contacts will handle the feedback to the controller. The main circuit is rated for 690 V, with motor power ratings given at common line voltages: 2.2 kW at 400 V, 3 kW at 500 V, and 4 kW at 690 V. This covers the 400 V three-phase standard across Europe and Asia, and the 690 V industrial networks common in mining and marine applications. The operating frequency is 50 to 60 Hz, so it works on either standard grid frequency without derating.
Mounting and wiring constraints
The relay is sized for the S00 contactor frame, with dimensions 45 mm wide, 87 mm high, and 70 mm deep. It mounts in any position, which simplifies panel layout — you can orient it vertically or horizontally without affecting the thermal trip curve. The main circuit uses spring-loaded terminals that accept 2 × (0.5 to 2.5 mm²) solid or stranded wire, so no screw tightening is needed for the power connections, which saves time on repetitive starter builds. The auxiliary switch uses a screwdriver slot (3 mm shaft, 3.0 × 0.5 mm tip) for the control wiring. Temperature compensation is active from -40 to +60 °C, meaning the trip curve stays accurate even in unheated enclosures or near hot machinery.