The Siemens 3RU2116-0GC0 is a SIRIUS thermal overload relay in size S00, designed for direct mounting to a contactor. Its CLASS 10 trip characteristic means it will open the circuit within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a locked-rotor start, but not so fast it nuisance-trips on a normal acceleration profile. Rated for 690 V, it covers most 400 V and 480 V motor circuits with headroom.
Ratings and what they mean for fit
The auxiliary contact set carries a range of switching ratings: 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. For a 24 VDC control circuit, the 2 A rating is generous enough to drive a PLC input or a small relay coil. At 120 VAC, the 3 A rating handles most pilot-duty loads. The 0.75 A at 690 V is the worst-case — if you're switching a 690 V control transformer, that's your limit. The relay uses a thermal bimetallic overload release with temperature compensation from -40 to +60 °C. That compensation matters: without it, a relay in a hot panel next to a drive would trip earlier than its dial setting suggests. The S00 size keeps the footprint tight — 45 mm wide, 87 mm tall, 70 mm deep — and it mounts directly onto the contactor, saving DIN-rail space. Spring-loaded terminals accept 2× (0.5 to 2.5 mm²) solid or stranded wire. No screw torque to verify, no loosening from vibration — good for a panel that ships on a truck. The integrated auxiliary switch provides a remote trip indication; the unit also carries a mechanical flag for message "Tripped", so the operator sees the state even without power to the coil.