What it is and what it does
The Siemens 3RU2116-0HC0 is a SIRIUS thermal overload relay — the part that sits between a contactor and the motor, watching current and tripping the contactor if the motor draws too much for too long. This one is sized for the S00 frame contactor family, so it bolts directly onto the bottom of a matching S00 contactor without extra brackets or wiring between them. Trip Class 10 means it will open the circuit within 10 seconds at a 7.2x overload — that's the standard for standard-duty motor starting where the load isn't a high-inertia flywheel. For a pump, fan, or light conveyor, this is the right call. The thermal bimetal release is temperature-compensated from -40 °C to +60 °C, so it won't nuisance-trip on a hot day or fail to protect in a cold plant. The built-in auxiliary contact (integrated, no add-on needed) is rated across a wide voltage range: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V — that covers the trip-signal circuit whether you're feeding a 24 VDC PLC input or a 230 VAC alarm light. The 690 V rated value means it's safe on 400 V and 480 V systems with headroom.
Mounting and wiring in the panel
Mounts directly to the contactor. Spring-loaded terminals on the main circuit accept 2x 0.5 to 2.5 mm² solid or stranded. A 3 mm diameter screwdriver tip is used for auxiliary terminal screws. Mounting position is any orientation, which helps when you're cramming this into a tight corner of an existing panel. Dimensions are 45 mm wide, 87 mm tall, 70 mm deep — it's a compact block.
Lifecycle and sourcing reality
Substance prohibitance date of October 1, 2009 aligns with the original EU RoHS deadline — so this part has been RoHS-compliant for over a decade. No REACH or UL marking is explicitly in the evidence, but the SIRIUS line typically carries IEC/EN 60947-4-1 certification.