What it is and what it does
The Siemens 3RU2116-0KC0 is a SIRIUS thermal overload relay in Size S00, designed for motor protection in control panels. It monitors motor current via a bimetallic thermal element (thermal overload release) and trips on sustained overcurrent, with a Trip Class 10 characteristic — meaning it must trip within 10 seconds at 7.2× the set current, a standard for standard-start induction motors. It mounts directly onto a contactor (contactor mounting) and connects to the main circuit via spring-loaded terminals (screwless push-in), accepting 2x (0.5... 2.5 mm²) solid or stranded wire. An integrated auxiliary switch provides a "Tripped" signal output. The relay is temperature-compensated from -40 to +60 °C and operates in ambient temperatures from -40 to +70 °C, making it suitable for unconditioned electrical rooms or outdoor cabinets within that range.
Key ratings and what they mean for fit
The headline motor rating is 0.37 kW at 400 V (AC-3e duty), which sets the maximum continuous motor load this relay can protect. At 500 V it is rated for 0.55 kW, and at 690 V for 0.75 kW — the higher voltage allows a slightly larger motor at the same current limit. Auxiliary contact ratings cover both signal-level and pilot-duty switching: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V. These are the current-carrying limits for the integrated trip-indication contact — useful for feeding a PLC input or a remote alarm lamp. The rated insulation voltage is 690 V, matching the maximum operational voltage listed for the main circuit. The auxiliary switch is rated for switching at 690 V as well, though at a reduced 0.75 A. Power dissipation per pole is 1.9 W — relevant for thermal budgeting inside a sealed enclosure when multiple relays are ganged.
Where it fits in the panel
Size S00 is the smallest frame in the SIRIUS family, with a 45 mm width that fits standard DIN-rail or screw-panel mounting patterns. Depth is 70 mm, height 87 mm — compact enough for dense contactor-assembly layouts. Fastening is via contactor mounting, meaning it clips directly onto the matching SIRIUS contactor (e.g., 3RT2 series Size S00) without extra hardware. The mounting position is any — no derating needed for horizontal or inverted orientation. Terminals accept a 3 mm diameter screwdriver shaft (3.0 x 0.5 mm tip) for the spring-release mechanism. Wire preparation: strip length per the spring-cage spec, no ferrule required for solid wire.
Lifecycle and sourcing reality
Substance compliance includes a RoHS prohibitance date of 10/01/2009, confirming the part meets EU RoHS restrictions for substances like lead, mercury, and cadmium. No separate UL or CSA listing is recorded in this data set, but the SIRIUS series typically carries IEC/EN 60947-4-1 certification — verify for your jurisdiction if a specific agency mark is required.