The Siemens 3RU1116-0EC1 is a SIRIUS-brand thermal overload relay, the component that sits between a contactor and a motor to protect against overloads and phase loss. This relay is in the Size S00 frame, the smallest of the SIRIUS overload relay sizes, so it pairs with S00 contactors and fits into compact motor starter assemblies. The main circuit uses Cage Clamp terminals — spring-loaded, no screw torque to check, and fast to wire on a panel build.
The 6 kV surge voltage resistance means the relay can handle the transients that come from switching motor loads without flashover — important for reliability in a panel with contactors and drives nearby. Power dissipation is 4.8 W total in hot operating state (1.6 W per pole). That's low enough that you don't need to derate adjacent components in a crowded S00 starter assembly, but worth checking if you're stacking multiple relays in a sealed enclosure with no airflow. The auxiliary contacts are rated for switching at various control voltages: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V. These are the contacts that signal the PLC or trip the upstream contactor — make sure your control circuit voltage matches one of these columns so you get the rated breaking capacity.
Mounts as stand-alone installation — no DIN rail required, though it can be snapped onto one if the contactor base provides the rail clip. Dimensions are 45 mm wide, 92 mm high, 78 mm deep — the S00 footprint. That means you can butt it against the contactor on four sides, but need 6 mm breathing room laterally for heat dissipation and wiring access. Wire range for the main circuit: solid 2x (0.5... 2.5 mm²) or finely stranded with ferrule 2x (0.5... 1.5 mm²). AWG equivalent 2x (24... 14). The Cage Clamp accepts both solid and ferruled stranded — strip length is standard for the clamp, no special tool needed.
Operating temperature range -20 to +70 °C, storage/transport -55 to +80 °C. The 100 % relative humidity rating during operation means it can run in condensing environments — think washdown areas or unheated pump houses — without internal moisture damage. Shock resistance is 8g for 10 ms, which covers most vibration from contactors and breakers in the same panel. The ATEX protection type DMT 98 ATEX G 001 means it's approved for use in potentially explosive gas atmospheres — check your zone classification against the certificate.