SIRIUS thermal overload relay for motor protection
The Siemens 3RU1116-1KB1 is a SIRIUS thermal overload relay sized S00, designed for three-phase motor protection in industrial control panels. Its CLASS 10 trip characteristic means it will trip within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal starts. Rated for main circuits up to 690 V AC-3, this relay uses screw-type terminals for the power connections and accepts solid or finely stranded conductors: 2x (0.5…1.5 mm²) and 2x (0.75…2.5 mm²) per clamp. The front face carries an IP20 protection rating, sufficient for enclosed panel installations where tools are the only access.
Integration and mounting flexibility
This relay mounts stand-alone on a vertical surface with ±135° rotation and ±45° tilt forward/backward, giving panel builders room to orient it for wiring access. The 45 mm width and 87 mm height fit standard DIN-rail spacing; depth is 78 mm. Side clearance of 6 mm is required for heat dissipation — no tight nesting against adjacent devices. Power dissipation at AC hot operating state is 6.6 W total, 2.2 W per pole. That thermal load must be factored into enclosure sizing, especially in a densely populated panel. The relay is rated for ambient operation from -20 to +70 °C and storage/transport from -55 to +80 °C.
Environmental and compliance profile
The 3RU1116-1KB1 carries ATEX type protection DMT 98 ATEX G 001, qualifying it for use in potentially explosive gas atmospheres when paired with an appropriate contactor. Surge voltage resistance is rated at 6 kV; shock resistance is 8g for 10 ms. Operating humidity tolerance is 100%, covering condensing environments. Maximum operating altitude is 2 000 m.