The Siemens 3RU1126-1JB0 is a SIRIUS Size S0 thermal overload relay, 3-pole, CLASS 10 trip class, designed to bolt directly onto a contactor via its integrated mounting feet — no separate base or wiring between the two. It's rated for motor protection in a standard panel layout, with a 45 mm width that matches the S0 contactor frame. Trip class CLASS 10 means it will open within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a stall or locked-rotor event, without nuisance tripping on normal startup inrush. Mounting position is flexible: vertical surface with ±135° rotation and ±45° tilt front-to-back, which helps when fitting into a crowded panel where the contactor assembly needs to sit at an angle.
Integration & Wiring
Main current circuit uses screw-type terminals accepting 2× (0.5…1.5 mm²) and 2× (0.75…2.5 mm²) solid or finely stranded with ferrule, or AWG equivalents 2× (16…12) and 2× (14…8). Auxiliary and control circuit terminals share the same screw-type format and wire ranges. Clearance distances: 0 mm upwards, forwards, backwards, and downwards — so the relay can be stacked directly against adjacent components without extra air gap. Side clearance is 6 mm. Power dissipation per pole is 2.2 W, totaling 6.6 W across three poles at full load — factor that into the panel thermal budget if mounting in a sealed enclosure.
Environmental & Compliance
Operating temperature range is -20 to +70 °C, storage and transport -55 to +80 °C. Relative humidity during operation can reach 100 %, making it suitable for unconditioned plant-floor environments. Shock resistance rated at 8g for 10 ms, which covers most industrial vibration profiles from conveyors and compressors. Front protection class is IP20 — finger-safe but not sealed against liquid ingress; keep it inside a cabinet or enclosure. The relay carries ATEX certification (DMT 98 ATEX G 001) for use in potentially explosive atmospheres when paired with an appropriate contactor and enclosure. Surge voltage resistance rated at 6 kV, reference code per IEC 81346-2 is F (protective device). Substance prohibitance date of 01.07.2006 aligns with RoHS compliance.