The Siemens 3RU1126-4CD1 is a SIRIUS-branded thermal overload relay in size S0, Trip Class 10, with 3 poles for the main current circuit. It is designed to protect motors against overload and phase failure by monitoring current and tripping the associated contactor when the thermal model exceeds the Class 10 curve — meaning it will trip within 10 seconds at 7.2× the set current, which is the standard for standard-duty motor starts.
Mounting and integration
Mounts stand-alone on a vertical surface with ±135° rotation and ±45° tilt front-to-back. Clearance: 0 mm upwards, forwards, backwards, and downwards; 6 mm at the side. The 96 mm depth and 45 mm width fit standard S0 contactor footprints — direct coupling to a 3RT2 contactor is the typical panel layout.
Termination and wiring
Main current circuit uses screw-type terminals accepting 1x (16…12) or 1x (14…8) AWG. Auxiliary and control circuit uses Cage Clamp terminals for 2x (20…14) AWG. Solid conductors up to 2x (0.5…2.5 mm²) and finely stranded with ferrule up to 2x (0.5…1.5 mm²) are supported. Per-pole power dissipation is 2.7 W.
Environmental and compliance
Operating temperature range -20 to +70 °C; storage and transport -55 to +80 °C. Relative humidity up to 100% during operation. Shock resistance 8g / 10 ms. Surge voltage resistance rated at 6 kV. IP20 protection on the front. ATEX approval for explosive atmospheres (DMT 98 ATEX G 001). RoHS compliance date 07/01/2006. Lifecycle status is current production.
Auxiliary contact ratings
Auxiliary contacts rated: 1 A at 24 V, 0.22 A at 110 V, 3 A at 120 V, 0.22 A at 125 V, 0.11 A at 220 V, 2 A at 230 V, 1 A at 400 V. These are the switching capacities for the built-in auxiliary contacts used for signaling or control interlocking.