The Siemens 3RU1136-4HD0 is a SIRIUS thermal overload relay in size S2, designed to protect motors against overload and phase failure by monitoring the motor current and tripping a connected contactor when the thermal limit is exceeded. It mounts directly to the contactor via the fastening method (contactor mounting), saving panel space and eliminating separate wiring between the relay and the contactor coil. The front face carries IP20 protection, meaning it is finger-safe and suitable for installation inside an enclosure where the front is accessible during commissioning or maintenance.
Trip Class 10 means the relay will trip within 10 seconds at 7.2× the current setting — this is the standard for standard-duty motor starting where the start-up time is under 10 seconds. The surge voltage resistance rated at 6 kV (impulse withstand) ensures the relay can handle transient overvoltages common in industrial networks without nuisance tripping or damage. The auxiliary contacts are rated for 1 A at 24 V, 3 A at 120 V, and 2 A at 230 V — these values govern the control-circuit load the relay can switch directly; for higher loads an interface relay is needed. Ambient operating temperature range of -20 to +70 °C and storage range of -55 to +80 °C cover most industrial environments, including unheated warehouses and outdoor cabinets.
Compliance and approvals
The part carries ATEX certification (DMT 98 ATEX G 001) for use in potentially explosive atmospheres — this is a documented declaration of conformity for the EU market. RoHS compliance is indicated by the substance prohibitance date of 07/01/2006, confirming the relay meets the RoHS directive for hazardous substance restrictions.
Mounting and wiring notes
Mounting position allows rotation of +/-135° on a vertical surface and tilting of +/-45° to front and back, giving flexibility in tight enclosures. Main circuit terminals accept solid conductors 2x (0.5... 2.5 mm²) and stranded up to 2x (0.75... 25 mm²) or single 0.75... 35 mm²; auxiliary/control circuit uses cage clamp terminals for 2x (0.5... 1.5 mm²) fine-stranded with ferrules.