SIRIUS thermal overload relay, Size S0, CLASS 10 — 3RU1126-1DB0-ZX95
The Siemens 3RU1126-1DB0-ZX95 is a SIRIUS thermal overload relay in the S0 frame size, designed for motor protection in industrial control panels. It provides CLASS 10 trip characteristics, meaning 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. Mounts directly to a Siemens contactor via the contactor mounting fastening method, saving DIN-rail space and reducing wiring. The relay accepts screw-type terminals for both main and auxiliary circuits, with solid and stranded wire ranges from 0.5 to 2.5 mm² (AWG 20 to 14 for aux, AWG 16 to 8 for main). Rated for 3-pole main current circuits, the relay dissipates 1.9 W per pole under load. Control circuit consumption is 1 A at 24 V, 3 A at 120 V, and 2 A at 230 V — figures that matter when sizing the control transformer or power supply feeding the contactor coil.
Mounting and integration
Dimensions are 45 mm wide, 97 mm high, and 96 mm deep — a compact S0 footprint that fits standard 45 mm modular enclosure slots. Mounting position is flexible: vertical surface with ±135° rotation or ±45° tilt front-to-back, giving panel builders layout options in tight cabinets. Clearance requirements are minimal: 0 mm upwards, forwards, backwards, and downwards, with only 6 mm needed at the side. This zero-clearance design allows dense packing of contactor-relay pairs on a DIN rail without derating for airflow. Front-side IP20 protection means the relay is touch-safe for panel interiors but not rated for washdown or outdoor exposure — standard for enclosed control panels.
Environmental and compliance
Operating temperature range is -20 to +70 °C, with storage and transport from -55 to +80 °C. The relay withstands 100% relative humidity during operation, suitable for unconditioned plant-floor environments. Shock resistance is rated at 8g for 10 ms. Carries DMT 98 ATEX G 001 certification for use in potentially explosive gas atmospheres, and surge voltage resistance rated at 6 kV. Reference code per IEC 81346-2 is F (protective device). Substance prohibitance date of 07/01/2006 aligns with RoHS compliance.