The Siemens SIRIUS 3RU1126-4AD0 is a thermal overload relay sized for the S0 frame, designed to protect three-phase motors by monitoring current and tripping within CLASS 10 timing — meaning it interrupts the circuit within 10 seconds at a 600% overload, the standard for normal-starting induction motors that aren't driving high-inertia loads. Rated for a maximum operating voltage of 690 V AC-3, this relay covers the common 400 V and 480 V motor circuits found across European and North American industrial panels. The screw-type main circuit terminals accept 2x (0.5... 2.5 mm²) solid or 2x (16... 12) AWG conductors, which handles standard motor lead sizes for the S0 amp range.
Mounting position allows +/-135° rotation and +/-45° tilt on a vertical surface, giving flexibility in tight cabinets. The ATEX type of protection DMT 98 ATEX G 001 certifies it for use in potentially explosive atmospheres (Group II, Gas), which is a key check for chemical, oil and gas, or grain handling applications. Depth is 96 mm from the mounting surface, and side clearance of 6 mm is required for heat dissipation. No clearance needed upwards, forwards, or backwards — the relay can be packed tight in those directions, useful when retrofitting into a crowded panel.
The SIRIUS series is a mature, widely deployed platform, so spares availability across multiple distributor stocking points is typical. If you're freezing a BOM or stocking spares for a line, this relay carries a predictable supply posture — not a phase-out risk.
Key specifications at a glance
Trip class CLASS 10 governs the overload response curve. Shock resistance is rated at 8g for 10 ms, adequate for most industrial vibration environments up to 2 000 m altitude. Auxiliary contact ratings: 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V, plus 0.22 A at 110/125 V and 0.11 A at 220 V — these cover PLC input signals and control relay coils across common control voltages.