What it is and what it does
The Siemens 3RU1116-0EB0 is a SIRIUS thermal overload relay, Size S00, designed to protect three-phase AC motors against overload and phase-loss conditions. It mounts directly to a contactor — contactor mounting is the specified method — and its Trip Class CLASS 10 means it will trip within 10 seconds at 7.2× the set current, which is the standard for standard-duty motor starting where the acceleration time stays under ten seconds. The relay has three poles for the main current circuit, screw-type terminals, and carries an ATEX approval (DMT 98 ATEX G 001) for use in potentially explosive atmospheres, provided the associated contactor and enclosure meet the installation rules.
Key ratings and what they mean for fit
The AC-3 rated maximum voltage is 690 V, so the relay can be used on 400 V and 690 V line-to-line systems common in European and IEC-sourced panels. The power loss in hot operating state is 4.8 W total, 1.6 W per pole — this matters for enclosure thermal rise calculations when the relay is packed inside a small glanded box. The operating temperature range is -20 to +70 °C, and storage/transport range is -55 to +80 °C, which covers most indoor and outdoor cabinet environments but not direct sunlight or steam-cleaning zones without a weathershield.
Terminal capacity and wiring
The main circuit terminals accept solid conductors: 2×(0.5…1.5 mm²) and 2×(0.75…2.5 mm²), plus AWG equivalents 2×(20…16) and 2×(18…14) and 2×12. Finely stranded conductors with core-end processing use the same cross-section ranges. That covers standard power wiring for motors up to the relay's rated current range — typically 0.1…0.4 A or similar low-range setting, depending on the specific 3RU1116 variant. The auxiliary contact terminals are rated for 1 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V, which is sufficient for signalling back to a PLC input or a contactor coil.
Mounting and clearances
Mounting is contactor mounting — the relay clips onto the contactor's body, not onto a DIN rail. The mounting position allows a vertical mounting surface with ±135° rotation and ±45° tilt to front and back. Clearance to adjacent devices: 0 mm upwards, forwards, backwards, and downwards; 6 mm at the side. That zero-clearance stacking on four sides means the relay can be packed tight against other SIRIUS S00 components in a motor control centre row, provided the side gap of 6 mm is observed for heat dissipation. IP20 on the front means finger-safe from the front but not protected against water ingress — keep it inside a cabinet.
Physical dimensions and identification
Width 45 mm, height 87 mm, depth 78 mm. The Size S00 form factor is the smallest in the SIRIUS relay family, designed for motor ratings up to about 7.5 kW at 400 V AC-3, depending on the specific setting range. The reference code per DIN EN 81346-2 is F, which designates a protective device in the function-oriented identification system. The product brand name is SIRIUS, and the product designation is thermal overload relay.