What it is and what it does
The Siemens 3RU2116-0DB1 is a SIRIUS-branded thermal overload relay, size S00, designed to protect motors against overload and phase failure by monitoring current and tripping a connected contactor via its integrated auxiliary switch. Trip Class 10 means it will trip within 10 seconds at 7.2× the full-load current setting — standard for standard-start induction motors driving pumps, fans, and conveyors in industrial panels. The auxiliary contact block is integrated into the relay body, rated 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V, so it directly switches the contactor coil or a PLC input without an interposing relay. Rated insulation voltage is 690 V, covering 400 V and 480 V line-to-line systems common in industrial distribution.
Mounting and wiring
Size S00 mounts directly to the contactor or standalone on a DIN rail (45 mm wide, 89 mm tall, 80 mm deep). Any mounting position is allowed. Main circuit terminals accept 2×(0.5…1.5 mm²) or 2×(0.75…2.5 mm²) solid or stranded wire; screw terminals require a PZ2 Pozidriv bit with 5–6 mm shaft diameter. Temperature compensation is active from –40 °C to +60 °C, so the trip curve stays accurate in unheated enclosures or near hot machinery.