What It Is and Where It Fits
The Siemens 3RU2116-1BB0-ZX95 is a SIRIUS thermal overload relay in size S00, designed for direct contactor mounting — it snaps onto the matching SIRIUS contactor without extra wiring brackets, saving panel space. It protects motors against overload and phase-loss conditions using a bimetallic thermal element. The Trip Class 10 rating means it will trip within 10 seconds at 7.2× the set current, which is the standard for standard-start induction motors driving pumps, fans, and conveyors — fast enough to prevent winding damage but slow enough to ride through normal starting inrush.
Key Ratings and What They Mean for Fit
The relay is rated for main circuit voltages up to 690 V, covering 400 V, 480 V, 500 V, and 690 V line supplies. At 400 V it is rated for 0.75 kW motor load; at 500 V also 0.75 kW; at 690 V it steps to 1.1 kW. These power ratings assume a standard three-phase induction motor — the relay's thermal element is sized to the motor's full-load current, not the kW directly, so the actual setting range on the dial must match the motor nameplate FLA. The auxiliary contacts are rated for switching: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V — these are the signal contacts that feed the 'tripped' indication back to the PLC or annunciator. The note 'for message Tripped' on the listing confirms the auxiliary switch is integrated and wired for that purpose.
Mounting and Integration
Fastening method is contactor mounting — no DIN rail adapter needed if paired with a SIRIUS S00 contactor (e.g., 3RT2 series). The relay measures 45 mm wide, 76 mm high, and 70 mm deep, fitting neatly into a standard motor starter assembly. Mounting position is any, which simplifies panel layout. Main circuit connections are screw-type terminals accepting 2×(0.5…1.5 mm²) or 2×(0.75…2.5 mm²) solid or stranded wire. The auxiliary switch is integrated, so no separate block is required for the trip signal. Temperature compensation is active from -40 to +60 °C, meaning the trip curve stays accurate across that ambient range — important for outdoor or unheated enclosures.