What it is and what it does
The Siemens 3RU2116-1FB0-ZW97 is a SIRIUS thermal overload relay, size S00, designed to protect motors against overcurrent and phase failure. It uses a thermal bimetallic release that tracks the motor's heating curve, and it trips a CLASS 10 characteristic — meaning it will disconnect within 10 seconds at 7.2× the set current, which is the standard for standard-duty induction motors like pumps and fans.
Key ratings and what they mean for fit
Rated insulation voltage is 690 V, so it can be used on 400 V and 480 V systems with headroom. The motor power assignments are given per voltage: 1.5 kW at 400 V, 2.2 kW at 500 V, and 4 kW at 690 V — these are the full-load motor sizes the relay can protect at those line voltages. The integrated auxiliary switch carries a "for message 'Tripped'" designation, meaning the N/C contact signals a trip condition. Its switching capacity is rated across multiple voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, and 1 A at 400 V — all AC values for the signal circuit. At 60 V and 125 V DC it handles 0.3 A and 0.22 A respectively, so it can drive a PLC input or a panel lamp directly. The relay compensates for ambient temperature changes from -40 to +60 °C, so it won't nuisance-trip in a hot panel or a cold warehouse. Operating temperature range is -40 to +70 °C; storage and transport handle -55 to +80 °C.
Mounting and integration
Mounts directly onto the contactor — the fastening method is "contactor mounting" — so it snaps onto the SIRIUS 3RT2 contactor of matching S00 frame size without extra brackets. Mounting position is any, which helps in tight enclosures. The main circuit uses screw-type terminals accepting 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded wire. A Pozidriv PZ 2 screwdriver with a 5 to 6 mm shaft diameter is specified for the terminals. Dimensions are 76 mm high, 45 mm wide, and 70 mm deep — a compact footprint that fits standard DIN-rail enclosures when paired with its contactor.