The Siemens 3RU2116-1BB0-ZW96 is a SIRIUS thermal overload relay, size S00, designed for direct contactor mounting onto Siemens 3RT2 contactors. Its primary job is to protect motors against overload and phase failure by tripping on a Class 10 curve — meaning it will open within 10 seconds at 7.2× the set current, fast enough for standard induction motor starts without nuisance tripping on normal acceleration. This variant carries an integrated auxiliary switch with a dedicated trip-indication function — the note "for message 'Tripped'" means the N/C contact opens and the N/O contact closes only when the relay has actually tripped, not when it is simply reset or powered down. That gives a clean, unambiguous fault signal back to the PLC or HMI, which is useful for remote diagnostics on a conveyor or pump line.
Switching capacity and contact ratings
The auxiliary contacts are rated for switching at multiple common control voltages: 3 A at 120 V, 2 A at 24 V and 230 V, 1 A at 400 V, and 0.75 A at 690 V. At 60 V and 125 V the rating drops to 0.3 A and 0.22 A respectively, and at 220 V it is 0.11 A. These are the make/break capacities for the integrated auxiliary switch — not the main overload current setting, which is set via the adjustment dial on the relay body. The main circuit is rated for a maximum of 690 V, with corresponding motor power ratings: 0.75 kW at 400 V and 500 V, 1.1 kW at 690 V. At 480 V and 600 V the current rating is 2 A. The relay is temperature-compensated from -40 °C to +60 °C, so the trip curve stays consistent across a hot panel or a cold startup.
Mounting and wiring
Fastening is via contactor mounting — the relay clips directly onto the front of a SIRIUS contactor, saving DIN rail space and reducing wiring between the contactor and overload. 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. Dimensions are 45 mm wide, 76 mm high, and 70 mm deep — the S00 footprint. Mounting position is any orientation, which simplifies panel layout. The M3 main contact screws are standard for this class.