The Siemens 3RU2136-4HB1 is a SIRIUS thermal overload relay, size S2, for motor protection in control panels. It trips on CLASS 10 curve, meaning it disconnects the motor within 10 seconds at 7.2× the set current — fast enough for standard induction motor starts but not so aggressive it nuisance-trips on a normal acceleration profile. Rated for 690 V, it handles 22 kW at 400 V (AC-3e duty) and 45 kW at 690 V. The integrated auxiliary switch signals the tripped state directly to the PLC or annunciator.
Ratings and what they mean for fit
CLASS 10 is the trip class — the relay opens the circuit within 10 seconds under locked-rotor current. That matches most standard 3-phase induction motors; CLASS 20 or 30 would be needed for high-inertia loads like fans or flywheels. The 690 V rated value covers 400 V and 480 V grids with headroom. At 400 V rated value it is sized for 22 kW, and at 690 V rated value for 45 kW. The auxiliary switch contacts are rated across a range: 2 A at 24 V, 3 A at 120 V, 1 A at 400 V, 0.75 A at 690 V — enough for a PLC input or a contactor coil, but check the load type (resistive vs inductive) for DC circuits.
Mounting and wiring
Designed for stand-alone installation — mounts directly to the contactor or on a DIN rail via an adapter. Screw-type terminals on the main circuit accept 2×(0.5…1.5 mm²) or 2×(0.75…2.5 mm²) solid or stranded wire. The main contact terminals are M6. A Pozidriv PZ 2 screwdriver tip with a 5–6 mm shaft diameter is specified. Mounting position is any.
Environmental and compliance
Operating temperature range is -40 to +70 °C; storage and transport range is -55 to +80 °C. Temperature compensation is active from -40 to +60 °C, meaning the trip curve stays accurate across that span. The substance prohibitance date (RoHS/REACH compliance) is 10/15/2014.