The Siemens 3RU2136-4AB0 is a SIRIUS thermal overload relay, size S2, designed for motor protection with a CLASS 10 trip characteristic. It is rated for a maximum of 690 V and delivers 7.5 kW at 400 V, with a rated operational current of 16 A at 480 V and 600 V. The relay mounts directly onto a contactor and uses screw-type terminals for the main circuit.
Ratings and fit
CLASS 10 trip means the relay trips within 10 seconds at locked-rotor current. Ambient-compensated from -40 to +60 °C. Auxiliary switching is integrated, with a note for message "Tripped" — the relay provides a dedicated signal contact that changes state on overload, which can be wired into a PLC input or a local indicator. The auxiliary contact ratings cover common control voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V, and 0.75 A at 690 V. Dimensions are 55 mm wide, 90 mm high, and 105 mm deep — fits the standard S2 footprint. Mounting position is any, and the relay fastens directly to the contactor, not to a DIN rail. Wire capacity accepts 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded.