SIRIUS 3RU2136-4QB0 — CLASS 10 thermal overload relay, size S2
The Siemens 3RU2136-4QB0 is a SIRIUS-brand thermal overload relay, size S2, designed for contactor mounting. Its CLASS 10 trip characteristic means it will trip within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during a stall or locked-rotor event without nuisance tripping on normal start-up. Rated for motor loads up to 30 kW at 400 V, 37 kW at 500 V, and 55 kW at 690 V, with a maximum current rating of 57 A at both 480 V and 600 V. The auxiliary contacts handle 2 A at 24 V and 230 V, 3 A at 120 V, 1 A at 400 V, and 0.75 A at 690 V — enough for signaling back to a PLC or contactor coil.
Integration — contactor-mount, size S2, any position
Mounts directly onto the matching SIRIUS contactor (size S2) without additional hardware — no DIN rail required, though it can be panel-mounted if needed. Fastening method is contactor mounting; the relay snaps onto the contactor's frame and connects electrically through the power terminals. Acceptable in any mounting position. Screw terminals on the main circuit accept 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded wire. A Pozidriv PZ2 screwdriver tip (shaft diameter 5–6 mm) is specified for termination. Dimensions: 90 mm high, 55 mm wide, 105 mm deep — fits standard S2 panel cutouts. The integrated auxiliary switch provides the trip-signal output (the "for message 'Tripped'" note on the label).
Lifecycle and compliance
Temperature compensation is active over -40 to +60 °C, ensuring the trip curve stays accurate across the operating range. Storage and transport range is -55 to +80 °C; operating ambient is -40 to +70 °C.