What this reversing starter packs
The Siemens 3RA2220-1JB24-0BB4 is a SIRIUS reversing starter in Size S0 — a factory-assembled pair of contactors with mechanical and electrical interlock, plus a link module, all on a common adapter plate. The supplied contactor is a 3RT2024-1BB40 and the link module is a 3RA2921-1BA00 — both are matched at the factory so the interlock timing and bus connections are correct out of the box. No separate wiring between the forward and reverse contactor is needed; the link module carries the power circuit crossover.
Mounting and panel fit
Mounts on a 35 mm DIN rail via the included adapter for screw and snap-on fastening, or can be screw-mounted directly to a backplate. The vertical mounting position is specified, and the clearance requirements are: 50 mm upwards, 32 mm forwards, 10 mm downwards, and 10 mm at the side — backwards clearance is zero, so the back of the unit can sit flush against the panel wall. The enclosure dimensions are 130 mm deep by 90 mm wide by 265 mm high. The main circuit uses screw-type terminals, so expect to torque the power wires to the contactor ratings.
Trip class and thermal limits
This covers most pump, fan, and conveyor applications. The operating temperature range is -20 to +60 °C, with storage and transport limits of -50 to +80 °C. The coil is rated at 24 V DC, and the unit is designed for AC-3 switching up to 690 V maximum.