What this reversing starter packs
The 3RA2220-1HB24-0AK6 is a Siemens SIRIUS reversing starter — a factory-assembled pair of contactors with a mechanical interlock and a thermal overload relay, all in one size S0 footprint. It's built for applications that need to reverse a three-phase motor's direction, like conveyors, elevators, or pump sequencing. The Class 10 trip curve means it will disconnect the motor before it overheats under a locked-rotor condition — the bimetallic thermal element tracks the motor's heating characteristic closely.
Mounts on a 35 mm DIN rail using the supplied adapter, or can be screw-mounted directly to a backplate. The vertical mounting position is specified, so keep that in mind when laying out the panel — horizontal mounting would change the thermal performance of the overload relay. Dimensions are 120 mm deep, 90 mm wide, and 265 mm tall. The clearance requirements: 50 mm upwards, 32 mm forwards, and 10 mm at the sides and downwards. That 32 mm forward clearance is the one that catches people — make sure the panel door or cover doesn't crowd the front of the starter.
What's inside the box
This reversing starter ships with the contactor 3RT2024-1AK60 and the link module 3RA2921-1AA00 pre-assembled. The control circuit voltage is 88–121 V at 50 Hz and 96–132 V at 60 Hz. That's a standard AC coil range for this class — confirm your control transformer taps match the 50 Hz or 60 Hz supply before wiring.