What this reversing starter carries
The Siemens 3RA2220-4BB26-0BB4 is a SIRIUS reversing starter in Size S0 — a pre-assembled combination of a contactor pair and a link module that handles forward/reverse motor control in one DIN-rail footprint. It ships with a 3RT2026-1BB40 contactor and a 3RA2921-1BA00 link module, so you are not piecing together the reversing interlock yourself. The coil is 24 V DC — that 24... 24 V entry in the spec is not a range, it is a confirmation of a fixed 24 V DC control voltage.
The starter measures 130 mm deep, 90 mm wide, and 265 mm tall. Mounting is vertical on a 35 mm DIN rail via the supplied adapter, or direct screw-mount to a backplate. Clearance requirements: 50 mm upwards, 32 mm forwards, 10 mm downwards, and 10 mm at the side — zero backwards clearance needed, so it can sit tight against a panel wall or busbar. Size S0 load feeder format means it shares the same busbar system and mounting hole pattern as other S0 components in the SIRIUS family. If you are swapping an older reversing starter out of a S0 panel, this drops in without redrilling the backplate.
Lifecycle and sourcing posture
Standard Siemens declarations (CE, UKCA, UL, IEC) apply to the SIRIUS series — request the specific declaration of conformity with your RFQ if your quality system requires it on file.