SIRIUS reversing starter — busbar-mount, AC-3 rated
The Siemens 3RA2220-1FD24-0AK6 is a SIRIUS reversing starter, Size S0, designed to snap directly onto 60 mm busbar systems — no separate DIN-rail adapter needed for the main power feed. The unit ships with the supplied contactor (3RT2024-1AK60) and link module (3RA2921-1AA00), so it arrives as a complete reversing assembly — the integrator wires the control voltage and motor leads.
AC-3 duty and motor protection — what the ratings mean
For a 400 V motor, this corresponds to a rated power of 1.5 kW — the spec table lists 1,500 W at 400 V. The short-circuit trip is magnetic (instantaneous), while the overload release is thermal bimetallic — a combined design that handles both fault types in one compact S0 frame.
Mounting and panel integration — busbar snap-on
This reversing starter is designed for vertical mounting by snapping onto 60 mm busbar systems — the fastening method is built into the housing, so no additional mounting plate or DIN rail is required for the main circuit connection. Dimensions are 155 mm deep, 90 mm wide, and 260 mm high — the width is the critical panel cut-out dimension when ganging multiple starters on the same busbar run. Clearance requirements: 50 mm upwards, 32 mm forwards, 10 mm at the side, and 10 mm downwards — the backwards clearance is 0 mm, meaning the unit sits flush against the back panel. Main circuit connections use screw-type terminals — a standard termination method for panel builders, compatible with ring or fork lugs up to the conductor size the S0 frame accepts.
The control voltage is 88–121 V at 50 Hz and 96–132 V at 60 Hz — confirm the control transformer taps match this range before specifying.