Reversing starter, S0 frame, 24 V DC coil
The Siemens 3RA2220-1CB23-0BB4 is a SIRIUS non-fused reversing motor starter in the S0 size, meaning it integrates a pair of contactors mechanically interlocked for forward/reverse control of a three-phase motor, plus a thermal bimetallic overload relay, all in one DIN-rail-mounted package. The control coil is 24 V DC, a common PLC-level signal voltage that avoids the inrush issues of AC coils in high-cycle reversing applications.
Class 10 overload and thermal design
This matters for a reversing starter because the frequent plugging and reversing cycles generate additional heating in the rotor; the Class 10 characteristic must be coordinated with the motor's thermal withstand curve to avoid nuisance trips during normal reversing duty.
Snap-on DIN rail mounting and clearances
Snap-on fastening on 35 mm DIN rail, vertical mounting position only — the S0 footprint is 90 mm wide, 130 mm deep, 265 mm tall, and requires 30 mm clearance upward, 10 mm forward, 10 mm downward, and 9 mm at the sides for airflow and wiring access. The supplied components include the 3RT2023-1BB40 contactor, the 3RA2921-1BA00 link module, the 3RA2922-1AA00 busbar adapter, and the 3RA2923-1BB1 RH assembly kit — everything needed for a reversing configuration except the upstream circuit breaker (size S00).