The Siemens SIRIUS 3RV1928-1A is a disconnector module designed specifically for Size S0 motor circuit breakers. It provides a visible isolating distance and can be locked in the disengaged position, giving a positive mechanical disconnect that meets lockout/tagout requirements on the line side of the breaker. This module mounts directly onto the S0 frame and adds 45 mm of width and 94 mm of depth to the assembly.
Snap the module onto the left or right side of the S0 circuit breaker — it shares the same 45 mm width and DIN-rail mounting. The visible isolating distance means you can confirm the circuit is open by eye, which is a nice safety check during maintenance. Lock it with a standard padlock in the disengaged position for LOTO.