The Siemens 3RV2928-1A is a SIRIUS disconnector module designed for use with circuit breakers in Size S00 and S0 frames. It provides a visible isolating distance and can be locked in the disengaged position, giving a clear physical break for safe maintenance. The module is 45 mm wide and 94 mm deep, matching the standard S0 footprint so it snaps onto the same DIN rail alongside the breaker.
The 45 mm width is the key panel-fit number — it occupies one standard S0 slot.
The visible isolating distance is a safety feature for lockout/tagout — the handle position shows the contact state at a glance, and the lockable disengaged position lets you padlock it out. No extra wiring needed; it connects through the breaker's own terminals.