The 3RV1938-1AA00-0FJ0: Disconnector block for the M3/50 series of Motor Protection Circuit Breakers (MPCB). Provides isolation between the motor feeder and the protection device for safe maintenance.
The block clips onto the MPCB base unit, adding a visible-break disconnection function without extra panel space. No separate enclosure or interlock is required — the block and breaker share the same DIN rail footprint. Torque the M3/50 terminal screws to the Siemens-specified value; under-torqued connections on a disconnector block create a hot spot that derates the assembly.