The Siemens 3RV1321-0EC10 is a SIRIUS circuit breaker designed for starter combinations, carrying a continuous current rating of 0.4 A and a breaking capacity of 100 kA at 400 V AC — that 100 kA figure means it can safely interrupt a fault current up to that level without upstream devices needing to clear it first, which simplifies coordination in a motor control center.
IP20 on the front means finger-safe touch protection against electrical shock; the screw-type terminals on both main and auxiliary/control circuits accept solid and stranded conductors up to 2x 6 mm², with a backwards clearance of 0 mm and side clearance of 0 mm — zero spacing needed between units on the rail.
The 0.4 A continuous current sets the motor full-load current it protects — pair it with a contactor rated for the same motor FLA. The 100 kA breaking capacity holds across 240 V, 400 V, 500 V, and 690 V AC (all rated 100 kA), so the same SCCR applies regardless of the supply voltage within that range. Rated for 5.5 W power loss in hot operating state (1.8 W per pole), which matters for thermal management inside a sealed enclosure — that's modest enough for a standard steel panel without forced ventilation.