The Siemens SENTRON 5SY5210-6 is a 2-pole miniature circuit breaker (MCB) with a B tripping characteristic, rated to interrupt 10 kA at 400 V AC per IEC/EN 60898-2 and 15 kA at 440 V DC per IEC 60947-2. It's designed for universal current operation, meaning it handles both AC and DC circuits without derating the breaker for DC use — a practical advantage when the same panel runs mixed loads.
The quick-assembly fastening system lets you snap it onto the rail and remove it with a screwdriver — no tools for the rail clip itself. Terminal design is combined top and bottom, which means the line and load conductors enter from the same side — useful when routing wires in a tight enclosure.
This is a current-production Siemens SENTRON part, widely specified across European and North American panel builds. If you're comparing it to the 5SY4140-7 (a 1-pole unit with the same B curve and 10 kA rating), the key difference is pole count and width: the 5SY5210-6 is a 2-pole breaker in a 2 MW footprint, while the 5SY4140-7 is a single-pole in 1 MW. They share the same SENTRON family, same trip curve, same breaking capacity — the choice is purely about whether your circuit needs both poles switched.