What it is and what the ratings mean
The Siemens 5SU9304-7KK06 is a SENTRON RCBO — a combined RCD and MCB in a single 18 mm wide module (1MW). It protects a single-phase final subcircuit against both overload/short-circuit (6 A, C-curve) and earth leakage (30 mA, Type A). The 10 kA breaking capacity per EN 60898 and IEC 60947-2 means it can safely interrupt a fault current up to that level without upstream cascading — sufficient for most domestic and light commercial distribution boards where the prospective short-circuit current stays under 10 kA. Type A residual current detection covers pulsating DC fault currents from electronics (SMPS, dimmers, EV chargers) that a plain AC type would miss.
DIN-rail fit and panel integration
Snaps onto standard 35 mm DIN rail. At 18 mm wide (1MW) and 77 mm deep, it leaves room for cable bending space in a 125 mm tall enclosure. Mounting position is any — vertical, horizontal, or flat — so panel layout constraints are minimal. Supply can enter from top or bottom; the design is instantaneous (no intentional time delay on the RCD element). Rated for overvoltage category III and pollution degree 2, which covers fixed-installation distribution boards.
Thermal derating — the real-world current rating
The 6 A nominal rating holds at 30 °C ambient. At 40 °C it derates to 5.64 A, at 45 °C to 5.46 A, at 50 °C to 5.22 A, and at 55 °C to 4.86 A. If the distribution board runs warm — say, inside a metal enclosure in a plant — the actual continuous load limit is lower than the label. Plan for the derated figure at your expected ambient; the 75 °C maximum is the storage/shipping limit, not an operating rating.