Siemens 5SU9356-7KN40 is a SENTRON 2-pole RCBO (RCD-operated circuit breaker) rated 40 A with Type A fault current sensitivity. It combines overcurrent protection and residual current detection in a single 36 mm wide module — two width units on the DIN rail. The C tripping characteristic handles moderate inrush from motorized loads like small pumps or compressors.
Ratings & fit
Breaking capacity: 6 kA per EN 60898 for branch-circuit protection in residential or light commercial panels, and 10 kA per IEC 60947-2 for industrial distribution boards — the higher figure applies when the prospective short-circuit current exceeds 6 kA, common in factory main panels. Type A detection catches pulsating DC fault currents from electronics and single-phase rectified loads, not just pure AC sine-wave faults. Thermal derating is specified: 40 A at 30 °C, 37.6 A at 40 °C, 36.4 A at 45 °C, 34.8 A at 50 °C, 32.4 A at 55 °C. Ambient operating range -25 to +45 °C; storage -40 to +75 °C. If the panel ambient runs above 40 °C, the continuous load must be reduced accordingly — the 40 A nameplate rating is at 30 °C. Terminal capacity accepts solid or stranded conductors 0.75 to 35 mm² — covers most branch-circuit feeds up to 6 AWG. Mounting position any orientation; installation depth 70 mm, device depth 77 mm. IP20 with distribution board installed and conductors connected. Halogen-free and silicon-free construction — relevant for clean-room or semiconductor fab environments where outgassing contaminants must be avoided. Touch protection integrated on the terminals.