The Siemens 5SU9356-7CN40 is a 1P+N RCBO (residual current circuit breaker with overcurrent protection) from the SENTRON series, combining a 40 A C-curve MCB with a 30 mA Type A RCD in a single 2-module-wide unit.
The 6 kA figure governs residential/commercial final circuits; the 10 kA rating applies when the device is used under the industrial standard, giving you headroom for higher fault-current installations. Type A RCD detects pulsating DC residual currents as well as sinusoidal AC — essential on circuits with single-phase rectifiers, variable-speed drives, or switching power supplies where pure AC-sensitive (Type AC) devices may blind. The 30 mA sensitivity provides additional protection against direct contact. Rated current of 40 A at 30 °C ambient (derate at higher temperatures). Power dissipation per pole is 0.75 W at rated load in hot operating state — relevant for thermal coordination in tightly packed enclosures.
Two-module-width (36 mm) design, 77 mm depth, 90 mm height, 70 mm installation depth. Mounts in any position on DIN rail.