The Siemens 5SU9356-1CN20 is a 1P+N RCD-operated circuit breaker (RCBO) from the SENTRON family, combining overcurrent protection and residual current protection in a single 2-module-width (36 mm) package.
For purely resistive loads or long cable runs where inrush is minimal, a B-curve would trip faster; for heavy motor starts, a D-curve would be needed. This part splits the difference. Temperature derating is published: 20 A at 30 °C, 18.6 A at 40 °C, 17.6 A at 45 °C, 17.2 A at 50 °C, and 16.6 A at 55 °C. It mounts on standard DIN rail in any orientation and can be fed from top or bottom. The IP20 rating applies when installed in a distribution board with connected conductors — it's not a standalone outdoor device.