The Siemens SENTRON 5SU9304-7KX25 is a 1P+N RCD-operated circuit breaker (RCBO) rated 25 A at AC, with a C tripping characteristic and a breaking capacity of 10 kA per EN 60898 and IEC 60947-2. It's a Type A (pulsating DC sensitive) device, meaning it catches both sinusoidal AC fault currents and pulsed DC from rectified loads like VFDs or LED drivers — a common requirement in modern panels where you can't guarantee a pure sine-wave fault.
Current derating and thermal limits
Full rated current is 25 A at 30 °C ambient. At 40 °C it's 23.75 A, at 45 °C 22.75 A, at 50 °C 22 A, and at 55 °C 21.5 A. The operating ambient range is -25 to +45 °C, so if your panel runs hot (say above 40 °C), you need to account for the drop — a 25 A circuit at 45 °C derates to 22.75 A continuous. That's the figure to use for wire sizing and load planning.
Physical fit and mounting
Width is 18 mm (1 width unit), depth 77 mm, height 125 mm, installation depth 70 mm. Mounts on DIN rail in any position. The supply feeds from below. Conductor cross-section range is 0.75 to 35 mm² for both solid and stranded — that covers everything from a 1.5 mm² lighting circuit to a 10 mm² feeder. IP20 with distribution board installed, IP40 with connected conductors. Overvoltage category III, so it's rated for fixed installation downstream of the main distribution board.
Compliance and documentation
Halogen-free and silicon-free construction. Touch protection is built in. Energy limiting class 3. The part carries designations per DIN EN 61346-2 and DIN EN 81346-2 (letter F). For compliance documentation (RoHS, REACH, CE, UKCA), the brand provides declarations of conformity and material declarations — these are available on request with the RFQ.