Siemens 5SL3103-7 SENTRON MCB — 1-pole C-curve 3 A
The Siemens 5SL3103-7 is a 1-pole miniature circuit breaker from the SENTRON 5SL series, rated 3 A at 30 °C with a C-curve trip characteristic. It breaks faults up to 4.5 kA per both EN 60898 and IEC 60947-2 at 400 V AC — enough for residential and light commercial distribution panels where the available fault current stays under that threshold.
At 3 A, this breaker protects a branch circuit drawing up to about 690 VA on a 230 V line or 1200 VA on 400 V three-phase. Temperature derates apply: at 40 °C the rating drops to 2.82 A, at 45 °C to 2.76 A, and at 55 °C to 2.52 A — factor that into the load calculation if the breaker sits in a warm enclosure.
The 1 MW width (18 mm) means one breaker occupies a single modular space. Any mounting position is allowed. Sealable with a lockable cover to prevent unauthorized switching. Halogen-free and silicon-free construction, so it won't outgas corrosive compounds in sensitive electronic environments.