Integrator note — 5SY6403-7
The Siemens 5SY6403-7 is a 4-pole miniature circuit breaker from the SENTRON family, rated 3 A with a C tripping characteristic. It occupies 4 modular width units (72 mm) on a DIN rail, mounts in any position, and is current production — no lifecycle concern for new builds. Breaking capacity is 6 kA per EN 60898 and 30 kA per IEC 60947-2, so it handles fault currents up to 30 kA in an industrial panel — enough for most downstream sub-distribution boards. The C-curve (5–10× In) suits moderate inrush loads like small motor starters or lighting banks. Temperature derating is specified: 3 A at 35 °C, 2.86 A at 40 °C, 2.78 A at 45 °C, 2.71 A at 50 °C, 2.62 A at 55 °C. If the panel ambient runs above 35 °C, the effective continuous current drops — factor that into the load schedule. Pollution degree 3 and overvoltage category III mean it's rated for fixed industrial installations where conductive contamination is possible. The housing is halogen-free and silicon-free, which matters for clean-room or sensitive electronics environments.
Panel fit & mounting
Width is 72 mm (4 module spaces), depth 76 mm, installation depth 70 mm. The quick-assembly system means it clips onto a standard 35 mm DIN rail without tools. Combined terminals top and bottom accept conductors up to the usual MCB range; touch protection is built in. IP20 with connected conductors — fine for enclosed panels; not for wet or outdoor exposure without a sealed enclosure.