The Siemens SENTRON 5SY6402-7 is a 4-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated 400 V AC and occupying 4 modular width units (72 mm) on a DIN rail. The 4-pole design switches all three phases plus the neutral, though the neutral conductor is not switched internally — a point to confirm if your load side requires a switched neutral.
C-curve and breaking capacity — what they mean on the line
The 6 kA rating under EN 60898-1 covers the typical prospective short-circuit current in a sub-distribution board; the 30 kA rating under IEC 60947-2 gives you headroom if this breaker sits close to a large transformer or in a high-fault industrial MCC. For DC circuits, it breaks 15 kA at 60 V (max 72 V DC), so it can also serve as a DC feeder breaker in control cabinets or solar combiner boxes up to that voltage.
The 70 mm installation depth (76 mm overall) fits standard distribution boards and small enclosures. Sealable with a lead seal or tag for tamper-proofing after commissioning.