What it is and what it does
The Siemens SENTRON 5SY6320-8 is a 3-pole miniature circuit breaker (MCB) rated 20 A with a D tripping characteristic. It protects branch circuits against overload and short-circuit in industrial control panels, distribution boards, and machinery — the D curve is specifically for loads with high inrush currents like motors, transformers, and welding equipment, where a B or C curve would nuisance-trip on startup.
Breaking capacity — the real-world fault clearance
Rated 6 kA per EN 60898 and 15 kA per IEC 60947-2 at 400 V AC. The IEC 60947-2 figure is the one that matters for industrial panel design — it tells you the breaker can safely interrupt a fault up to 15 kA without welding contacts or venting arc. For UL 1077 / CSA C22.2 No. 235 installations, the interrupting rating is 5 kA.
Mounting and integration
Snaps onto DIN rail via the quick assembly system — no tools needed. Occupies 3 width units (54 mm wide) on the rail. Mounting position is any, so it fits horizontal busbars or vertical sub-distribution boards without derating. Depth is 76 mm (70 mm installation depth), which clears most standard enclosure gland plates. IP20 with connected conductors — fine for enclosed panels, not for wet areas.
Sourcing reality
This is a current-production Siemens SENTRON part. Sourced and quoted to order against an RFQ through independent distribution — availability and current pricing confirmed at quote time. No last-time-buy window, no broker scramble.