What this part does
The Siemens 5SY7450-8 is a 4-pole miniature circuit breaker from the SENTRON series, with a D tripping characteristic. It is designed for branch-circuit protection in industrial control panels and distribution boards, where high inrush currents — typical of motor loads, transformers, or welding equipment — would nuisance-trip a B or C curve. The D curve tolerates short-duration surges up to 10–20 times rated current before opening, so it coordinates with downstream inductive loads without false trips. Rated breaking capacity is 15 kA per IEC/EN 60898-1 and IEC/EN 60947-2, and 15 kA at DC per IEC 60947-2. That means it can safely interrupt a fault current up to 15 kA at 400 V AC without welding contacts or cascading failure upstream. For UL 1077-listed applications, the interrupting rating is 5 kA. The part also carries pollution degree 3 and overvoltage category III ratings, so it is suited for fixed installations in industrial environments where conductive dust or condensation may be present.
Mounting and panel fit
Occupies 4 modular width units (72 mm wide) on a DIN rail. Fastening is via the quick assembly system — snap-on without tools. Mounting position is any, and the combined terminal top and bottom accept supply from either direction. Installation depth is 70 mm; overall depth is 76 mm. The enclosure is IP20 with connected conductors, so it is intended for enclosed panel use, not open washdown areas.
Sourcing and availability
The 5SY7450-8 is sourced through independent distribution and quoted to order against an RFQ. Availability and current pricing are confirmed at quote time. For volume purchases or BOM commitments, submit an RFQ through the storefront; the supply posture is active and the part can be specified into new designs without lifecycle risk.