What this 5SY4245-7 is and what it carries
Out here in the grease, when a breaker's gotta go in and stay in, the 5SY4245-7 is a Siemens SENTRON 2-pole miniature circuit breaker rated 45 A at 35 °C with a C tripping curve — so it'll handle moderate inrush from motor starters and general branch circuits without nuisance tripping. It's sealable, halogen-free, and silicon-free — that last one matters if you're potting or conformal-coating a panel and don't want any silicone outgassing fouling contacts downstream.
Mounting and fit — what the DIN rail sees
Width is 36 mm — exactly two modular units — so it clips onto a standard DIN rail without eating extra space. Depth is 76 mm, height is 90 mm. Installed depth from the rail face is 70 mm, which leaves clearance behind most panel gland plates. Mounting position is any; the quick-assembly system clicks onto the rail without tools. IP20 protection with connected conductors — enough for a closed panel, but not for washdown zones. Temperature derating matters: at 40 °C it's still able to carry 42.27 A continuous, at 50 °C it drops to 39.33 A. If your panel ambient runs hot, factor that in — the raw 45 A label is only at 35 °C.
Lifecycle and compliance — what procurement needs to know
It's designed to IEC / EN 60898-1 and IEC / EN 60947-2 / UL1077, so it carries the dual label for domestic and industrial approvals. Pollution degree 3, overvoltage category III — it's built for industrial environments where you've got dirty mains and voltage surges.