What it is and what it does
The Siemens SENTRON 5SJ4115-7HG42 is a 1-pole miniature circuit breaker (MCB) rated 1.6 A at 30 °C with a C tripping characteristic. It occupies a single 18 mm modular width on standard DIN rail and is designed for branch-circuit protection in industrial control panels and mechanical engineering applications. The C characteristic means it trips between 5 and 10 times rated current, so it handles moderate inrush from small motors or transformers without nuisance tripping, while still clearing short circuits fast enough for cable protection.
Key ratings and what they mean for fit
Rated current derates with ambient temperature: at 30 °C and 40 °C it holds 1.6 A, at 45 °C and 50 °C it drops to 1.5 A, at 55 °C to 1.4 A, and at 60 °C to 1.3 A. If the panel ambient runs above 40 °C, size up one frame to keep the load within the thermal curve. DC rating is 60 V maximum. Overvoltage category 3 and pollution degree 3 suit fixed-installation distribution boards. IP20 with conductors connected, IP40 in the handle area. That's fine for enclosed panels; not rated for washdown or outdoor exposure without an enclosure.
Mounting and wiring
Supply feed can enter from either top or bottom — no polarity restriction. Sealable for tamper-proof installations. Halogen-free and silicon-free construction meets clean-room and low-smoke requirements.