What it is and where it fits
The Siemens SENTRON 5SY6118-7 is a single-pole miniature circuit breaker (MCB) with C-curve tripping characteristic, rated 15 A at AC. It snaps onto a DIN rail — 18 mm wide, one modular unit — and mounts in any position, so panel layout is flexible. The IP20 rating (with connected conductors) means it belongs inside a closed enclosure, not exposed to washdown.
Breaking capacity — what it means for your panel
This breaker carries two breaking-capacity ratings: 6 kA per EN 60898 (the household / light commercial standard) and 15 kA per IEC 60947-2 (the industrial standard). The 15 kA figure governs fault-current handling in industrial panels — it safely interrupts a short-circuit up to that level without welding contacts or cascading failure upstream. The same 15 kA rating applies for DC circuits per IEC 60947-2, so it works on DC branches too.
Thermal derating — don't oversize the bus
The 15 A rating holds at 35 °C ambient. At 40 °C it derates to 14.28 A; at 50 °C to 13.53 A; at 55 °C to 13.12 A. If the panel runs hot — say, 50 °C inside a sealed enclosure — expect the breaker to carry about 10 % less than its nameplate. Plan the branch load accordingly.