What it is and where it fits
The Siemens SENTRON 5SY6218-7 is a 2-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated 15 A at AC. It snaps onto a DIN rail in any mounting position, taking up 2 modular width units (36 mm). The IP20 rating applies with connected conductors, so it lives inside a panel or enclosure — not exposed to washdown.
Breaking capacity and selectivity
Rated breaking capacity is 6 kA per EN 60898 and 15 kA per IEC 60947-2, with the same 15 kA figure for DC applications per IEC 60947-2. The 15 kA rating gives headroom for industrial panels where fault currents run higher than residential levels — useful for selectivity studies downstream of a larger feeder breaker.
Thermal derating — the real-world current
At 35 °C the breaker carries its full 15 A. At 40 °C it derates to 14.28 A, at 45 °C to 13.9 A, at 50 °C to 13.53 A, and at 55 °C to 13.12 A. If the panel ambient runs hot — say inside a sealed enclosure near a drive — that derating curve is what determines whether the breaker holds or nuisance-trips. The surrounding temperature influence table also caps humidity: 95 % up to 55 °C, 55 % up to 70 °C, 35 % up to 75 °C.
Panel integration notes
Depth is 76 mm, height 90 mm, installation depth 70 mm. The quick-assembly fastening system and any mounting position simplify panel layout. Combined terminals top and bottom accept the supply cord in any position. Touch protection is built in, and the unit is sealable — useful for installations that require tamper-evident sealing after commissioning.
Environmental and material compliance
Halogen-free and silicon-free construction, rated for pollution degree 3 and overvoltage category III. Energy limitation class 3. The wide temperature range (-40 to 75 °C) covers cold storage or unheated enclosures. Suitability is marked for mechanical engineering and industry.