What the 5SY7140-6 Is and What It Does
The Siemens 5SY7140-6 is a 1-pole SENTRON miniature circuit breaker rated 40 A with a B tripping characteristic, designed to protect branch circuits in industrial control panels and distribution boards. Its 15 kA breaking capacity per EN 60898 covers most commercial and light industrial fault levels; the higher 20 kA per IEC 60947-2 gives you headroom when the installation standard requires that rating schedule. The single-pole format and 18 mm width (one modular unit) mean it slots into a standard DIN-rail panel without crowding adjacent breakers.
Ratings That Matter for Fit
The 40 A rating at 35 °C is the nominal current; the breaker carries a published derating curve so you can size it for warmer enclosures. At 40 °C it handles 37.56 A, at 50 °C it handles 34.96 A, and at 60 °C it handles 32.16 A. If your panel ambient runs above 35 °C, use the derated figure — not the nameplate 40 A — to avoid nuisance tripping on a fully loaded circuit. The B-curve trips between 3 and 5 times rated current, which suits resistive and general-purpose loads — lighting, heaters, control transformers — rather than motor-starting inrush. For motor branch circuits you would typically reach for a C or D curve. Breaking capacity: 15 kA per EN 60898 covers the standard domestic/commercial installation; 20 kA per IEC 60947-2 is the industrial rating. The DC rating of 15 kA per IEC 60947-2 means it also works in DC distribution circuits, common in battery-backed or solar-combiner panels. Pollution degree 3 and overvoltage category III mean it is rated for the conductive environment inside a control cabinet — not just clean-room or residential backplanes. The IP20 rating (with connected conductors) is standard for enclosed distribution boards; the breaker itself is not meant for wet or washdown locations.
Deployment Context — Panel Integration
Snap-on DIN-rail mounting, any position, with a quick-assembly fastening system. The 70 mm installation depth and 76 mm overall depth mean it fits shallow enclosures where a deeper breaker would foul the gland plate or door. Combined terminals top and bottom accept standard copper conductors; the touch-protection feature (fingertip-safe terminals) is built in, so no separate terminal covers are needed for the panel builder. Halogen-free and silicon-free construction matters if this breaker lives in a sealed enclosure near sensitive electronics — no corrosive off-gassing during a fault arc. Sealable design allows the panel OEM to lock the toggle position after commissioning.