What it is and what it does
The Siemens 5SY4340-7CC11 is a 3-pole miniature circuit breaker from the SENTRON family, rated 40 A at 400 V AC with a C tripping characteristic. The C curve means it tolerates moderate inrush — typical for motor and transformer circuits — before tripping on short-circuit or sustained overload. Its 10 kA breaking capacity per EN 60898 is sized for standard industrial distribution panels where fault levels stay under that threshold.
Deployment context and mounting
Mounts on DIN rail via the quick-assembly system — snaps into any position, no tools needed. The 54 mm width (3 width units) and 76 mm depth fit standard SENTRON enclosures; installation depth is 70 mm. Rated IP20 with connected conductors, so it belongs inside a closed panel, not exposed to washdown. Designed for railway applications per the evidence, which means it meets vibration and temperature cycling beyond typical commercial-grade MCBs.
Lifecycle and sourcing reality
The lifecycle stage is marked current — this is an active, in-production part. For a BOM line that calls out 5SY4340-7CC11, the part is sourced through independent distribution and quoted to order against an RFQ; availability and current pricing are confirmed at quote time.
Key ratings and what they mean for fit
Rated 40 A at 400 V AC — sized for a 3-phase load drawing up to that current, such as a small motor group or a lighting sub-panel. The C characteristic (magnetic trip between 5 and 10 times In) handles the start-up surge of induction motors without nuisance tripping. Maximum DC voltage is 72 V, so it can also serve DC circuits up to that level, but the breaking capacity at DC is not stated — verify for DC-only applications. The 10 kA rating per EN 60898 is the standard for most commercial and light industrial distribution boards; if your available fault current exceeds that, you need an upstream current-limiting device.