The Siemens SENTRON 5SY3040-7KL is a 1P+N miniature circuit breaker rated 40 A at 230 V AC, with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898. The C curve means it tolerates moderate inrush — typical for lighting banks, small motor loads, and general-purpose branch circuits in residential or light commercial panels. The 1P+N pole design switches both phase and neutral, with the neutral pole switching alongside the protected pole; the neutral conductor is not overload-protected but is disconnected when the breaker trips, which matters for circuits where an isolated neutral is required after the protective device opens.
Mounting position is unrestricted — horizontal, vertical, or flat — which simplifies layout in a crowded enclosure. Terminal torque range is 17.7 to 22.1 lbf·in; a torque screwdriver set to the middle of that band avoids overtightening the spring cage.
The 5SY3040-7KL carries a current-production lifecycle status; it is an active catalog item in the SENTRON family. No last-time-buy or phase-out notice is recorded for this order code. Sourcing is straightforward through independent distribution channels — quoted and confirmed against an RFQ for availability and current pricing.