Siemens 5SY6540-8 — 40 A D-Curve MCB for Industrial Branch Circuits
The Siemens 5SY6540-8 is a SENTRON 5SY6 miniature circuit breaker rated 40 A with a D tripping characteristic, in a 2-pole (1P+N) form factor. At 40 A it handles typical branch circuits feeding several small motors or a single larger drive. Breaking capacity is 6 kA per EN 60898 and 10 kA per IEC 60947-2, with a DC rating of 15 kA per IEC 60947-2 at 72 V DC maximum. For UL 1077 / CSA C22.2 No.235 recognition, the interrupting rating is 5 kA. The neutral pole is switched (1P+N), so this breaker opens both line and neutral on a fault — important for single-phase sub-circuits where an unswitched neutral would leave the circuit live after trip.
Panel Integration & Environmental Fit
IP20 with connected conductors, plus touch protection on the terminals, means it is safe for open-panel installation where only qualified personnel access the enclosure. Sealable with a lead seal for tamper-evident metering or safety circuits.
Approvals & Compliance
Designed to EN 60898 (6 kA) and IEC 60947-2 (10 kA AC, 15 kA DC). Also carries UL 1077 and CSA C22.2 No.235 recognition at 5 kA, 250 V AC single-phase. The product designation per DIN EN 61346-2 and DIN EN 81346-2 is letter F (protective device).