Siemens 5SJ6540-6 SENTRON MCB — 1P+N, B Curve, 40 A, 6 kA
The Siemens 5SJ6540-6 is a 1P+N miniature circuit breaker from the SENTRON 5SJ6 series, rated 40 A with a B tripping characteristic and a 6 kA breaking capacity per EN 60898 (also 6 kA per IEC 60947-2). It operates at 240 V AC, with a maximum DC rating of 60 V. The 1P+N configuration switches the phase and provides a switched neutral, common in single-phase final sub-circuits.
The B characteristic (3–5× In) gives a magnetic trip threshold of 120–200 A — fast enough to clear a hard short but tolerant of the mild start-up draws typical of lighting, socket outlets, and small appliances. The 1P+N pole count means it occupies 2 width units (18 mm per unit) on a DIN rail and switches the neutral as well as the phase.
Ambient temperature range is -20 to +45 °C, with a storage range of -40 to +75 °C. The device is halogen-free and silicon-free, and the terminals are sealable for anti-tamper applications. Touch protection is provided per the design.