What this 50 A B-curve MCB is for
The Siemens 5SL3550-6 is a 1P+N miniature circuit breaker from the SENTRON 5SL3 family, rated 50 A at 230 V AC with a B tripping characteristic. The B curve (3–5× In) means it trips fast on short-circuit but tolerates modest inrush — typical for residential and light commercial lighting or socket-outlet circuits where loads are resistive rather than motor-heavy. Breaking capacity is 4.5 kA per EN 60898 and IEC 60947-2, adequate for most domestic distribution boards; the 1P+N configuration switches the phase and switches the neutral, so the neutral is opened when the breaker trips.
Installation depth is 70 mm. Sealable terminals are a plus for utility or metering applications where tamper evidence is required.
Halogen-free and silicon-free construction. Overvoltage category III, energy limiting class 3. Touch protection is built in. Mechanical endurance is 10 000 switching cycles typical.