Rated current and tripping curve — what the B-curve means on a 50 A frame
B-curve means the magnetic trip activates between 3 and 5 times rated current — so on a 50 A breaker, instantaneous trip starts at 150 A and is guaranteed by 250 A. For DC circuits, the same 10 kA rating applies per EN 60898-2, with the polarity observed as noted on the device — AC supply can be connected either way, DC requires correct polarity.
Temperature derating — the 50 A rating holds only at 35 °C ambient
The 50 A rating is specified at 35 °C ambient. At 40 °C the breaker must be derated to 47.6 A, at 45 °C to 46.35 A, at 50 °C to 45.1 A, at 55 °C to 43.75 A, and at 60 °C to 42.4 A. The breaker is rated for ambient up to 75 °C and as low as -40 °C, with humidity limits of 95% up to 55 °C, 55% up to 70 °C, and 35% at 75 °C.
It mounts in any position and uses a quick-assembly fastening system — clips onto the rail without tools.