The Schneider Electric MGN60887 is a C60N miniature circuit breaker from the Multi9 range, rated 63 A at 50 °C per EN/IEC 60947-2.
The C-curve trips magnetically at 8.5 x In (±20 %), so at 63 A that's roughly 536 A instantaneous pickup. That's sized for motor-starting inrush or transformer energization — a B-curve would nuisance-trip on those loads, while a D-curve would let a fault ride too long. It's not a one-shot device. The 10 kA Icu at 415 V and 6 kA at 440 V tell you the interrupting capability drops as voltage climbs; for a 400 V distribution board this breaker is fine on a 6 kA prospective fault level, but don't put it where the available fault current exceeds that. The IP20 finger-safe terminals are standard for enclosed gear; if the breaker lives exposed, you'll need a cover.
Mounting and wiring in the panel
Snaps onto 35 mm symmetrical DIN rail. Tunnel terminals accept 1.5 to 35 mm² flexible or rigid copper, with a 14 mm strip length and 3.5 N.m torque. That's enough lug for a 35 mm² feeder on the line side and 25 mm² downstream. Busbar compatible top or bottom, so daisy-chaining phases across a row is straightforward.