Reference 2N data-centre power train, side B: 10 kV intake, 2.5 MVA 10/0.4 kV transformer, 2.5 MVA 400 V genset, main board MSB-B, board B (DB-B) 40 m away, sub-board SB-B 60 m further. Every state below is precomputed.
Short-circuit currents follow the IEC 60909-0:2016 method. On generator the current decays as the alternator’s does (subtransient, transient, then about 3 × rated current held by the excitation). Trip units are generic long-time, short-time and instantaneous settings with tolerance bands; arc duration uses the slow edge of each band.
Incident energy is integrated millisecond by millisecond over the decaying arcing current, at the working distance shown, for both the full and the reduced arcing current; the larger one is shown. That time-stepping is an engineering extension of the model, which was fitted to constant-current tests.