4000 A distribution breaker, EasyPact NW series
Its 66 kA Icu at 220...440 V AC (50/60 Hz) per IEC 60947-2 means it can safely interrupt fault currents up to that level without upstream cascading — a figure that governs the SCCR headroom for the entire panel. At 690 V AC the breaking capacity holds at 50 kA Icu, with a corresponding Ics of 50 kA, so the breaker clears service faults and remains usable afterward within that range. Rated insulation voltage is 1000 V AC, operational voltage 690 V AC, with an impulse withstand of 12 kV. Pollution degree 4 per IEC 60664-1 is the harshest standard — conductive pollution is expected, so the creepage distances are designed for industrial environments where dust, moisture, or condensation are present.
Mechanical and electrical endurance
Electrical durability is rated 5000 cycles at 440 V AC without maintenance (Category B per IEC 60947-2), and 2500 cycles at 690 V AC. Mechanical durability reaches 20000 cycles with maintenance, 10000 without. Maximum breaking time is 25 ms; maximum closing response time is 70 ms. These figures matter for coordination studies — the 25 ms clearing time sets the lower bound for downstream device let-through.