800 A MCCB with ETU350 — interrupting capacity and thermal derating
Its interrupting capacity reaches 242 kA at 240 V, 187 kA at 415 V, and 74 kA at 690 V — figures that define the maximum fault current it can safely clear at each voltage level without upstream coordination failure. Thermal derating is flat from 40 °C through 60 °C at the full 800 A; at 65 °C the rating drops to 767 A, and at 70 °C to 703 A. This means the breaker holds its nameplate rating across most common panel ambient temperatures, but above 60 °C you must account for the reduction.
Adjustable trip settings and selectivity
The ETU350 release offers adjustable long-time pickup Ir from 0.5 to 1.0 × Iu (400 A to 800 A), with long-time delay tr adjustable from 0.5 to 17 seconds. Short-time pickup Isd and delay tsd (0.04 to 0.4 s) are also field-configurable, as is instantaneous pickup Ii up to 8000 A. These settings let the breaker be coordinated downstream for selective tripping — the short-time delay band is critical for maintaining supply to non-faulted feeders during a downstream fault.
The breaker measures 210 mm wide, 320 mm high, and 120 mm deep — a 3-pole frame that mounts into a standard switchboard or panel enclosure. The 8.3 in width and 12.6 in height help with cutout planning.