What this 800 A MCCB carries — and where the rating holds
The Siemens SENTRON 3VA2580-5KQ32-0KH0 is a 3-pole molded case circuit breaker rated for 800 A continuous current at 40 °C, with the same 800 A holding through 60 °C — only at 65 °C does it begin to derate to 767 A, and at 70 °C to 703 A. That flat thermal curve means this breaker delivers its full 800 A rating across most normal panel ambient conditions without headroom loss. Its interrupting ratings are tiered by system voltage: 187 kA at 240 V, 121 kA at 415 V, and 53 kA at 690 V. For a main breaker on a 415 V distribution board, the 121 kA SCCR gives substantial fault-clearing headroom — enough to coordinate with downstream feeders without cascading. The ETU860 electronic trip unit provides adjustable long-time pickup (Ir) up to 800 A, short-time delay (tsd) from 0.05 s to 0.5 s, and ground-fault summation sensing on the line conductors.
The breaker measures 210 mm wide, 320 mm high, and 120 mm deep — a 3-pole frame that fits standard SENTRON mounting patterns.