Emax Low voltage air circuit-breakers - ABB Download Center

Derating at different altitudesSACE Emax air circuit-breakers do not undergo any changesin their rated performance up to an altitude of 2000 meters.As the altitude increases the atmospheric properties alter interms of composition, dielectric capacity, cooling power andpressure.The performance of the circuit-breakers therefore undergoesderating which can be measured through the variation in significantparameters such as the maximum operating voltageand the rated uninterrupted current.The table below shows these values in relation to altitude.Altitude H [m]