Emax Low voltage air circuit-breakers - ABB Download Center

WarningThe curves of the motor and trip units are not directly comparable,since they both express time-current links, but have conceptuallydifferent meanings:– the motor starting curve represents the values taken by thestarting current instant by instant;– the trip unit curve represents the currents and correspondingtrip times for the protection device.The overload trip curve is set correctly when it is immediatelyabove point A (figure below), which identifies the top of the rectanglewith sides formed by the starting time “ta” and the current“Ia” thermally equivalent to the variable starting current respectively.t [s]I [A]1SDC200210F00016Three-phase operationThe overload protection device at 1.05 times the setting currentshall not trip in less than 2 hours starting from the cold state.When the current is 1.2 times the setting current, the trippingshall occur in less than 2 hours, as indicated in the table whichfollows (page 6/39)ABB SACE 6/37