Standard decrement curves

THE DETERMINATION of decrement in power system short-circuit currents frequently is necessary for circuit breaker and relay application. For this purpose certain standard decrement curves originally appearing in 1918 and revised in 1923, have been in general use. New decrement curves now have been derived to supersede the former ones, the new curves having been made desirable by the considerable progress in analysis of transients in synchronous machines, and to the use of symmetrical components for calculating unbalanced faults.