Abridgment of calculation of stray load losses

Early in the history of the development of the a-c. generator, it was recognized that there were losses present under load conditions in addition to the no-load losses and the armature copper loss due to load current. Because no one had a satisfactory means of measuring this loss it was not included in the early definitions of conventional efficiency. As competition increased and economic pressure demanded higher and higher efficiencies, the necessity of approximating this loss was apparent.