The concept of in-phase transfer applied to industrial systems serving essential service motors

THE PROBLEM of transferring industrial loads from a preferred source to an emergency source has become more important as an increasing number of electric motors are being used to drive critical loads. The previous practice of having turbines drive these critical loads has, as the trend shows, shifted to replacement of turbines by motors. In those cases it is desirable that the continuity of electrical service should be such that an unscheduled shutdown of this type of load be practically eliminated.