Analysis of "SK" Generator (Self-Excited A.C. Generator for Ship Using New Methods of Parallel Running) and Its Application

Abstract

This paper reports about parallel running of self-excited A.C. generators. Generally, on parallel running of A.C. generators, cross current compensators are used not to circulate the reactive current among generators. But the cross current compensator is not able to distinguish the cross current from the load current. Therefore, when generator supplies the power to lag P.F. load, even if the cross current wouldn't occur, the voltage across terminals of generator varies according to the load. This characteristic is not desirable. To operate generators in parallel on constant voltage characteristic, SK generator is developed by the authors. SK generator is a kind of the self-excited A.C. generators, of which the feature is differential coil wounded in potential and current transformer supplying the exciting current. In parallel running, the differential coils of each generator are connected to each other through the equalizer, and the automatic voltage regulator without the cross current compensator is provided only in one of running generators. Thus it is possible to operate the generators in parallel on constant voltage characteristic. This method is the most profitable for ship generators, because two or more generators are installed so close in each other that the equalizer may be installed easily and the instantaneous voltage drop is very slight, starting the induction motor of large capacity across the line.