Discussion at Winter convention: Synchronous machines — III

J. F. H. Douglas: I wish to ask a question regarding the paragraph which reads, “It will be observed that the slope of the dotted line is still positive beyond the maximum power point of stable, steady-state operation. This means that if a machine were operating beyond the angle corresponding to maximum, steady-state power, say at 100 electrical degrees, the machine would be stable under sudden changes, although the steady-state characteristics at that point indicate instability.” I am somewhat curious to know under what operating conditions, if any, this becomes of interest?