A Basic Analysis of Synchronous Machines-Part I

The equivalent circuits presented here differ from those previously presented in two principal respects: 1. By a different choice of coefficient in the defining equations for id and iq, the equivalent circuits have been made reciprocal inherently, so that a special choice of base or turns ratio is not required to accomplish this desirable result. 2. The circuits have been so developed that they may be easily established either in a per-unit system, as has been the practice heretofore, or in a physical system, as may be more convenient. These two features should make circuits of this type easier to use and more convenient for practical calculation. The programming of the solution of the corresponding equations on a digital computer should make possible the routine use of these methods for computation of the starting performance of synchronous motors in design work. Since many variations can be tried easily and rapidly, it would now be possible to achieve optimum design proportions for specified needs. The further development of these circuits and their specific application to the calculation of starting performance of synchronous motors is treated in a paper by Giaever.14 It has been shown that the turns ratios used to modify the field and damper circuits are arbitrary, but that there is a definite range of ratios which will ensure that each branch of an equivalent circuit used to represent the relations between any two windings will be positive.