Determination of Synchronous Machine Constants by Test Reactances, Resistances, and Time Constants

Abstract

In recent years there have been many advancements made in the art of analysis of three-phase synchronous machine operation. Most treatments to date have very properly stressed the theoretical point of view, the practical point of view receiving less attention due in part to the complications involved, particularly those due to saturation effects. In this paper the practical stand-point is stressed and discussed on the basis of observations made from many tests; an important feature of these tests is that saturation effects under short circuit were studied by applying short circuits to machines operating at rated voltage. Due to serious saturation effects, the so-called constants of synchronous machines may have different values under different conditions. What are considered to be the most important of these values are discussed, and by defining certain saturated and other values, an attempt is made to provide a definite basis for the specification of machine constants. Part I reviews certain basic concepts and discusses practical considerations of test methods. Part II describes methods of determining the more important constants by test. Part III illustrates the application of these methods to actual power machinery, and presents tabulated test results as well as a table of typical constants. The Appendixes are devoted to certain additional tests and conclusions, and to development of formulas.