Simplified Measurement of Subtransient and Negative Sequence Reactances in Salient-Pole Synchronous Machines [includes discussion]

The principles and practical results of a greatly simplified and much improved method of measuring subtransient and negative sequence reactances of generators are explained. This method is based upon the acceptance of methods now approved in an AIEE Standard1 and a Westinghouse reference book2 for measurement respectively of direct-axis and quadrature-axis subtransient reactances of salient-pole synchronous generators, and is subject to the same reasoning regarding the merits of testing with stationary rotor and with stator currents of lower than rated or saturated values. This is a radical modification of these methods; it avoids many serious mechanical and electrical difficulties, delays, and consequently some expense usually experienced in field testing and gives consistent and reliable results. No special test equipment is required. The method of making the test is described fully and the equations to be used in calculating the constants are given.