Measurement of the load angle of synchronous machinery

The paper describes a method of determining by direct measurement the synchronizing power flowing to or from an alternator for a given angular displacement of the rotor from the normal running position.¿ The method was developed in connection with some experiments on the natural free period of alternators, but the results of the measurements can be used to obtain the effective reactance of the machine and the demagnetizing and cross-magnetizing coefficients for the armature field. It may, therefore, prove useful in providing data for the prediction of the performance of alternators on partial faults. Experimental results are quoted to show the accuracy that can be obtained by this method of measurement.