New method of measuring 2-axis quantities

The paper describes a new measuring technique in which synchro resolvers are used to generate the transformed 2-axis variables from the armature phase quantities. It is applicable to any a.c. machine under dynamic conditions, and the technique has particular significance in the analysis of synchronous machines, enabling much information to be obtained from a single starting test. Frequency-response loci of the axis impedances are readily obtained from an oscillogram of the 2-axis quantities, and in certain cases the loci may be extrapolated to yield the usual machine reactances. The technique also enables the instantaneous electromagnetic torque to be determined and analysed with the aid of the complex admittance loci into components associated with the direct and quadrature axes.