Measurement of D-C Machine Parameters

An, equivalent circuit is suggested to represent the d-c machine when operating under near normal current conditions. This equivalent circuit contains resistances, inductances, and speed-voltage constants. Certain d-c tests are suggested for obtaining the resistances and speed-voltage constants. Either the transient or a-c methods may be employed for ascertaining the inductances although the a-c method seems the simpler; circuits and techniques are described for both methods. Experimental verification of the equivalent circuit and methods of measurement take the form of application to a compound motor and to the amplidyne, a complex d-c machine with many diverse windings on the same magnetic circuit.