Transient performance of D-C machinery — I

PREVIOUS STUDIES HAVE STRESSED the need for more accuracy in the calculation of transient currents than is provided by present methods. For the design of shipboard power systems, these methods are not sufficiently accurate and do not adequately reflect the influence of initial conditions of load, voltage, and speed on peak currents. There was also a disappointing lack of experimental verification of the important assumptions upon which the theoreticians were proceeding. Before developing a new approach or following a published calculation, it becomes evident that the limitations of any relations are determined by the validity and accuracy of the assumptions employed. It is concluded from this work that a more fundamental knowledge of the internal phenomena of rotating machinery is required before developing relations describing transient response of a d-c machine within design accuracy. Flux variations are fundamental to machine behavior in that they govern generated voltage, leakage fluxes, commutation, coefficients of induction, and eddy currents.