Transient Characteristics of DC Machinery Transient Behavior of Flux.

摘要

Accurate calculation of the current flow in a d-c machine during a transient requires a study of the flux behavior which governs generated voltage, leakage flux, commutation, coefficients of induction and eddy-current. It was found that the magnitude of air-gap flux suffers a small decrease up to peak transient current while its distortion is considerable and effects commutation adversely. The quality of commutation further deteriorates with vicious sparking and arcing due to the slow growth of interpolar flux. It was also noted that the main-pole leakage flux does not keep in step with the induced shunt field current. Application of the theorem of constant flux linkages is in small error up to peak armature current. Blocked rotor testing is found to be a practical method to determine flux variations under transient conditions approaching those of a short circuit. Techniques for flux measurements during static and rotating conditions and the measurement of bar-to-bar voltages are outlined. (Author)