Transient Commutation of Direct Current Machines (2)

Abstract

When load current change is suddenly, commutation conditions of d. c. machines are impaired and then the brush sparks appear instantaneously under the transient state.
Commutation condition depends upon the relation between load current and interpole flux density. Under the transient state, eddy currents of the flux path tend to oppose the interpole flux change.
This paper describes a method of calculating the rise of interpole flux by equivalent circuit of eddy currents, and analyzes the commutation condition under the transient state in relation to the black band of d. c. machine under the steady state.