Transient Commutation of Direct Current Machines (3)

Abstract

Commutation condition is determined by load current and interpole flux density. Then authors framed a equipment for observing black band of d.c. machine by cathode ray oscillograph. The oscillograph draw a black band and commutation condition under the transient state, and the intensity of the beam spot is modulated by the brush sparks. Then we are able to observe the sphere of spark on commutation condition under the transient state.
The results show that the brush sparks occur when the commutation condition under the transient state is off the black band under the steady state. And the time constant of eddy current is smaller than the calculated result of Rudenberg's equation.