Load current representation of a D-C machine

FOR SOME TIME the interpole winding on d-c machines has been used to provide a signal for control circuits. The voltage drop across the interpole winding resistance can be used as a practical indication of large values of load current. However, for machine operation producing rapid changes in load current, the voltage across the interpole winding fails to remain proportional to load current. The purpose of this article is to present a system that will represent the load current for transient as well as for steady-state operation.