Electronic computers applied to commutation analysis

The paper deals with the analysis of armature-coil currents and voltages during commutation, and bar-brush currents and voltages, for d.c. machines. The application of electronic digital and analogue computers to solution of the simultaneous differential equations for coil currents is described. It is assumed that the bar-brush dynamic contact conductance is directly proportional to the area of geometric contact. Good correlation is obtained between calculated and measured curves of coil current and voltage during commutation. The analysis may be used for the calculation of black-band curves. Methods of calculating the components of coil e.m.f. required for the analysis are described in two companion papers.