A 100 kW, 600 V, 600 rpm dc series wound railway motor has a combined field and armature resistance (including brushes) of 0.155 Ω. The full-load current at the rated voltage and speed is 206 A. The magnetization curve at 400 rpm is as follows:
(a) Determine the armature reaction in equivalent demagnetizing field current at 206 A.
(b) Calculate the internal (developed) torque at the full-load current.
(c) Assuming demagnetizing armature reaction mmf proportional to deter mine the internal starting torque at the starting current of 350 A.