A separately excited, 200 V, DC motor runs with a speed of 1500 rpm at no load current of 5 A. When operated at full load current is found to be 50 A. Assuming constant flux operation with armature resistance of 0.2 Ω, calculate full load speed.

Correct option is C

· N₁ = 1500 rpm
· V = 200 V
· Ra = 0.2 Ω
· Ia at no load = 5 A
· Ia at full load = 50 A
Step 1: ENL = 200 - 0.2 × 5 ENL = 199 V
Step 2: EFL = V - Ia × Ra EFL = 200 - 0.2 × 50 EFL = 190 V
Step 3: 199/1500=190/N2
Step 4: N₂ = 1432 rpm