A 200 V d.c machine as Ra = 0.5 Ω and its full-load Ia= 20A. Determine the induced e.m.f when the machine acts as a motor

• A. 190 V
• B. 200 V
• C. 215 V
• D. 210 V

Answer: (A)

Given Data
Voltage Va = 200 v
Armature Resistance Ra = 0.5Ω
Armature Current Ia = 20 A
Induced EMF = Ea = ?
The Induced EMF of a DC machine working as a Motor is
Ea = Va − IaRa
Ea = 200 − 20 × 0.5
Ea = 190 V