Question

A series generator, having external characteristics which is a straight line through 0 to 50 V at 200 A is connected as a booster, between a station bus-bar and feeders of 0.5 ohm resistors. The voltage at the far end of feeder at current of 50 A is?

(a) 25 V

(b) 17 V

(c) 8 V

(d) 50 V

The question was asked in a national level competition.

The doubt is from Methods of Excitation in portion DC Machines of Electrical Machines

Answer 1

Right answer is (a) 25 V

Explanation: V = voltage drop-voltage added up by boosters

               = (0.3*50 – 50*50/200)

      = 15-12.50

      = 2.5 V.