Question

A shunt generator has an induced voltage on open circuit of 127 V. When the machine is on load the terminal voltage is 120 V. The load current if the field resistance be 15 ohm and armature resistance be 15 ohm.

(a) 342 A

(b) 350 A

(c) 358 A

(d) 8 A

I got this question in an interview for internship.

Origin of the question is Circuit Model of DC Machines topic in chapter DC Machines of Electrical Machines

Answer 1

Right answer is (a) 342 A

To explain I would say: Ia*Ra = E-V

                   = 127 – 120

     = 7 V

       Ia = 350 A

             Ish = 120/15

                 = 8 A

      I = 350 – 8

               = 342 A