EC question of 2015 semester five

Let us assume that no load voltage is Eg, load voltage is V, load current is I, shunt current is Is, current through armature is Ia and armature resistance is Ra.

The equation governing the current and voltages in shunt generator is -

V = Eg - IaRa
and Ia = I + Is

using them we get -

120 = 127 - Ia*0.02
so Ia = 350 ampere
and load current I = 120/15 = 8 ampere

Let us assume the following,

E = Voltage
E1 = Voltage at No Load = 127V
E2 = Voltage at Load = 120V
Ia = Armature Current
I = Load Current
Rsh = Field Resistance = 150 Ohms
Ra = Armature resistance = 0.02 Ohms

Now,
Ia = Net Voltage / Resistance
Ia = (E1 - E2) / Ra
= (127 - 120) / 0.02
= 7 / 0.02
= 350 Amp

E = Eb + IaRa
or, Eb = E - IaRa

I = E / Ra
= 120 / 15
= 8 Amp