Question # $3$:

$(20)$

A $2300V,1000$kVA, $0\mathrm{.}8-$PF$-$Lagging. $60-$Hz$.$ two$-$pole, Y$-$connected synchronous generator has a synchronous reactance of $1\mathrm{.}1$ ohms and an armature resistance of $0\mathrm{.}15$ ohms $.$ At $60$ Hz $,$ its friction and windage losses are $24$ kW $,$ and its core losses are $18$ kW $.$ The field circuit has a dc voltage of $200$ V $,$ and the maximum $I_F$ is $10$ A $.$ The resistance of the field circuit is adjustable over the range from $20$ to $200$ ohms. The OCC of this generator is shown below. Assume that the field current of the generator has been adjusted to a value of $4\mathrm{.}5$ A $.$

a$)$ What will the terminal voltage of this generator be if it is connected to a Delta$-$connected load with an impedance of $20L30$ ohms?

b$)$ Sketch the phasor diagram of this generator.

c$)$ What is the efficiency of the generator at these conditions?

d$)$ Now assume that another identical Delta$-$connected load is to be paralleled with the

e$)$ first one. What happens to the phasor diagram for the generator?

f$)$ What is the new terminal voltage after the load has been added?

g$)$ What must be done to restore the terminal voltage to its original value?