PART B

a. A separately excited dc generator running at 4500/17 rpm has the following pararneters
rr 80 OLI — 40 Hr.— 0.1 QL. 0.3m ಗ, Kg =120V/feild ampere.

(i) Feild is unexcited and amature is open .Find the arrnature voltage as a function
of time and sketch it if a constant voltage of 160% is suddenly impressed across the feild
terminals?

(ii) Sketch the Hse of armature current in part (i) ifthe armature terminals are
initially short circuited?

(iii) Armature voltage has attained a steady value in part (i) Now the armature is
suddenly connected to load of |. 1 0 in with inductance of 1. 7೧1. Determine armature
terminal voltageand armature 04116111 858 र time.

(iv) Find the electrical torque as a filnction oftime? Obtain the mez! value of torque

also? (6) b. Obtain the transfer function of separately excited dc generator? (3)

a. Obtain the expression for armature current of a separately excited dc generator if its
amature terminals are suddenly short circuited? (6)

b. Write notes on synchronous machine reactance? (3)

a. Obtain the steady state power angle characteristics of synchronous machine? (
6)

b. Derive the expression for reactive power of synchronous machine? (3)

PART C
a. Obtain the equivalent circuit of three phase induction machine from the primitive
modeP (9)
b. Obtain the torque slip :haracteristicsof three phase induction machine? (3)

9. VVhat happens to a three phase induction motor if one of its three supply leads
disconnected? Explain? (3)
b. Athree phase induction machine continues to run if one of the line fuses blows off

but does not start under one off condition. How &li.s feature explained with the
help of double field revolving theory? (4)