1. a) Explain in
detail the principle of flux in transformer is always constant at all loads.
b) Derive the emf equation of transformer? Draw the NO-Load phasor
diagram? (6+9)
2. a) Define
voltage regulation of a transformer. Deduce the expression for the voltage
regulation.
b) Derive the equivalent circuit diagram of single phase
transformer? (7+8)
3. a) The
number of turns on the primary and secondary windings of a single phase
transformer is 350 and 35 respectively. If the primary is connected to a 2.2 kV
50 HZ supply. Determine the secondary voltage.
b) Describe the procedure for conducting sumpners test on pair of
transformers? (5+10)
4. What are the
different losses occurring in a transformer on load? How can these losses be
determined experimentally? (15)
5. A 5 KVA,
1000/200V, 50Hz single phase transformer gave the following test results:
Open-circuit test: (l.v side): 200V, 1.2 A, 90 W
Short-circuit
test (h.v Side): 50 V, 5 A, 110 W
Compute the
parameters of the approximate equivalent circuit referred to l.v side. Also
draw the exact equivalent circuit referred to l.v side. (15)
6. A three
phase transformer is used to step down the supply voltage from 10000 V to 440
V. If the output capacity of the transformer is 132 kVA, find the secondary and
primary currents of the transformer. (15)
7. a) Why does the magnitude of the magnetic
field remain constant, and also what is the speed of rotation of the magnetic
field, so formed? Also what is meant by the term ‘Synchronous Speed’.
b) Derive
the relationship between mechanical power developed, rotor input and rotor
copper loss. (6+9)
8. Explain the speed control of induction motor
form stator side? (15)
