EE6504 ELECTRICAL MACHINES-II, Third year, Department of Electrical
and Electronics Engineering, Model Exam Questions.
ANSWER ALL THE QUESTIONS
PART A(10*2=20)
2. What are the advantages
of salient pole type of construction use for synchronous
Machines?
3. What is meant
by synchronous condenser?
4. What is meant
by hunting of synchronous motor?
5. Why are slots
on the cage rotor of induction motor usually skewed?
6. Define slip
of an induction motor?
7. What are
different methods of speed control employed in three phase cage induction
motor?
8. Why starter
is necessary for three phase induction motor?
9. What is the
advantages of capacitor start induction motor over split phase induction motor?
10.Mention the
application of hysteresis motor.
PART B(5*16=80)
11(a).Explain
briefly the construction and working principle of alternator with neat
sketch (16)
(OR)
(b). (i).Derive
an EMF equation of an alternator
(8)
(ii).A 2000 KVA,11KV, 3 phase star
connected alternator has a resistance of 0.3Ω and reactance of 5Ω/ phase. It
delivers full load current at 0.8 lagging power factor at rated voltage.
Compute the
terminal voltage for the same excitation and load current at 0.8 power factor
leading.
(8)
12 (a).Describe
various method of starting of synchronous motor. (16)
(OR)
(b). A 3 Phase, 11000V, star connected
synchronous motor takes a load of 100A. The effective synchronous reactance and
resistance per phase are 30Ω and 0.8Ω respectively. Find the power supplied to
the motor and induced emf for (i). 0.8 pf lag, (ii). 0.8 pf lead. (16)
13.(a). A 3
phase ,6 pole 50 Hz induction motor has
a slip of 1% at no load and 3% at full load. Find (1).synchronous speed (2).no
load speed (3). Full load speed (4).frequency of rotor current at stand still
(5).frequency of rotor current at full load.
(16)
(OR)
(b).(i). Draw and explain slip torque
characteristics of 3 phase induction motor (8)
(ii). Derive the torque equation of 3
phase induction motor. (8)
14. (a)With neat
sketch explain the two type of starters used for 3 phase squirrel cage
inductance
motor
(16)
(OR)
(b). Explain slip power recovery
scheme.
(16)
15. (a).Explain
briefly the operation of capacitor start and split phase induction motor. (16)
(OR)
(b). Discuss briefly the operation and
characteristics of
(i). Repulsion motor
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