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D1015 Pages:

A 3-phase star connected alternator supplies a load of 10001177 at a pf of 0.8
lagging with a terminal voltage of 11kV. Its armature resistance is 0.462 per
phase while synchronous reactance is 3Q per phase. Calculate the line value of
emf induced and full load regulation.

PART C
Answer any twofull questions, each carries 10 marks.

Explain the procedure to conduct slip test with a neat circuit diagram
Explain synchronisation of alternators using dark lamp method.
Explain any one method of starting of synchronous motor.
A 2000V, 3-phase, 4 pole star connected synchronous motor runs at 1500 rpm.
The excitation is constant and corresponds to an open circuit voltage of 2000V.
The resistance is negligible compared to synchronous reactance of 3Q per phase.
Determine power input, power factor, torque developed for an armature current
of 200A
Explain the effect of change in excitation of an alternator?
A 400V, 4-pole, 3-phase, 50Hz, star connected induction motor has rotor
resistance and reactance per phase 0.01Q and 0.1Q respectively. Determine a)
starting torque b) slip at maximum torque and c) maximum torque. Given rotor to
stator turns is 0.25.
PART D

Answer any twofull questions, each carries 10 marks.

Draw the circle diagram of a 20 Hp, 400 V, 50 Hz, 3-phase, star-connected

induction motor from the following test data (line values)

No load Test : 400V, 9 A , 0.2 pf

Blocked Rotor Test : 200V, 50 A, 0.4 pf

From the circle diagram, find the line current and power factor at full load.
The stator and rotor copper losses are divided equally in the blocked rotor test.
Explain with neat diagram, star-delta starter in 3-phase induction motor.
Compare induction generator with synchronous generator.

Explain types of single-phase induction motors with relevant figures?

Draw the equivalent circuit of single-phase induction motor

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