STUPIDSID
Solve any one question from Q.1(a,b) & Q.2(a,b)
1(a)
With a neat diagram explain consturction of three phase Alternator.
5 M
1(b)
Effective resistance of a 1200 kVA, 3300 V, 50Hz three phase star connected alternator is 0.3Ω per phase. A field current of 35A produces a current of 200A of short circuit and 1100 V across line on open circuit. Find the per unit change in terminal voltage when full load of 1200kW at 0.8 power factor lagging is thrown off.
5 M
2(a)
Explain pitch factor with diagram.
4 M
2(b)
Explain the procedure to determine the regualation of three pahse alternator by m.m.f, method.
6 M
Solve any one question from Q.3(a,b) & Q.4(a,b)
3(a)
Compare three phase synchronous motor with three phase induction motor on following point.
i) Starting
ii) Speed
iii) Power factor iv) Cost/k VA
v) Size kVA
i) Starting
ii) Speed
iii) Power factor iv) Cost/k VA
v) Size kVA
5 M
3(b)
A three phase 10kW synchronous motor is connected to 1000V supplyand has synchronous reactance of 10Ω per phase. Find the value of minimum. current and the corresponding induced emf for full load condition the efficiency of the motor is 0.8 Neglect the armature resistance.
5 M
4(a)
Define short circuit ratio of alternator. Elaborate its significance.
4 M
4(b)
An alternator has direct axis synchronous reactance of 0.9 per unit and quadrature axis reactance of 0.55 per unit. Find the per unit open circuit voltage for full load at lagging power factor of 0.8.
6 M
Solve any one question from Q.5(a,b) & Q.6(a,b)
5(a)
Explain construction and working of brushless d.c. motor.
8 M
5(b)
Explain stator side speed control methods of three phase induction motor.
8 M
6(a)
Explain consturction and working of variable reluctance stepper motor.
8 M
6(b)
Draw complete slip- torque characteristics of three phase induction motor and explain working of induction generator.
8 M
Solve any one question from Q.7(a,b) & Q.8(a,b)
7(a)
Explain procedure to plot circle diagram of a.c. series motor.
8 M
7(b)
Explain the working of univeral motor with its operating characteristics.
8 M
8(a)
Comapare uncompensated a.c. series motor with compensated a.c. series motor.
8 M
8(b)
A universal motor having resistance of 40Ω and inductance of 0.3H connected to 240V d.c. supply and loaded draws 1A at 200rpm. Find the speed and torque when the motor is connected with 240V, 50Hz a.c. supply and loaded to draw the same value of current when connected with d.c. supply.
8 M
Solve any one question from Q.9(a,b) & Q.10(a,b)
9(a)
With neat diagram explain double revolving field thoery. Hence draw torque-speed characteristics of single phase induction motor.
8 M
9(b)
With a suitable diagram explain no load and blocked rotor test on single phase induction motor. How equivalent parameters are obtained form these tests. Draw equivalent circuits of the motor under two test conditions.
10 M
10(a)
With neat diagram explain construction and working of split phase induction motor. Draw its torque speed characteristics.
8 M
10(b)
A230V, 50Hz, 4pole single pahse induction motor has the following equivalent circuit parameters R1=3ΩR2=5Ω, X1=3Ω,X2=2.5Ω and Xm=75Ω. Friction, windage and core losses are 50W and slip is 0.025. Calculate:
i) Input current
ii) Power factor
iii) Developed power
iv) Output power
v) Efficiency
i) Input current
ii) Power factor
iii) Developed power
iv) Output power
v) Efficiency
10 M
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