STUPIDSID
1(a)
Define inrush current in three phase transformer
5 M
1(b)
Explain the Dd0 phasor group of three phase transformer connection along with connection diagram and phasor diagram.
5 M
1(c)
Name the different methods of starting of single phase induction motor and explain any one.
5 M
1(d)
Explain the working principle of three phase induction motor.
5 M
2(a)
A three phase, star connected , 400V, 50MHz, 4 pole induction motor has the following per phase constants in ohm referred to stators
R1=0.15, XR1=0.45, RR2=0.12, XR2=0.45, XRm=28.5
R1=0.15, XR1=0.45, RR2=0.12, XR2=0.45, XRm=28.5
10 M
2(b)
Explain star-delta starter for a 3 phase induction motor. Derive the expression for starting current and starting torque.
10 M
3(a)
Explain the necessity of controlling voltage along with frequency fro speed control of an induction motor for v/f control method. Also draw torque-speed characteristics for constant v/f ratio at different frequencies.
10 M
3(b)
Explain double field revolving theory for a single phase induction motor.
10 M
4(a)
A 500 KVA , 3 phase transformer, having per phase leakage impedance of 0.004+j0.018 ohm is connected in parallel with another transformer of the same voltage ration having a rating of 1000 KVA and per phase leakage impedance of 0.002+j0.012 ohm. Find the load shared by each transformer and their operating power factors for a load of 1500 KVA at 0.8 pf lagging.
10 M
4(b)
Conditions required for successful parallel operation of three phase transformers.
10 M
5(a)
Draw & explain torque-speed characteristics of 3 phase induction motor at variable rotor resistance.
10 M
5(b)
Develop equivalent circuit for a single phase induction motor
10 M
Write a short note on:
6(a)
Excitation phenomenon in 3 phase transformer
10 M
6(b)
Oscillating Natural
10 M
6(c)
Double cage induction motor
10 M
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