STUPIDSID
Answer the following in brief:
1 (a) (i)
What is commutation in SCR circuits? Explain self commutation in SCR circuits.
4 M
1 (a) (ii)
Compare SCR and TRIAC.
4 M
Answer the following:
1 (b) (i)
List the various turn on methods of SCR. Explain resistance triggered circuits.
3 M
1 (b) (ii)
Explain how fly wheel diode improves the power factor of the systems.
3 M
2 (a)
Explain the operation of single phase fully controlled bridge converter with inductive load. Draw the associated waveforms.
7 M
Solve any one question from Q2(b) & Q2(c)
2 (b)
What are the needs of series and parallel operations of thyristor? Explain the problems with series and parallel operations of thyristor and possible
solutions
7 M
Define the following terms for SCR.
2 (c) (i)
Latching and holding current (ii) dv/dt and di/dt rating.
4 M
2 (c) (ii)
Thermal and current rating
3 M
Solve any two question from Q3(a), Q3(b) & Q3(c), Q3(d)
3 (a)
Explain the principle of an inverter. With help of neat diagram and associated waveform explain the operation of single phase half bridge voltage source inverter.
7 M
3 (b)
Explain the principle of operation of step up Chopper with resistive load. Differentiate between constant frequency and variable frequency operation of this chopper.
7 M
3 (c)
Explain the circuit diagram and operation of three phase bridge inverter. Draw phase and line voltage waveforms on the assumption that each thyristor conducts for 120° and resistive load is star connected.
7 M
3 (d)
With the help of a neat circuit diagram and associated waveforms, discuss the operation of Buck converter. List the advantages and disadvantages of this type of converter.
7 M
Solve any two question from Q4(a), Q4(b) & Q4(c), Q4(d)
4 (a)
What is forced commutation? With help of circuit diagram and necessary waveform explain the complementary commutation
7 M
4 (b)
Explain the construction and characteristics of GTO. Compare the turn on and turn off method of GTO with SCR.
7 M
4 (c)
Draw a circuit diagram for ramp and pedestal trigger circuit used for the single phase semi converter. Describe its operation with appropriate
waveforms.
7 M
4 (d)
Write short note on IGBT.
7 M
Solve any two question from Q5(a), Q5(b) & Q5(c), Q5(d)
5 (a)
Explain the circuit diagram and working of single phase semi converter with freewheeling diode.
7 M
5 (b)
Write short note Uninterrupted Power Supply.
7 M
5 (c)
Write short note on four quadrant Type E chopper.
7 M
5 (d)
Write short notes on dielectric heating and induction heating.
7 M
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