STUPIDSID
Answer the following in brief
1(a)i
What are the requirements to make the SCR on? Explain the various Turn On methods in brief.
4 M
1(a)ii
Make the comparison between DIAC and TRIAC.
4 M
Answer the following
1(b)i
A 200 A SCR is to be used in parallel with 150 A SCR. The on state voltage drops of the SCRs are 2 and 1.8 V, respectively. Calculate the series resistance that should be connected with each SCR if two SCRs have to share the total current 250 A in proportion to their rating
3 M
1(b)ii
Explain the snubber circuits for SCR.
3 M
2(a)
Explain the operation of single phase semi controlled bridge converter with resistive and inductive load. Draw the associated waveforms.
7 M
Solve any one question from Q.2(b) & Q.2(c)
2(b)
Calculate the average output voltage of a three phase half controlled bridge operating with triggering angle π/2 and connected to three phase ac
supply of 400V and 50 Hz. The load current is assumed to be continuous.
7 M
2(c)
A single phase half wave converter is used to supply power to a load of impedance 10 Ω from 230 V, 50 Hz ac supply at the firing angle of 30°. Calculate average load voltage, load current and RMS load voltage.
7 M
Solve any one question from Q.3 & Q.4
3(a)
With help of neat circuit diagram and waveforms, explain the operation of
three phase bridge inverter with resistive load in 120° conduction mode.
7 M
3(b)
With help of neat circuit diagram and waveforms describe the working of a two quadrant chopper. List out its applications.
7 M
4(a)
Explain the single phase PWM, transformer connection, multiple commutation and filter methods used for reduction of harmonics in inverter output.
7 M
4(b)
Compare the step up and step down chopper.
7 M
Solve any one question from Q.5 & Q.6
5(a)
What is commutation? With help of circuit diagram and necessary waveform explain the complementary (Class C) forced commutation.
7 M
5(b)
Explain the construction and characteristics of UJT and working of UJT as an oscillator for generation of triggering pulses.
7 M
6(a)
With help of circuit diagram explain the half wave and full wave RC firing circuits of SCR.
7 M
6(b)
Draw and explain the structure of power MOSFET. Also explain principle of operation and I-V characteristics of power MOSFET.
7 M
Solve any one question from Q.7 & Q.8
7(a)
Write short note on isolation circuits and pulse transformer.
7 M
7(b)
Write short note on On-line UPS.
7 M
8(a)
Write short note on Boost converter.
7 M
8(b)
Write short notes on RF heating.
7 M
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