STUPIDSID
1 (a)
Differentiate between SCR and IGBT.
5 M
1 (b)
State and explain the conditions to operate fully controlled bridge converter as an inverter.
5 M
1 (c)
Draw and explain equivalent circuit of heat sink.
5 M
1 (d)
Explain UJT with the help of equivalent circuit and characteristics.
5 M
2 (a)
What do you understands by commutation of SCR. Explain class C commutation with the help of waveforms.
10 M
2 (b)
Design the beginning circuit for SCR using UJT. The UJT parameters are VS=30, η=0.51, Ip=1 μA, Vv=3.5V Iv=10 mA. Frequency of oscillation is 50 Hz. Width of the trigger pulse is 50 7mu;s.
10 M
3 (a)
What is the need of freewheeling diode in case rectifier with R-L load. Draw and explain full bridge controlled rectifier with R-L load and freewheeling diode. Derive the relation for load voltage.
10 M
3 (b)
Draw and explain single AC voltage controller circuit using DIAC and TRIAC. Draw waveforms.
10 M
4 (a)
Explain the role of snubber circuit to protect SCR against high di/dt and dv/dt.
10 M
4 (b)
What is the difficulty in parallel connection of SCRS. Draw and explain equalising network with design criterion for components.
10 M
5 (a)
A single phase semiconverter is operated from 120V, 50Hz, ac supply. The load resistance is 10 Ω. The average O/P voltage is 25% of the maximum possible average output voltage. Determine
i) Firing angle
ii) RMS and average output current
iii) RMS and average thyristor current.
i) Firing angle
ii) RMS and average output current
iii) RMS and average thyristor current.
10 M
5 (b)
Explain three phase bridge full converter with R load with continuous load current.
10 M
6 (a)
Draw and explain over voltage protection circuit for SCR.
5 M
6 (b)
Differentiate between symmetrical IGBT and asymmetrical IGBT.
5 M
6 (c)
Draw and explain RAMP and pedestal triggering circuit using UJT. Draw waveforms.
10 M
7 (a)
Performance parameters of controlled rectifier.
5 M
7 (b)
Soft start circuit.
5 M
7 (c)
Half waving effect in controlled rectifier.
5 M
7 (d)
GTO switching characteristics.
5 M
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