Exam Details
| Subject | Power Electronics | |
| Paper | ||
| Exam / Course | B.Tech. VIEP- Electrical Engineering III | |
| Department | School of Engineering & Technology (SOET) | |
| Organization | indira gandhi national open university | |
| Position | ||
| Exam Date | June, 2016 | |
| City, State | new delhi, |
Question Paper
Explain the I characteristics of SCR.
What is the difference between a thyristor and a TRIAC? Draw and explain the V characteristics of TRIAC.
2.(a) What is reverse recovery time of the power semiconductor diode The forward voltage drop of a power diode is VD= 1·2 V at ID 300 A. Assuming that n 2 and VT 25·7 mV, find the reverse saturation current What is the purpose of dv/dt protection? What is the common method of dv/dt protection
3.(a) Differentiate between semi-converter and full converter circuit. Draw anyone semi-converter and full-converter circuit.
Explain gate trigger controller circuit of SCR.
4. Draw the two-transistor model of a thyristor. Explain the turn-off and turn-on characteristics of a thyristor.
5. Ten thyristors are used in a string to withstand a d.c. voltage of Vs=15 kV. The maximum leakage current and recovery charge differences of the thyristors are 10 rnA and 150 micro respectively. Each thyristor has a voltage-sharing resistance of R =56 k.ohm and capacitance of C1 0·5 micro F. Determine
the maximum steady state voltage sharing VDS the steady state voltage derating factor, the maximum transient voltage sharing and the transient voltage derating factor.
6. Draw and explain the working of a single-phase dual converter. Also draw its V characteristics. What is the cause of circulating current in dual converters?
7. What are the main effects of source inductance for a full-converter? A three-phase full-converter is fed by 400 volts, three-phase, 50 Hz supply. The average load current is 150 A and the load is highly inductive. For a firing angle of 60° find the output power, average output voltage, rms and peak current through the thyristors and peak inverse voltage.
8. With the help of a neat circuit diagram and waveforms, explain briefly the operation of a transistorised 3-phase bridge inverter with resistive load in 180° conduction mode.
9. Circuit in Figure 1 employing complementary commutation has Vs= 200 R1 10 ohms and R2 =100 ohms. Determine the peak value of current through thyristors T1 and T2, value of capacitor C if each thyristor has a turn-off time of 40 micro Sec. Take a factor of safety 2.
<br> <img src='./qimages/12234-9b.jpg'>
10. Write short notes on any two of the following: Thyristor Firing Circuits Series and Parallel Connections of Diode Impulse Commutation
Sinusoidal Pulse Width Modulation
What is the difference between a thyristor and a TRIAC? Draw and explain the V characteristics of TRIAC.
2.(a) What is reverse recovery time of the power semiconductor diode The forward voltage drop of a power diode is VD= 1·2 V at ID 300 A. Assuming that n 2 and VT 25·7 mV, find the reverse saturation current What is the purpose of dv/dt protection? What is the common method of dv/dt protection
3.(a) Differentiate between semi-converter and full converter circuit. Draw anyone semi-converter and full-converter circuit.
Explain gate trigger controller circuit of SCR.
4. Draw the two-transistor model of a thyristor. Explain the turn-off and turn-on characteristics of a thyristor.
5. Ten thyristors are used in a string to withstand a d.c. voltage of Vs=15 kV. The maximum leakage current and recovery charge differences of the thyristors are 10 rnA and 150 micro respectively. Each thyristor has a voltage-sharing resistance of R =56 k.ohm and capacitance of C1 0·5 micro F. Determine
the maximum steady state voltage sharing VDS the steady state voltage derating factor, the maximum transient voltage sharing and the transient voltage derating factor.
6. Draw and explain the working of a single-phase dual converter. Also draw its V characteristics. What is the cause of circulating current in dual converters?
7. What are the main effects of source inductance for a full-converter? A three-phase full-converter is fed by 400 volts, three-phase, 50 Hz supply. The average load current is 150 A and the load is highly inductive. For a firing angle of 60° find the output power, average output voltage, rms and peak current through the thyristors and peak inverse voltage.
8. With the help of a neat circuit diagram and waveforms, explain briefly the operation of a transistorised 3-phase bridge inverter with resistive load in 180° conduction mode.
9. Circuit in Figure 1 employing complementary commutation has Vs= 200 R1 10 ohms and R2 =100 ohms. Determine the peak value of current through thyristors T1 and T2, value of capacitor C if each thyristor has a turn-off time of 40 micro Sec. Take a factor of safety 2.
<br> <img src='./qimages/12234-9b.jpg'>
10. Write short notes on any two of the following: Thyristor Firing Circuits Series and Parallel Connections of Diode Impulse Commutation
Sinusoidal Pulse Width Modulation
Other Question Papers
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- Centre for Corporate Education, Training & Consultancy (CCETC)
- Centre for Corporate Education, Training & Consultancy (CCETC)
- National Centre for Disability Studies (NCDS)
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Subjects
- Power Electronics
- Power System Planning And Load Forecasting