STUPIDSID
1 (a)
Compare symmetrical and asymmetrical and semiconverter
5 M
1 (b)
What is meant by voltage and current commutation?
5 M
1 (c)
Compare series and parallel inverter.
5 M
1 (d)
What is four quadrant D.C drive?
5 M
2 (a)
Explain sinusoidal pulse width modulation as used in PWM inverter.
10 M
2 (b)
A load commutated chopper fed from 230V D.C source has a constant current of 50A. For a duty cycle of 0.4 and chopping frequency of 2 kHZ calculate:
1. Value of commutating capacitor.
2. Average output voltage.
3. Circuit turn off time for 1 ? pair of SCR?s
4. Total commutation interval
1. Value of commutating capacitor.
2. Average output voltage.
3. Circuit turn off time for 1 ? pair of SCR?s
4. Total commutation interval
10 M
3 (a)
Explain the working of single phase series inverter with appropriate circuit diagrams and waveforms.
10 M
3 (b)
Explain constant torque and constant power generation of a separately excited D.C motor. Give the schematic diagram of control unit.
10 M
4 (a)
A single phase fully controlled bridge with 230V, 50 Hz supply feeds continuous ripple free current of 20A. if La=2.5mH calculate:
i. Calculate overlap angle for the firing angle 60o.
ii. What will be the new value of the overlap angle for same firing angle if load is reduced by 50%.
i. Calculate overlap angle for the firing angle 60o.
ii. What will be the new value of the overlap angle for same firing angle if load is reduced by 50%.
10 M
4 (b)
Draw and explain the variable voltage and variable frequency control method for 3 ? phase squirrel cage induction motor. What is the significance of v/f control.
10 M
5 (a)
A single phase full converter is used to drive separately excited D.C shunt motor with Ra=0.25&Omega. Motor rating are 220V, 750 RPM, 50A. If input voltage to converter connected to armature is 250V ac 50 Hz. Calculate:
i. Firing angle delay for 500 RPM rated torque.
Speed of motor for firing angle ?=600 at half load.
i. Firing angle delay for 500 RPM rated torque.
Speed of motor for firing angle ?=600 at half load.
10 M
5 (b)
Explain the working of Jone?s chopper with the help of waveforms.
10 M
6 (a)
Give the advantages of flyback converter compared to forward converter. With the help of neat circuit diagram and waveform, explain the operation of isolated forward converter.
10 M
6 (b)
Using block diagram discuss different configurations of UPS.
10 M
Write Short notes on:
7 (a)
Dual converter.
10 M
7 (b)
Mc'Murray Inverter.
10 M
7 (c)
Four quadrant chopper.
10 M
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