When the firing angle α of a single phase, fully controlled rectifier feeding constant d.c. current into a load is 30o, the displacement power factor of the rectifier is

1.  1

2.  0.5

3.  

4.  

View Answer  
4
Correct Answer :

0.5


Explanation :
No Explanation available for this question

A 3 phase, fully controlled, converter is feeding power into a d.c. load at a constant current of 150 A. The rms current through each thyristor of the converter is

1.  50 A

2.  100 A

3.  

4.  

View Answer  
4
Correct Answer :


Explanation :
No Explanation available for this question

Resonant converters are basically used to

1.  generate large peaky voltage

2.  reduce the switching losses

3.  eliminate harmonics

4.  convert a square wave into a sine wave.

View Answer  
4
Correct Answer :

reduce the switching losses


Explanation :
No Explanation available for this question

A three phase semiconverter feeds the armature of a separately excited dc motor, supplying a non-zero torque. For steady state operation, the motor armature current is found to drop to zero at certain instances of time. At such instances, the voltage assumes a value that is

1.  equal to the instantaneous value of the ac phase voltage

2.  equal to the instantaneous value of the motor back emf

3.  arbitrary

4.  zero

View Answer  
4
Correct Answer :

equal to the instantaneous value of the motor back emf


Explanation :
No Explanation available for this question

In the single phase diode bridge rectifier shown in the given figure, the load resistor is R = 50 Ω ; source voltage is v = 200 sinωt, where ω2π X 50 radians per second. The power dissipated in the load resistor R is

1.  

2.  

3.  400 W

4.   800 W

View Answer  
4
Correct Answer :

400 W


Explanation :
No Explanation available for this question

A six pulse thyristor rectifier bridge is connected to a balanced 50 Hz, three phase ac source. Assuming that the dc output current of the rectifier is constant, the lowest frequency harmonic component in the ac source line current is

1.  100 Hz

2.  150 Hz

3.  250 Hz

4.  300 Hz

View Answer  
4
Correct Answer :

150 Hz


Explanation :
No Explanation available for this question

A half-wave thyristor converter supplies a purely inductive load, as shown in the figure below. If triggering angle of the thyristor is 120o, the extinction angle will be

1.  240o

2.  180o

3.  200o

4.  120o

View Answer  
4
Correct Answer :

120o


Explanation :
No Explanation available for this question

A three phase semiconverter feeds the armature of a separately excited dc motor, supplying a non-zero torque. For steady state operation, the motor armature current is found to drop to zero at certain instances of time. At such instances, the voltage assumes a value which is

1.  equal to the instantaneous value of the ac phase voltage

2.  equal to the instantaneous value of the motor back emf

3.  arbitrary

4.  zero

View Answer  
4
Correct Answer :

equal to the instantaneous value of the motor back emf


Explanation :
No Explanation available for this question

A thyristorised, three phase, fully controlled converter feeds a dc load that draws a constant current. Then input ac line current to the converter has

1.  an rms value equal to the dc load current

2.  an average value equal to the dc load current

3.  a peak value equal to the dc load current

4.  a fundamental frequency component, whose rms value is equal to the dc load current

View Answer  
4
Correct Answer :

a peak value equal to the dc load current


Explanation :
No Explanation available for this question

Fig. (a) given below shows an inverter circuit with a dc source4 voltage V8. The semiconductor switches of the inverter are operated in such a manner that the pole voltages v10 and v20 are as shown in Fig. (b). What is the rms value of the pole-to-pole voltage v12

1.  

2.  

3.  

4.  

View Answer  
4
Correct Answer :


Explanation :
No Explanation available for this question
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