MCQs on Cycloconverters

Power Electronics

1. Assertion (A): A cycloconverter essentially a dual converter but so operated as to produce an alternating output voltage.

Reason (R): Each SCR in a cycloconverter works as a phase-controlled converter with a varying firing angle.

a. A is false but R is true

b. A is true but R is false

c. Both A and R are true but R is not the correct explanation of A 

d. Both A and R are true and R is the correct explanation of A

2.  A cycloconverter requires_____.

a. Natural commutation in step-down mode and forced commutation in step-up mode

b. Forced commutation in step-down mode and natural commutation in step up mode

c. Forced commutation in both step-up and step-down mode

d. Natural commutation in both step-up and step-down mode

3. The number of thyristors required for single-phase to single-phase cycloconverter of the mid-point type and for three-phase 3-pulse type cycloconverter are respectively____.

a. 4 and 36

b. 4 and 18

c. 8 and 18

d. 4 and 6

4. The controlled rectifier used in which application_______.

a. Solar cells 

b. Magnet Power supply

c. High power ac drive

d. Ceiling fan drive

5. Cycloconverter used in which application_______.

a. Solar cells 

b. Magnet Power supply

c. High power ac drive

d. Ceiling fan drive

6.  Inverter used in which application________.

a. Solar cells 

b. Magnet Power supply

c. High power ac drive

d. Ceiling fan drive

7. Voltage controller used in which application_______.

a. Solar cells 

b. Magnet Power supply

c. High power ac drive

d. Ceiling fan drive

8. Compared to a cycloconverter, a d.c link converter______.

a. Requires natural commutation

b. Is suitable for low frequencies only

c. Has high input power factor if diode rectifier is used

d. All of the above

9. A cycloconverter power electronic equipment is a______.

a. Device which converts dc to ac

b. Device which converts ac to dc

c. frequency converter which has no intermediate dc state

d. None of the above

10. An intergroup reactor is used in a single-phase cycloconverter circuit to______.

a. Limit  di/dt in the semiconductor switch

b. Limit circulating current

c. Reduce voltage ripples

d. Reduce current ripples