AP ECET EEE 2017-10

1. An advantage of a Cycloconverter is

A. Very good power factor
B. Requires few number of thyristors
C. Commutation failure does not short circuit the source
D. Load commutation is possible

Answer : Very good power factor
Explain:-

2. In single phase to single phase cycloconverter, if alpha 1 and alpha 2 are the trigger angles of positive converter and negative converter, then

A. alpha 1 + alpha 2 = π/2
B. alpha 1 + alpha 2 = π
C. alpha 1 + alpha 2 = 3π/2
D. alpha 1 + alpha 2 = 2π

Answer : alpha 1 + alpha 2 = π
Explain:-

3. A four quadrant chopper cannot be operated as

A. One quadrant chopper
B. Cycloconverter
C. Inverter
D. Bidirectional rectifier

Answer : Cycloconverter
Explain:-

4. If an AC chopper is feeding an inductive load, the firing pulse to the SCR

A. May have a width equal to turn ON time of the SCR
B. Should be a series of pulses of short duration
C. Should be a single pulse of long duration
D. Should be a train of pulses of duration equals to the conduction period of the SCR

Answer : Should be a train of pulses of duration equals to the conduction period of the SCR
Explain:-

5. A converter which can operate both in 3-pulse and 6-pulse modes is

A. 1-phase full converter
B. 3-phase half wave converter
C. 3-phase semi converter
D. 3-phase full converter

Answer : 3-phase semi converter
Explain:-

6. Which one of the following is the main advantage of SMPS over linear power supply

A. No transformer is required
B. Only one stage of conversion
C. No filter is required
D. Low power dissipation

Answer : Low power dissipation
Explain:-

7. Among the following special function registers which is not bit addressable

A. PSW
B. TCON
C. SCON
D. PCON

Answer : PCON
Explain:-

8. Which of the following instruction represents Indexed addressing

A. MOV Ro, 89H
B. MOV A, #100
C. JMP \@A+DPTR
D. ADD A, R7

Answer : JMP \@A+DPTR
Explain:-

9. Which of the following 8051 interfacing peripheral acts as a Programmable interrupt controller

A. 8251
B. 8259
C. 8255
D. 8257

Answer : 8259
Explain:-

10. In 8051 microcontroller ________register is used to control the operation of the serial port

A. TMOD
B. PSW
C. PCON
D. SCON

Answer : SCON
Explain:-