Controllers Digital Control Systems - Electronic Engineering (MCQ) questions & answers

1)   Which architectural unit/block of PLC decides the sequence of different operations to be executed by means of instructions written in memory?

a. Memory
b. Programming software
c. I/O interface
d. CPU
Answer  Explanation 

ANSWER: CPU

Explanation:
No explanation is available for this question!


2)   Which among the following units of PLC is adopted to convey the control plan to CPU?

a. Memory
b. Power supply unit
c. I/O interface
d. Programming software
Answer  Explanation 

ANSWER: Programming software

Explanation:
No explanation is available for this question!


3)   How many digital inputs are present in PLCs?

a. 4
b. 8
c. 16
d. 32
Answer  Explanation 

ANSWER: 16

Explanation:
No explanation is available for this question!


4)   Which is the correct sequence of operational steps necessary for proper operation of an elevator (lift) control mechanism?

1. Up switch
2. Stop switch
3. Down switch
4. Start switch


a. 1-2-3-4
b. 2-1-4-3
c. 4-2-1-3
d. 3-1-2-4
Answer  Explanation 

ANSWER: 4-2-1-3

Explanation:
No explanation is available for this question!


5)   In addition to storage instructions, PLC controls __________

a. Logic sequence timing
b. Counting
c. Arithmetic operations
d. All of the above
Answer  Explanation 

ANSWER: All of the above

Explanation:
No explanation is available for this question!


6)   In P-D controller, the derivative action plays a significant role in increasing _______ of response.

a. Time
b. Distance
c. Speed
d. Volume
Answer  Explanation 

ANSWER: Speed

Explanation:
No explanation is available for this question!


7)   In P-I controller, what does an integral of a function compute?

a. Density of curve
b. Area under the curve
c. Volume over the curve
d. Circumference of curve
Answer  Explanation 

ANSWER: Area under the curve

Explanation:
No explanation is available for this question!


8)   Which controller has the potential to eliminate/overcome the drawback of offset in proportional controllers?

a. P-I
b. P-D
c. Both a and b
d. None of the above
Answer  Explanation 

ANSWER: P-I

Explanation:
No explanation is available for this question!


9)   Which time is responsible for introducing an error in the temperature regulation of applications associated with ON-OFF controllers?

a. Rise time
b. Dead time
c. Switching time
d. Decay time
Answer  Explanation 

ANSWER: Dead time

Explanation:
No explanation is available for this question!


10)   If an error signal e(t) of an ON-OFF controller is found to be greater than zero, what would be its output?

a. 10%
b. 50%
c. 80%
d. 100%
Answer  Explanation 

ANSWER: 100%

Explanation:
No explanation is available for this question!