Control System Engineering Set 1

Electrical Engineering

Practice Mode Next
On This Page

This set of Control System Engineering (CSE) Multiple Choice Questions & Answers (MCQs) focuses on Control System Engineering Set 1

Q1 | What is the algebraic sum of the reference input and feedback?
  • error signal
  • error detector
  • controlled system
  • controlled output
Answer: error signal
Explaination:
in the block diagram of a basic control system we see that the reference input is passed through error detector or comparator. the signal which leaves the same is the algebraic sum of reference input and feedback as the feedback wire is connected to the detector, so we call it error
Q2 | Feedback control systems are referred to as closed loop systems.
  • true
  • false
Answer: true
Explaination:
feedback control systems are also referred to as closed loop systems. in a closed loop, the actuating error signals, which is the difference between the input signal and
Q3 | Which principle does the linear system follow?
  • principle of energy conservation
  • principle of mass conservation
  • principle of electromagnetism
  • principle of superposition
Answer: principle of superposition
Explaination:
a linear system is one who obeys the principle of superposition. the principle of superposition states that the response produced by simultaneous application of two different forcing functions is equal to the sum of individual responses.
Q4 |              control systems have unpredictable & non-repeatable.
  • static
  • dynamic
  • deterministic
  • stochastic
Answer: stochastic
Explaination:
stochastic control systems are those who have unpredictable and non- repeatable response due to involvement of random parameters. static systems is the
Q5 | The pressure inside the furnace is measured by                
  • gauge
  • thermometer
  • manometer
  • barometer
Answer: gauge
Explaination:
the pressure inside the furnace is measured by pressure gauge. in case the pressure increases or decreases beyond the desired value, the controller and the actuator will cause a change in the position of the damper.
Q6 | On what difference does the pneumatic system works?
  • speed
  • pressure
  • area
  • length
Answer: pressure
Explaination:
a pneumatic system works due to pressure difference of air or any other gas. air at a pressure, pi is injected through the input manifold. it also consists of mass, coefficient of viscous friction and spring constant and the pressure difference created due to that, gives rise to pneumatic system.
Q7 | In a thermal system, the temperature of the medium is              
  • increasing
  • decreasing
  • zero
  • uniform
Answer: uniform
Explaination:
to analyze a thermal system and determine its transfer function the temperature of the medium should be uniform. if the temperature is varying or zero
Q8 | How many parameters does process control refer to?
  • 1
  • 3
  • 5
  • 7
Answer: 5
Explaination:
process control refers to control of five parameters which are level, flow, pressure, temperature, acidity of the process variable. a particular parameter has only one desired value.
Q9 | What is the effect of feedback in the overall gain of the system?
  • increases
  • decreases
  • zero
  • no change
Answer: decreases
Explaination:
the feedback reduces the overall gain of the system. as soon as we introduce feedback in the system to make the system stable, gain is reduced.
Q10 | In a temperature control system, what conversion in signal takes place?
  • digital to analog
  • analog to digital
  • error to digital
  • error to analog
Answer: analog to digital
Explaination:
in a temperature control system, analog to digital conversion of signals take place. automatic systems don’t understand analog signals as they only take digital inputs in the form of 0 & 1 so we use a analog to digital converter which converts the signal.
Q11 | Which of the following are the not characteristics of the closed loop systems?
  • it does not compensate for disturbance
  • it reduces the sensitivity of plant-parameter variations
  • it does not involve output measurements
  • it does not has the ability to control the system transient response
Answer: it does not has the ability to control the system transient response
Explaination:
feedback refers to the comparison of the final output to the desired output at respective input so as to get accurate and error free result and in the system improves the transient response of the system.
Q12 | Which one of the following effect in the system is not caused by negative feedback?
  • reduction in gain
  • increased in bandwidth
  • increase in distortion
  • reduction in output impedance
Answer: increase in distortion
Explaination:
distortion refers to the error in the open loop system and it has many oscillations in the output and is reduced in case of negative feedback.
Q13 | Which of the statement is correct with regard to the bandwidth of the control loop system:
  • in systems where the low frequency magnitude in 0 db on the bode diagram, the bandwidth is measured at the -3 db frequency
  • the bandwidth is the measurement of the accuracy of the closed loop system
  • the stability is proportional to the bandwidth
  • the system with larger bandwidth provides slower step response and lower fidelity ramp response
Answer: in systems where the low frequency magnitude in 0 db on the bode diagram, the bandwidth is measured at the -3 db frequency
Explaination:
bandwidth is the frequency measured at the gain of 3db and for the good control system the value of the bandwidth must be large but the large value of the bandwidth increses the noise in the system.
Q14 | Which of the statements are the advantages of closed loop systems over the open loop system:
  • the overall reliability of the open loop system is more than the closed loop system is more than closed loop system.
  • the transient response in closed loop system decays more quickly than in open loop system.
  • in open loop system closing the loop increases the gain of the system
  • in open loop system the effect of parameter variation is reduced
Answer: the transient response in closed loop system decays more quickly than in open loop system.
Explaination:
speed of response refers to the time taken to give the final output and it depends upon the rise and settling time of the transient response and speed of response of closed loop system is more than that of open loop system.
Q15 | In control system excessive bandwidth is not employed because
  • noise is proportional to bandwidth
  • it leads to low relative stability
  • it leads to slower time response
  • noise is proportional to the square of the bandwidth
Answer: noise is proportional to bandwidth
Explaination:
in closed loop system the bandwidth of the system is more as compared to the open loop system and this is so required as higher the bandwidth means lower the selectivity and hence higher the noise.
Q16 | Feedback control system is basically
  • high pass filter
  • low pass filter
  • band pass filter
  • band stop filter
Answer: low pass filter
Explaination:
low pass filter is mainly as integral controller and it is used as the controller in the system so as to increase the accuracy by reducing or proper eliminating the steady state error of the control system.
Q17 | Which of the following will not decrease as a result of introduction of negative feedback?
  • instability
  • bandwidth
  • overall gain
  • distortion
Answer: bandwidth
Explaination:
bandwidth always increases due to negative feedback as the speed of response is directly proportional to the bandwidth.
Q18 | As compared to the closed loop system, an open loop system is
  • more stable but less accurate
  • less stable as well as less accurate
  • more stable as well as more accurate
  • less stable but more accurate
Answer: more stable but less accurate
Explaination:
open loop system always follows the input but closed loop system always reduces the error irrespective of the input applied.
Q19 | Insertion of negative feedback in control system affects:
  • the transient response to vanish uniformly
  • the transient response to decay very fast
  • no change in transient response
  • the transient response decays at slow rate
Answer: the transient response to decay very fast
Explaination:
feedback can be positive or negative but practically positive feedback is not used as it causes oscillations in the system with more gain and hence negative feedback
Q20 | Open loop system is                        stable than closed loop system
  • more
  • less
  • inclined
  • exponential
Answer: more
Explaination:
open loop system always follows the input but closed loop system always reduces the error irrespective of the input applied.
Q21 | For the gain feedback system, does not affect the system output if KG is :
  • small
  • negative
  • one
  • very large
Answer: very large
Explaination:
t(s)=kg/(1+kgh) if kg>>1: then c(s)=r(s)/h.
Q22 | Determine the sensitivity of the overall transfer function for the system shown in the figure below, at w=1 rad/sec with respect to the feedback path transfer function.
  • 1.11
  • -1.11
  • 2.22
  • -2.22
Answer: -1.11
Explaination:
s= -g(s)h(s)/1+g(s)h(s)-1.1.
Q23 | Primary purpose of using Feedback is :
  • to reduce the sensitivity of the system to parameter variations.
  • to increase the bandwidth of the system
  • to reduce the noise and distortion of the system
  • to increase stability of the system
Answer: to reduce the sensitivity of the system to parameter variations.
Explaination:
the major requirement of the feedback is to reduce of the system with parameter variations that may vary with age, with changing environment.
Q24 | Which of the following is not the feature of modern control system?
  • quick response
  • accuracy
  • correct power level
  • no oscillation
Answer: no oscillation
Explaination:
for a good control system the speed of response and stability must be high and for the slow and sluggish response is not used and undesirable.
Q25 | The output of the feedback control system must be a function of:
  • reference input
  • reference output
  • output and feedback signal
  • input and feedback signal
Answer: input and feedback signal
Explaination:
feedback control system has the property of reducing the error and that is by differencing the output with the desired output and as the equation of the output of the system is c=gr/1+gh.
Next