Control System Engineering MCQs | Page - 5

Dear candidates you will find MCQ questions of Control System Engineering here. Learn these questions and prepare yourself for coming examinations and interviews. You can check the right answer of any question by clicking on any option or by clicking view answer button.

📊 Control System Engineering
Q. Consider the unity feedback system with open loop transfer function the minimum value of the steady state error to a ramp input r(t) = 6tu(t) is OLTF = K/s(s+1)(s+2)
  • (A) 1
  • (B) 2
  • (C) 3
  • (D) 4
💬 Discuss
✅ Correct Answer: (B) 2

Explanation: routh-hurwitz criterion is used to calculate the stability of the system by checking the sign changes of the first row and

📊 Control System Engineering
Q. A ramp input applied to a unity feedback system results in 5% steady state error. The type number and zero frequency gain of the system are respectively
  • (A) 1 and 20
  • (B) 0 and 20
  • (C) 0 and 1/20
  • (D) 1 and 1/20
💬 Discuss
✅ Correct Answer: (A) 1 and 20

Explanation: steady state error is the error calculated between the final output and desired output and for the good control system the error must be less and this steady state error is inversely proportional to gain.

📊 Control System Engineering
Q. A particular control system yielded a steady state error of 0.20 for unit step input. A unit integrator is cascaded to this system and unit ramp input is applied to this modified system. What is the value of steady- state error for this modified system?
  • (A) 0.10
  • (B) 0.15
  • (C) 0.20
  • (D) 0.25
💬 Discuss
✅ Correct Answer: (D) 0.25

Explanation: the integrator is similar to the phase lag systems and it is used to reduce or eleminate the steady state error and when it is cascaded with the ramp input hence the acceleration error constant is calculated which is equal to 0.25.

📊 Control System Engineering
Q. The error constants described are the ability to reduce the steady state errors.
  • (A) true
  • (B) false
  • (C) ---
  • (D) ---
💬 Discuss
✅ Correct Answer: (A) true

Explanation: as the type of the system becomes higher more steady state errors are eliminated.

📊 Control System Engineering
Q. Systems of type higher than 2 are not employed in practice.
  • (A) true
  • (B) false
  • (C) ---
  • (D) ---
💬 Discuss
✅ Correct Answer: (A) true

Explanation: these are more difficult to stabilize and dynamic errors are much larger.

📊 Control System Engineering
Q. Steady state refers to
  • (A) error at the steady state
  • (B) error at the transient state
  • (C) error at both state
  • (D) precision
💬 Discuss
✅ Correct Answer: (A) error at the steady state

Explanation: steady state errors are the change in the output at the steady state with respect to the change in the input.

📊 Control System Engineering
Q. The disadvantages of the error constants are:
  • (A) they do not give the information of the steady state error when the inputs are other than the three basic types
  • (B) error constant fail to indicate the exact manner in which the error function change with time.
  • (C) they do not give information of the steady state error and fail to indicate the exact manner in which the error function change with time
  • (D) they give information of the steady state error
💬 Discuss
✅ Correct Answer: (C) they do not give information of the steady state error and fail to indicate the exact manner in which the error function change with time

Explanation: the disadvantages of the error constants are as they do not give the information of the steady state error when the inputs are other than the three basic types and error constant fail to indicate the exact manner in which the error function change with time.

📊 Control System Engineering
Q. The input of a controller is
  • (A) sensed signal
  • (B) error signal
  • (C) desired variable value
  • (D) signal of fixed amplitude not dependent on desired variable value
💬 Discuss
✅ Correct Answer: (B) error signal

Explanation: controller is the block in the control system that control the input and provides the output and this is the first block of the system having the input as the error signal.

📊 Control System Engineering
Q. Phase lag controller:
  • (A) improvement in transient response
  • (B) reduction in steady state error
  • (C) reduction is settling time
  • (D) increase in damping constant
💬 Discuss
✅ Correct Answer: (B) reduction in steady state error

Explanation: phase lag controller is the integral controller that creates the phase lag and does not affect the value of the damping factor and that tries to reduce the steady state error.

📊 Control System Engineering
Q. Addition of zero at origin:
  • (A) improvement in transient response
  • (B) reduction in steady state error
  • (C) reduction is settling time
  • (D) increase in damping constant
💬 Discuss
✅ Correct Answer: (A) improvement in transient response

Explanation: stability of the system can be determined by various factors and for a good control system the stability of the system must be more and this can be increased by adding zero to the system and improves the transient response.

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