Control System Engineering Set 7

Electrical Engineering

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This set of Control System Engineering (CSE) Multiple Choice Questions & Answers (MCQs) focuses on Control System Engineering Set 7

Q1 | The addition of open loop zero pulls the root loci towards:
  • the left and therefore system becomes more stable
  • the right and therefore system becomes unstable
  • imaginary axis and therefore system becomes marginally stable
  • the left and therefore system becomes unstable
Answer: the left and therefore system becomes more stable
Explaination:
the system can become stable by reducing the damping and also by adding zeroes in the s plane and moving left of the s plane system becomes more stable.
Q2 | If root loci plots of a particular control system do not intersect the imaginary axis at any point, then the gain margin of the system will be:
  • 0
  • 0.707
  • 1
  • infinite
Answer: infinite
Explaination:
the gain margin is the inverse of the intersection of the root loci plot to the imaginary axis and if it does not intersect then the gain margin will be infinite.
Q3 | System transformation on function H(z) for a discrete time LTI system expressed in state variable form with zero initial condition
  • -1b+d
  • c(zi-a)-1
  • (zi-a)-1z
  • (zi-a)-1
Answer: -1b+d
Explaination:
transfer function which is ratio of laplace output to the laplace input when the initial conditions are zero in discrete is same as continuous but in the z-domain.
Q4 | State space analysis is applicable for non- linear systems and for multiple input and output systems.
  • true
  • false
Answer: true
Explaination:
state space analysis is the technique that used state variables and state model for the analysis and is applicable for non-linear systems and for multiple input and output systems.
Q5 | When human being tries to approach an object, his brain acts as,
  • an error measuring device
  • a controller
  • an actuator
  • an amplifier
Answer: a controller
Explaination:
brain of human being acts as a controller in the human body system as human body is the control system and when
Q6 | For two-phase AC servomotor, if the rotor’s resistance and reactance are respectively R and X, its length and diameter are respectively L and D then,
  • x/r and l/d are both small
  • x/r is large but l/d is small
  • x/r is small but l/d is large
  • x/r and l/d are both large
Answer: x/r is small but l/d is large
Explaination:
small x/r gives linear speed torque characteristic. large l/d gives less inertia and good acceleration characteristic.
Q7 | Error detector:
  • armature controlled fhp dc motor
  • a pair of synchronous transmitter and control transformer
  • tach generator
  • amplidyne
Answer: armature controlled fhp dc motor
Explaination:
error detector is the part in the armature controlled fhp dc motor where
Q8 | Servomotor:
  • armature controlled fhp dc motor
  • a pair of synchronous transmitter and control transformer
  • tach generator
  • amplidyne
Answer: a pair of synchronous transmitter and control transformer
Explaination:
servomotor is a rotary actuator or linear actuator that allows for precise control of angular or linear position, velocity and acceleration a pair of synchronous transmitter and control transformer.
Q9 | Amplifier:
  • armature controlled fhp dc motor
  • a pair of synchronous transmitter and control transformer
  • tach generator
  • amplidyne
Answer: amplidyne
Explaination:
amplifier is an amplidyne which is an amplidyne is an electromechanical amplifier invented during world war ii by ernst alexanderson. it consists of an electric motor driving a dc generator.
Q10 | A differentiator is usually not a part of a control system because it
  • reduces damping
  • reduces the gain margin
  • increases input noise
  • increases error
Answer: increases input noise
Explaination:
a differentiator is the phase lead compensator which increases the speed of response and bandwidth and manages the transient response of the system.
Q11 | If the gain of the critical damped system is increased it will behave as
  • oscillatory
  • critically damped
  • overdamped
  • underdamped
Answer: underdamped
Explaination:
gain of the critical system is inversely proportional to the root of the damping factor and hence on increasing the gain the damping reduces and system becomes the underdamped.
Q12 | In a control system integral error compensation                steady state error
  • increases
  • minimizes
  • does not have any effect on
  • all of the mentioned
Answer: minimizes
Explaination:
integral error compensation is the phase lag compensation and reduces the steady state error and eliminates the error.
Q13 | With feedback            reduces.
  • system stability
  • system gain
  • system stability and gain
  • none of the mentioned
Answer: system gain
Explaination:
feedback reduces the gain as it causes the stability to the closed loop system and for the good control system the stability of the system should be high and also the speed of response.
Q14 | An amplidyne can give which of the following characteristics?
  • constant current
  • constant voltage
  • constant current as well as constant voltage
  • constant current, constant voltage and constant power
Answer: constant current, constant voltage and constant power
Explaination:
an amplidyne has constant current, voltage and power.
Q15 | Which of the following can be measured by LVDT?
  • displacement
  • velocity
  • acceleration
  • all of the mentioned
Answer: all of the mentioned
Explaination:
lvdt can measure displacement, velocity and acceleration which is a linear variable differential transformer and inductive transducer.
Q16 |                         directly converts temperature into voltage.
  • thermocouple
  • potentiometer
  • gear train
  • lvdt
Answer: thermocouple
Explaination:
thermocouple is a device that converts the change in the temperature into voltage in which the change in temperature of
Q17 | The transfer function technique is considered as inadequate under which of the following conditions?
  • systems having complexities and non- linearity’s
  • systems having stability problems
  • systems having multiple input disturbances
  • all of the mentioned
Answer: all of the mentioned
Explaination:
transfer function is the ratio of laplace output to the laplace input with the zero initial conditions and is considered inadequate due to complexity, stability problems and multiple input disturbances.
Q18 | Which of the following is the output of a thermocouple?
  • alternating current
  • direct current
  • a.c. voltage
  • d.c. voltage
Answer: d.c. voltage
Explaination:
thermocouple is the device that is used to convert the change in temperature gives output in dc form.
Q19 | A system is said to be                           if it is possible to transfer the system state from any initial state to any desired state in finite interval of time.
  • controllable
  • observable
  • cannot be determined
  • controllable and observable
Answer: controllable
Explaination:
by definition a system is said to be controllable, if it is possible to transfer
Q20 | A system is said to be                                    if every state can be completely identified by measurements of the outputs at the finite time interval.
  • controllable
  • observable
  • cannot be determined
  • controllable and observable
Answer: observable
Explaination:
by definition, a system is said to be observable, if every state can be completely identified by measurements of the outputs at the finite time interval.
Q21 | Kalman’s test is for :
  • observability
  • controllability
  • optimality
  • observability and controllability
Answer: observability and controllability
Explaination:
kalman’s test is the test that is done for the controllability and observability by solving the matrix by kalman’s matrix individually for both tests.
Q22 | Consider a system if represented by state space equation and x1 (t) =x2 (t), then the system is:
  • controllable
  • uncontrollable
  • observable
  • unstable
Answer: uncontrollable
Explaination:
after calculating the matrix which for controllable system and finding the determinant and should not be zero but in this case comes to be zero.
Q23 | A transfer function of the system does not have pole-zero cancellation? Which of the following statements is true?
  • system is neither controllable nor observable
  • system is completely controllable and observable
  • system is observable but uncontrollable
  • system is controllable and unobservable
Answer: system is completely controllable and observable
Explaination:
if the transfer function of the system does not have pole-zero cancellation then it is completely controllable and observable.
Q24 | Complex conjugate pair:
  • center
  • focus point
  • saddle point
  • stable node
Answer: focus point
Explaination:
complex conjugate pair is the complex pair of the roots of the equation and has a focus point.
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