Control System Interview Questions
In this article we will study of control system interview question and answer. we will also learn in detail of various type interview question and answer.
Control System Interview Questions
1. What is control system?
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A control system is an arrangement of physical components connected or related in such a manner as to command, direct or regulate in such a manner as to command, direct or regulate itself or another system.
Control system can be of two viz. open-loop control system and closed-loop control system.
2. What is feedback in control system? What are its characteristics?
Feedback is that property of a closed loop control system which allows the output or some other controlled variable of the system, to be compared with the input to the system, so that the appropriate control action may be formed as some function of the output and input.
A feedback is said to exist in a system if the cause and effect between variables is interrelated.
The characteristics of feedback are: increased bandwidth, increased accuracy, reduced distortion and non linearity and tendency towards oscillations or instability.this control system interview questions maximum ask in interviews.
3. What is system error?
The system error is the ideal value of the controlled variable minus the value of the final controlled variable.
4. What are control system components?
Various components employed in control systems are servo-motors, amplidynes, synchros, stepper motors, tachometers, gyroscopes etc.
5. Which types of servomotors generally lend themselves to small horse power requirements?
Two phase and shaded pole type induction motor are used.
6. Give one advantage of the two phase servomotor over the shaded pole type.
Better response to very small controls signals
7. Why are drag-cup-construction used in rotors of certain fhp machines for control purposes?
In drag-cup-construction all heavy iron lamination remain stationary and only a light cup rotates, so the inertia is quite small.
8. Why is series compensating winding employed in the amplidynes?
Compensating winding is connected in series with the power output brush terminals of the amplidyne to neutralize the armature reaction mmf set up by the load current and increase amplification factor.
9. Why area commutating poles required in amplidynes?
Com mutating poles are required in amplidynes to give satisfactory commutation
10. Why amplidynes are not extremely over-compensated
In case of extreme over-compensation, undesirable self-excitation of the amplidyne that is spontaneous rise in voltage and load current at constant control current (or with the control circuit open) can occur. Self-excitation can caus3e considerable over-loading of the amplidyne and totally disrupt operation of system containing the amplidynes. it most important control system interview question.
11. Why Amplidynes are provided with split-poles?
Amplidynes are provided with split-poles to provide space for inter poles.
12. What is stepper motor?
A motor in which the rotor turns in discrete movements is called a stepper motor.
13. What are the two types of stepper motors?
Permanent –magnet type and variable reluctance type motor are stepper motor.
14. For the same number of poles which stepper motor produces?
1. Largest stepping angle
2. Smallest stepping angle?
1. Permanent magnet type- largest stepping angle
2. Variable reluctance type-smallest stepping angle.
15. Where is stepper motor used?
Super motors are used in industrial situations which call for precise positioning of an object or precise control of speed without having to resort to closed-loop feedback. ,, it is most important question of control system.
16. How an ac tachometer is superior to dc tachometer.
AC tachometer does not cause any maintenance problem of commentators and brushes.
17. What is transfer function?
It is the mathematical expression that relates the system output to the system input and so describes the behavior of a system. It is expressed as ratio of the Laplace transform of the output variable to the lap lace transform of the input variable with the assumption that all the initial conditions are zero.
18. What is linear system?
A linear system is a system that follows the law of superposition and homogeneity.
19. What is analogous system?
Systems which are governed by the same types of equations are called analogous systems. Analogous systems may have entirely different physical appearances. For example, a given electrical circuit consisting of resistances, inductance and capacitance may be analogous to a mechanical system consisting of a suitable combination of dash pots, weights and springs or it may be analogous to an acoustical device consisting of an appropriate arrangement of fine mesh screens, tubes and cavities.
20. What is signal flow graph?
A signal flow graph is pictorial representation of the simultaneous equations describing a system. It graphically displays the transmission of signals through the system, as does the block diagram.
21. What is meant by overshoot?
Over shoot is maximum difference between the transient and steady-state solutions for a unit step function input.
22. Enlist the applications of sampled data systems.
Sampled data system finds applications in
1. High speed tin plate rolling mills using quantized data for control.
2. Numerically controlled machine tool operations.
3. Pulse controlled or digital controlled electric drives.
4. Large complex systems using telemetry links based on pulse modulation (PM) translation of data.