M.Sc. (Semester II) (CBCS) Examination Nov/Dec-2018
Electronics Science
CONTROL SYSTEMS
Time: 2½ Hours Max. Marks: 70
Instructions: Q.1 and Q. 2 are compulsory.
Answer any three questions from Q.3 to Q.7.
Figures to the right indicate full marks.
Use of nonprogrammable calculator is allowed.
Q.1 Select the most correct alternative 14
A control system in which the control action is dependent on the output is
known as
Closed loop system Semiclosed loop system
Open loop system Both a and c
The transfer function is applicable to which of the following?
Linear and time-in variant systems Linear and time-variant systems
Linear systems Non- linear systems
The laplace transform of unit impulse signal is
1/s 1
1/s2 1/s3
filter is similar to the phase lead compensation and leads to
increase in bandwidth and also increase in speed of response.
High pass Low pass
Band pass Band reject
In root locus systems, while specifying the angle and magnitude conditions,
angles are added whereas magnitudes get
subtracted multiplied
divided all of the above
If any root of the characteristic equation has a negative real part, the system
is
stable unstable
oscillatory conditionally stable
Consider the following statement regarding Routh Hurwitz criterion:
It gives absolute stability
It gives gain and phase margin
It gives the number of roots lying in RHS of the s-plane
It gives gain, phase margin and number of roots lying in RHS of the splane.
When two blocks are connected in series, the transfer functions are to be

added subtracted
multiplied divided
With feedback increases.
system stability sensitivity
gain effects of disturbing signals
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SLR-VH-237
10) Which of the following is exhibited by root locus diagrams?
The poles of the transfer function for a set of parameter values.
The bandwidth of the system.
The response of a system to a step input
The frequency response of a system
11) Mass, in force-voltage analogy is analogous to
charge current
inductance resistance
12) A.C. servomotor resembles
two phase induction motor three phase induction motor
direct current series motor universal motor
13) According to signal flow graph, which among the following represents the
relationship between nodes by drawing a line between them?
Branch Self-loop
Semi- node Mesh
14) Which condition is used to verify the existence of a particular point on the
root locus?
Amplitude Frequency
Magnitude Angle
Q.2 Attempt the followings:
Explain closed loop control system by giving suitable example also
highlights its merits demerits.
05
What is a PI controller? 05
Briefly describe the frequency response specifications. 04
Q.3 Derive an expression for the time response of a first order system to unit step input.08
What is a transfer function? Derive an appropriate expression for the same. 06
Q.4
x2 a22 x1 a32 x3
x3 a23 x2 a34 x4
x4 a24 x2 a34 x3 a44 x4
x5 a25 x2 a45 x4
Find the gain of the system represented by the following equations.
Here, the input node is x1 and output node is x5.
08
What are the various types of control systems? Explain them in brief. 06
Q.5 Consider the system with K/S and -0.75 and is
confirmed to be on the root locus. Determine at what value of -0.75 is
one of the roots of (Use magnitude condition)
08
Explain the stability of a given equation using Hurwitz method.
7S3 5S2 4S 9
06
Q.6 Explain in detail the state space representation for nth order differential equation. 08
Explain state model from transfer function using parallel method. 06
Q.7 What is tachogenerator? Draw and explain the working of DC and AC
tachogenerators and represent them in block diagram forms.
10
Explain briefly ON-OFF controller. 04