M.Sc. (Semester II) (CBCS) Examination Mar/Apr-2018
Electronics
CONTROL THEORY
Time: 2½ Hours
Max. Marks: 70
Instructions: Attempt five questions. Q. 1 and 2 are compulsory. Answer any three questions from Q.3 to Q.7. Figures to the right indicate full marks.
Q.1
Choose the alternatives given below.
08
If roots are on positive real axis of the S plane then the system said to be
Stable
Unstable
Marginally stable
None of these
The transfer function of the circuit containing L and C is function.
Second order
First order
Third order
None of these
The time that the system output takes to reach from 10 to 90% of its final value is known as time.
Peak time
Settling time
Rise time
Delay time
In case of second order system if then poles are
Purely imaginary
Real and equal
Real
All of these
If velocity error constant is Kv then steady state error for ramp input is given by ess
Kv
1 Kv

A/Kv
For polar plots the magnitude is determined by varying gain constant K
From 0 to ∞
From 0 to 1
From 1 to 0
From to ∞
Frequency response is the response of
magnitude against log of frequency
log of magnitude against frequency
log of magnitude against log of frequency
log of magnitude and phase against frequency
According to Angle condition the phase angle of the function is given by
s H s
s H s
s H s
s H s
Page 2 of 2
SLR-UJ-326

State True or false.
06
The graph of log of magnitude in dB against log of frequency is called Bode Plot.
The standard test signal of the type step results into velocity error constant.
The transfer function is System is said to be second order system.
If the function is having single pole at origin then slope of the Bode plot is 20dB/decade.
According to Hurwitz's criterion, for stable system all Hurwitz determinants should be negative.
PI controller is an example of discontinuous controller.
Q.2
Attempt any two.
10
Write a note on Poles and Zeros of the Transfer function of the system.
Define the term signal flow graph. State properties of signal flow graphs.
What do you mean by Bode Plots?
With suitable diagram describe discontinuous controllers.
04
Q.3
What do you mean by feedback and feed forward control system? Discuss with help of suitable block diagram.
08
What do you mean by transfer function of the system? Derive expression for transfer function of the system consisting R and C connected in series and output is taken across Capacitor.
06
Q.4
Define the terms transient response and steady state response. Discuss specification of the transient response.
08
Discuss transient response of first order system with unit step input. Represent poles of closed loop transfer function in s-plane.
06
Q.5
What do you mean by frequency response? Explain with suitable examples.
08
What do you mean by Routh-Hurwitz Criteria for stability?
06
Q.6
What is need of block diagram reduction? Explain in detail the rules used for block diagram reduction.
08
Using standard rule reduce following block diagram.
06
Q.7
Describe in detail the concept of Polar plots. Draw polar plot for the function 10/jw
08
What is concept of composite control mode? Discuss PID mode in detail.
06