Tuesday 16 July 2013

3-1 CONTROL SYSTEMS BITS


                                                      CONTROL SYSTEMS

                                                            JNTUH BITS   

                                                      UNIT-I: Introduction

NOTE:  Don't think that these bits only will be repeated in first mid.Prepare concepts thoroughly then solve these bits .These bits to cross check your knowledge in subject. 



 1. The principle of homogeneity and Superposition theorem is applied to [a ]

(a) Linear Time Invariant System (b) Non Linear Time variant system
(c) Linear Time variant system (d) Non Linear Time Invariant system

2.  Any physical system which does not automatically correct for variation in its output is called [a]
(a) Open loop (b) closed loop (c) unstable (d) stable


3.  Transfer function of a system is defined as [ b  ]
a) ratio of Laplace transform of input variable to the Laplace transform of the output variable when all initial conditions are zero
b) ratio of Laplace transform of output variable to the Laplace transform of the input variable when all initial conditions are zero
c) Laplace transform of the output variable when all initial conditions are zero
d) Laplace transform of the input variable when all initial conditions are zero



SECTION-II: Fill in the blanks

1.      The elements of a mechanical rotational system are  J,B,K

2.      The transfer function of a feedback control system is  G(s)/ [1+G(s) H(s)]

       3.An example of closed loop system is  Air Conditioner or Microprocessor based traffic control system

                                  

                                 UNIT-II:  Transfer function Representation


1.  The equation based on which a Signal Flow Graph is drawn must be [    c  ]
(a) Differential Equations (b) Algebraic equation (c) Algebraic equation in the form of cause- and effect relations (d) Differential Equations in the form of cause- and effect relations


2.  The shape of rotor in control Transformer is [   b  ]
(a) Drag cup (b) cylindrical (c) Toothed rotor (d) Dumb-bell


3.  In a 2Φ AC servo motor , the rotor has a resistance ( R) and reactance ‘X’ , Torque -speed characteristics of the servo motor will be linear provided that ______ [   a ]
(a)X/R<<1 (b) X/R>>1 (c) X/R=1 (d) X2 = R


4. Synchro is a/an   [ c]
(a) Frequency transmitter (b) Electronic rectifier
(c) Electromagnetic transducer (d) Electro mechanical device


5.  In Masons gain formula Δ is calculated as [ A]
a) 1-(sum all individual loop gains) +(sum of gain products of all combinations of 2 nontouching loops)-(sum of gain products of all combinations of 3 nontouching loops)+……….
b) 1+(sum all individual loop gains)+(sum of gain products of all combinations of 2 nontouching loops)+(sum of gain products of all combinations of 3 nontouching loops)+……….
c) (sum all individual loop gains)+(sum of gain products of all combinations of 2 nontouching loops)+(sum of gain products of all combinations of 3 nontouching loops)+……….
d) (product all individual loop gains)-(sum of gain products of all combinations of 2 nontouching loops) +(sum of gain products of all combinations of 3 nontouching loops)-……….

SECTION-II: Fill in the blanks


1.      The functional operation of the system can be visualized more readily by examining the Block diagram than by examining the physical system itself.

       2.Mason’s gain formula is  __________


                              



                               UNIT-III: TIME RESPONSE ANALYSIS

1.  An on-off controller is [C ]
(a) P controller (b) Integral controller (c) Non linear controller (d) PID controller


2.  Damping is proportional to _____________ [ D ]
(a) Gain (b) 1/Gain (c) √ (gain) (d) 1/√ (gain)



3.  The time response T is an indicative of     [ a]
a) how fast the system tends to reach a final value b) how slow the system is
c)how fast the system output decays to zero value d) the system’s steady state behavior

4.  A large time response corresponds to a     [  a ]
a) sluggish system b) faster system c) overdamped system d) underdamped system


5.Knowledge of the transfer function is necessary for the calculation of [b ]
a) time constant b)output for a given input c) order of a system d)none of these

6. A PID controller is an [c ]
a) Proper integral derivative control b) Parameter Intermediate defined control
c) Proportional Derivative control d) Pulsating Interval dependent control

SECTION-II: Fill in the blanks:

        1. The formulae for steady state error by using dynamic error co-efficient

  Ess=K0 R (t) + k1 R1 (t) + k2/2! R11 (t) +….

        2. Delay time, Td=  (1+0.7ζ)/ωn

      3. Static error Coefficient  method cannot give the error if the input is other than standard input.

      4.For a second order Differential Equations if the damping ratio is unity then the poles are

    Equal & same

      5. In proportional control, the actuating signal is  proportional to the error signal.

      6. The time required for the response to reach and stay within a particular percentage of final value is called Settling time

     7. The inverse laplace transform of the transfer function of a system is its  impulse response

      8. The  steady state error constants describes the ability of a system to eliminate steady state errors.

      9. Steady state error for a unit ramp input for a type-0 system is infinity


                    

                   UNIT-IV: STABILITY ANALYSIS IN S-DOMAIN

1.  The starting points for root loci. are [a ]
(a) Open loop poles (b) closed loop poles (c) Open loop zeros (d) closed loop zeros

2.  In Routh Hurwitz’s criterion, if all the elements in one row are zero, then there are [c]
 (a) All the roots lies in LHS (b) Lies in RHS
(c) Pair of conjugate roots lies on Imaginary axis (d) insufficient data


3.  A control system is stable if [a ]

a) all the roots of the characteristic equation has negative real parts
b) all the roots of the characteristic equation has positive real parts
c) any root of the characteristic equation has negative real part
d) any root of the characteristic equation has positive real part


4.  If there are repeated roots of the characteristic equation on the jw-axis, the system is [d ]
a) conditionally stable b) oscillatory c) stable d) unstable



5.  The roots of the characteristic equation are the same as the poles of the [a ]
a) closed loop transfer function b)open loop transfer function
c)forward path transfer function d) none

6. The technique which gives transient response quickly as well as stability information is [d ]
a) Nyquist plot b) Routh-Hurwitz criteria c) Bode plot d) Root locus



SECTION-II: Fill in the blanks:


1.      The routh’s stability criterion gives information only Absolute  stability of a system but fails to indicate the  Relative stability of a system.

2.      Root locus diagram can be used to determine Relative stability.

3.      The root loci of G(s) H(s) =k(s+1) (s+3)/s(s+2) (s+6) no of asymptotes of 1

4.The angle condition of an open loop Transfer function is  G(s) H(s) =+ (2q+1) 180, q=0, 1, 2,…

5.The no of poles lies at the origin of open loop Transfer function is called as________
6.The root locus is Symmetrical about the real axis



                                                                                     Prepared By
                                                                                                                                                   B.Sridhar