PBR VISVODAYA INSTITUTE OF TECHNOLOGY
AND SCIENCE
Course File
III Year B.Tech (EEE) – I Semester
Contents
1. Syllabus
2. Objective
3. Lesson Plan
4. Question Papers – Mid-semester
examinations
5. Question Bank
6. Previous years’ question papers – JNTUA
CONTROL SYSTEMS
Syllabus
JAWAHARLAL NEHRU
TECHNOLOGICAL UNIVERSITY ANANTAPUR
B.Tech III-I Sem. (E.E.E)
T
P
C
4
0
4
(9A02503) CONTROL SYSTEMS
(Common to EEE, ECE, E Con E, EIE)
Objective:
In this course it is aimed to introduce to the students the principles and applications of control systems
in everyday life. The basic concepts of block diagram reduction, time domain analysis solutions to time
invariant systems and also deals with the different aspects of stability analysis of systems in frequency
domain and time domain.
UNIT – I INTRODUCTION
Concepts of Control Systems- Open Loop and closed loop control systems and their differencesExamples of control systems- Classification of control systems, Feed-Back Characteristics, Effects of
feedback. Mathematical models – Differential equations, Impulse Response and transfer functions Translational and Rotational mechanical systems
UNIT II TRANSFER FUNCTION REPRESENTATION
Transfer Function of DC Servo motor - AC Servo motor- Synchro transmitter and Receiver -Block diagram
algebra –Signal flow graph - Reduction using Mason’s gain formula.
UNIT-III TIME RESPONSE ANALYSIS
Standard test signals - Time response of first order systems – Characteristic Equation of Feedback
control systems, Transient response of second order systems - Time domain specifications – Steady state
response - Steady state errors and error constants – Effects of proportional, integral, derivative Controls.
UNIT – IV STABILITY ANALYSIS IN S-DOMAIN
The concept of stability – Routh’s stability criterion – qualitative stability and conditional stability –
limitations of Routh’s stability. The root locus concept - construction of root loci-effects of adding poles
and zeros to G(s)H(s) on the root loci.
UNIT – V FREQUENCY RESPONSE ANALYSIS
Introduction, Frequency domain specifications-Bode diagrams-Determination of Frequency domain
specifications and transfer function from the Bode Diagram-Phase margin and Gain margin-Stability
Analysis from Bode Plots.
UNIT – VI STABILITY ANALYSIS IN FREQUENCY DOMAIN
Polar Plots-Nyquist Plots-Stability Analysis.
UNIT – VII CLASSICAL CONTROL DESIGN TECHNIQUES
Compensation techniques – Lag, Lead, Lead-Lag Controllers design in frequency Domain, P, PD, PI, PID
Controllers.
UNIT – VIII STATE SPACE ANALYSIS OF CONTINUOUS SYSTEMS
Concepts of state, state variables and state model, derivation of state models from block diagrams,
Diagonalization- Solving the Time invariant state Equations- State Transition Matrix and it’s Properties.
TEXT BOOKS:
1. Automatic Control Systems– by B. C. Kuo and Farid Golnaraghi – John wiley and son’s, 8th edition,
2003.
2. Control Systems Engineering – by I. J. Nagrath and M. Gopal, New Age International (P) Limited,
Publishers, 5th edition, 2007.
3. Control Systems – A. Anand Kumar, Prentice Hall of India Pvt. Ltd.,
REFERENCE BOOKS:
1. Modern Control Engineering – by Katsuhiko Ogata – Prentice Hall of India Pvt. Ltd., 5th edition, 2010.
2. Control Systems Engineering - by NISE 5th Edition – John wiley.
3. “Modelling & Control Of Dynamic Systems” by Narciso F. Macia George J. Thaler, Thomson
Publishers.
4. Modern Control Engineering – by Yaduvir Singh and S. Janardhan, CENGAGE Learning.
Objective
Objective:
In recent years, control systems have assumed an increasingly important role in the
development and advancement of modern civilization and technology. Practically every aspect of our
day-to-day activities is affected by some type of control systems.
Control systems are found in abundance in all sectors of industry, such as equality control of
manufactured products, automatic assembly line, machine-tool control, space technology and weapon
systems, computer control, transportation systems, power systems, robotics, Micro Electro Mechanical
systems (MEMS), nano technology and many others.
In this subject it is aimed to introduce to the students the principles and application of control
systems in everyday life. The basic concepts of block diagram reduction, time domain analysis solutions
to time invariant systems and also deals with the different aspects of stability analysis of systems in
frequency domain and time domain.
Lesson Plan
PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE: KAVALI
LESSON PLAN
Year
: 2012 – 2013
Branch: EEE-A
Class : III BTech / Isem
Subject : CONTROL SYSTEMS
Faculty :P.Srihari
No.of
Total
Periods
Periods
required
Per unit
Periods
S.No.
Dates
Topic to be covered
per week
Unit 1
1
5
2
5
Introduction, examples of control systems
1
Open loop and closed loop control systems
1
Classification of control systems
1
Definition of transfer function and mathematical models
2
Impulse response
1
Translational and rotational mechanical systems and
analogies
10
Feed back characteristics and effects
2
2
Unit-2
3
Transfer function of DC & Ac servo motor
2
Synchro transmitter and receiver
1
Transfer functions of other systems
2
5
Block diagram algebra- reduction technics
4
5
Problems
2
Advantages of Signal flow graph
1
Reduction of SFG by using Mason’s gain formulaProblems on SFG
10
2
Unit-3
ST
Standard Test signals – time response of 1 order
Systems
5
2
5
CE of feedback control systems, Transient response of 2
order systems
6.
4
1
nd
9
Time domain specifications- Steady state response
2
Steady state errors and error constants and problems
1
Effects of Proportional, derivative control
1
Proportional integral controller, PID controller
2
Unit-4
7.
4
Concept of stability- Routh’s criterion & problems
2
Qualitative and conditional stability & limitations to
Routh’s criterion
2
Root locus concept – construction of Root loci
8.
4
Problems on root locus
2
Effects of addition of poles and zeros
2
9
1
9.
5
Revision of 1-4 chapters and important bits
3/9/12 To 5/9/12
5
5
I MID exams
Unit-5
10
11
Introduction to frequency response analysis
1
Frequency domain specifications
1
Bode diagrams procedure
1
Transfer fuction – gain margin and phase margin from
Bode plots
2
2
5
Stability analysis from Bode plots
Problems on Bode plot
12
2
2
Unit-6
4
13
9
Polar plots & problems on polar plots
1
Nyquist plots introduction, Theory regarding Nyquist plots
1
Problems on Nyquist plots
2
Stability analysis using Nyquist plots
2
Unit-7
1
5
Compensation techniques –lag & lead
6
4
14
Problems on lag, lead compensators
2
Lead-lag controllers in frequency domain
1
P,PI Controllers
6
1
PD, PID Controllers
1
Unit-8
State space analysis- concepts of state
State variables – state model
15
Derivation of state models from block diagrams
5
Diagonalisation – Solution to time invariant state
equations
1
1
1
1
State transition matrix and its properties problems on
obtaining state transition matrix
1
8
2
Controllability and observability
16
5
17
2
18
3
Total
77
1
Revision of previous model papers and important topics
Revision for II- MID
2
2
3
3
77
Total
FACULTY SIGNATURE
HOD SIGNATURE
Question Papers – Mid-semester examinations
PBR Visvodaya Institute of Technology and Science
Class: III B.Tech.I-Sem.
Branch: EEEI MID (Objective)
Subject: CONTROL SYSTEMS
Max Marks: 10
NAME:…………………………………
Time: 20 MIN
Date: 04/09/2012(AN)
ROLL NO:………………………
Answer all Questions
1. The transfer function of a system is the Laplace transform if its
(a) ramp response (b) impulse (c) square wave (d) step
[
]
2. In force-voltage analogy, mass equal in electrical system
[
]
[
]
[
]
(a) voltage (b) capacitance (c) inductance (d) resistance
3. In force-current analogy, dashpot equal in electrical system
(a)voltage (b) capacitance (c)conductance (d) resistance
4. Applied force equal to opposing forces. It is called ________ law
(a) Newtons first law (b) newtons second law (c) newtons third law (d)KVL
5. AC servo motor is a
[
(a)open loop CS (b) closed loop CS (c) mixed loop CS (d) None
6. The time that it takes to settle to the final value is called
[ ]
(a) Steady state (b) transient state (c) both (d) None
7. The time domain specification which is dependent only on the damping factor is
[
(a)Rise time (b)peak time (c)settling time (d) peak overshoot
8. Root locus diagram can be used to determine
[
]
[
]
(a) Conditionally stability (b) absolute stability (c) relative stability (d) none
9. The value of K for which the system s^3+3S^2+3S+1+K=0 become stable is
]
]
(a) K=8 (b) K=7 (c) K>7 (d) None
10. The transfer function is K/(S+1)(S+2)(S+3) the break point will lie between
(a) 0 and -
(b) -1 and -2
(c) -2 and -3
[
]
(d) beyond -3
11. The system is represented by its transfer function has some poles lying on
[
the imaginary axis, it is
(a) Unconditionally stable (b) Conditionally stable (c) Unstable (d) marginally stable
12. The time that it takes to settle to the final value is called
[
]
]
(a)Steady state (b) transient state (c) both (d) None
13. When the gain K of a system is increased, the steady state error of the system
[
]
(a)Increase (b)remains unchanged (c)may increase or decrease (d) decrease
14. Classification of servo motor based on nature of supply [True/False]
15. The static acceleration constant of a type 2 system is zero [True/False]
16. The control systems are normally designed with damping factor less than unity [True/False]
17. Unit impulse function is derivative of _____________ function
18. Parabolic function is called _____________________________
19. The time that output takes to reach the steady state ______________________
20. Laplace transform of unit ramp function ____________________
PBR Visvodaya Institute of Technology and Science
Class: III B.Tech.I-Sem.
Branch: EEEI MID (Subjective)
Subject: CONTROL SYSTEMS
Max Marks: 20
NAME:…………………………………
Time: 90 MIN
Date: 04/09/2012(AN)
ROLL NO:………………………
Answer any three questions and each one carry equal marks
1. What are the various types of control systems given an example of each? What are the advantages and
disadvantages of open loop and closed loop systems?
2. (a). Derive the transfer function of an AC servo meter and draw its characteristics
(b). Explain the synchro error detector with circuit diagram
3. (a). Derive the expression for time domain specification of a standard second order system to a
step input.
(b). Explain the generalized error coefficients and given relevant expressions to compute them.
4. The characteristic equation of a feedback control system is S^3+(K+0.5)S^2+5KS+50=0
criterion determined the value of K which the system is stable.
using RH-
5. Convert the block diagram to signal flow graph and determined the transfer function using
gain formula.
mason’s
PBR Visvodaya Institute of Technology and Science
Class: III B.Tech.I-Sem.
Branch: EEEI MID (Subjective)
Subject: CONTROL SYSTEMS
Max Marks: 20
NAME:…………………………………
Time: 90 MIN
Date: 04/09/2012(AN)
ROLL NO:………………………
Answer any three questions and each one carry equal marks
1. What are the various types of control systems given an example of each? What are the advantages and
disadvantages of open loop and closed loop systems?
2. (a). Derive the transfer function of an AC servo meter and draw its characteristics
(b). Explain the synchro error detector with circuit diagram
3. (a). Derive the expression for time domain specification of a standard second order system to a
step input.
(b). Explain the generalized error coefficients and given relevant expressions to compute them.
4. The characteristic equation of a feedback control system is S^3+(K+0.5)S^2+5KS+50=0
criterion determined the value of K which the system is stable.
using RH-
5. Convert the block diagram to signal flow graph and determined the transfer function using
gain formula.
mason’s
PBR Visvodaya Institute of Technology and Science
Class: III B.Tech.I-Sem.
Branch: EEEI MID (Objective)
Subject: CONTROL SYSTEMS
Max Marks: 10
Time: 20 MIN
NAME:…………………………………
Date: 04/09/2012(AN)
ROLL NO:………………………
ANSWER ALL THE QUESTIONS
1. The range of damping ratio for correlating time domain and frequency domain specifications is
______________________.
2. The slope of log magnitude curve near cut-off frequency is known as_____________.
3. The frequency at which the phase angle of the open-loop system is 180 deg. _______________
[phase crossover / Gain crossover] frequency.
4. The reciprocal of magnitude of open loop system at phase crossover frequency is
_________________
a) Phase margin b) Gain margin
[
]
c) phase crossover frequency d) None
5. If Wgc = Wpc, the system becomes marginally stable.
[True/ False]
6. The corner frequency for the factor 1/( S2+ 20S+ 64) is
[
]
a) 8 rad/sec b) 6 rad/sec c) 5 rad/sec d) 9 rad/sec
7. Type of the minimum phase system indicates the _______________(starting/ terminating) point
of the polar plot.
8. The circles in the polar plot indicates the ____________ ( magnitude/phase) of the system.
9. Polar plots are best suitable for marginally stable system.
[True/False]
10. If a point is found to be inside the path, then the point is enclosed. [True/False]
11. Lag compensator improves the ______________ [steady state/ Transient] performance.
12. Lag compensator act as __________controller.
13. Lag compensator improves the ______________ performance.
14. Lead compensation ____________[increases/ decreases] the Bandwidth.
15. Speed of response increases with the help of _________ compensation.
16. If ‘n’ is the no. of state variables, ‘r’ be the no. of i/p variables, then the order of the matrix B is
_________
17. State space model of an LTI system can be represented by the equations?
18. The matrix A for the given transfer function 10/ (s3 +4s2+2s +1)is
____________________
19. Transfer function model can be applicable to only linear systems. [True/ False]
20. Write the state equations for Homogenous LTI system _________________
PBR Visvodaya Institute of Technology and Science
Class: III B.Tech.I-Sem.
Branch: EEEI MID (Subjective)
Subject: CONTROL SYSTEMS
Max Marks: 20
Time: 90 MIN
NAME:…………………………………
Date: 04/09/2012(AN)
ROLL NO:………………………
ANSWER ANY THREE QUESTIONS
1. a) State advantages & limitations of frequency domain analysis?
b) Sketch the Bode plot for G(s) = 28.5e-0.1s / s(1+s)(1+0.1s) and find gain cross over
frequency?
2. The open-loop transfer function of unity feedback control system is
G(s) = 10/s(s+1)(s+5). Draw its polar plot?
3. Explain the design procedure of Lag compensator using Bode plot?
4. a) Obtain the state space model for the given transfer function
Y(S) / U(S) = 2/S3 +6s2+11S+ 6?
a) Explain the properties of state transition matrix?
5. Draw the Nyquist plot for the system whose transfer function is
G(s)H(s) = k/s(s+2)(s+10)?
Question Bank
UNIT-I (DESCTRIPTIVE & OBJECTIVES)
1. What are the various types of control systems given an example of each? What are the
and disadvantages of open loop and closed loop systems?
advantages
2 .Explain the significance of impulse response. Also explain the feedback characteristics and
feedback system.
effect of
3(a). Define transfer function also explain advantages and disadvantages of transfer function.
(b). Find the transfer function X1(s)/F(s) for the system shown.
4. Write the differential equations governing the mechanical system shown in figure. Draw the forcevoltage and force-current electrical analogous circuits and verify by writing mesh and node equations.
UNIT-I BITS
1. The output of a feedback control system must be a function of
(a)reference I/P & O/P (b)output (c)reference I/P (d) reference I/P& error signal
2. The transfer function of a system is the Laplace transform if its
[ d ]
[ b ]
(a) ramp response (b) impulse (c) square wave (d) step
3. Any physical system which does not automatically correct for variation on it O/P [ b ]
is called
(a) unstable system (b) open loop system (c) closed loop system (d) None
4. Transfer function of a control system depends on
(a) nature of output
[ d ]
(b) nature of input
(c) initial conditions of I/P & O/P (d) system parameters only
5. Potentiometers are used in control system
[ c ]
(a)to improve stability (b) to improve frequency response
(c) as error sensing transducer (d) to improve time response
6. In force-voltage analogy, mass equal in electrical system
[ c ]
(a) voltage (b) capacitance (c) inductance (d) resistance
7. In force-voltage analogy, velocity equal in electrical system
[ b ]
(a) voltage (b) current (c) inductance (d) resistance
8. In force-current analogy, dashpot equal in electrical system
[ a ]
(a) voltage (b) capacitance (c)conductance (d) resistance
9. In force-current analogy, mass equal in electrical system
[ c ]
(a) voltage (b) capacitance (c) inductance (d) resistance
10. Applied force equal to opposing forces. It is called ________ law
[ b ]
(a) Newtons first law (b) newtons second law (c) newtons third law (d)KVL
UNIT-II (DESCTRIPTIVE & OBJECTIVES)
1(a). With a neat sketch explain the construction and principle of working of the synchro
transmitter and receiver.
(b). Derive the transfer function for the synchro transmitter and receiver.
2(a). Derive the transfer function of an AC servo meter and draw its characteristics
(b). Explain the synchro error detector with circuit diagram
3.
Convert the block diagram to signal flow graph and determined the transfer function using
mason’s gain formula.
4. Using block diagram reduction technique find closed loop transfer function of the system
whose block diagram is shown in figure.
UNIT II BITS
1. The block diagram contains
(a) System output variable (b) system input variable
[ d ]
(c)the functional relations of the variables (d) all of the above
2. The transfer function Eo(s)/Ei(s) of the RC-network shown is given by
3.
4.
5.
6.
7.
8.
[ a ]
(a) 1/(RCS+1) (b) 1/(RCS) (c) RCS/(RCS+1) (d) None
In a signal flow graph, the nodes represents
[ a ]
(a) The system variables
(b) (b) the system gain
(c) (c)the system parameters
(d) (d)all of the above
The branch of a signal flow graph represents
[ b ]
(a) The system variable (b) the functional relations of the variables (c) the system
parameters (d) none of the above
By applying masons gain formula, it is possible to get
[ c ]
(a) The ratio of output variable to input variable only
(b) The system functional relations between any two variables
(c) The overall gain of the system
(d) The ratio of any variable to input variable only
Two or more loops in signal flow graph are said to be non touching
[ d ]
(a) If they do not have any common loop
(b) If they do not have any common branch
(c) If they have common node
(d) If they do not have any common node
Classification of servo motor based on
[ a ]
(a) Nature of supply (b) output (c) response (d) none
AC servo motor is a
[ b ]
(a)open loop CS (b) closed loop CS (c) mixed loop CS (d) None
9. DC field controlled servo motor is a
[ a ]
(a)open loop CS (b) closed loop CS (c) mixed loop CS (d) None
10. DC armature controlled servo motor is a
[ b ]
(a)open loop CS (b) closed loop CS (c) mixed loop CS (d) None
UNIT-III (DESCTRIPTIVE & OBJECTIVES)
1(a). Derive the expression for time domain specification of a standard second order system to a
step input.
(b). Explain the generalized error coefficients and given relevant expressions to compute them.
2. A unity feedback system is characterized by the open loop transfer function
G(s)=1/(s(0.5s+1)(0.2s+1)) Determine the steady state errors for unit step, unit ramp and unit
acceleration input. Also determined the damping ratio and natural frequency of the dominant roots.
3. The unity feedback system is characterized by an open loop transfer function G(s)= K/(s(s+10))
determined the gain K, so that the system will have a damping ratio of 0.5 for this value of K.
Determined settling time and peak over shoot for a unit step input.
4. A position control system with velocity feedback is shown what is the response C(t) to the unit
step input given that ξ =0.5also calculate rise time, peak time, maximum overshoot and settling time.
UNIT III BITS
1. The time that it takes to settle to the final value is called
(a) Steady state (b) transient state (c) both (d) None
2. The time that output takes to reach the steady state
(a) Steady state (b) transient state (c) both (d)none
3. Laplace transform of unit ramp function
(a) 1/S (b) 1/S^2 (c) 1/S^3 (d) 1
[ b ]
[ a ]
[ b ]
4. Parabolic function is called
(a) Position function (b)velocity function (c)Acceleration function (d) None
5. Unit impulse function is derivative of _____________ function
(a) Ramp (b) step (c) impulse (d) sine
6. The static acceleration constant of a type 2 system is
(a) Infinite (b) zero (c) cannot be found out (d) finite
7. The time domain specification which is dependent only on the damping factor is
(a) Rise time (b)peak time (c)settling time (d) peak overshoot
8. When the gain K of a system is increased, the steady state error of the system
(a) Increase (b)remains unchanged (c)may increase or decrease (d) decrease
9. The static error constants depends on
(a) The order of the system (b) the type of the system
[ c ]
[ b ]
[ d ]
[ d ]
[ d ]
[ b ]
(c)Both type and order of the system (d) None
10. The control systems are normally designed with damping factor
(a) More than unity (b) of zero (c) less than unity (d) of unity
[ c ]
UNIT-IV (DESCTRIPTIVE & OBJECTIVES)
1. Sketch the root locus of the system whose open loop transfer function is G(s)=
K/(S(S+2)(S+4)) find the value of K so that the damping ratio of the closed loop system
is 0.5
2. Sketch the root locus for the unity feedback system whose open loop transfer function is
G(s)H(s)= K/((S(S+4)(S^2+4S+20))
3(a). The characteristic equation of a feedback control system is
S^3+(K+0.5)S^2+5KS+50=0
using RH-criterion determined the value of K which the
system is stable.
(b) Determine (i) the number of root loci (ii) number of asymptotes
(c) root loci on the real axis if any for the following : G(s)H(s)= K(S+1)/((S^3(S+2)(S+3))
4. Construct routh array and determine the stability of the system represented by the
characteristic equation S^5+S^4+2S^3+3S+5=0 comment on the location of the roots of the
characteristic equation.
UNIT IV BITS
1. Consider characteristic s equation S^4+3S^3+5S^2+6S+K+10=0 condition
[ ]
for stability is
(a) K>5 (b) -10≤K (c) K>-4 (d) -10<K<-4
2. The characteristic equation of unity feedback system is given by S^3+S^2+4S+4=0[ b ]
(a) The system has one pole in the RH-S plane
(b) The system has no pole in the RH-S plane
(c) The system is asymptotically stable
(d) The system exhibits oscillatory behavior
3. The system is represented by its transfer function has some poles lying on
[ d ]
the imaginary axis, it is
(a) Unconditionally stable (b) Conditionally stable (c) Unstable (d) marginally stable
4. A step function is applied to the input of a system and output is of the form Y=t,
[ c ]
the system is
(a) conditionally stable (b) not necessarily stable (c) Unstable (d) stable
5. When gain K of the loop transfer function is varied from zero to infinity
[ d ]
the closed loop system
(a) Stability is improved (b) always become unstable (c) Stability is not effected
6. The transfer function is K/(S+1)(S+2)(S+3) the break point will lie between
(a) 0 and -
(b) -1 and -2
(c) -2 and -3
[ b ]
(d) beyond -3
7. For the root locus, the phase angle criterion of
[ a ]
(a) odd multiple of 180o(b) Even multiple of 180o (c) odd multiple of 90o(d) None
8. The root of a system has three asymptotes. The system can have
[ d ]
(a) 4 pole and one zero (b) 3 poles (c) 5 poles and 2 zeros (d) All of these
9. Root locus diagram can be used to determine
[ c ]
(a) Conditionally stability (b) absolute stability (c) relative stability (d) none
10. The value of K for which the system s^3+3S^2+3S+1+K=0 become stable is
(a) K=8 (b) K=7 (c) K>7 (d) None
[ d ]
Previous years’ question papers – JNTUA
AnsweranyFIVEq
uestions
All
questionscarryequal
marks
*
*
*
*
*
1
(a) Explain theclassificationofcontrol systemswithexamples.
(b) Find thetransferfunction
for thefollowingsystem showninfigure1.
J1
J2
T
(AppliedTorque)
K
(output)
Figure1
2
B
(a) Drawtheconnectiondiagram ofSynchropair usedasapositionindicator.
(b) Drawthesignalflowgraphfor thesystemofequationsgivenbelowandobtain
theoverall transferfunctionusingMason’s rule:
X2=X1–X6
X3=G1X2-H2X4-H3X5
X4=G2X3-H4G6
X5=G5X4
X6=G4X5
3
(a) Derive thestaticerrorconstantsand list thedisadvantages.
(b) Aunitfeedbacksystemischaracterizedbyanopen-looptransferfunctionG(s)=
.
DeterminethegainKsothatthesystemwillhaveadampingratioof0.5.
Forthisvalue
ofKdeterminesettlingtime,peakovershootand times topeakovershoot foraunit-step input.
4
(a)
(b)
Howthe rootsof thecharacteristicequationarerelated tostability?
The open loop transfer function of negative unity feedback system is given by
G(s)=
.SketchtherootlocusforK>0. DeterminetherangeofKforwhich
thesystemisstable. AlsofindthevalueofKforwhichthesystemoscillatesand frequency
ofoscillation.
5
(a)
(b)
Explain thecorrelationbetween timeandfrequency responseofasystem.
Explain thefrequency responsespecifications.
6
(a)
(b)
Draw&explainpolarplotsfor type–0, type -1&type–2systems.
Writeanoteonrelationbetween rootloci&Nyquistplots.
Contd.in Page2
P
a
g
e
10
f2
1
Code:9A19401
7
AunityfeedbacksystemhasanopenlooptransferfunctionG(s)=
. Designa
0
suitablelogcompensatorsothatphasemarginis40 andthesteadyerrorforrampinput
islessthanor equalto0.2.
8
(a) Considerthenetworkshowninfigure2andobtain thestatevariableform: A
iL
L
iC
i
R
VC
Vo
C
Figure2
(b) Explainpropertiesandsignificanceofstate transition matrix.
*****
Page20f2
2
Code:9A19401
II B.TechII Semester (R09)Regular Examinations,April/May2012
CONTROLSYSTEMS
(Electronics &Computer Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a)
(b)
Explain thedifferencebetweenopenloopandclosedloopsystems.
Derive thetransfer functionfor thefollowingrotational mechanical systemsshowninfigure1
Disc
K
Shaft
B
Stiffness
K
T
Viscousfluid
Rotational
Figure1
2
(a) Explain theneedofMason’s gainformulafor anysystem reduction.
(b) Obtainthe transfer functionof
oftheelectrical networkshowninfigure2
R1
ei
c1
R2
L
c2
C
eo
figure2
3
(a) Explainerror constantsKp,Kv,Kafor type -1system.
(b) TheopenlooptransferofaunityfeedbackcontrolsystemisgivenbyG(s)=
where
KandTarepositiveconstants. Bywhat factor should theamplifier gainbe reducedsothat
thepeakovershoot ofunitstepof thesystemisreducedfrom 75%to25%.
Contd.inpage2
Page1of2
2
Code:9A19401
4
(a)
(b)
A unity feedback control system is characterized by the open-loop transfer function
G (s)=
.
(i) UsingtheRouth’scriterion,determinetherangeofvaluesofKforthesystemtobe
stable.
(ii) Checkif forK= 1, all therootsof thecharacteristicequationof theabovesystemhave
dampingfactor greater than0.5.
Calculate the values of K and for the point in S-plane at which the root locus of
G(s)H(s)=
intersectstheimaginaryaxis.
5
Drawthebodeplotsandfindthegainmarginandphasemarginofasystemrepresented
byG(s)H(s) =
6
What isNyquistpath?PlotNyquiststabilityforG(s)H(s) =
7
FortheunityfeedbackcontrolsystemforwardpathtransferfunctionG(s)=
0
lag-leadcompensatorsothatPM 40 andsteadystateerrorforunitramp input
8
(a)
(b)
Definestate, statevariableandexplain thesignificanceofstatevariableanalysis.
Asystem isdescribedby:
u.
Find thetransferfunctionandconstruct thesignalflowgraph.
*****
Page2of2
.
Designa
0.04rad.
3
Code:9A19401
II B.TechII Semester (R09)Regular Examinations,April/May2012
CONTROLSYSTEMS
(Electronics &Computer Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a) What isfeedback?Explain theeffectof feedbackonstability.
(b) Obtainthe transfer functions
and
ofthemechanical system showninfigure1
4
x1
K1
x2
K3
K2
m1
m2
b2
b1
Figure1
2
(a)
(b)
Explain thedifferencesbetweenAC servomotorandDC servomotor.
Determinethe transfer functionC(s)/ R(s) for thefollowingblockdiagram (figure2)
R
+
G1
C
G2
+
+
H1
G3
Figure2
3
(a)
(b)
Definetimeconstant andexplainitsimportance.
Foranegativefeedbackcontrolsystem having forwardpathtransferfunction:
G(s)=
andH(s)=1,determinethevalueofgainKforthesystemtohavedamping
ratio of 0.8. For this value of gain K, determine the complete time response
specifications.
4
(a) Definetheterms:(i)Absolutestability (ii)Marginal stability
Plottherootlocifor theclosedloopcontrol systemwithG(s) =
5
(a)
(b)
(iii)Conditional stability. (b)
H(s)= 1.
Showthatinbodemagnitudeplottheslopecorrespondingtoaquadraticfactoris-40
dB/dec.
Explainwith thehelpofexamples: (i) Minimumphasefunction
(ii)Nonminimum phasefunction (iii)All pass function.
Contd.in Page2
Page1of2
3
Code:9A19401
6
(a)
(b)
ExplainNyquiststabilitycriterion.
Aunityfeedbackcontrolsystemhasanopenloop transfer functiongivenby
G(s)H(s)=
. Drawthe Nyquistdiagramanddetermineitsstability.
7
For G(S) =
8
Writethestateequationsofthesystemshowninfigure3inwhichX1,X2andX3constitute
thestatevector. Determinewhetherthesystem iscompletelycontrollableandobservable.
. Designalagcompensator givenphasemargin 350andKv
U(s)+
+
+
X3(s)
x1(s)
-
20.
S
Figure3
**Code:
9A19401
II B.TechIISemester(R09)RegularExaminations,April/May2012
CONTROLSYSTEMS
(Electronics&ComputerEngineering)
Time:3hours
1
(a)
(b)
MaxMarks:70
AnsweranyFIVEquestio
ns
Allquestionscarryequalmark
s
Explainwithexample,theuseof controlsystemconceptstoengineeringandnonengineeringfields.
Forthemechanicalsystemfigure1given,writedownthedifferentialequationsofmotionandhence
determinethe
.
F(t)
Y2
K1
K2
B2
M1
M2
B1
1
2
(a)
(b)
Derivethetransferfunctionforthefieldcontrolledd.c.servomotorwithneatsketch.
Explaintheadvantagesandfeaturesof transferfunction.
3
(a)
(b)
Derivethetimeresponseof secondorderunderdampedsystemduetounitstepinput.
-6t
Theunitstepresponseofasecondorderlinearsystemwithzeroinitialstateisgiven by c(t)=1+1.25 e
-1
(sin8t-tan 1.333). Determinethedampingratio,undampednaturalfrequencyofoscillationsandpeak
overshoot.
4
(a)
(b)
ShowthattheRouth’sstabilitycriterionandHurwitzstabilitycriterionareequivalent.
Drawtheroot locusdiagramforafeedbacksystemwithopen-looptransferfunction
G(s)=
followingsystematicallythe rulesforthe constructionofroot locus. Showthattherootlocus
inthecomplexplaneis acircle.
5
6
(a)
(b)
Definebandwidthandderivetheexpressionforthebandwidthof asecondordersystem.
Bring out the correlation between time response &frequencyresponse and hence show that the
correlationexistsfortherangeof dampingration0<<0.707.
TheopenlooptransferfunctionofaunityfeedbackcontrolsystemisG(s)=
andhencedetermineitsphasemarginandgainmargin.
. Drawitspolarplot
7
TheuncompensatedopenlooptransferfunctionofaunityfeedbacksystemisG(s)=
. Designa
phase-leadcompensatortomeetthespecifications:(i)Foraunitramp-inputthe steadystateerrorshould
0
belessthanorequalto 0.1units.(ii)Phasemarginof thesystembegreaterthan40 .
8
(a)
(b)
Definecontrollabilityandobservability.
Considernowthatthesystemhasforcingfunctionandisrepresentedbythefollowingnonhomogeneous
stateequation
whereu is thestepfunction. Computethesolutionof this
equationassumingtheinitialstatevectoris x0= .
ELECTRICAL AND ELECTRONICS MEASUREMENT
Syllabus
JAWAHARLAL NEHRU
TECHNOLOGICAL UNIVERSITY ANANTAPUR
B.Tech III-I Sem. (E.E.E)
T
P
C
4
0
4
(9A02501) ELECTRICAL & ELECTRONIC MEASUREMENTS
Objective :
Electrical measurements course introduces the basic principles of all measuring instruments. It also deals with the
measurement of RLC parameters voltage, current Power factor, power, energy and magnetic measurements and
Digital Meters
UNIT-I MEASURING INSTRUMENTS
Classification – deflecting, control and damping torques – Ammeters and Voltmeters – PMMC, Dynamometer,
moving iron type instruments – expression for the deflecting torque and control torque – Errors and compensations,
extension of range using shunts and series resistance.
UNIT –II INSTRUMENT TRANSFORMERS AND P.F METER
CT and PT – Ratio and phase angle errors – design considerations. Types of P.F. Meters – dynamometer and moving
iron type – 1-ph and 3-ph meters.
UNIT –III MEASUREMENT OF POWER / ENERGY
Single phase dynamometer wattmeter, LPF and UPF, Double element and three element dynamometer wattmeter,
expression for deflecting and control torques. Single phase induction type energy meter – driving and braking
torques – errors and compensations. Three phase energy meter.
UNIT –I V POTENTIOMETERS
Principle and operation of D.C. Crompton’s potentiometer – standardization – Measurement of unknown resistance,
current, voltage.
A.C. Potentiometers: polar and coordinate types standardization – applications.
UNIT – V D.C & A.C BRIDGES
Method of measuring low, medium and high resistance – sensitivity of Wheatstone’s bridge – Kelvin’s double bridge
for measuring low resistance, measurement of high resistance – loss of charge method. Measurement of inductance
- Maxwell’s bridge, Anderson’s bridge. Measurement of capacitance and loss angle - Desauty bridge. Wien’s bridge –
Schering Bridge.
UNIT – VI MAGNETIC MEASUREMENTS
Ballistic galvanometer – equation of motion – flux meter – constructional details, comparison with ballistic
galvanometer. Determination of B-H Loop methods of reversals - six point method – A.C. testing – Iron loss of bar
samples.
UNIT – VII OSCILLOSCOPE
Cathode Ray Oscilloscope- Cathode Ray tube-Time base generator-Horizontal and Vertical amplifiers – application of
CRO – Measurement of phase , frequency, current & voltage- Lissajous pattern
UNIT – VIII DIGITAL METERS
Digital Voltmeter-Successive approximation, ramp and integrating type-Digital frequency meter-Digital multimeterDigital Tachometer
TEXT BOOK:
1. Electrical Measurements and measuring Instruments – by E.W. Golding and F.C. Widdis, 5th Edition, Reem
Publications.
2. Electrical & Electronic Measurement & Instruments by A.K.Sawhney Dhanpat Rai & Co. Publications.
3. Electrical & Electronic Measurement & Instrumentation by R. K. Rajput, 2nd Edition, S. Chand & Co.
4. Electronic Instrumentation by H. S. Kalsi, Tata Grawhill Mc, 3rd Edition.
REFERENCE BOOKS:
1. Electrical Measurements – by Buckingham and Price, Prentice – Hall
2. Electrical Measurements: Fundamentals, Concepts, Applications – by Reissland, M.U, New Age International (P)
Limited, Publishers.
Objective
IMPORTANCE OF THE ELECTRICAL AND ELECTRONICS MERASUREMENTS
Electrical measurements course introduces the basic principles of all measuring instruments. It also
deals with the measurements of RLC parameters, voltage, current, power, power factor , energy and
magnetic measurements and digital meters.
The first unit comprises of the various measuring instruments to measure our basic electrical
quantities I.e, DC voltage and DC current by PMMC instruments, AC voltage and AC current by using MI
instruments and AC power by using Electro Dynamometer type instruments.
In second unit we will discuss about CT and PT which are used to step down the voltages and
currents in our transmission lines respectively for relay operation. We also discThe single phase and three
phase power factor of the load by using single phase and three phase power factor meters.
In third unit we will discuss how we can measure power . Basically we have DC power and AC
power. To measure DC power we have V-A method and A-V method. To measure Ac power we have
wattmeter methods. By watt meters we can measure single phase power and three phase power. In the
third unit we will discuss about the energy meters also.By using this energy meters we can know the tariff
of our homes.
In this measurements subject in the remaining units we will know about how we can
measure resistance by using DC bridges and how we can measure L & C by using AC bridges.We also know
about the Electronic Measurements In last two units.
Lesson Plan
PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCE::KAVALI
LESSON PLAN Department of EEE
Academic Year: 2012 – 2013
Faculty Name: G.SUMAN
CLASS: III YEAR- I SEM
Subject: Electrical Measurements
S.No
Dates
No. of
periods
Topic to be covered
In week
1
No. of
Periods
Required
UNIT -I : measuring instruments Classification –
1
deflecting, control and damping torques-
2
5
ammeters and voltmeters-PMMC, moving iron type
Total
Periods
Per unit
2
instruments –expression for deflecting torque
2
Moving iron type instruments –expression for
2
deflecting torque and Control torque –errors and
1
4
compensations, extension of range using shunts and
1
series resistance.
Dynamometer type instruments-torque equations
3
1
Errors and extension of range
1
UNIT –II: instrument transformer
1
CT and–ratio and phase angle errors –
2
11
5
Design Considerations.
4
PT –ratio and phase angle errors –design
1
Considerations.
2
5
Type of P.F meters- dynamometer and
2
moving iron type-1-ph and 3-ph mete
5
UNIT –III: measurement of power
2
Single phase dynamometer wattmeter , LPF and UPF,
2
5
double element and three element dynamometer
8
1
wattmeter. expression for deflecting and control torques
2
3
6
Single phase induction type energy meter – driving
1
8
and braking torques-errors and compensations.
three phase energy meter.
1
7
UNIT-IV: potentiometers: Principle and operation
5
of d.c Crompton’s potentiometer –standardization –
2
2
measurement of unknown Resistance ,current ,voltage
A.C. potentiometers : polar type and
coordinate types
8
4
standardization
1
2
1
9
5
5
applications
9
5
Revision for I Mid Exams
I MID EXAMINATIONS (03-09-2012 to 05-09-2012)
UNIT-V: D.C and A.C Bridges:
Method of measuring low, medium and high resistance-
10
2
2
Sensitivity of WHEATSTONE’S bridge- KELVIN’S
double bridge-for measuring low resistance
,measurement
of high Resistance
loss of charge method.
5
11
Measurement of inductance- Maxwell’s bridge,
Anderson’s bridge.
Measurement of capacitance and loss angle –
DesautyBridge. Wien’s bridge- Schering bridge.
1
1
1
2
7
12
5
UNIT-VII : magnetic measurements:
1
Ballistic galvanometer –equation of motion
2
Flux meter-constructional details, comparison with
2
Ballistic galvanometer. determination of b-h loop
methods reversals
six point method –A.C testing –iron losses of
13
2
8
bar samples
1
Unit VII: Oscilloscope: Cathode Ray Oscilloscope
1
Cathode ray tube
1
Time base generators-
1
horizontal and vertical amplifiers
2
5
14
4
applications of frequency- measurement of phase
1
Frequency, current and voltage.
15
5
8
lissajous pattern
2
UNIT-VIII:Digital meters
1
Digital voltmeter-Successive approximation
2
Ramp type digital frequency meter
16
5
integrating type digital frequency meter
1
8
Digital multimeter
Digital Tachometer
4
2
2
4
Revision for II Mid Exams
17
Total Available
4
76
Signature of the staff-in charge
Total Required
76
Signature of the HOD
Question Papers – Mid-semester examinations
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE :: KAVALI
(Approved by
A.I.C.T.E- New Delhi, Affiliated to J.N.T. University, Anantapur)
Janata peta, Kavali,
S.P.S.R Nellore (Dist), A. P
Subject Name: EEMIstMID-Descriptive test
Year & Branch:III B.Tech -I SemEEE
Answer any three questions.each one carries 10 marks.
10X3=30
1.a) explain the working of a universal shunt used for multi range ammeter?b)write the significance of control and
damping torque?
2.)explain the working of attraction type moving iron instruments. List the advantages and
moving iron instruments?
disadvantages of the
3.)With a neat diagram ,explain the working of dynamometer type power factor meter?
4.)Show that Tanϴ=
.if
and
are the readings of two watt meters used in two wattmeter method ?
5.)explain the measurement of unknown emf using dc crompton’s potentiometer?
VISVODAYA ENGINEERING COLLEGE :: KAVALI
(Approved by A.I.C.T.E- New
Delhi, Affiliated to J.N.T. University, Anantapur)
Janata peta, Kavali, S.P.S.R Nellore
(Dist), A. P
Subject Name: EEMIstMID-Descriptive test
Year & Branch:III B.Tech -I SemEEE
Answer any three questions.each one carries 10 marks.
10X3=30
1.a) explain the working of a universal shunt used for multi range ammeter?b)write the significance of control and
damping torque?
2.)explain the working of attraction type moving iron instruments. List the advantages and
moving iron instruments?
disadvantages of the
3.)With a neat diagram ,explain the working of dynamometer type power factor meter?
4.)Show that Tanϴ=
.if
and
are the readings of two watt meters used in two wattmeter method ?
5.)explain the measurement of unknown emf using dc crompton’s potentiometer?
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE :: KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University, Anantapur)Janata peta,
Kavali, S.P.S.R Nellore (Dist), A.P.
Subject Name: EEM
IstMID-Objective test Year & Branch:III B.Tech -I Sem EEE
Name:
Roll No:
Max Marks:10M
1.)The high torque to weight ratio in an analog indicating instrument indicates
[
]
a)high friction loss b)low friction lossess c)hysteresis loses d)frequency losses
2.) The scale of the moving iron instrument is
[
]
a)uniform
b)Non-uniform
c)neither uniform nor non –uniform
3.)In gravity control system
[
]
a) I α cosϴ
b) I α sinϴ
c)I α ϴ
d) I α tan ϴ
4.)The controlling torque in 1-Ø power factor meter is provided by
[
]
a)spring control b)gravity control c)stiffness of suspension
d)none of the above
5.)The transformers use in conjunction with measuring instruments for measurement purpose
[
]
is called
a)C.T.
b)P.T.
c)Power transformers
d)Instrumental transformers
6.)The deflection of the power factor meter is
[ ]
a)Ø
b)cosØ
c)sinØ
d)none
7.)In rotating field type power factor meter we have
[ ] a)3 fixed
coils
b)one fixe coils
c)two fixed coils
8)In rotating field type moving iron power factor meter the field of the fixed coil is
[
]
a)alternating field
b)rotating field
c)constant field
9.)The moving coil in a dynamometer wattmeter is connected
[
] a)In series
with the fixed coil b)across the supply c)In series with the load d.)across the load
10.)A potentiometer is basically a
[ ]
a)Deflecting type instruments b)null type instrument c)digital instrument d)None
11.)in moving coil instruments the deflection is directly proportional to
12.)By using potentiometers we can
measure
13.)A dc potentiometer is designed to measure
up to 2V with a slide wire of 800mm.A standard cell emf 1.18V .obtains balance at 600cm.A test cell is seen to
obtain balance at 680mm.The emf of test cell is
14.)A dynamometer type watt meter responds to the value of active power.
15.)A dc ammeter has a
resistance of 0.1Ω and its current range is (0-100A).If the range is to be
extended to (0-500A), then shunt
resistance is
.
16.)The power of a 3-Ø,3-wire balanced system
was measured by two wattmeter method. The reading of One of wattmeter was found to be double that of the
other. What is the power factor of the system
.
17.)The minimum NO. of wattmeters required to measure 3-Ø,3-wire balanced or unbalanced power is
18.)The power expression in 3-Ø circuit in terms of line voltage ,line current and power factor of the load is
.Where Ø is the angle between voltage and current.
19.) The scale of the moving iron
instrument is
20) The minimum NO. of wattmeters required to measure 3Ø,4-wire unbalanced power is
VISVODAYA ENGINEERING COLLEGE :: KAVALI
(Approved by A.I.C.T.ENew Delhi, Affiliated to J.N.T. University, Anantapur)Janata peta, Kavali, S.P.S.R Nellore (Dist),
A. P
Subject Name: EEMIstMID-Objective test Year & Branch:III B.Tech -I Sem EEE
Name:
Roll No:
Max Marks:10M
1.)The high torque to weight ratio in an analog indicating instrument indicates
[
]
a)high friction loss b)low friction lossess c)hysteresis loses d)frequency losses
2.) The scale of the moving iron instrument is
[
]
a)uniform
b)Non-uniform
c)neither uniform nor non –uniform
3.)In gravity control system
[
]
a) I α cosϴ
b) I α sinϴ
c)I α ϴ
d) I α tan ϴ
4.)The controlling torque in 1-Ø power factor meter is provided by
[
]
a)spring control b)gravity control c)stiffness of suspension
d)none of the above
5.)The transformers use in conjunction with measuring instruments for measurement purpose
[
]
is called
a)C.T.
b)P.T.
c)Power transformers
d)Instrumental transformers
6.)The deflection of the power factor meter is
[ ]
a)Ø
b)cosØ
c)sinØ
d)none
7.)In rotating field type power factor meter we have
[ ] a)3 fixed
coils
b)one fixe coils
c)two fixed coils
8)In rotating field type moving iron power factor meter the field of the fixed coil is
[
]
a)alternating field
b)rotating field
c)constant field
9.)The moving coil in a dynamometer wattmeter is connected
[
] a)In series
with the fixed coil b)across the supply c)In series with the load d.)across the load
10.)A potentiometer is basically a
[ ]
a)Deflecting type instruments b)null type instrument c)digital instrument d)None
11.)in moving coil instruments the deflection is directly proportional to12.)By using potentiometers we can
measure
13.)A dc potentiometer is designed to measure
up to 2V with a slide wire of 800mm.A standard cell emf 1.18V .obtains balance at 600cm.A test cell is seen to
obtain balance at 680mm.The emf of test cell is
14.)A dynamometer type watt meter responds to the value of active power.
15.)A dc ammeter has a
resistance of 0.1Ω and its current range is (0-100A).If the range is to be
extended to (0-500A), then shunt
resistance is
.
16.)The power of a 3-Ø,3-wire balanced system
was measured by two wattmeter method. The reading of One of wattmeter was found to be double that of the
other. What is the power factor of the system
.
17.)The minimum NO. of wattmeters required to measure 3-Ø,3-wire balanced or unbalanced power is
18.)The power expression in 3-Ø circuit in terms of line voltage ,line current and power factor of the load is
.Where Ø is the angle between voltage and current.
19.) The scale of the moving iron
instrument is
Ø,4-wire unbalanced power is
20) The minimum NO. of wattmeters required to measure 3-
PBR VISVODAYAYA INSTITUTE OF TECHNOLGY AND SCIENCE::KAVALI
III.B.TECH,I-SEM,II MID EXAMINATION,November-2012
Branch: EEE
Time:1:30 Mins
Subject: EEM(Descriptive)
**Answer any three questions. Each one carries equal marks.
3X10=30
1.(a)Draw the circuit of a Kelvin’s double bridge used for measurement of low
resistances .Derive the
conditions for balance.
(b)A 4terminal resistor approximately of 50 resistances was measured by means of Kelvin double bridge having
the following component resistances:
standard resistor=100.02µΩ
Inner ratio arms=100.30Ω and 200Ω
Outer ratio arms=100.23Ω and 200Ω
Resistance of link connecting the standard and the unknown resistance is 700µΩ . Find unknown
resistance
2.(a).Derive the equation of balance for an Anderson’s bridge .Draw the phasor diagram for conditions under
balance. Discuss the advantages and disadvantages of this bridge.
(b)Write the CRO applications
3.(a) How the phase and frequency can be measured with the use of a CRO. Explain?
(b)Explain the functions of the following controls:
i). intensity
iii). Horizontal and vertical positioning
ii). Focus
iv). synchronization
4.) Explain the method of measuring voltage in successive approximation method.
5.(a)Explain the determination of B-H loop method of reversals.
(b)Discuss the constructional details of Ballistic galvanometer?
*THERE IS NO SUBSTITUTE FOR HARDWORK*
VISVODAYA ENGINEERING COLLEGE :: KAVALI
III.B.TECH,I-SEM,II MID EXAMINATION,November-2012
Branch: EEE
Time:1:30 Mins
**Answer any three questions. Each one carries equal marks.
Subject: EEM(Descriptive)
3X10=30
1.(a)Draw the circuit of a Kelvin’s double bridge used for measurement of low
resistances.Derive the
conditions for balance.
(b)A 4terminal resistor approximately of 50 resistances was measured by means of Kelvin double bridge having
the following component resistances:
standard resistor=100.02µΩ
Inner ratio arms=100.30Ω and 200Ω
Outer ratio arms=100.23Ω and 200Ω
Resistance of link connecting the standard and the unknown resistance to the nearest 0.01µΩ.
2.(a).Derive the equation of balance for an Anderson’s bridge.Draw the phasor diagram for conditions under
balance.Discuss the advantages and disadvantages of this bridge.
(b)Write the CRO applications
3.(a) How the phase and frequency can be measured with the use of a
CRO.Explain?
(b)Explain the functions of the following controls:
i). intensity
iii). Horizontal and vertical positioning
ii). Focus
iv). synchronization
4.) Explain the method of measuring voltage in successive approximation method.
5.(a)Explain the determination of B-H loop method of reversals.
(b)Discuss the constructional details of Ballistic galvanometer?
*THERE IS NO SUBSTITUTE FOR HARDWORK*
PBR VISVODAYAYA INSTITUTE OF TECHNOLGY AND SCIENCE::KAVALI
III.B.TECH,I-SEM,II MID EXAMINATION,November-2012
Branch: EEE
Time:20 Mins
Subject: EEM(Objective)
NAME:
ROLL NO:
1.)The common bridge for precise measurement of inductance over a wide range is
a)Maxwell’s bridge b)Hay’s bridge c)Anderson bridge d)None
[
]
2.)The bridge most commonly employedfor measurement of frequency is
[
]
[
]
a)Owen’s bridge b)Hay’s bridge c)schering bridge d)Wein’s bridge
3.)A multimeter is used to measure
a)resistance
b)Voltage
c)Current
d)all of the above
4.)Which one of the following is measured by the loss of charge method
a)Low R
b)High R
c)Low L
[
]
d)High L
5.) A dc voltage of 1V is applied to the X-plates of a CRO and ac voltage 2sin100t is applied to
resulting display on the CRO screen will be
[
]
a)vertical stright line
b)horizontal stright line
c)sine wave
the Y-plates .The
d)slant line
6)While measuring the phase difference between the V1(t)=10sinwt and V2(t)=10sin(wt +Ø),the
observed on CRO was a circle. The value of Ø is
[
]
a)zero
b)Π/4
c)Π/2
d)Π
7.) A certain oscilloscope with 4cmX4cm screen has its own sweep output fed to its input.If the
sensitives are same ,the oscilloscope will display a
[
]
a)sawtooth
b)triangular
c)diagonal line
b)Horizontal line
X and Y
d)horizontal line
8.)The X and Y inputs to a CRO are respectively 10cos(wt +Ø) and 10sin(wt +Ø) . The resulting
[
]
a)Stright line
Lissajous pattern
c)ellipse
Lissajous pattern is
d)Circle
9.)Voltages Vy=100sin100t and Vx=50sin100t are connected to Y and X terminals of a CRO respectively. What is the
shape of the screen on the CRO
[
]
a)Circle
b)straight line
c)An ellipse
10.) Paramanent magnets are tested by
d)A parabola
[
]
a)ballistic methods
b)using an electric circuit having mutual inductance
c)potentiometer method
d)None
11.)The approximate input impedance of the CRO
a)1MHz
b)10MHz
[
c)100MHz
d)20MHz
12.)The construction of Fluxmeter is similar to ____________milli ammeter
a)MC
b)MI
]
c)Dynamometer type
[
]
d)electrostatic
13.)High resistances are in the range of
a)99.9KΩ
b)1MΩ
c)>100KΩ d)None
14.)The meter used to measure resistance is____________________.
15.)Medium resistances are from _____to________.
16.)The continuity in underground cables can be detected by using_______________.
17.) The flux meter have__________ damping torque __________ control torque.
18.) If hysteresis loop of a particular material is widen then the permittivity of the material is
_______________.
VISVODAYAYA ENGINEERING COLLEGE::KAVALI
III.B.TECH,I-SEM,II MID EXAMINATION,November-2012
Branch: EEE
Time:20 Mins
NAME:
Subject: EEM(Objective)
ROLL NO:
1.)The common bridge for precise measurement of inductance over a wide range is
a)Maxwell’s bridge b)Hay’s bridge c)Anderson bridge d)None
2.)The bridge most commonly employedfor measurement of frequency is
a)Owen’s bridge b)Hay’s bridge c)schering bridge d)Wein’s bridge
[
]
[
]
3.)A multimeter is used to measure
a)resistance
b)Voltage
[
c)Current
d)all of the above
4.)Which one of the following is measured by the loss of charge method
a)Low R
b)High R
c)Low L
[
]
d)High L
5.) A dc voltage of 1V is applied to the X-plates of a CRO and ac voltage 2sin100t is applied to
resulting display on the CRO screen will be
[
]
a)vertical stright line
b)horizontal stright line
c)sine wave
the Y-plates .The
d)slant line
6)While measuring the phase difference between the V1(t)=10sinwt and V2(t)=10sin(wt +Ø),the
observed on CRO was a circle. The value of Ø is
[
]
a)zero
b)Π/4
]
c)Π/2
Lissajous pattern
d)Π
7.) A certain oscilloscope with 4cmX4cm screen has its own sweep output fed to its input.If the
sensitives are same ,the oscilloscope will display a
[
]
a)sawtooth
b)triangular
c)diagonal line
d)horizontal line
8.)The X and Y inputs to a CRO are respectively 10cos(wt +Ø) and 10sin(wt +Ø) . The resulting
[
]
a)Stright line
b)Horizontal line
X and Y
c)ellipse
Lissajous pattern is
d)Circle
9.)Voltages Vy=100sin100t and Vx=50sin100t are connected to Y and X terminals of a CRO respectively. What is the
shape of the screen on the CRO
[
]
a)Circle
b)straight line
c)An ellipse
d)A parabola
10.) Paramanent magnets are tested by
a)ballistic methods
[
]
b)using an electric circuit having mutual inductance
c)potentiometer method
d)None
11.)The approximate input impedance of the CRO
a)1MHz
b)10MHz
c)100MHz
[
d)20MHz
12.)The construction of Fluxmeter is similar to ____________milli ammeter
a)MC
b)MI
c)Dynamometer type
13.)High resistances are in the range of
a)99.9KΩ
b)1MΩ
c)>100KΩ d)None
d)electrostatic
[
]
]
14.)The meter used to measure resistance is____________________.
15.)Medium resistances are from _____to________.
16.)The continuity in underground cables can be detected by using_______________.
17.) The flux meter have__________ damping torque __________ control torque.
18.) If hysteresis loop of a particular material is widen then the permittivity of the material is
_______________.
Question Bank
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT-1
1.a) explain the working of a universal shunt used for multi range ammeter?
1.b)write the significance of control and damping torque?
2)explain the construction and working of PMMC instrument and also derive the
torque equation for that?
3.)with a neat diagram explain the working of dynamometer type instrument?
4.)explain the working of attraction type moving iron instruments. List the
advantages and disadvantages of
the moving iron instruments?
BITS
1.) The high torque to weight ratio in an analog indicating instrument indicates
]
a)high friction loss
b)low friction losses
c)hysteresis losses
c)frequency losses
2.) Horizontally placed instruments are used
[a]
a)spring control system
b)gravity control system
c)both
c)none
3.) Which meterial is used for shunts of dc instrument
[a]
a) manganin
b)constantan
c)copper
d)silver
[b
4.)In moving iron instruments the deflection is directly proportionalto
[c]
a) I
b)I/2
c)
d)
5)A 100µA ammeter has an internal resistance of 100Ω .For extending its range to
measure 500µA,the
shunt required is
a) 20Ω
b)22.22Ω
c)25
d)50
6.)in moving coil instruments the deflection is directly proportional to
[a]
a) I
b)I/2
c)
d)
7.) The scale of the moving iron instrument is
[b]
a)uniform
b)Non-uniform
c)neither uniform nor non –uniform
8)An ammeter with input resistance of 50Ω gives full scale deflection for 50µA
current.The input resistance of (0-1mA) ammeter obtained by connecting a shunt
across the (0-50µA)meter will be[d]
a)50Ω
b)25Ω
c)5Ω
d)2.5Ω
9.)A dc ammeter has a resistance of 0.1Ω and its current range is (0-100A).If the
range is to be extended to
(0-500A), then shunt resistance is
[c]
a)0.010Ω
b)0.011Ω c)0.025Ω
d)1.0Ω
10.)In gravity control system
[b]
a)I α cosϴ b)I α sinϴ
c)I α ϴ
d) I α tan ϴ
[C]
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT – 2
1.)Discuss C.T. and P.T. Define ratio’s of instrument transformers?
2.)Explain the advantages and disadvantages of instrument transformers?
3.)With a neat diagram ,explain the working of dynamometer type power factor
meter?
4.)With a neat diagram ,explain the working of rotating field type moving iron
power factor meter?
BITS
1.)The controlling torque in 1-Ø power factor meter is provided by
[d]
a)spring control
b)gravity control
c)stiffness of suspension
d)none of the above
2.)The transformers use in conjunction with measuring instruments for
measurement purpose
is called
a)Current transformer
b)Potential transformer
c)Power transformers
d)Instrumental transformers
3.)The transformer used for measurement of current is called
a]
a)Current transformer
b)Potential transformer
[d]
[
c)Power transformers
d)Instrumental transformers
4.)The transformer used for measurement of voltage is called
[
b]
a)Current transformer
b)Potential transformer
c)Power transformers
d)Instrumental transformers
5.)The current in the primary winding of a current transformer depends upon
[b]
a)burden of the secondary winding of transformer
b)load connected to the system in which C.T. is installed
c)both buren of the transformer secondary winding and load connected to the
system
d)none of the above
6.)The burden of the current transformer is expressed in terms of the
[b
]
a)secondary winding current
b)VA rating of the transformer
c)voltage,current and power factor of the system
d)None of the above
7.)The deflection of the powerfactor meter is
[a]
a)Ø
b)cosØ
c)sinØ
d)none
8.)In current transformer ,the error in phase angle and transformation ratiois mainly
due to
a)Ie,Im,δ
[a]
b)n,Is,δ
c)n,Is,ϴ
d)none
9.)In rotating field type power factor meter we have
[ a]
a)3 fixed coils
b)one fixe coils
c)two fixed coils
d)none
10)In rotating field type moving iron power factor meter the field of the fixed coil is
[b]
a)alternating field b)rotating field
c)constant field
d)none
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT -3
1.)Discuss the errors and
compensations of singlephase energy meter?
2.)With a neat sketch explain the working of 1-Ø electro dynamometer wattmeter?
3.)What is the significance of driving torque and breaking torquesin 1-Ø induction
type energy meter?
4.)Show that Tanϴ=
.if
and
are the readings of two watt meters used
in two wattmeter method ?
BITS
1.)Which one of the following defect is responsible for creeping in an induction type
energy meter
[b]
a)imperfect lag compensation
b)over friction compensation
c)imperfect overload compensation
2.)The power of a 3-Ø,3-wire balanced system was measured by two wattmeter
method. The reading of
One of wattmeter was found to be double that of the other. What is the power
factor of the system [ d ]
a)1
b)0.866
c)0.707
d)0.5
3.)The voltage coil of a single phase house service energy meter
[b]
a)Highly resistive
b)highly inductive
c)highly inductive
4.)The moving coil in a dynamometer wattmeter is connected
[b]
a)In series with the fixed coil
b)across the supply
c)In series with the load
d.)across the load
5.)A dynamometer type watt meter responds to the
[a]
a)Average value of the active power
c)Peak value of the reactive power
b)Average value of the reactive power
d)Peak value of the active power
6.)The minimum number of wattmeters required to measure 3-Ø,3-wire balanced or
unbalanced power [ b ]
a)1
b)2
c)3
d)4
7.)Which of the following condition must be satisfied for the two wattmeter method
of 3-Ø power
measurement
[c]
a)Load must be balanced
b)source must be balanced
c)system should be 3-Ø,3-wire type
d)none
8.) The minimum number of wattmeters required to measure 3-Ø,4-wire balanced
power is
[a]
a)1
b)2
c)3
d)4
9) The minimum number of wattmeters required to measure 3-Ø,4-wire unbalanced
power is
[c]
a)1
b)2
c)3
d)4
10.)The power expression in 3-Ø circuit in terms of line voltage
power factor of the
load is
,line current
and
.Where Ø is the angle between
[c]
a)Line voltage and line current
c)Phase voltage and line current
b)Line voltage and phase current
d)Phase current and phase voltage
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT-4
1.)explain the measurement of unknown emf using dc crompton,s potentiometer?
2.)Explain the applications of dc potentiometers?
3.)Explain about standardization of dc potentiometer?
4.)With a neat diagram explain the working of polar type AC potentiometer?
BITS
1.)A potentiometer is basically a
[b]
a)deflection type instrument
b)null type instrument
)deflection as well as nulltype instrument
d)digital instrument
2.)When a potentiometer is used for measurement of voltage of an unknown
source,the power consumed
in the circuit of the unknown source under null conditions
[d]
a)is very high
b)is high
c)is small
d)is ideally zero
3.)Standardization of potentiometer is done in order that ,they become
[d]
a)accurate b)precise
reading
c)accurate and precise
4.)The standardization of AC potentiometer is one by
[b]
a)directly using AC standard voltage sources
d)accurate and direct
b)Using DC sources and transfer instruments
c) Using AC sources and transfer instruments
5.)Potentiometers used in control systems are
[c]
a)To improve stability
b)To improve frequency response
c)As error sensing transducers d)To improve time response
6.)In order to achive high accuracy, the slide wire of a potentiometer should be
[a]
a)As long as possible
b)As short as possible
c)neither too small nor too large
d)very thick
7.)By using potentiometers we can measure
[c]
a)High voltages
b)voltages greater than 100V
c)voltages less than 2V
d)None
8.)A dc potentiometer is designed to measure up to 2V with a slide wire of 800mm.A
standard cell emf 1.18V obtains balance at 600cm.A test cell is seen to obtain
balance at 680mm.The emf of test cell is
[b]
a)1.00V
b)1.34V
c01.50V
d)1.70V
9.)The reading of a polar type AC potentiometer when measuring the reactance of a
coil are
I=12
,V=27.8
.The reactance of a coil is
[b
]
a)2.317Ω
b)0.634Ω
c)2.22Ω
d)-2.22Ω
10.)In the potentiometer circuit shown in the figure. balance is obtained. The
unknown emf is.
[a]
a)200mV
b)2.8mV
c)3.0mV
400mV
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT - V
1.Draw the circuit of a Kelvin’s double bridge used for measurement of low resistances
.Derive the conditions for balance.
2. A 4terminal resistor approximately of 50 resistances was measured by means of Kelvin
double bridge having the following
component resistances:
standard resistor=100.02µΩ ; Inner ratio arms=100.30Ω and 200Ω;
arms=100.23Ω and 200Ω
Outer ratio
Resistance of link connecting the standard and the unknown resistance is 700 µΩ .
Find unknown resistance
3.Derive the equation of balance for an Anderson’s bridge .Draw the phasor diagram for
conditions under balance.
Discuss the advantages and disadvantages of this bridge.
4.Obtain the balancing conditions for the schering bridge with its phasor diagram.
BITS
1.)The common bridge for precise measurement of inductance over a wide range is
]
a)Maxwell’s bridge b)Hay’s bridge c)Anderson bridge d)None
[
2.)The bridge most commonly employed for measurement of frequency is
]
[
a)Owen’s bridge b)Hay’s bridge c)schering bridge d)Wein’s bridge
3.)A multimeter is used to measure
a)resistance
b)Voltage
[
c)Current
]
d)all of the above
4.)Which one of the following is measured by the loss of charge method
]
a)Low R
b)High R
c)Low L
d)High L
5.)High resistances are in the range of
a)99.9KΩ
b)1MΩ
[
[
c)>100KΩ
d)None
6.)The meter used to measure resistance is____________________.
7.)Medium resistances are from _____to________.
8.)The continuity in underground cables can be detected by using_______________.
9.)The low resistance is in the range of____________________.
10.)The high resistance is in the range of from __________to_______________.
]
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT-VI
1.Explain the determination of B-H loop method of reversals.
2.Discuss the constructional details of Ballistic galvanometer?
3.)Explain the construction details and operation of the flux meter?
4.) Explain the determination of B-H loop by step by step method?
BITS
1) Paramanent magnets are tested by
[
]
a)ballistic methods
b)using an electric circuit having mutual inductance
c)potentiometer method
d)None
2.)The construction of Fluxmeter is similar to ____________milli ammeter
]
a)MC
b)MI
c)Dynamometer type
3.)The loop which represents the relation of B & H is
]
[
d)electrostatic
[
a) Hysteresis loop
b)Eddy current loop c)closed loop
d) None
4.)A multimeter is used to measure
a)resistance
b)Voltage
c)Current
[
]
d)all of the above
5.)The unit of flux is
[
]
a)Weber
b) Tesla
c) Newton
d) Joul
6) The flux meter have__________ damping torque __________ control torque.
7) If hysteresis loop of a particular material is widen then the permittivity of the material
__________
8) As air gap increases the reluctance becomes________________.
9) Permanent magnets are tested by_______________.
10.) In Ballistic galvanometer the controlling Torque is_____________.
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT-VII
1. How the phase and frequency can be measured with the use of a CRO. Explain?
2.Explain the functions of the following controls:
i). intensity
iii). Horizontal and vertical positioning
ii). Focus
iv). Synchronization
3.What ate the applications and advantages of the CRO?
4.Explain the functions of the vertical and horizontal amplifiers in the CRT tube?
BITS
1.) A dc voltage of 1V is applied to the X-plates of a CRO and ac voltage 2sin100t is applied
to
the Y-plates
The resulting display on the CRO screen will be
[
]
a)vertical stright line
b)horizontal stright line
c)sine wave
d)slant line
2)While measuring the phase difference between the V1(t)=10sinwt and V2(t)=10 sin(wt
+Ø),the Lissajous pattern observed on CRO was a circle. The value of Ø is[
]a)zero
b)Π/4
c)Π/2
d)Π
3.) A certain oscilloscope with 4cmX4cm screen has its own sweep output fed to its input.If
the X and Y sensitives are same ,the oscilloscope will display a
[
]
a)sawtooth
b)triangular c)diagonal line
d)horizontal line
4.)The X and Y inputs to a CRO are respectively 10cos(wt +Ø) and 10sin(wt +Ø) . The
resulting Lissajous pattern is
[ ]
a)Stright line
b)Horizontal line
c)ellipse
d)Circle
5.)Voltages Vy=100sin100t and Vx=50sin100t are connected to Y and X terminals of a CRO
respectively. What is the shape of the screen on the CRO
[
]
a)Circle
b)straight line
c)An
ellipse
d)A parabola
6.)The approximate input impedance of the CRO
a)1MHz
b)10MHz
c)100MHz
[
d)20MHz
7.)The material used in the CRT screen
[
]
a)Zinc
b) Phosphorous c) Molybdenum
d.)copper
8.)The Lissajous patterns can be used to find the___________________.
9.)The CRT of the Television can be worked on the _____________________ principle.
10.)_______________ system can be used as intensity knob.
]
ELECTRICAL & ELECTRONICS MEASUREMENTS
UNIT-VIII
1. Explain the method of measuring voltage in successive approximation method.
2. Explain the operation of the ramp type DVM?
3. What are the applications and advantages of digital instruments?
4. Explain the working and operation of digital multimeters?
BITS
1.)A multimeter is used to measure
[
]
a)resistance
b)Voltage
c)Current
d)all of the above
2.)Digital instruments deals with ___________ voltage
[
]
a)Low
b) High
c) Moderate
d) None
3.) Digital instruments deals with ___________ frequency
[
]
a)Low
b) High
c) Moderate
d) None
4.) By using successive approximation method we can measure
[
]
a) voltage
b) current
c)power
d)none
5.) The accuracy in case of digital instruments compared with analog instruments is
[
]
a)more
b)less
c)none of these
6.) The voltage can be measured by ___________ method.
7) If hysteresis loop of a particular material is widen then the permittivity of the material
__________
9) As air gap increases the reluctance becomes________________.
10.) If hysteresis
is
loop of a particular material is widen then the permittivity of the material
Previous years’ question papers – JNTUA
IIIB. TechI Semester (R09)Regular Examinations,November 2011
ELECTRICAL&ELECTRONIC MEASUREMENTS
(Electrical &Electronics Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a)
(b)
Explainhowthecurrent rangeofPMMC instrumentisextendedwith thehelpofshunts.
Discussabout ErrorsandCompensationsof measuringinstruments.
2
(a)
(b)
Listtheadvantagesanddisadvantagesofinstrumenttransformers.
Discussphaseangleerror.
3
(a)
(b)
Explaindrivingsystem,movingsystemandbreakingsystemina1-Φ inductiontype
energymeter.
Writeshortnotesonthreephaseenergymeter.
4
(a)
(b)
Writeshortnotesonpolarstandardization.
Explain theoperationof DC Crompton’spotentiometer.
5
(a)
(b)
Withneat figureexplain theworkingofawheatstone’sbridge.
Howdoyou measureinductanceusingMaxwell’sbridge?
6
(a)
(b)
DiscussA.Ctesting.
Writeexplanatorynotesonfluxmeter.
7
(a)
(b)
Withneat figureexplain theworkingofa CRO.
Howdoyou measurephaseandfrequency usingCRO?
8
(a)
(b)
Explain thefunctionofdigitaltachometer.
Discusstheworkingofanintegrating typevoltmeter.
*****
IIIB. TechI Semester (R09)Regular Examinations,November 2011
ELECTRICAL&ELECTRONIC MEASUREMENTS
(Electrical &Electronics Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a)
(b)
Explain themethodofreducingerrors in measuringinstruments.
Withaneatfigureexplaindynamometer.
2
(a)
(b)
Explain theworkingofadynamometer.
DiscussCTand PT.
3
(a)
(b)
Explain themeasurementofLPFandUPF.
Whatisthesignificanceofdrivingandbreakingtorquesina1-Φinductiontypeenergy
meter?
4
(a)
(b)
Explain themeasurementofunknown resistanceusingDC Crompton’spotentiometer.
Listtheapplicationsofpotentiometer.
5
(a)
(b)
Explain themeasurementofhighresistance-loss ofchangemethod.
Explain theworkingofAndersonbridge.
6
(a)
(b)
Explain thedeterminationofB-H loopmethodof reversals.
WriteshortnotesonLissajouspattern.
7
(a)
(b)
Explain theconstructional detail andworkingofa CRT.
ListtheapplicationsofCRO.
8
(a)
(b)
Explain theworkingofadigitalfrequencymeter.
Listtheadvantagesof digital voltmeter.
*****
IIIB. TechI Semester (R09)Regular Examinations,November 2011
ELECTRICAL&ELECTRONIC MEASUREMENTS
(Electrical &Electronics Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a)
(b)
Deriveanexpressionforthedeflecting torqueandcontrol torque.
Give thegeneral requirementsfor theconstructionofshunts.
2
(a)
(b)
Discussthedifferent errorsofPMMC.
Withneat figureexplain thefeaturesofmovingiron typePFmeter.
3
(a)
(b)
What isaphasemeter? Discussthemeritsanddemeritsofit.
Withaneat sketchexplain theworkingofasinglephasedynamometer wattmeter.
4
(a)
(b)
Withneat figureexplain theworkingofanACpotentiometer.
Discussthesignificanceofstandardization.
5
(a)
(b)
Howdoyou measurecapacitanceusingWien’sbridge? Explain.
Explain thesensitivityofwheatstone’sbridgeandhowdoyou measureit.
6
(a)
(b)
DiscusstheconstructionaldetailsofBallisticgalvanometer.
ListtheapplicationsofCRO.
7
(a)
(b)
Howdoyou measurecurrent andvoltageusingCRO?
Discusshorizontal andvertical amplifiersofCRO.
8
(a)
(b)
Explain themethodofmeasurementofvoltageusingRamp typevoltmeter.
Listtheadvantagesof digitalmultimeter and limitationsof thesame.
*****
IIIB. TechI Semester (R09)Regular
Examinations,November 2011
ELECTRICAL&ELECTRONIC
MEASUREMENTS (Electrical
&Electronics Engineering)
Time:3hours
MaxMarks:70
AnsweranyFIVE
questions
All
questionscarryequal
marks
1
(a)
(b)
Explain theworkingofauniversal shuntusedfor multirangeammeter.
Writethesignificanceof controlanddamping torques.
2
(a)
(b)
Define transformation ratio, nominal ratio and turns ratio as used for instrument
transformers.
Listtheadvantagesanddisadvantagesof movingirontypeinstruments.
3
(a)
(b)
Discusstheerrorsandcompensationofsinglephaseenergymeter.
Obtaintheexpressionfordeflectingandcontroltorquesofadoubleelementwattmeter.
4
(a)
(b)
Howdoyou measurecurrent andvoltageusingpotentiometer?
Discusscoordinatetypeofstandardization.
5
(a)
(b)
Explain theworkingofa Kelvin’sdoublebridgefor measuringlowresistance.
Explain thefeaturesofDesautybridgewithaneat sketch.
6
(a)
(b)
Derive theequationofmotioninBallisticgalvanometer.
Explainsixpointmethods.
7
(a)
(b)
What doyou meanbyLissajouspatterns? Howdoyou measurethem usingaCRO?
Drawaneat figureandexplain theworkingofaCRO.
8
(a)
(b)
Explain themethodofmeasuringvoltage insuccessiveapproximation method.
Givesalient featuresofdigitalmultimeter.
*
Electrical Machines _III
Syllabus
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR
B.Tech III-I Sem. (E.E.E)
T
4
0
P
C
4
(9A02505) ELECTRICAL MACHINES - III
UNIT – I CONSTRUCTION AND PRINCIPLE OF OPERATION
Constructional Features of round rotor and salient pole machines – Armature windings – Integral slot
and fractional slot windings; Distributed and concentrated windings – distribution, pitch and winding
factors – E.M.F Equation.
UNIT-I SYNCHRONOUS GENERATOR CHARACTERISTICS
Harmonics in generated e.m.f. – suppression of harmonics – armature reaction - leakage reactance –
synchronous reactance and impedance – experimental determination - phasor diagram – load
characteristics.
UNIT – III
REGULATION OF SYNCHRONOUS GENERATOR
Regulation by synchronous impedance method, M.M.F. method, Z.P.F. method and A.S.A. methods –
salient pole alternators – two reaction analysis – experimental determination of Xd and Xq (Slip test)
Phasor diagrams – Regulation of salient pole alternators.
UNIT – IV
PARALLEL OPERATION OF SYNCHRONOUS GENERATORS
Synchronizing alternators with infinite bus bars – synchronizing power torque – parallel operation and
load sharing - Effect of change of excitation and mechanical power input. Analysis of short circuit
current wave form – determination of sub-transient, transient and steady state reactances.
UNIT – V
SYNCHRONOUS MOTORS – PRINCIPLE OF OPERATION
Theory of operation – phasor diagram – Variation of current and power factor with excitation – V and
Inverted V Curves - Power developed – Synchronous Condenser.
UNIT-VIPOWER CIRCLES
Excitation and power circles – hunting and its suppression – Methods of starting – synchronous
induction motor.
UNIT – VII
SINGLE PHASE MOTORS
Single phase induction motor – Constructional features - Double revolving field theory – Elementary
idea of cross-field theory – split-phase motors – shaded pole motor.
UNIT – VIII
SPECIAL MOTORS
Principle & performance of A.C. Series motor-Universal motor – Principle of permanent magnet and
reluctance motors.
TEXT BOOKS
1. Electric Machines – by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-Hill Publishers, 4th Edition, 2010.
2. Electrical Machines – by P.S. Bimbra, Khanna Publishers.
REFERENCE BOOKS:
1. The Performance and Design of A.C.Machines – by M.G.Say, ELBS and Ptiman & Sons.
2. Electric Machinery – by A.E. Fitzgerald, C.Kingsley and S.Umans, Mc Graw-Hill Companies, 5th
edition, 1990.
3. Theory of Alternating Current Machinery by Langsdorf, Tata Mc Graw-Hill, 2nd edition.
4. Electromachanics-III (Synchronous and single phase machines), S.Kamakashiah, Overseas publishers
Pvt Ltd.
5. Electric Machines - by M. S. Sarma and M. K. Pathak, CENGAGE Learning.
Objective
ELECTRICAL MACHINES – III
Objective :
This subject is an extension of previous machines courses. It deals with the detailed analysis of
Synchronous generators and motors which are the prime source of electrical power generation and its
utilities. Also concerns about the different types of single phase motors which are having significant
applications in house hold appliances and control systems.
Synchronous generators are the prime source of electrical power generation in many power plants. In
our INDIA, the highest rating of 3-ph alternator for generating 3-ph AC power is 500MW at voltage range
of 6.6KV to 33KV with 50 Hz cycles/sec
In industry, most of the machines for different applications are 3-ph Induction motor, only a small
amount synchronous machines are used for some special purposes because of its excellent advantages.
The main advantages of 3-ph synchronous motors are it is used as synchronous condenser for power
factor correction, for improvement of voltage regulation in power system, used to drive constant speed
drives of loads etc.
There are two basic reasons for the use of 1-ph motors than 3-ph motors. Those are (i) For the reason
of economy, most houses, offices and also rural areas are supplied with 1-ph ac power. (ii) Economy of
motor and its branch circuit. The 1-ph m/cs are simple in construction, reliable, easy to repair, cheaper
in cost etc.
Lesson Plan
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE
ACADIMIC YEAR: 2013–14
LESSON PLAN
S.N
o.
Dates
No.of
periods
CLASS: III B.Tech-EEE
Faculty Name: P. Gopi
Subject: EM-III
No.of
Topic to be covered
In week
1
2
Periods
required
Basic laws in electrical engg. and introduction
to electrical machines
Total
Periods
Per
unit
2
02
Unit-I
1
2
4
Operating principle and working
1
Constructional Features of round rotor and
salient pole machines
2
Armature windings – Integral slot and
fractional slot windings; Distributed and
concentrated windings
Distribution, pitch and winding factors
3
5
E.M.F Equation.
09
2
1
2
Problems solved
Unit-II
Harmonics in generated e.m.f.
4
5
suppression of harmonics
1
1
2
1
10
1
1
1
2
11
Problems solved
Armature reaction
Leakage reactance – synchronous reactance
and impedance
Experimental determination
5
5
Phasor diagram – load characteristics.
Problems solved
Unit-III
6
3
Regulation by synchronous impedance
method and problems solved.
2
1
M.M.F. method
7
5
Problems solved on M.M.F. method
1
Z.P.F. method and A.S.A. methods and
problems solved
3
1
Salient pole alternators two reaction analysis
Experimental determination of Xd and Xq (Slip
test) Phasor diagrams
1
2
Regulation of salient pole alternators.
Unit-IV
8
5
1
1
Synchronizing alternators with infinite bus
bars
Synchronizing power torque
Parallel operation and load sharing
9
5
Effect of change of excitation and mechanical
power input.
1
2
1
08
Analysis of short circuit current wave form
1
Determination of sub-transient, transient and
steady state reactances.
10
02.09.13 TO 07.09.13
Revision of Mid paper –I
2
Introduction to Sym. Motors
1ST MID EXAMS
1
1
Unit-V
Theory of operation – phasor diagram
11
5
Types of excitation systems
Variation of current and power factor with
excitation
V and Inverted V Curves
Power developed and problems solved
Synchronous Condenser and problems solved
12
5
Unit-VI
1
1
2
1
2
2
1
Hunting and its suppression
Excitation and power circles
13
5
Methods of starting
02
09
2
2
1
06
Synchronous induction motor.
Unit-VII
14
4
Single phase induction motor
1
1
Constructional features
2
Double revolving field theory and cross-field
theory
Split-phase motors
15
2
Shaded pole motor.
Problems solved
5
1
1
2
Unit-VIII
16
08
2
1
Principle & performance of A.C. Series motor
Universal motor
17
5
Principle of permanent magnet
1
06
Reluctance motors.
1
1
2
Problems solved
Revision
No. of periods
available
72
No. of periods required
72
TEXT BOOKS:
1. Electric Machines – by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-Hill Publishers, 4th Edition, 2010.
2. Electrical Machines – by P.S. Bimbra, Khanna Publishers.
REFERENCE BOOKS:
6. Electric Machinery – by A.E. Fitzgerald, C.Kingsley and S.Umans, Mc Graw-Hill Companies, 5th
edition, 1990.
7. Electromachanics-III (Synchronous and single phase machines), S.Kamakashiah, Overseas publishers
Pvt Ltd.
Faculty In-charge
Head of the Department
Faculty In-charge
Head of the Department
Question Papers – Mid-semester
examinations
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE ::
KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University,
Anantapur)
Janata peta, Kavali, S.P.S.R Nellore (Dist), A. P
Subject Name: EM – III
2nd -Descriive test
Year & Branch: III B.Tech -I Sem EEE
Answer any three questions, each question carries equal marks
1.(a) Explain Why the Syn. Motor is not self starting with suitable diagrams.
(b) An industrial load of 4 MW is supplied at 11 kV, the power factor being 0.8 lagging. Asynchronous
motor is required to meet an additional load of 1103.25 kW and at the sametime to raise the
resultant power factor to 0.95 lagging. Determine the kVA capacity of the motor and the p.f. at
which it must operate. The efficiency of motor is 80%.
2.(a) Explain in details about V & /\ curves with suitable phasor diagrams.
(b) A 75KW, 400V,Y connected syn. motor has armature resistance and reactance/ph of 0.04ohms and
0.4ohms respectively. Find the open ckt voltage/ph and the load angle and also find the mech.
power developed for full load at 0.8 p.f leading. Assume an effiency of 93%.
3.(a) Explain the construction of power circles for sym. motor with suitable diagrams.
(b) Explain principle of operation and performance char. of Syn. Induction motor.
4.(a) Show that a single phase winding when excited by a single phase supply produce two equal
andopposite revolving fields.
(b) Write a short note on Capacitor Start Induction Motor with suitable diagrams.
5.(a) Explain about Universal motor with its performance characteristics.
(b) Explain the operating principle Reluctance motor briefly.
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE ::
KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University,
Anantapur)
Subject Name: EM – III
Janata peta, Kavali, S.P.S.R Nellore (Dist), A. P
2nd -Descriive test
Year & Branch: III B.Tech -I Sem EEE
Answer any three questions, each question carries equal marks
1.(a) Explain Why the Syn. Motor is not self starting with suitable diagrams.
(b) An industrial load of 4 MW is supplied at 11 kV, the power factor being 0.8 lagging. Asynchronous
motor is required to meet an additional load of 1103.25 kW and at the sametime to raise the
resultant power factor to 0.95 lagging. Determine the kVA capacity of the motor and the p.f. at
which it must operate. The efficiency of motor is 80%.
2.(a) Explain in details about V & /\ curves with suitable phasor diagrams.
(b) A 75KW, 400V,Y connected syn. motor has armature resistance and reactance/ph of 0.04ohms and
0.4ohms respectively. Find the open ckt voltage/ph and the load angle and also find the mech.
power developed for full load at 0.8 p.f leading. Assume an effiency of 93%.
3.(a) Explain the construction of power circles for sym. motor with suitable diagrams.
(b) Explain principle of operation and performance char. of Syn. Induction motor.
4.(a) Show that a single phase winding when excited by a single phase supply produce two equal
andopposite revolving fields.
(b) Write a short note on Capacitor Start Induction Motor with suitable diagrams.
5.(a) Explain about Universal motor with its performance characteristics.
(b) Explain the operating principle Reluctance motor briefly.
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE ::
KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University,
Anantapur)
Subject Name: EM – III
2nd -Objective test
Year
&Branch:III B.Tech -I Sem EEE
Name:
Roll No:
Max Marks:10M
1). An under excited syn. motor operates at ____
[ ]
a). Lagging p.f
None
b). Leading p.f
c). Unity p.f
d).
2).The function of Damper winding in a syn. motor is _____
[ ]
a). to prevent hunting
None
b). to provide starting torque
c). Both a & b
d).
3). Improvement in power factor _________________ losses.
4). A salient pole syn. motor is operating at no load. If excitation is suddenly switched off, _________
[ ]
a). Motor will comes to stop b). Motor will continue to run at a speed less than syn. speed
c). Motor will continue to run at a speed less than syn. speed
d). None
5). When a syn. motor started _________________
[ ]
a). The field is excited by DC voltage
b). The field wdg is opened initially
c). The field wdg is shorted initially
d). Any of the above
6). For fixed load on the shaft, the armature current of a syn. motor is minimum when the p.f is
[ ]
a). less than unity & leading
not unity
b).Unity
c). Lagging
d). leading or lagging,
7). The negative phase sequence in a 3-ph syn. motor exists when the motor is ________
[ ]
a). Under loaded
b). Over loaded
c). Supplied with Unbalanced voltage
d). hot
8). A syn. motor supplying its rated load and is operating at UPF. If excitation is increased, then
[ ]
a). Its load increased
b). its p.f is constant
c). p.f being lagging
d). p.f being leading
9).V curves of syn. motor shows the relation between _____
[ ]
a). p.f Vs load
b). Ia Vs If
c). p. f Vs If
d). p.f Vs Ia
10). In salient pole syn. machine, the condition for max mech. power developed is __________.
11). The starting torque of a 3-ph syn. motor is______________.
12). In capacitor start motor, the capacitor is connected
___
[
a). In series with main wdg
d).None
]
b). in series with running wdg
c).
both
a
&
13). As compared to split phase motor, a capacitor start motor has_____________starting torque.
14). A permanent magnet AC motor has ________ excitation.
[ ]
a). AC
b). DC
c). zero
d). None
15). A ceiling fan uses_______ motor
[ ]
a). Split phase
d). None
b). Capacitor start & run
c). Capacitor start
16). A shaded pole runs in the direction from _________________________________ part of pole.
17). AC series motors are built with as few field turns as possible to reduce ___________
[ ]
b
a). Flux
d). None
b). Eddy current loss
c). reactance
18). In case of reluctance motor, the torque is proportional to_____________.
19). The function of compensating winding in AC series motor is to ________________
[ ]
a). provide starting torque
b). reduce the reactance of arm.wdg.
c). convert into 2-ph
d). None
20). If a centrifugal switch of a capacitor start motor fails to open, ______
[ ]
a).The capacitor & running wdg will be destroyed
b). Only the running wdg may destroyed
c). Only the capacitor will be destroyed
d). None
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE ::
KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University,
Anantapur)Subject Name: EM – III Ist-Descriive test
SemEEE
Date: 12-11-2012(AN) Duration: 90 min
Year & Branch:III B.Tech -I
Marks:30M
1. (a) Explain different types of armature windings with example.
(b) A 3-Ph star connected alternator, on open circuit is required to generate a line voltage of 3600 V,
50 Hz, when driven at 500 rpm. The stator has 3 slots per phase per pole and 10 conductors per slot.
Calculate: (i) The number of poles, (ii) The useful flux per pole.All the conductors in a phase are
connected in series and the coils to be full pitch.
2. (a) Explain the effect of power factor on armature reaction of an alternator.
(b) Calculate the RMS value of EMF induced per phase of a 10 pole, 3-ph, 50 Hz, alternator with 2 slots
per pole per phase and 4 conductors per slot in two layers. The coil span is 150 o electrical. The flux
per pole has a fundamental component of 0.12 wb & a 20% of third harmonic component.
3. (a)What is Voltage regulation. Explain ZPF method of calculating regulation of alternator
(b) A 3-Ph, alternator has a direct axis & quadrature axis reactances of 0.8 pu & 0.5 pu respectively.
Draw a vector diagram for full load 0.8 pf leading & obtain there from load angle & no load per unit
voltage.
4. (a) Define Syn reactance (Xs), Syn Impedance (Zs). Also explain the load characteristics of alternator.
(b) The following results are obtained on 6600v, 3-Ph alternator.A field current of 20A is found
necessary to circulate full load current on short circuit of thearmature. Calculate the load regulation
of 0.8 p.f (lag) by MMF method.
Voc(volts)
3100
4900
6600
7500
8300
If(Amps)
16
25
37.5
50
70
5. (a) Explain the conditions for parallel operation of two alternators.
(b) What is synchronization of an alternator? Explain Two bright & one dark lamp,
Synchronoscope methods for synchronization of alternators
PBR VISVODAYA INSTITUTE OF TECHNOLGY AND SCIENCE ::
KAVALI
(Approved by A.I.C.T.E- New Delhi, Affiliated to J.N.T. University,
Anantapur)Janata peta, Kavali, S.P.S.R Nellore (Dist), A. P
Subject Name: EM – III
Name:
Ist -Objective test
Roll No:
Year & Branch:III B.Tech -I Sem EEE
Max Marks:10M
1. Modern Alternators usually have fractional pitch wining to improve ___
[ ]
a) Voltage wave shape
b) Magnitude of generated emf c) Power factor d) None
2. If the armature current in an alternator is lagging w.r.t emf, the effect of armature reaction is __
[ ]
a) Magnetizing
b) X- Magnetizing
c) De-magnetizing
d) None
3. The maximum speed of Turbo alternator in India is ___
[ ]
a) 1500 rpm
b) 900 rpm
c) 3000 rpm
d) None
4. Salient pole alternators are generally used on:
[ ]
a) High speed prime movers
b) Low and medium speed prime movers
b) Hydrogen cooled prime movers
d) None
5. The relation between the d-axis and q-axis reactance is
[ ]
a) Xd=Xq
b) Xd > Xq
c) Xd < Xq
d) none
6. If an alternator winding has a fractional pitch of 5/6, the coil span is :
[ ]
a) 150˚
b) 300˚
c) 30˚
d) 50˚
7. The leakage reactance and armature reaction emf of Synchronous Machine are determined by
[ ]
a) OC test
b) ZPF test
c) OC & ZPF tests
d) OC &
SC tests
8. The magnetizing curve represents the relationship between ____
[ ]
a) P.f Vs terminal to load voltage
b) Magnetic flux and armature current
c) Exciting current and generated voltage
d) None
9. The winding of an armature is distributed in different slots, for____
[ ]
a) Reducing the cost
b) increasing the efficiency
c) increasing the regulation
reducing harmonics
10. Synchronous reactance of an alternator is
[ ]
a) Xa + XL
b) Xa - XL
c) Xa / XL
d)
d) None
11. Synchrono scope is used for ___
[ ]
a) Measuring P.f of alternator
d) All
b) Measuring active power of alternator c) for synchronization
12. At leading P.f, the armature flux in an alternator ____ the main flux.
[ ]
a) Opposes
b) aids
c) Distorts
d) no effect
13.What is the expression for PSY, when the alternator is connected to bus bar with rated load
[ ]
a) αEVt / ZS
b) αEVt / 2ZS
c) αE2 / ZS
d) αE2 / 2ZS
14. If the voltage across R & Y phases of 3-Ph alternator is 100V(dc), current is 10A(dc). What is the
resistance
of armature.
[ ]
a) 10Ω
b) 15Ω
c) 7.5Ω
d) 5Ω
15. Which of the following method gives the accurate voltage regulation results
[ ]
a) EMF method
b) AT method
c) ZPF method d) ASA method
16. The results of a slip test for determining Xd and Xq of a Y connected salient pole alternator are given
below:Vmax =108v; Vmin = 96v; Imax = 12Aand Imin=10A. Then Xd= _____ and Xq = ____
17. It is never advisable to connect a stationary alternator to live bus bar because it
[ ]
a) is likely to run as Syn Motor
c) will decrease bus bar voltage through momentarily
b) will get short circuited
d) None
18. EMF method is not accurate because the value of ZS so found is always __ than its value under
normal
voltage and saturation.
[ ]
a) More
b) Less
c) Zero
d) Infinity
19. The ZPF char. for potier diagram can be obtained by loading the alternator using ___ loads
[ ]
a) Resistive
b) Lamp
c) Pure Inductive
d) Pure capacitive
20. In the case of ____ load p.f., the terminal voltage will fall on removing the full load
[ ]
a) UPF
b) ZPF
c) Lagging P.f
d) Leading P.f
Today’s pain is tomorrow’s gain
Answers:
1. B, 2. C, 3. C 4. 5. B, 6. A, 7. D, 8. c, 9. d, 10. a, 11. c, 12. b, 13. , 14. c, 15. c, 17. b, 18. b, 19. c,
20. d
16. Xd=10.8 and Xq=8 ohms.
Aim to one and only
Question Bank
UNIT-I (DESCTRIPTIVE & OBJECTIVES)
1.(a). Explain the constructional details of round rotor m/c with neat diagrams.
(b). What are the various terms related to armature winding. Explain.
2.(a). Explain briefly about different types of armature windings.
(b). Write the advantages of (i) Short pitch wdg over Full pitch wdg (ii) Distribute wdg over
Concentrated wdg.
3.(a) Define and derive the expressions for Coil span factor an distribution factor in terms of slot angle,
no.of slots/pole/ph and short chording.
(b) Calculate the distribution factor for a 1-ph alternator having 6 slots/pole, (i) when all slots are
wound (ii) only 4 adjacent slots/pole are wound and remaining being not wound.
4.(a) Why the stationary armature is preferred over rotating armature. Write the differences between
salient pole and smooth cylindrical type rotors.
(b) A 3-ph, 4 pole, star connected alternator has 60 slots with 2 conductors perslot. The pitch of the
coil is 3 slots less than pole pitch. The flux per pole is0.125 wb. Calculate the no load terminal voltage
if the speed of alternator is1500 rpm.
5.(a) From the fundamental, derive the expression for induced emf/ph in 3-ph alternator.
(b) A 1-ph, 1500 rpm, 4 pole alternator has 8 conductors/slot with total of 24 slots. The wdg is short
pitched by 1/6th of full pitch. Assume distributed wdg with flux/pole as 0.05wb. Find the inducted
emf per ph and Frequency of the induced emf.
BITS
10.
Modern Alternators usually have fractional pitch wining to improve ___ [ B ]
b) Voltage wave shape b) Magnitude of generated emf c) Power factor
d) None
11.
The maximum speed of Turbo alternator in India is ___
[ C ]
b) 1500 rpm
b) 900 rpm
c) 3000 rpm
d) None
12.
Salient pole alternators are generally used on:
[ A ]
c) High speed prime movers
b) Low and medium speed prime movers
d) Hydrogen cooled prime movers
d) None
13.
If an alternator winding has a fractional pitch of 5/6, the coil span is :
[ A ]
b) 150˚
b) 300˚
c) 30˚
d) 50˚
5. The winding of an armature is distributed in different slots, for____ [ C ]
a) Reducing the cost b) increasing the efficiency
c) reducing harmonics
6. The biggest size of alternator in India is 500MVA, 6.6KV to 33KV.
7. The stator core of alternator is laminated to reduce______a) Hysteresis loss
b) Eddy current loss
[ B]
c) Copper loss
d) none
8. In modern alternators, generally double layer, distributed and short pitched wdg is commonly used.
9. The armature winding of 3-ph alternator is of _________ type
a) open
b)closed
c) a or b
10. If coil span is less than pole pitch, it is called _____ wdg
a) Short pitch b) Full pitch
[C]
d)none
[a]
c) concentrated d) distributed
11. If AC generator has 4 poles, no.of slots are 16, the type of wdg is ____
a)Full pitch
b) short pitch
c) Fractional slot
[c ]
d) integer slot
12. The winding factor is defined as product of coil span factor and distribution factor.
13.If the winding is full pitched and concentrated type, Kc and Kd values respectively[ b]
a) 1.0, 0.966
b) 1.0, 1.0
c) 0.966, 1.0
d) none
14. In large AC generator, the field is rotating and armature stationary.
UNIT-II (DESCTRIPTIVE & OBJECTIVES)
1. (a) Define Harmonics. Explain the causes for generation of harmonics? Explain the effect of harmonics
on generated emf.
(b) The flux distribution curve of a smooth core 50Hz generator is B = sinØ+0.2µ sin3 µ
+0.2sin5Ø+0.2sin7Øwb/m2 where Øis the angle measured from neutral axis. The pole pitch is35cm,
the core length is 32cm and stator coil span is four - fifth of pole pitch. Find equationfor emf induced
in one turn and its rms value.
2.(a) Explain the effect of power factor on armature reaction of an alternator.
(b) Calculate the RMS value of EMF induced per phase of a 10 pole, 3-ph, 50 Hz,alternator with 2 slots
per pole per phase and 4 conductors per slot in twolayers. The coil span is 150o electrical. The flux
per pole has a fundamentalcomponent of 0.12 wb & a 20% of third harmonic component.
3. (a)Explain the load characteristics of alternator with equivalent circuit.
(b) Data from tests performed to determine the parameters of a 200 kVA, 480 V,60 Hz, 3-ph, star
connected alternator are Voc=480V, Isc=209.9A for constant If& for DC test VDC= 91.9V, IDC=72.8 A
(stator). Determine synchronous impedance, syn. reactance and regulation at 08 p.f lagging and
leading.
4.(a) Explain how the synchronous reactance can be calculated by experimentally.
(b)The SC, OC & DC test data for a star connected 25 kVA, 240 V, 60 Hz,alternator are (between two
terminals):VOC = 240 V, ISC = 60.2 A - - - - For same field current and VDC = 120.6 V, IDC = 50.4 A
Determine: Synchronous reactance, no load induced emf at p.f of 0.707 lagging, leading and UPF
5. (a) Draw the phasor diagrams for 3-ph alternator at various loads.
(b) Write a short note on synchronous impedance and synchronous reactance.
BITS
1. At leading P.f, the armature flux in an alternator ____ the main flux. [ B ]
a) Opposes
b) aids
c) Distorts
d) no effect
2. If the voltage across R & Y phases of 3-Ph alternator is 100V(dc), current is 10A(dc). What is the
resistance of armature.
[ C]
b) 10Ω
b) 15Ω
c) 7.5Ω
d) 5Ω
3. In the case of __load p.f., the terminal voltage will fall on removing the full load [ D ]
c)
a) UPF
b) Zero PF
c) Lagging P.f
d) Leading P.f
4. If the armature current in an alternator is lagging w.r.t emf, the effect of armature reaction is __
[ C ]
b) Magnetizing
b) X- Magnetizing
c) De-magnetizing
d) None
5.The arm. reaction effect in a syn.machine depends on both load current and load p.f.
6. In syn.Generator, the effect of X-magnetization is to make the generated voltage _ [B ]
a)pure sinusoidal
b) Non-sinusoidal
c) Free from harmonics
d)none
7. In 3-ph round rotor syn.machine, the effect of armature reaction is taken care by __[ a ]
a) Syn. reactance
b) armature resistance
8. Unbalanced 3-ph stator currents causes
a) Vibrations b) heating of rotor
c) leakage reactance d) self reactance
[d]
c) double frequency in rotor current
d)all
9. A leading p. f loads on an alternator implies that its voltage regulation shall be [ c ]
a) zero b) positive
c) negative
d) none
10. In 3-ph Y connected generator, if the fundamental an 3rd harmonic rms voltages in each phase are
V1and V3, the line voltage of the generator will be _____
[b ]
a) sqrt(3(V12 +V32))
b) sqrt(3)V1
c) sqrt(3)V1+V3/3
UNIT-III (DESCTRIPTIVE & OBJECTIVES)
d) none
1. Describe the EMF and MMF methods of determining the regulation of a non salient polealternator.
Discuss the errors in both the methods.
2. (a) What is potier reactance? How it is determined by potier triangle? How it is used todetermine
regulation.
(b) A 5000KVA, 6.6KV, 3-ph, Y connected alternator has a resistance of 0.075ohms/ph. Estimate by
ZPF method, the regulation for a load of 500A at a p.fs (i) Unity, (ii) 0.8lag, (iii) 0.8 lead. Use the
following data.
Field current (A)
32
50
75
100
140
O.C voltage (V)
3100
4900
6600
7500
8300
ZPF voltage (V)
0
1850
4250
5800
7000
3. (a) The following table gives the OCC & SCC of a 2 pole, 11kV, 50 Hz, 3-ph starconnected alternator.
The stator resistance between two terminals is 0.2 .Calculate the regulation at full load current of 125
A at 0.8 pf lagging (bysynchronous impedance method).
If(A): 16 20 25 32 45 ;
EOL(kV): 4.4 5.5 6.6 7.7 8.8(where EoL is line voltage at no load)
(b) Explain the ASA modification of MMF method.
4. (a) Write a short note on slip test for determination of Xd and Xq.
(b) A 1 MVA, 6.6 kV, 3-ph star connected synchronous generator has a synchronous reactance of 25
per phase. It supplies full load current at 0.8 lagging pf and arated terminal voltage. Compute the
terminal voltage for the same excitationwhen the generator supplies full load current at 0.8 leading
pf.
5. A 3-ph, 440V, 50Hz, delta connected alternator has d-axis & q-axis reactance of 0.12 &0.09
respectively. If the alternator supplies 900 A at 0.8pf lagging, calculate the following:Neglect
armature resistance.
(a) the excitation EMF, neglecting saliency (Xd = Xq)(b) the excitation EMF, taking into account the
saliency.
Objectives
1. The effect leading pf loads on voltage regulation of an alternator is ____ in nature.[ B]
a) Increasing
b) decreasing
c) constant
d) none
2. The leakage reactance of a 3-ph alternator is determined by ____ tests.
a) ZPF & S.C tests
b) ZPF & O.C Tests
[
c) O.C & S.C tests
C]
d) None
3. The syn. impedance method of finding voltage regulation is generally considered as a pessimistic
method bcz saturation is not considered.
4. The ZPF char. for potier diagram can be obtained by loading the alternator using Inductive load.
5. EMF method give higher than actual value of regulation of alternator.
6. Potier triangle method of ZPF method gives accurate results for determination of voltage regulation of
alternator.
7. Slip test is performed to determine ______
a) Xs and Zs
[ B]
b) d-axis and q-axis reactances c) Slip
d) None
8. The results of a slip test for determining Xd and Xq of a Y connected salient pole alternator are given
below:
Vmax =108v; Vmin = 96v; Imax = 12Aand Imin=10A. Then Xd=10.8 & Xq=8 ohms.
9. Highersyn.reactance is preferred in the present day alternators to reduce transient currents.
10. For capacitive loads on alternator, the terminal voltages may falls when loads is turns off.
11. For inductive loads and UPF loads, the terminal voltage is more the its generated emf (ph). For
Capacitive loads Vt(ph) < EMF (ph).
12. The max. current during slip test on a syn. machine, the arm. mmf aligns along __[ A]
a) Q-axis
b) D- Axis
c) X-axis
d) Y-axis
13. The leakage reactance and armature reaction emf of Synchronous Machine are determined by
[ C ]
b) OC test
b) ZPF test c) OC & ZPF tests
d) OC & SC tests
14. The magnetizing curve represents the relationship between ____
[C ]
b) P.f Vs terminal to load voltage
c) Exciting current and generated voltage
b) Magnetic flux and armature current
d) None
15. Synchronous reactance of an alternator is
a) Xa + XL
b) Xa - XL
[ A ]
c) Xa / XL
d) None
16. Which of the following method gives the accurate voltage regulation results [ C ]
a) EMF method
b) AT method
c) ZPF method d) ASA method
UNIT-IV (DESCTRIPTIVE & OBJECTIVES)
1. (a) What are the conditions to be satisfied before a 3-phase alternator is synchronized to aninfinite
bus-bar?
(b) A 750KVA, 11KV, 4 pole, 3-ph star connected alternator has % resistance and reactanceof 1 and 15
respectively. Calculate the synchronous power per mechanical degree of displacement at(i) No load
(ii) Full load 0.8 pf lag.Where, terminal voltage in each case is given to be 11KV.
2. (a) What is synchronizing power of an alternator? Derive an expression for the synchronizingpower
between the two alternators connected in parallel.
(b) Two 3-ph star connected alternators supply a load of 3000KW at 0.8pf lagging and sharethe load
equally. The excitation of second machine is so adjusted that it supplies 150Aat a lagging pf. The
synchronous impedance are 0.4 + j12 and 0.5 + j10. Find current,power factor, induced emf and load
angle of each machine. The terminal voltage is 6.6KV.
3. (a) Explain the various methods of synchronization of alternators.
(b) Two similar 4 MVA alternators operate in parallel. The governor of firstmachine is such that
frequency drops from 50 Hz at no load to 47.5 Hz at fullload. The corresponding drop for second
machine is 50 Hz to 48 Hz. (i). How will they share a load of 6 MW (ii). What is the maximum load
they can share at UPF without over loadingany generator?
4. (a) Explain the effect of change in excitation on the parallel operation of twoalternators.
(b) Two similar stat connected alternators 3-ph alternators share a load of 7500kW equally at 6000 V
and 0.8 pf lagging. The synchronous impedance of (2.5+ j50) /ph. The excitation of second machine is
changed, so that it delivers40 A at a lagging pf. Find: i. Armature current of 1st m/cii. EMF of each m/c
iii. P.fof each m/c.
5. (a) Explain the effect of change in steam supply on the parallel operation of twoalternators.
(b) The EMFs of two alternators are 3000L200&2900L00 V. Their synchronous impedances are 2+j20
/ph & 2.5+ j30 /ph. The load impedance is 10+j4 /ph. Find the circulating current.
Objectives
1. Synchronoscope is used for ___
a) Measuring P.f of alternator
synchronization
d) All
[ C ]
b) Measuring active power of alternator
c) for
2.What is the expression for PSY, when the alternator is connected to bus bar with rated load
[ ]
a) αEVt / ZS
b) αEVt / 2ZS
c) αE2 / ZS
d) αE2 / 2ZS
3. An infinite bus bar has Constant voltage, Constant frequency and infinite voltage.
4. A salient pole alternator connected to infinite bus bar will deliver max power at power angle of δ=900
5. A salient pole alt. connected to infinite bus bar will deliver max power at δ=900
6. The power factor of an alternator is determined by
a) Speed
b) Excitation
[ B ]
c) Prime mover d) Load
7. While synchronizing a 3-ph alternator to a bus-bar the paralleling switch should be close just before
the pointer reached vertical position when moving in the fast direction.
8. Two alternators A and B are sharing an inductive load equally. If the excitation of alternator A is
increased Alternator B delivers less current and alternator delivers more current.
9. It is never advisable to connect a stationary alternator to live bus bar because it
[B ]
a) is likely to run as Syn Motor
b) will get short circuited
c) will decrease bus bar voltage through momentarily
d) None
UNIT-V
1. (a) Discuss with suitable vector diagrams, the behavior of 3-ph syn motor at no load with the change
in excitation.
(b) A 400v, 7.46KW, 3-ph, Y connected SM has syn. impedance of (0.35+j2.8) ohms/ph. Find
graphically of otherwise, the voltage to which the motor must be excited to give the full load output at
0.867leading p.f. Assume an efficiency of 88%.
2. (a) Explain about Syn. Condenser with suitable vector diagrams.
(b) A sub-station operating at full load of 1200 kVA supplies a load at 0.7 power factorlagging. Calculate
the permissible additional load at this power factor and the rating ofsynchronous condenser to raise the
substation power to 0.9 lagging.
3.(a) Derive the expression for the maximum power developed by a synchronous motor.
(b) A syn. motor takes 25Kw from400V supply. The syn. reactance of the motor is 4ohms. Find the
power factor at which the motor would operate when the exciting current is so adjusted that the
generated emf is 500V.
4. (a) Explain in details about V & /\ curves with suitable phasor diagrams.
(b) Explain the advantages and disadvantages of syn.motor.
5.(a) Explain the load characteristics of syn. motor.
(b) A 75KW, 400V,Y connected syn. motor has armature resistance and reactance/ph of 0.04ohms and
0.4ohms respectively. Find the open ckt voltage/ph and the load angle and also find the mech.power
developed for full load at 0.8 p.f leading. Assume an effiency of 93%.
UNIT-VI
1. Why the syn. motor is not self starting. Explain the starting methods of syn. motor.
2.(a) What is hunting. With neat diagram, explainhow the damper winding prevents oscillations.
(b) An industrial load of 4 MW is supplied at 11 kV, the power factor being 0.8 lagging. Asynchronous
motor is required to meet an additional load of 1103.25 kW and at the sametime to raise the resultant
power factor to 0.95 lagging. Determine the kVA capacity of the motor and the p.f. at which it must
operate. The efficiency of motor is 80%
3. (a) Explain principle of operation and performance char. of Syn. Induction motor.
(a) Explain the various power stages of synchronous motor. What are the various losses takingplace in
synchronous motor?
4. Explain the construction of excitation and power circles for sym. motor with suitable diagrams.
UNIT-VII
1. (a) Explain with neat diagrams the construction of 1-ph Induction motor.
(b)Explain with neat diagrams theprinciple of operation ofShaded pole motor
2. Show that a single phase winding when excited by a single phase supply produce two equal
andopposite revolving fields. (or) Explain why the 1-phInduction motor is not self starting.
3. Explain the various starting methods of synchronous motor.
UNIT-VIII
1. (a) Describe the construction and principle of operation of a ac series motor with a neatdiagram. Give
its industrial applications.
(b) Compare the performance characteristics of a.c. series motor when it is connected across (i). A.C.
supply (ii). D.C. supply.
2. Explain about Universal motor with its performance characteristics.
3. Explain the operating principles of (i) Reluctance motor (ii) permanent magnet motor.
UNIT-V& VI
1. An under excited syn. motor operates at ____
a. Lagging p.f b. Leading p.f
c. Unity p.f
[ A]
d. None
2.The function of Damper winding in a syn. motor is _____
a. to prevent hunting b. to provide starting torque
[C]
c. Both a & b
3. When a syn. motor started ?___
a. The field is excited by DC voltage
c. The field wdg is shorted initially
[C]
b. The field wdg is opened initially
d. Any of the above
4. For fixed load on the shaft, the armature current of a syn. motor is minimum when the p.f is
[ B]
a. < unity & leading
b.Unity
c. Lagging
d. leading or lagging, not unity
5. A syn. motor supplying its rated load and is operating at UPF. If excitation is increased, then
[D]
a. Its load increased
b. its p.f is constant
c. p.f being lagging
d. p.f being leading
6. A 3-ph 230V, Y-connected syn. motor produces a back emf of 320 V, the p.f of syn. motor is _____
[C]
a. Unity
b. Lagging
c. Leading
d. None
7.V curves of syn. motor shows the relation between _____
a. p.f Vs load
b. Ia Vs If
c. p. f Vs If
[ B]
d. p.f Vs Ia
8. As the load on syn. motor increased, the torque angle _______
a. Increases
b. Decreases
[ A]
c. Independent of Load d. None
9. In a syn. motor _____
[D ]
a.E is less than V b.E equal to V c.E is more than V d.E may be more or less than V
10. In a syn. motor _____
[B]
a. The speed of stator mmf is always more than that of rotor mmf
b. rotor and stator mmfs are stationary w.r.t each other
c. speed of stator mmf is always less than that of rotor mmf
d. None
11. The rotor of the syn. Induction motor is ____
a. Salient pole b. Squirrel Cage c. Slip ring
[C]
d. Round rotor
12. The 3-ph Syn. motor is not self starting machine.
13. A syn. motor is a constant speed motor.
14. When field current is 0 the torque developed by syn.motor is called Reluctance torque
15. A syn. motor is a double excited machine, since it requires A C supply for stator an DC supply for field
winding.
16. In salient pole syn. machine, the condition for max mech. power developed is δ = ϴ
17. Syn. capacitor is an over excited syn. motor without mechanical load.
18. The negative phase sequence in a 3-ph syn. motor exists when the motor supplied with unbalanced
voltage.
19. Stability of syn. motor increases with the increase in excitation.
20. A 3-ph syn. motor has zero starting torque.
UNIT-VII & VIII
1. In capacitor start motor, the capacitor is connected as ___
a. In series with main wdg
b. in series with running wdg
[B]
c. both a & b
2. As compared to split phase motor, a capacitor start motor has higher starting torque.
3. If a centrifugal switch of a capacitor start motor fails to open, ______
a. The capacitor will be destroyed
[C]
b. The running wdg may destroyed
c. The capacitor & running wdg will be destroyed
d. None
4. A ceiling fan uses_______ motor
[ C]
a. Split phase b. Capacitor start & run c. Capacitor start
d. None
5. A DC series motor is switched on to AC supply
[C ]
a. Motor will not start b. Motor will damage c. Motor start with poor performance
6. The function of compensating winding in AC series motor is to _____
a. provide starting torque
b. reduce the reactance of arm.wdg.
[B]
c. convert into 2-ph
7. The electrical motor, generally used for house hold food mixers is ______
a. Universal motor
b. shaded pole motor
c. Capacitor start motor
[ A]
d. None
8.A reluctance motor runs at _______
a. Syn. speed
[A ]
b. speed slightly less than syn. speed
c. above syn. speed
d. None
9. A shaded pole runs in the direction from un-shaded to shaded part of pole.
10. AC series motors are built with as few field turns as possible to reduce ___
a. Flex b. Eddy current loss
c. reactance
[C ]
d. None
11. under no load operating conditions the speed of the universal motor is limited by windage and
friction.
12. In an AC series motor, the p.f is improved by ____
[B ]
a. increasing the no.of arm. conductors b. reducing the inductance of arm. & field wds
c. increasing the supply voltage
d. Both a & b
13. A 1-ph reluctance motor is a self stating and needs no DC excitation.
14. In case of reluctance motor, the torque is proportional to sin2δ.
15. The 1-ph Induction motors produces torque at starting is zero.
16. A permanent magnet AC motor has ________ excitation.
a). AC
b). DC
c). zero
[
d). None
]
Previous years’ question papers – JNTUA
1
(a) Explain theeffectofharmonicsonpitchanddistributionfactors.
(b) Analternatorhas18slots/poleandthefirstcoilliesinslots1and16.Calculatethe pitchfactor for:
(i)Fundamental (ii)3rdharmonics (iii)5thharmonics and (iv)7thharmonics.
2
(a) Explain theeffectsof harmonicsonelectrical powersystem&utility.
(b) CalculatetheRMSvalueofEMFinducedperphaseofa10pole,3-phase,50Hz,
alternatorwith2slotsperpoleperphaseand4conductorsperslotintwolayers.The coil
spanis150oelectrical.Thefluxperpolehasafundamental componentof0.12wb&
a20% ofthirdharmoniccomponent
3
A3-ф,200kVA,1.1kV,50Hzstarconnectedalternatorhavinganeffectiveperphase
resistanceof0.62Ωgave thefollowingresults:
Fieldcurrent (A)
20
35
50
80
100
120
O.C.Voltage V1 692.82 1120 1450 1750 1953 2180
S.C.Current (A)
0
22
44
66
88
110
UsingMMF method, findthevoltageregulationat
100A, (a) 0.8p.f.lagging
(b)0.8p.fleading.
4
(a) What ismeant bysynchronization?Howthealternator issynchronizedwithinfinitebus? A3(b) phasealternatorwithsynchronousreactanceof10ohmperphaseandnegligible
armatureresistanceisconnectedto6.6kVconstantfrequencysupplyanditsupplies
100Aatunitypowerfactortothesystem.Iftheprimemoverinputiskeptconstantand
theexcitationofthealternatorisincreasedby20%.Whatwouldbethenewcurrentand
powerfactor?
5
(a)
6
(a) What ishunting?Whyit isessential tosuppress thehunting?
(b) Explain thevariousstaring methodsof synchronousmotor.
7
(a) Whyacapacitorstart motor isbetterthansplit-phasemotor,explain?
(b) Describe theconstructionandworkingofshadedpole motor.
8
The
fullloadcurrentofa3.3
kV,starconnectedsynchronousmotoris160Aat0.8
pf
lagging.Theresistance&synchronousreactanceofthemotorare0.8Ω/ph&5.5Ω/ph
respectively.Calculate
theexcitationEMF,torqueangle,efficiency,and
theshaftoutput
ofthemotor. Assumethe mechanicalstray lossestobe30kW.
(b) Whatistheoverexcitationofasynchronousmotor?Whatistheeffectofoverexcitation
ofasynchronousmotor?
Withneatdiagramexplaintheconstruction&workingofvariablereluctancestep-per motor.
Alsoexplainitsstatic&dynamiccharacteristics.
*****
IIIB. TechI Semester (R09)Regular &Supplementary Examinations,November 2012
ELECTRICALMACHINES III
(Electrical &ElectronicsEngineering)
Time:3hours
Max.Marks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a) Brieflydescribethephasespread,phaseband.Calculatetheirvaluesforintegralslot
windingwithsuitableexample.
(b) A3-phasestarconnectedalternatorhas ratingof120kVAat2.5kVwith12poles.The
ratedspeed ofthealternatoris800 rpm. Therearethreeslots perpoleperphaseand
thenumberofconductorsperslotis5.Determinethefluxperpoleforfullpitched
windingtogive
theratedterminal voltageatnoload.
2
Theeffectiveresistanceofa2200V,50Hz,440kVAsinglephasealternatoris0.5
ohm.Onshortcircuit,a
fieldcurrentof4amp,
givesthe
fullloadcurrent.
TheEMFon
opencircuitforthesame
fieldcurrentis1160V.findsynchronousimpedance,
synchronousreactanceand%regulationof0.6p.flagging.
3
Explain the‘ZeroPowerFactor’methodof findingvoltageregulationofanalternator.
4
(a)
Whatismeantbysynchronization?Explainthewayofsynchroninganalternatortothe
infinitebusbars.
(b) Twostarconnectedalternatorssupplyaloadof1500kVAat0.8pflaggingandshare
theloadequally.Theexcitationofsecondmachineisadjustedsothatitissupplying
60A
at alaggingpf.Thesynchronousimpedances
are(0.4+j12)ohm/phand (0.5+
j10)ohm/ph.Findcurrent,powerfactor,
inducedEMFandloadangleofeach
machine.Terminal voltage is6.6kV.
5
(a)
6
(a) What ishunting?Whyit isessential tosuppress thehunting?
(b) Explain theconstructionofdamper winding.
7
(a) Explaintheprincipleofoperationofsinglephaseinductionmotorbasedondoublefield
revolvingtheory.
(b) Comparethecapacitorstartmotorandcapacitorstartandrunsinglephaseinduction
motor.Whichtypeofmotor hasbetterperformance,Explain?
8
(a) Listapplicationsofstepper motor&universal motor.
(b) Explain theconstructionofAC seriesmotor.
Asub-stationoperatingatfullloadof1200
kVAsuppliesaloadat0.7powerfactor
lagging.Calculatethepermissibleadditionalloadatthispowerfactorandthe
ratingof
synchronouscondenser toraisethesubstationpowerto0.9 lagging.
(b) Explainwhysynchronousmotor isnotselfstarting.
*****
1
(a) Explaintheeffectofshortchordingandspreadingthewindingina3-phasealternatoron
theemfinducedinthewinding.Derivetheexpressionsfortheseeffectsintermsofslot
pitch,numberofslotsperpoleperphaseandshort chording.
(b) Describethemeritsoffractionalslotwinding.Whyitsarmatureslotsshouldbedivisibleby
3incaseof3-phasemachine?
2
(a) ExplaintheeffectofarmaturereactionontheEMFinduced.Isitpossibletoobtainload
voltagemorethan EMF induced?Ifyes,how?
ThephaseEMFofa3-phasealternatorconsistsoffundamental,20%3rdharmonic&10
(b)
%fifthharmonic.Theamplitudeoffundamentalis1000V.Calculatethe RMSvalueofline
&phasevoltage, when thealternator isconnectedin (i) Star (ii) Delta.
3
A1MVA,11kV,3-phasestar-connectedsynchronousmachinehasfollowingOCCtest data,
If
50 110
140 180
Eol-kV 7 12.5 13.75 15)theshortcircuittestyieldedfullloadcurrentata
(Where
Eolisthelinevoltageatnoload
fieldZPFyieldedafullloadcurrentatterminalvoltagefora
fieldcurrentof150A.the
armature
resistanceisnegligible.Calculatethe voltage regulationat fullloadof0.866 p.f laggingbypotier
trianglemethod.
4
(a) Explainthewayofparalleloperationoftwoalternatorsandsynchroninganalternatorto
theinfinitebusbars.
(b) Twostar-connectedalternatorsareconnectedinparalleltosupplyaloadof1500kVAat
11kVlinevoltageand0.8pflaggingpowerfactor.Bysuitableadjustmentofprime
governorsthetwoalternatorscansharetheloadequally.Theexcitationofonemachineis
adjustedsothatitissupplying43Aatalaggingpf.Thesynchronousreactancesofthe
twomachinesrespectivelyare:35ohmand40ohm.Findphasecurrentinthesecond
machine, inducedEMFofeachmachine,power factor at eachmachineoperates.
mover
5
(a) Explainwhysynchronousmotor isnotselfstarting.
(b) A3-phase,600V,starconnectedsynchronousmotorhaseffectiveperphasearmature
resistance&synchronousreactanceof0.Ω
4
&3.6Ωrespectively.Calculatetheinduced
EMFperphaseifthemotorworksonfullloaddelivering326kW.Thefullloadefficiencyis
87% havingpower factorof0.8leading. Alsocalculate the loadangle.
6
(a) Explain thevariousstarting methodsof synchronousmotor. (b)
Explain theconstructionofdamper winding.
7
(a) Whyacapacitorstart motor isbetterthancapacitorstartandrun,explain?
(b) Withneatdiagramsexplain theconstructionandworkingofshadedpolemotor.
8
Withneatdiagram explain theconstructionandworkingof:
(a)ACseriesmotor. (b)Permanent magnet stepper motor.
*****
1
(a)
(b)
2
(a)
(b)
Explain thefactorsaffectingsynchronousreactanceofalternator.
CalculatetheRMSvalueofEMFinducedperphaseofa10pole,3-phase,50Hz,
alternatorwith2slotsperpoleperphaseand4conductorsperslotintwolayers.The
coilspanis150oelectrical.The fluxperpolehasafundamentalcomponentof0.12Wb&
ofthirdharmoniccomponent.
(a)
(b)
Describetheeffectsofchangeinexcitationandchangeinprimemoverinputofthe alternator.
Howtheyareuseful intheoperationof alternator?
A15MVA,11kV,50Hz,3-phase,4-polestarconnectedcylindrical-rotorsynchronous
generatorsuppliesatratedoutputatpfof0.9laggingtoan
infinite
busbar.Its
synchronousreactanceis0.35
pu.Determine
the
synchronizingtorque
forashaft
displacementof0.4o(mechanical).Neglectlossesandsaturation.
5
(a) What isasynchronouscondenser?What istheuseofsynchronouscondensers?
(b) A220V,3-phase,starconnectedsynchronousmotorhasaresistanceof0.22ohmper
phaseandasynchronousreactanceof2.4ohm perphase. Themotorisoperatingat0.6
pfleadingwithalinecurrentof180 A. Determine thevalueof generatede.m.f.
6
(a)
(b)
7
(a)
(b)
8
a20%
A3-ф,440V,50Hz,deltaconnectedalternatorhasadirectaxisandquadratureaxis
reactanceof0.12Ωand0.09Ωrespectively.Ifthealternatorsupplies900Aat0.8p.f lagging,
calculatethefollowing:(a)TheexcitationE.M.F,neglectingsaliency (Xd=Xq). (b)
TheexcitationE.M.F,takingintoaccount thesaliency.
Neglectarmature resistance.
3
4
Explainthedifferencesbetweenstationaryarmatureandrotatingarmature.Whatare the
advantagesofrotatingarmatureover stationaryarmature?
Describethemeritsoffractionalslotwinding.Whyitsarmatureslotsshouldbedivisible
by3incaseof3-phasemachine?
(a)
(b)
Explaintheproceduretoplot‘Vcurves’&‘invertedV’curvesforagivensynchronous
machinewithhelpofitscirclesdiagrams.
Calculatethesynchronouscoefficient(inkW&Nmpermechanicaldegree)atfullload
fora1MVA,0.8pflagging,6.6kV,8pole,starconnectedgeneratorofnegligible
resistance&synchronousreactanceof0.8pu.
Whythesinglephaseinductionmotorsarenotselfstartingexplainwiththehelpof doublefield
revolvingtheory?
Explaintheconstructionandoperationofcapacitorstartandrunsinglephaseinduction
motor.
Describe the working of dc series motor when connected to ac supply. What
modificationshave tobeadoptedtoachieve thesatisfactoryoperation?
Withneatdiagram explain theconstructionandworkingofreluctancemotor.
*
MANAGERIAL ECONOMICS & FINANCIAL
ANALYSIS
Syllabus
2009-10
35
JAWAHARLAL NEHRU
TECHNOLOGICAL UNIVERSITY ANANTAPUR
B.Tech III-I Sem. (E.E.E) T P C
404
(9AHS401) MANAGERIAL ECONOMICS & FINANCIAL
ANALYSIS
(Common to BOT, CE, ECM, EEE, ME)
UNIT I: INTRODUCTION TO MANAGERIAL ECONOMICS
Definition, nature and scope of managerial economics- relation with
other disciplines- Demand Analysis: Demand Determinants, Law of
Demand and its exceptions
UNIT II: ELASTICITY OF DEMAND
Definition, Types, Measurement and Significance of Elasticity of
Demand. Demand forecasting, factors governing demand forecasting,
methods of demand forecasting (Survey methods, Statistical
methods, Expert opinion method, Test marketing, Controlled
experiments, Judgmental approach to Demand Forecasting)
UNIT III :THEORY OF PRODUCTION AND COST ANALYSIS
Production Function – Isoquants and Isocosts, MRTS, least cost
combination of inputs, Cobb-Douglas production function, laws of
returns, internal and external economies of scale.
Cost Analysis: Cost concepts, opportunity cost, fixed Vs variable costs,
explicit costs Vs Implicit costs, out of pocket costs Vs Imputed costs.
Break-Even Analysis (BEA) - Determination of Break Even Point
(Simple Problems)- Managerial significance and limitations of BEA.
UNIT IV: INTRODUCTION TO MARKETS AND PRICING
POLICIES
Market structures: Types of competition, features of perfect
competition, monopoly- monopolistic competition. Price-Output
determination under perfect competition and monopoly - Methods of
Pricing-cost plus pricing, marginal cost, limit pricing, skimming
pricing, bundling pricing, sealed bid pricing and peak load pricing.
2009-10
36
UNIT V: BUSINESS ORGANISATIONS AND NEW ECONOMIC
ENVIRONMENT
Characteristic features of business, features and evaluation of sole
proprietorship, partnership, Joint Stock Company, public enterprises
and their types, changing business environment in post-liberalization
scenario.
UNIT VI: CAPITAL AND CAPITAL BUDGETING
Capital and its significance, types of capital, estimation of fixed and
working capital requirements, methods and sources of raising finance.
Nature and scope of capital budgeting, features of capital budgeting
proposal, methods of capital budgeting – payback method, accounting
rate of return (ARR) and Net present value method (Simple problems).
UNIT VII: INTRODUCTION TO FINANCIAL ACCOUNTING
Double-Entry Book Keeping, Journal, Ledger, Trial Balance- Final
Accounts (Trading Account, Profit and Loss Account and Balance
Sheet with simple adjustments).
UNIT VIII: FINANCIAL ANALYSIS THROUGH RATIOS
Computation, Analysis and Interpretation of financial statements
through Liquidity Ratios (Current and Quick ratio), Activity ratios
(Inventory Turnover Ratio and Debtor Turnover Ratio), Capital
Structure Ratios (Debt- Equity Ratio, Interest Coverage Ratio) and
Profitability ratios (Gross Profit Ratio, Net Profit Ratio, Operating
Ratio, P/E Ratios and EPS), Du Pont Chart.
TEXT BOOKS:
1. Aryasri: Managerial Economics and Financial Analysis, 4/e, TMH,
2009.
2. Varshney & Maheswari: Managerial Economics, Sultan Chand,
2009.
REFERENCES
1. Premchand Babu, Madan Mohan:Financial Accounting and
Analysis,Himalaya, 2009
2. S.A. Siddiqui and A.S. Siddiqui: Managerial Economics and
Financial Analysis, New Age International,. 2009.
3. Joseph G. Nellis and David Parker: Principles of Business
Economics, Pearson, 2/e, New Delhi.
2009-10
37
4. Domnick Salvatore: Managerial Economics in a Global Economy,
Cengage, 2009.
5. H.L.Ahuja: Managerial Economics, S.Chand, 3/e, 2009
Objective
Course Objective
The course aims to equip the budding engineering student with an understanding of concepts and tools
of economic analysis. The focus does not only on understand the concepts but apply them in real life by
developing problem solving skills. In short, Managerial Economics imparts to students those aspects of
Economic theory and applications which are directly relevant to the practice of Management and
decision making processes within an enterprise. This aim confines the syllabus only to Microeconomic
Theory and their applications and leaves out Macroeconomic theory and Public Policy.
There exists a relationship between Managerial Economics and Accounting and same is dealt in the
second part of the course. The focus here is on picking up the basics of Accounting such as Accounting
Data and Financial Statements, which constitute the language of Business. The student is exposed and
made familiar with generation, interpretation and use of Accounting Data.
Lesson Plan
Week
Dates
No.of
periods
in week
1
5
2
4
3
5
4
5
5
5
6
3
7
4
8
4
Topics to be covered
No.of
periods
required
Unit-1
Introduction to Managerial Economics
Definition, Nature and scope of managerial Economics
Relation with Other Disciplines
Demand Analysis :Demand Determinants
Law of Demand and its Exceptions
1
1
1
1
Unit-2
Elasticity of Demand
Definition,Types of Elasticity of Demand
Measurement of Elasticity of Demand
Significance of Elasticity of Demand ,demand
forecasting
Factors Governing Demand Forecasting
Methods of demand Forecasting
(Survey Method,Statistical Method
Expert Opinion Method, Test Marketing
Controlled Experiments
Judgemental approach to demand forecasting
UNIT-3
Theory of production and cost analysis
Production function
Isoquants and Isocosts
MRTS
Least cost combination of inputs
Cobb-Douglars production function
Law of returns
Internal and External Economics of sale
Cost analysis
Cost concepts : opportunity cost,fixed VS variable
costs
Explicit costs VS Implicit costs
Out of packet costs VS imputed costs
Break –Even analysis(BEA)
Determination of Break Even point
(simple problem)
Managerial significance and limitations of BEA
UNIT -4
Introduction to markets and pricing policies
Market structures
Types of competition,features of perfect competitions
Monopoly
Monopolistic competition
Price-output determination under perfect competition
Monopoly
Methods of pricing –cost plus pricing
Marginal cost,limit,pricing,skimming pricing
Bundling pricing
Sealed bid pricing and peak load pricing
Total
Periods
per unit
PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND
SCIENCE
ACADEMIC YEAR:2012-13CLASS:III
5
1
1
1
1
9
1
1
1
1
1
1
1
1
1
1
13
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
8
Subject:MEFA
FACULTY:G.KoteswaraRao
9
5
10
2
11
5
UNIT-5
Business organizations and new Economics
development
Charecteristic features of business
Features and Evaluation of sole proprietorship
Joint stock company
Public enterprices and their types
Changing business environment in
post liberalization scenario
UNIT-6
Capital and capital budgeting
Capital and it’s significance
Types of capital
Estimation of fixed and working capital requirements
Methods and sources of raising finance
1
1
1
1
1
9
Simple problems
Balance sheet
With simple adjustments
Problems
1
1
1
1
UNIT-8
Financial analysis through ratios,Computation
Analysis and interpretation of financial statements
Through liquidity ratios(current and quick ratio)
Activity ratio and
Debtor turnover ratio
1
1
1
1
1
13
5
5
1
1
1
1
1
UNIT-7
Introduction to financial accounting
Double –entry book keeping
Jounal,Ledger,Trial balance
Final accounts(trading accounts)
Profit and loss account
Nature and scope of capital budgeting
Features of capital proposal
Methods of capital budgeting –pay back method
Acconting rate of return(ARR) and
Net present value method
(simple problems)
15
1
1
9
4
4
7
1
1
1
1
12
14
1
1
1
1
1
10
16
4
17
1
Capital structure ratios(Debt-Equity ratio,
Interest coverage ratio)and
Probability ratios(gross profit ratio
Net profit ratio
Operating ratio
p/E ratios and DU point chart
revision
Total
1
1
1
1
1
70
Question Papers – Mid-semester
examinations
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI
III B.Tech(I-Sem) MID-I
Branch: EEE
Time:90min
Sub: MEFA
Date: 09-2012
Max.marks:30
ANSWER ANY THREE OF THE FOLLOWING
1.Explain the scope and nature of managerial economics?
2. What are the factors influencing demand?
3. Explain the break even analysis.
4. Explain the price determination in perfect competition.
5.Explain the methods of measuring demand forecasting.
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI
III B.Tech(I-Sem)
MID-II
Time:90min
Branch: EEE
Sub: MEFA
ANSWER ANY THREE OF THE FOLLOWING
1.Explain the factors affecting the requirements of working capital?
2.Define company? Explain its features?
3. Define accounting and explain its functions
4. Explain features,advantages and disadvantages of sole trader?
Date: 11-2012
Max.marks:30
5.What is meant by ratio analysis? Discuss its objectives and limitations?
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI
III. B.Tech I Sem: EEE (A&B)
I Mid
SUB: MEFA
TIME : 0.30Min
Marks: 10
NAME____________________________________________ROLL NO____________________________
CHOOSE THE CORRECT ANSWER
1. Integration of Economic Theory with business practice is called
A. Managerial Economics
B. Economics
C. Macro Economics
[
D. Micro Economics
2. Managerial Economics as a subject gained popularly first in___________
A. India
B. Germany
C. U.S.A
B. Prof. Lionel Robbins
C. Adam smith
B. Car and petrol
C. Tea and Coffee
B. Tea and Coffee
C. Shirt and Pant
6. In case of Giffen goods, the demand curve
A. Slopes downwards
B. Intersects supply curve C. Slopes upwards
7. In case of unity elasticity, the elasticity is equal to
*
+
[
]
[
]
[
]
D. Shirt and Pant
5. Which of the following pairs of goods is example of complementary goods
A. Car and Petrol
]
D. Alfred Marshall
4. Which of the following pairs of goods is an example of substitutes ?
A. Tea and sugar
[
D. England
3.”Economics is the study of scarce resources and unlimited wants”, Who is said that?
A. Paul A. Samuelson
]
D. Pen and Fan
D. Meets cost curve
[
]
A. One
B. Greater than one
C. Less than one
D. Two
8. The elasticity between two separate points of demand curve is called_______ elasticity
A. Point
B. Arc
C. Total outlay
B. Relation
C. Regression
B. Cyclic trend
C. Seasonal trend
B. Expenditure
C. Income
B. Iso product curves
C. AR curves
C. Sunk costs
B. Sales control
C. Break one point
C. Selling price+ variable cost
D. Selling price—variable cost
16. ______________ is the example for perishable goods
C. Vegetables
C. Duopoly
B. Total cost
19. The price discrimination is also called as
C. Total revenue
]
[
]
[
]
[
]
D. Perfect competition
18. The firm is said to be in equilibrium, when its marginal cost equals to
a. Marginal revenue
]
D. Cloths
17. ______is a form of market organization in which there is only one seller of the commodity
B. Monopoly
]
D. Break even Analysis
B. Fixed cost+ profit
A. Oligopoly
[
[
A. Total cost—variable cost
B. Belts
]
C. Opportunity cost D. Controllable cost
15. Contribution is defined as
A. Pens
[
[
14. Which of the following is a technique for profit planning and control
A. Cost control
]
D. MR curves
13. The cost of the next best alternative foregone is known as
A. Implicit cost
[
D. Sales
12. Iso-quants are also called
A. Iso cost curves
]
D. Erratic trend
11. Conversion of inputs into output is called ___________
A. Production
[
D. Precision
10. Which of the following results from the sporadic occurrence of strikes, riots and so on
A. Trend
]
D. Zero
9. _________ describes the degree of association between two variables
A. Correlation
[
[
]
[
]
D. Average cost
A. Standard pricing
B. Differential pricing
C. Preferential pricing D. Equal pricing
20. Under which pricing method, price just equals Average cost
A. Marginal cost pricing
B. Cost plus pricing
C. Full cost pricing
[
D. Equal pricing
Question Bank
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE, KAVALI
III B. Tech(EEE & Mechanical & CIVIL)
SUB: MEFA
UNIT-1 :INTRODUCTION TO MANAGERIAL ECONOMICS
1.
2.
3.
4.
5.
Define Managerial Economics? Explain its nature and Scope?
Eleborate the importance of Managerial Economics in decision-making.
Managerial Economics is multidimensional discipline. Explain.
Define Demand and explain the factors that influence the demand of product.
What is Demand? State and explain the Law of Demand. Are there any exceptions to the law?
UNIT-2 : ELASTICITY OF DEMAND
1.
2.
3.
4.
5.
6.
Define Elasticity of demand. Explain its Types and Significance.
Define Price Elasticity of demand. Explain different types of price Elasticity of demand.
Define Price Elasticity of demand. How do you measure it?
What is demand forecasting? Explain various factors governing demand forecasting.
What are the steps in Scientific approach to demand forecasting?
What do you understand by demand forecasting? What is the need for it?
UNIT-3 : THEORY OF PRODUCTION AND COST ANALYSIS
1. Draw Total Product, Average product and Marginal Product Curves on your answer book.
Explain how output changes with Fixed Capital and Variable Labour inputs.
2. What are the economies of scale? Explain different types of Internal and External economies of
scale.
3. Explain the following:
]
A) Explicit and Implicit cost B)Fixed cost and Variable cost C)Opportunity cost
4. Define B.E.P. How do you determine it show graphical presentation of B.E.A?
5. Write short notes of the following:
(A) Margin of safety (B) Contribution (C) Angle of incidence (D) P.V. Ratio
6. Explain the law of returns to scale.
UNIT-4 : INTRODUCTION TO MARKETS & PRICING STRATEGIES
1. Define Market. Explain how the Markets are classified?
2. Explain important features of Perfect Competition Market and how price is determined under
perfect Market?
3. Define Monopoly. How is price determined under Monopoly?
4. Define Market. Distinguish between perfect and imperfect markets?
5. Explain price-output determination under Monopolistic Competition?
6. Define Market. Explain any four methods of pricing based on Strategy.
1
(a) Definemanagerialeconomics.Explainits scope.
(b) Distinguishbetweeneconomicsandmanagerial economics withsuitableexamples.
Previous years’ question papers – JNTUA
2
Whatdoyouunderstandby‘ElasticityofDemand’?Whataretypesofelasticityof demand?
3
Explainhowdoyoudeterminebreakevenpointinvolumeandvalue?Explaingraphically.
IVB.TechISemester (R09)
RegularExaminations,November2012
How does anindividualfirm
behaveunder perfectcompletion?Alsoexplain thefirm and
industryequilibriumunder MANAGERIALECONOMIC
perfectcompetition.
S& FINANCIALANALYSIS
Discussabouttheshort-comingsofthepublicsectorenterprisesinIndiaandwhatis
theirfuture.
(
C
o
Definecapitalbudgeting.Explainitsimportance.
m
How is useful ofpaybackperiodmethod?Explain
itsfeaturesandlimitations.
m
o
Whatis‘JournalEntry’anddescribesitsimportanceinaccountbooks?
n
Explainthebasic accountingconceptsandconvention,Giveexamples.
t
o
Discuss the importance of ratio analysisCfor inter firm and intra-firm comparison,
includingcircumstancesresponsiblefor itslimitations,if
any.
S
E
,
I
T
&
C
S
S
)
Time:3hours
Max.Marks:70
A
n
s
w
e
r
a
n
4
5
6
(a)
(b)
7
(a)
(b)
8
y
F
I
V
E
q
u
e
s
t
i
o
n
s
All
qu
es
tio
ns
ca
rry
eq
ua
l
m
ar
ks
*
*
*
*
*
*
*
*
*
*
IVB.TechISemester (R09) RegularExaminations,November2012
MANAGERIALECONOMICS& FINANCIALANALYSIS
(CommontoCSE,IT&CSS)
Time:3hours
Max.Marks:70
1
AnsweranyFIVEquestions
All questionscarryequal marks
*****
Elaboratethe importanceofmanagerial economicsindecisionmaking.
2
How doyoumeasureelasticityofdemand?Illustrategraphically.
3
Whatdoyouunderstandbycostoutputrelationship?Explainhowcostsbehaveinthe shortrun.
4
Definemarket.Distinguishbetweenperfectandimperfectmarkets.
5
(a) Definepartnershipandexplain its silentfeatures andlimitations.
(b) Whatarethequalities ofagoodpartner?
6
(a) Whatiscapital?Explainthetypesandsignificanceofcapital.
(b) Explaintheconceptofworkingcapital,itsfeatures&limitations.
7
8
Explainthefollowinginbriefly:(a) Doubleentry system.
(c)Capital.
(b) Book–keeping.
(d) Income.
Howratiosareclassifiedforthepurposeoffinancialanalysis?Withassumeddata,
illustrateanytwotypes ofratiosundereachcategory.
*****
IVB.TechISemester (R09) RegularExaminations,November2012
MANAGERIALECONOMICS& FINANCIALANALYSIS
(CommontoCSE,IT&CSS)
Time:3hours
1
Max.Marks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
Whatarethecontributionsandlimitations ofmanagerialeconomicstobusiness managers?
2
Whatisthesignificanceofelasticityofdemand?Explaindifferenttypesofelasticityof demand.
3
AfirmhastwoproductsBandC.Theparticularsofthepriceperunit,variablecostper
unitandpercentageofshareinthetotal salesvolumearegiveninthefollowingtable:
Products Sellingprice
Variablecost
%ofshare
B
Rs.400
Rs.160
30%
C
Rs.500
Rs 200
50%
Thetotalfixedcostsduringtheyear amounttoRs:10,00,000.Thetotal volumeofsalesis
Rs:80,00,000.
ThecompanywantstodropproductBasitisyieldinglesscontributionper unit.
Instead,itwantstoaddproductD.IfDisadded,thenewfixedcostislikelytobeupby
10% andthesalesvolume islikelytoincreaseby5%.
Doyourecommendfor addingproductD?
4
Explainhow thepriceisdeterminedunder conditions of perfectcompetition.Illustratethis
withhelpof diagrams.
5
Discuss thecompanyfeatures offormof businessorganization.
6
(a) Explainthefactors affectingtherequirements ofworkingcapital.
(b) Determinethecapital,anditsfeatures.
7
(a) Defineaccountingandexplainitsfunctions.
(b) Explainclassificationof accountswithsuitableexamples.
8
Thefollowingisthebalancesheetof SriAnuragEnterprisesason31stDec 20007.
Liabilities
Assets
Rs.
Rs.
Sharecapital
2,00,000
Buildings
2,00,000
Reservefund
50,000
Machinery
1,50,000
Profitbalance
30,500
Stock onhand 1,00,000
Bankloan
1,50,000 Sundrydebtors
60,000
Sundry creditors
70,000
Cashonhand
20,500
Provisionfor Tax
30,000
5,30,000
5,30,000
Youarerequiredtocommentonliquidityandsolvencypositionoftheconcern.
*****
2
Explainwithexamples:(a)Priceelasticityofdemand.(b) Crosselasticity of
demand.
3
Amachinetoolsfactoryhasaplantcapacityofenoughhours9000.Annualfixed
chargesareofRs.50,000per year.Itcanproducetwoproducts ofXandY.Ithasthree
options:makeXormakeYormakesomeunitsofXandsomeunitsofY.Lookatthe followingdata:
X
Y
Sellingprice
Rs.2,500
Rs.4,000
Variablecost(Rs)
1,000
2,000
Demand
2500units
5000units
Timetakenforproduction
3hours
5hours
Whatproductmixwill maximizethenetprofits ofthefactory?Calculatethemaximum net profit.
4
Definemonopoly.How ispricedeterminedundermonopoly?
5
(a) Definecompany.Explainitsfeatures.
(b) Whatareitsadvantagesanddisadvantages?
6
(a) Whatistheimportanceofcapital?
(b) Whatfactorsdeterminetheworkingcapital requirements ofacompany?
7
(a) How areaccountsfinalizedattheendof anaccountingperiodwiththehelpofa trial
balance?Illustrate.
(b) Definefinancial statements,andexplainits objectivesand importance.
8
From theinformationgivenbelow calculate:
(a) InventoryTurnover ratio,and (b) ReceivablesTurnover ratio
AmountinLakhs (Rs.)
Sales(100% credit)
42.00
Openingstock
6.00
Closingstock
7.00
Salesreturns
3.00
Openingbalance ofsundry debtors
6.00
Closingbalanceofsundrydebtors
4.00
Openingbalance ofBillsreceivable
3.00
Closingbalanceof Billsreceivable
5.00
Gross profit=30% ofshares
*
*
*
*
*
TRANSMISSION OF ELECTRIC POWER
Syllabus
B.Tech III-I Sem. (E.E.E)
(9A02502) TRANSMISSION OF ELECTRIC POWER
Objective :
This course is an extension of Power systems-I course. It deals with basic theory of transmission lines
modeling and their performance analysis. Also this course gives emphasis on mechanical design of
transmission lines, cables and insulators.
UNIT-I TRANSMISSION LINE PARAMETERS
Types of conductors - calculation of resistance for solid conductors -Calculation of inductance for single
phase and three phase, single and double circuit lines, concept of GMR & GMD, symmetrical
andasymmetrical conductor configuration with and without transposition,Numerical Problems.Calculation
of capacitance for 2 wire and 3 wire systems, effect of ground on capacitance, capacitance calculations for
symmetrical and asymmetrical single and three phase, single and double circuit lines,Numerical
Problems.
UNIT-II PERFORMANCE OF SHORT AND MEDIUM TRANSMISSION LINES
Classification of Transmission Lines - Short, medium and long line and their model - representations Nominal-T, Nominal-Pie and A, B, C, D Constants. Numerical Problems. Mathematical Solutions to
estimate regulation and efficiency of all types of lines - Numerical Problems.
UNIT-III PERFORMANCE OF LONG TRANSMISSION LINES
Long Transmission Line-Rigorous Solution, evaluation of A,B,C,D Constants, Interpretation of the Long
Line Equations – Representation of Long lines – Equivalent T and Equivalent – π – surge Impedance and
surge Impedance loading - wavelengths and Velocity of propagation – Ferranti effect , Charging current.
UNIT – IV POWER SYSTEM TRANSIENTS
Types of System Transients - Travelling or Propagation of Surges -Attenuation, Distortion, Reflection
and Refraction Coefficients -Termination of lines with different types of conditions - Open Circuited
Line, Short Circuited Line, T-Junction, Lumped Reactive Junctions(Numerical Problems). Bewley’s
Lattice Diagrams (for all the cases mentioned with numerical examples).
UNIT-V CORONA
Corona - Description of the phenomenon, factors affecting corona, critical voltages and power loss, Radio
Interference.
UNIT-VI OVERHEAD LINE INSULATORS
Types of Insulators, String efficiency and Methods for improvement, Numerical Problems - voltage
distribution, calculation of string efficiency, Capacitance grading and Static Shielding.
UNIT-VII SAG AND TENSION CALCULATIONS
Sag and Tension Calculations with equal and unequal heights of towers, Effect of Wind and Ice on weight
of Conductor, Numerical Problems -Stringing chart and sag template and its applications.
UNIT-VIII UNDERGROUND CABLES
Types of Cables, Construction, Types of Insulating materials, Calculations of Insulation resistance and
stress in insulation, Numerical Problems. Capacitance of Single and 3-Core belted cables, Numerical
Problems.Grading of Cables - Capacitance grading, Numerical Problems,Description of Inter-sheath
grading.
TEXT BOOKS:
1. A Text Book on Power System Engineering by M.L.Soni,
P.V.Gupta, U.S.Bhatnagar, A.Chakrabarthy, Dhanpat Rai & Co Pvt.
Ltd.
2. Electrical power systems - by C.L.Wadhwa, New Age International
(P) Limited, Publishers,1998.
3. Power System Engineering by R. K. Rajput, Laxmi Publications, 1st
Objective
Electric Power Transmission Course Description:
Electrical Power Transmission Systems engineering along with distribution network
planning and design, play a critical role in the technical management, development, and
acquisition of complex power and energy technology systems. They are the
professionals responsible for planning, coordinating, and overseeing group efforts that
translate operational need into technology solution, and whose tools and skills
determine whether a system will meet cost, schedule, and performance goals.
Along with the increasing complexity of the problems confronting our civilization, system
complexity has dramatically increased over the last several decades. It is even more
important today to deploy advanced methods and improved processes to effectively
track life-cycle costs, calculate risk and complexity, and leverage best solutions and
techniques.
Lesson Plan
PBR VISVODAYA INSTITUTE OF TECHNOLOGY AND SCIENCES
LESSON PLAN
YEAR: 2012 – 2013
BRANCH: EEE
NAME OF FACULTY : S. Mahesh Reddy
S.No.
Dates
No.of
periods
CLASS: IIIyear / Isem
SUBJECT: TEP
Topic to be covered
In week
No.of
Total
Periods
Periods
required
Per unit
Unit - 1
Types of conductors- calculation of
resistance for solid conductors
1
6
Calculation of inductance for single
phase, three phase
1
2
Inductance for double circuit lines
1
Concept of GMR and GMD
Symmetrical and asymmetrical single
and three phase
2
5
single and double circuit lines
1
1
1
Numerical problems
2
1
Numerical problems
Calculation of capacitance
3
6
2
Effect of ground capacitance
Capacitance for single and double lines
for symmetrical and unsymmetrical
problems
1
1
14
Unit – 2
Classification of Transmission lines
4
6
Representation of short transmission
lines
Medium transmission line
Long transmission line
5
6
2
1
10
1
1
A,B,C,D constants for symmetrical and
asymmetrical networks, problems
2
Regulation and efficiency of all types of
lines and problems
1
2
Unit -3
6
6
Long transmission line- rigorous
solution, evaluation of A,B,C,D constants
Interpretation of the long line equations
7
5
Surge impedance and SIL of long lines
wave length and velocity of propagation
2
2
2
9
of waves
Representation of long lines- equivalent
T and equivalent Pie network models
3
Unit-4
Types of system transients- travelling of
surges
2
Attenuation, Distortion, Reflection and
Refraction Coefficients
2
Coefficients for open circuited line, short
circuited line,
2
T junction
5
Lumped reactive junctions and problems
and Bewley’s lattice diagrams
–
2
8
1
4
8
Unit – 5
-corona – factors affecting corona
Critical voltages and power loss- radio
interference
2
1
9
6
2
Unit – 6
Types of insulators- Voltage distribution,
10
2
string efficiency and methods for
improvement, problems calculation of
string efficiency
capacitance grading and static shielding
11
problems
6
1
1
1
2
10
Unit – 7
Sag and tension -calculation with equal
and unequal heights of towers
2
5
12
6
Effect of wind and ice on weight of
conductor
2
problems
1
Stringing chart and sag template and its
applications
1
Unit – 8
13
Types of cables, construction
1
Types of insulating materials
1
6
3
14
5
Calculation of insulation resistance and
stress in insulation , problems
Capacitance of single
2
11
and 3 core belted cables
15
6
16
2
problems Grading of cables- capacitance
grading
Description of intersheath grading
3
1
Revision
Total
HOD
FACULTY
72
Question Papers – Mid-semester
examinations
Name:_________
Roll No:__________
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE I SEMESTER
I QUIZ EXAM
TRANSMISSION OF ELECTRIC POWER
Time: 20 Min
MARKS: 10
1.The inductance of a power transmission line increases with
(a) decrease in length
(b) Increase in diameter of conductor
(c) increased spacing between conductor
(d) Increased in load current
2. The inductance of the line is minimum when
(a) GMD is high
(b) GMR is high (c)GMD is low and GMR is high (d) none
3.The DC resistance of conductor is less than AC resistance due to _____________
4.Use of the bundle conductor increases __________
5. The internal inductance of a long straight cylindrical conductor is ____________
6. For a short line with r/x ratio 1.0, the regulation will be zero when load
power facor is _________
7. The ABCD constants for a short line are __________
8.The most important cause of power loss in transmission line is _____
9. Transmission lines having length between 80Km and 160Km are known as ____lines
10.Draw nominal T and nominal Π models 11For high voltage3-ph lines ____ Cables are preferred
11. the C and L per unit length of a 3-ph line operating at 110KV are 0.01uF and 2.5mH. the surge
impedance of the line is ________
12. For a long transmission line open circuited then the receiving end voltage is _____
13.The surge impedance of a double circuit trmn.line is ________
14.The charging current in the trmn.line
(a) lags voltage by 90 (b) leads voltage by 90
15.For a good voltage profile at no load a long line needs ---------------------16. If a line of impedance Z is terminated through a resistor R the voltage transmitted in the resistor is
______
17.For no reflections of travelling waves the line should be terminated by ________
18. A transmission line near a station is terminated by means of a cable because _________
19.Bewley’s lattice diagram is useful for ___________
20.The magnitude of attenuated voltage wave after travelling a distance of ‘x’ meters is_______
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE
I SEMESTER
I MID EXAM
TRANSMISSION OF ELECTRIC POWER
MARKS: 30
Answer any three questions
1.(a) What are bundled conductors? Discuss the advantages of bundled conductors
(b) distinguish between AC and DC resistance of a conductor
2. Derive expression for inductance per phase of a 3-ph over head line when conductors are Un
symmetrically placed but completely transposed.
3.Prove that inductance of a group of parallel wires carrying current can be represented interms of their
geometric distances. Explain the meaning of the term self G.M.D and Mutual G.M.D
4. Show how regulation and transmission efficiency are determined for medium lines
using nominal T method with vector diagram
5. Explain the physical significance of A,B,C,D constants of a transmission line. Find their values for
nominal π method and nominal T method.
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE
I SEMESTER
I MID EXAM
TRANSMISSION OF ELECTRIC POWER
MARKS: 30
Answer any three questions
1.(a) What are bundled conductors? Discuss the advantages of bundled conductors
(b) distinguish between AC and DC resistance of a conductor
2. Derive expression for inductance per phase of a 3-ph over head line when conductors are Un
symmetrically placed but completely transposed.
3.Prove that inductance of a group of parallel wires carrying current can be represented interms of their
geometric distances. Explain the meaning of the term self G.M.D and Mutual G.M.D
4. Show how regulation and transmission efficiency are determined for medium lines
using nominal T method with vector diagram
5. Explain the physical significance of A,B,C,D constants of a transmission line. Find their values for
nominal π method and nominal T method.
Name:_________
Roll No:__________
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE I SEMESTER
II QUIZ EXAM
TRANSMISSION OF ELECTRIC POWER
Time: 20 Min
MARKS: 10
1. Corona loss is less when shape of the conductor is __
(a) triangular
(b) circular
[
(c) square
(d) none
2.The formula for air density correction factor is given by
(a) 3.92t/(273+b)
(b) 3.92b/(273+t)
[
(c) 3.92b/100
(b) equal
[
]
[
]
(c) less (d) None
4Over head line insulators are mainly made of
(a) Ceramic
(b) PVC (c) Glazed porcelain
(d)Jute
5.The pin type insulators are uneconomical beyond
(a)11KV
(b) 33KV
(c) 132KV
[
(b) Cement
(c) Water
[
(b)WL^2/T
(c) WL^2/2T
(b) increases
(c)decreases
(a) Hyperbola (b) Straight line (c) Inclained line
[
(b) To block Chemicals entry
11For high voltage3-ph lines ____ Cables are preferred
(b) 3cored cable
[
]
]
(d) none
10.ThePurpose of Sheath in Underground Cables is_____
(a) 2cored cables
]
(d) none
9.The span of the transmission line between tower take the form of
(a) To block Moisture entry
[
(d)None
8.If the sag of transmission line increases ,tension
(a) Becomes half
]
(d) Led
7.Formula for sag when supports are at equal level is___
(a) WL/2T
]
(d) None
6. ______ is used between metal and porcelain of pin insulator
(a) Paper
]
(d) none
3.Critical Disruptive voltage for strandad wire is ___ compared to solid wire
(a) more
]
[
(c) both (a) and (b)
[
(c) 3single cored cables (d) none
]
(d) None
]
12. The potential gradient in insulator is maximum at_____
(a) Center of core
(b) Surface of sheath
[
(c) Surface of conductor (d) none
13.Peterson’s formula for power loss due to corona is________
14. Corona at hilly areas is more (TRUE/FALSE)
15. Over head line insulators are mainly made of Glazed porcelain (TRUE/FALSE)
16.Sag Template is used to _______________
17.Stringing Chart is a plot drawn between _____________ & ____________
18. Cables generally used beyond 66Kv are _____________
19.In capacitance grading of the cables we use a _________ dielectric
20. Capacitance between core and earth of a 3-ph cable forms _____________ circuit
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE
I SEMESTER
II MID EXAM
TRANSMISSION OF ELECTRIC POWER
MARKS: 30
Answer any three questions
1. What do you mean by critical visual disruptive voltage and visual critical voltage of
corona? Derive expressions.
(10)
2. List various methods of improving the string efficiency
(10)
]
3. Derive the expression for sag when the supports are at equal heights and the wind and ice
effects are also considered.
(10)
4.An overhead line at a river crossing is supported from two towers at hights of 40m and
90m above water level. The horizontal distance between the towers is 400mt. If the
max.allowable tension is 2000Kg, find the clearance between the conductor and water at a
point midway between the towers. Weight of the conductor is 1Kg/m
(10)
5. (a)Give the list of various types of UGcables. Classify the UG cables according to various
Parameters
(4)
(b) Derive an expression for insulation resistance, capacitance of a single core Cable(6)
PBR VISVODAYA INSTITUTE OF TECHNOLOGY & SCIENCE: KAVALI
III EEE
I SEMESTER
II MID EXAM
TRANSMISSION OF ELECTRIC POWER
MARKS: 30
Answer any three questions
1. What do you mean by critical visual disruptive voltage and visual critical voltage of
corona? Derive expressions.
(10)
2. List various methods of improving the string efficiency
(10)
3. Derive the expression for sag when the supports are at equal heights and the wind and ice
effects are also considered.
(10)
4.An overhead line at a river crossing is supported from two towers at hights of 40m and
90m above water level. The horizontal distance between the towers is 400mt. If the
max.allowable tension is 2000Kg, find the clearance between the conductor and water at a
point midway between the towers. Weight of the conductor is 1Kg/m
(10)
5. (a)Give the list of various types of UGcables. Classify the UG cables according to various
Parameters
(b) Derive an expression for insulation resistance, capacitance of a single core Cable(6)
(4)
Question Bank
QUIZ BITS
TRANSMISSION OF ELECTRIC POWER
UNIT-1
1.The inductance of a power transmission line increases with
(a) decrease in length
(b) Increase in diameter of conductor
(c) increased spacing between conductor
(d) Increased in load current
2. The inductance of the line is minimum when
(a) GMD is high (b) GMR is high
(c)GMD is low and GMR is high (d) none
3.The DC resistance of conductor is less than AC resistance due to _____________
4.Use of the bundle conductor increases __________
5. The internal inductance of a long straight cylindrical conductor is ____________
6. GMD is defined as ___________
7. Transposition of transmission lines is done for____________
8. Capacitance is defined as____________
9. The capacitance to neutral of a 3 ph line with un equilateral spacing and transposed is
10.Capacitance per phase of a 3-ph double circuit line with vertical configuration is ____
UNIT-2
1. The length of a short transmission line is upto about_____________ KM
2. The formula for percentage requlation is ___________
3.A 1-ph line transmitting 1100kw power to a factory at 33KV at 0.9p.f lagging. It has a total resistance of 10ohms
and a loop reactance of 15ohms. The transmission efficiency is
4.Voltage regulation of a short line is either positive , negative, or zero
5. ______ is usually neglected in the calculations of short trams. lines
6. For a short line with r/x ratio 1.0, the regulation will be zero when load
power facor is 0.707 lead
7. The ABCD constants for a short line are __________
8.The most important cause of power loss in transmission line is _____
9. Transmission lines having length between 80Km and 160Km are known as ____lines
10.Draw nominal T and nominal Π models
UNIT-3
1. the C and L per unit length of a 3-ph line operating at 110KV are 0.01uF and 2.5mH. the surge impedance of the
line is ________
2. For a long transmission line open circuited then the receiving end voltage is _____
3.The surge impedance of a double circuit trmn.line is ________
4.The charging current in the trmn.line
(a) lags voltage by 90 (b) leads voltage by 90
5.For a good voltage profile at no load a long line needs shunt reactor at receiving end
6.the line parameters for long line are taken as ________
7. the Constants A, B for a long line in equivalent Π representation is ____
8. To get series branch of eq. T circuit the series branch of nominal T circuit should be multiplied by ____
9. Two lines with constants A1,B1 ,C1,D1 and A2,B2,C2,D2 are connected in series. Then A = __________
UNIT-4
1.Transients in power system are generally due to the presence of _____ & ____
2.The voltage wave on transmission line travels with a velocity of ______
3.The coefficient of reflection of voltage wave at open circuit end is _____
4. the characteristic impedance of the transmission line is ____ and for cable is____
5. The coefficient of reflection of current wave at open circuit end is_________
6. If a line of impedance Z is terminated through a resistor R the voltage transmitted in the resistor is ______
7.For no reflections of travelling waves the line should be terminated by ________
8. A transmission line near a station is terminated by means of a cable because _________
9.Bewley’s lattice diagram is useful for ___________
10.The magnitude of attenuated voltage wave after travelling a distance of ‘x’ meters is_______
Descriptive questions:
UNIT-1
1.(a) What are bundled conductors? Discuss the advantages of bundled conductors
(b) distinguish between AC and DC resistance of a conductor
2. Derive expression for inductance per phase of a 3-ph over head line when conductors are Un symmetrically
placed but completely transposed.
3.Prove that inductance of a group of parallel wires carrying current can be represented interms of their geometric
distances. Explain the meaning of the term self G.M.D and Mutual G.M.D
4.Derive an expression for the capacitance of a single phase over head transmission line.
5.Calculate the capacitance of a 3-ph overhead line for unsymmetrical spacing. Also explain the effect of earth on
the capacitance of a line.
6.Determine the capacitance of a 3-ph double circuit line with symmetrical spacing.
7. Show that inductance per loop meter of two wire transmission line using solid round conductors is L=4x10
7
ln(d/r’)
UNIT-2
1.(a)How do you classify transmission line?
(b) A short line ha impedance of (0.2+j0.45)ohm/phase. The sending end voltage being
3.3KV and the load at the receiving end being 250MW perphase at a p.f of
0.8lagging. calculate(a)receiving end voltage,(b) efficiency
2. Define regulation of a short 3-ph transmission line and develop an expression for
approximate voltage regulation
3. Show how regulation and transmission efficiency are determined for medium lines
using nominal π method with vector diagram
4. Show how regulation and transmission efficiency are determined for medium lines
using nominal T method with vector diagram
-
5. Explain the physical significance of A,B,C,D constants of a transmission line. Find their values for nominal π
method and nominal T method.
UNIT-3
1.Derive the equivalent ABCD constants of a transmission line connected in series with an impedance at both ends.
2.Derive the expressions for voltage and current distribution over a long line. Explain the significance of
characteristic impedance loading and propagation constant in connection with a long line.
3.Using rigorous method, derive expressions for sending end voltage and current for a long transmission line.
4.What is equivalent π circuit of a long line? Derive an expression for parameters of this circuit in terms of line
parameters.
-6
5.The per unit length parameters of a 215KV, 400Km,60Hz, three phase long transmission line are y = j3.2x10 mho
per phase per Km and z = (0.1+j0.5) ohm/Km/ph. The line supplies a 150MW load at unity power factor. Determine
(i) the voltage regulation
(ii) The sending end power
(iii) the efficiency of transmission.
UNIT-4
1.Deduce expressions for surge impedance and velocity of propagation.
2.Starting from first principals show that surges behave as travelling waves.
3. derive reflection and refraction coefficient of transmission line when receiving end is open circuited
4.When transmission line is terminated by a capacitive load, how do you find out the expressions of reflected
voltage and current wave?
5. Discuss about attenuation of travelling waves.
TRANSMISSION OF ELECTRIC POWER
BITS AND DESCRIPTIVE QUESTIONS FOR II MID
UNIT-5
1.Corona loss is less when shape of the conductor is __circular____
2.Corona loss increases withincrease in supply frequency and reduction in conductor size
3.The formula for air density correction factor is given by 3.92b/(273+t)
4.Critical Disruptive voltage for strandad wire is _less_ compared to solid wire
5. For polished wires, the irregularity factor is 1.0
6.Peek’s formula for power loss due to corona is __________
7. The frequency of supply being high, corona loss are high
8. peterson’s formula for power loss due to corona is________
9.Corona at hilly areas is more (TRUE/FALSE)
UNIT-6
1.Over head line insulators are mainly made of Glazed porcelain
2.The major draw back of glass is moisture condensing very easily on its surface.
3.The pin type insulators are uneconomical beyond 33KV
4.Define String efficiency
5.The capacitance of guard ring with respect to pins of insulator is Cn = nc/k-n
6.cement is used between metal and porcelain
7.The shunt capacitance is increased then the string efficiency is decreased
8.The main cause of insulator puncture is __flashover__
9. When the potential across each disk is the same then the string efficiency is 100%
10.Use of lengthy cross arms increases string efficiency by decreasing shunt capacitance
UNIT-7
1.The difference in level between points of supports and lowest point on the conductor is called
sag.
2.Formula for sag when supports are at equal level is WL^2/2T.
3.If the sag of transmission line increases ,tensiondecreases.
4.Sag is provided in over head lines so that safe tension z not exceeded.
5.In a power transmission line,the sag depends on
[ d ]
a. a)Conductor material
b)Tension in conductor
b. c)Transmission line span
d)All of d above
6.Define Saftey factor?
Saftey factor is defined as the ratio of the ultimate strength to the working stress.
7.The span of the transmission line between tower take the form of Hyperbola.
8.Sag Template is used to allocate loacation of poles
9.Stringing Chart is a plot drawn between Sag and Tension Verses Temperature
10.Standered conductor materials are used in order to Increase the flexibility
UNIT-8
1.ThePurpose of Sheath in Underground Cables is_____
2. For high voltage3-ph lines __3Single cored__ Cables are preferred
3.The potential gradient in insulator is maximum at___Surface of conductor___
4. Belted cables are generally used upto___33KV____
5. Cables generally used beyond 66Kv are oil filled
6. Dielectric strength of the rubber is around 30KV/mm
7.Cables in power transmission line are provided with inter sheaths to provide uniform
stress distribution.
8.In capacitance grading of the cables we use a __Composite____ dielectric
9.Which of the following protects a cable against mechanical injury
(a) bedding
(b) Sheath
(c) armouring
(d) paper
10.the most economic conductor size for less potential gradient is r = eR
Questions
Unit-5
1. What do you mean by critical visual disruptive voltage and visual critical voltage? Derive expressions.
2. What is corona and what are the factors affecting corona loss? Discuss them briefly.
3. Write a short note on radio interference.
4. Problem
5. Problem
Unit-6
1.Explain why suspension type insulators are preferred for HV over head lines. Sketch a sectional view of
one unit of suspension type insulator and describe the construction.
2.Discuss the method of grading the string unit in sulations.
3.List various methods of improving the string efficiency
4.Problem
5.Problem.
Unit-7
1.Derive the expression for sag when the supports are at equal heights and the wind and ice effects are
also considered.
2.Discuss the consideration which govern the selection of span and conductor configuration of a high
voltage line.
3.What are sag template and stringing chart and what are their use?
4.Problem
5.Problem
Unit-8.
1.Give the list of various types of UGcables. Classify the UG cables according to various parameters.
2.What are limitations of solid cables and how are these overcome in pressure cable.
3.Derive an expression for insulation resistance, capacitance and max,minimum gradients in a single
core cable.
4.Explain about grading of UG cables
5.Problem
6.Problem
Previous years’ question papers – JNTUA
Code:9A02502
1
IIIB. TechI Semester (R09)Regular &Supplementary
Examinations,November 2012
TRANSMISS
IONOF
ELECTRIC
POWER
(Electric
al
&Electr
onicsEn
gineerin
g)
Time:3hours
Max.Marks:70
1
(a)
Show that the capacitance per conductor per meter of a double circuit regular
2πε0
hexagonalspacingtransmissionlineisC=
(b)
2
(a)
F/meter/conductor,WhereDis
3D
ln
2r
conductor spacingandr istheradiusof theconductor.
Determinetheinductanceperkmperphaseofasinglecircuit20kVlineofgiven
configurationasshowninfig.Theconductorsaretransposedandhaveadiameterof5 cm.
Explain the physical significance of the generalized A, B, C, D constants of a
transmissionline.State theunitsof theseconstants.
(b)
Using
nominal-TmethodfindA,B,C,Dparametersofa3-Φ 80kmlong50Hz transmission
line with series impedance of (0.15+j0.78)Ω per km and a shunt admittanceof5x106
mhoperkm.
3
Startingfromthefundamentalsdeterminetheequivalent-Tnetworkparametersofa long
transmissionline. AndalsoproveAD-BC=1for thesamenetwork.
4
A3-Φ transmissionlinehasconductors1.5cmindiameterspaced1mapartin
equilateralformation. The resistanceand leakagearenegligible.Calculate:
(i) thenatural impedanceofthe line
(ii)the linecurrentsifavoltagewaveof11kVtravelsalongthe line
(iii)therateofenergyabsorption,therateofreflectionandthestateandtheformof
reflectionifthelineisterminatedthroughastarconnectedloadof1000 Ω/ph.
5
Writeshortnoteson:
(a)Corona.
(b)Radiointerference.
(c) Powerlossduetocorona.
Contd.in Page2
Page1of2
1
Code:9A02502
6
(a)
Deducethe mathematicalexpression forpotentialdistributionoverastringof4insulator discs.
(b)
Thethreebusbarconductorsinanoutdoorsubstationaresuppliedbyunitsofpost
insulators.Eachunitconsistsofastackof3-pintypeinsulatorsfixedoneonthetopof
theother.Thevoltageacrossthelowestunitis8.45kvandthatacrossnextis7.25kv.
Find thebusbarvoltageofthestation.
7
8
Assumingtheshapeofanoverheadlinecanbeapproximatedbyaparabola,deduce
theexpressionforthesag,tensionandconductorlength.Howcantheeffectofwind
andiceloadingsaretakenin to account?
(a)
(b)
Writedown theadvantagesofundergroundcableover overhead transmissionlines.
Asingle-corecablehasaconductordiameterof2.5cmandinsulationthicknessof1.2
cm.Ifthespecificresistanceofinsulation4.5×1014 ohm-cm,calculatetheinsulation
resistanceperkilo merelengthof thecable.
*****
Page2of2
2
Code:9A02502
IIIB. TechI Semester (R09)Regular &Supplementary Examinations,November 2012
TRANSMISSIONOF ELECTRIC POWER
(Electrical &ElectronicsEngineering)
Time:3hours
Max.Marks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a) Find theexpressionforinductanceof atwo-wire1-ø transmission line.
(b)
Determinetheinductanceofathreephaselineoperatingat50Hzandconductors
arrangedasfollows:Theconductordiameteris1cm.
Fig
2
Anoverhead3-Φshorttransmissionlinedelivers4000kWat11
kVat0.8pflagging.
The
resistanceand
reactanceofearth
conductorare1.5Ωand
4Ωperphase
respectively.Determine:
(i)Thesendingend linevoltage. (ii)Percentageregulation.(iii)Transmissionefficiency.
3
Determine
thesendingendvoltagecurrentandpower
for160kmsectionof3-Φline
delivering45MVAat132KVandpf0.8lagging.
Also,
find
theefficiencyandregulation
ofline.Resistanceperlineis0.16Ω/km, spacingis3.5m,6.5m and7.4mtransposed. Diameter
oftheconductoris1.9cm.
4
Derivetheexpressionfortransientcurrentwave,showthattransientcurrentissumof
incidentcurrent,andreflectedcurrent.
5
A110KV,3Phase,50Hz
transmissionline,175kmlongconsists
ofthree1cm
diameterstranded copperconductorsspacedin3-meterdelta arrangement. Temperature
taken at260Candbarometricpressureas74 cmofmercury.Assume surfaceirregularityfactor
m0=0.85,mvfor local corona=0.72andmvforgeneral corona
=0.82Findcritical voltagesandpowerloss.
6
(a)
(b)
Explainabout theimprovement ofstringefficiency usinglonger crossarms.
Astringof5insulatorunitshasaself-capacitanceisequalto11timesthepintoearth
capacitance. Calculate thestringefficiency if theoperatingvoltageis66kv.
7
Deduce the expressions for total length of conductor, tension and sag when the
transmissionlineconductorsaresupportedontransmissionline towers.
8
Writeshortnoteson:(a) Intersheathgrading. (b)Capacitancegrading.
*****
3
Code:9A02502
IIIB. TechI Semester (R09)Regular &Supplementary Examinations,November 2012
TRANSMISSIONOF ELECTRIC POWER
(Electrical &ElectronicsEngineering)
Time:3hours
Max.Marks:70
AnsweranyFIVEquestions
Allquestionscarryequalmarks
*****
1
(a)
(b)
Startingfromthefundamentalsderivetheexpressionfortheinductanceofa3-øunsymmetricallyspaced transmissionline.
Determinethecapacitanceandchargingcurrentperkmofasinglecircuit220kVline
usingtwobundleconductorsperphaseasshowninthefigure.Thediameterofeach conductor
is4.5cm
2
Derive theexpressions forefficiency and regulationandA,B, C, D parametersofa
nominal-πmediumlengthtransmission linebyusingitsphasordiagram.
3
Startingfrom thefundamentalsdetermine theequivalent-Tnetworkandequivalent-π
networkparametersof a long transmissionline.
4
Asurgeof25kV
travelingonalineofnaturalimpedance500ohmsarrivesata
junction
withtwolinesofimpedances500ohms
and
50ohms
respectively.Findthe
surge
voltagesandcurrents
transmittedintoeachbranchline.Also
findthereflectedsurge
voltageandcurrent.
5
(a)
(b)
Discusstheeffectof thesizeoftheconductor on Coronaloss.
Acertain3-phaseequilaterallyspacedtransmissionlinehasatotalcoronalossof55
KWat110kvandalossof110KWat120KV.Whatisthedisruptivecriticalvoltage
betweenlines?What isthecorona lossat125kv?
6
(a)
(b)
Explainabout theimprovement ofstringefficiency by gradingofunits.
A threephaseoverheadlineissuspendedbyasuspensiontype insulator,which
consistsofthreeunits.Thepotentialacrosstopunitandmiddleunitare12kvand18
kvrespectively.Calculate:(i)The
ratioofcapacitancebetweenpinandearthtotheself
capacitanceofeachunit(ii) Thelinevoltageand (iii)Stringefficiency.
7
(a)
(b)
Derive theexpressions forsagandtensionwhen thesupportsareat equal heights
Anoverheadtransmissionlineatarivercrossingissupportedfromtwotowersat
heightsof40mand90mabovewaterlevel.Thehorizontaldistancebetweenthe
towersbeing400
m.Ifthemaximumallowabletensionis2000kg,find
theclearance
betweentheconductorandwateratapointmid-waybetweenthetowers. Weightof conductor
is1kg/m.
8
Whatisthenecessityofgradingofcables?Explainbriefly thevariousgradingmethods
ofcables.
*****
4
Code:9A02502
IIIB. TechI Semester (R09)Regular &Supplementary Examinations,November 2012
TRANSMISSIONOF ELECTRIC POWER
(Electrical &ElectronicsEngineering)
Time:3hours
Max.Marks:70
AnsweranyFIVEquestions
All questionscarryequal marks
*****
1
(a) Derivetheexpressionforthecapacitanceofa3-ødoublecircuithexagonalspacing
configuration.
(b)
Determinetheinductanceofa3-ølineoperatingat50Hzandconductorsarrangedas
follows.Theconductordiameteris0.8 cm.
Fig
2
DerivetheexpressionsforefficiencyandregulationandA,B,C,Dparametersofa nominalπmediumlengthtransmission linebyusingitsphasordiagram.
3
Athree phase200kmlonghigh voltage linehasZ=(14.1+j51.48)ohmsand y=(0+j1.194x106
)siemens.Findthecharacteristicimpedance,propagationconstant andconstants A, B, C
andDfor the line.
4
Asurgeof200kVtravelingonalineofnaturalimpedance500ohmsarrivesata
junction
withtwolinesofimpedances700ohmsand300ohms respectively.Findthe surgevoltagesand
currentstransmittedintoeachbranchline.Also find thereflected surgevoltageandcurrent.
5
TUWO
(a)
(b)
Writeshortnotesonradiointerferenceduetocorona.
A3-phaselinehasconductorsofradius1.0cm,spacedatthecornersofanequilateral
triangleofside2.5mapart.Ifthedielectricstrengthofairis30kv/cm.determine
disruptivecriticalvoltageatwhichcoronawilloccur.Takeairdensityfactorδis0.96
andirregularityfactor m0is0.94. Assumetherequireddata.
Contd.in Page2
Page1of2
Code:9A02502
4
6
Eachlineofathree-phasesystemissuspendedbyastringofthreeidenticalinsulators
ofselfcapacitanceofC
farad.Theshuntcapacitanceofconnectingmetalworkofeach
insulatoris0.2C
toearthand0.1C
toline.Calculatethestringefficiencyofthesystem
andalsocalculatestringefficiencyifa guard-ringincreasesthe capacitanceto theline ofmetalworkof the lowestinsulator to0.3C.
7
(a)
(b)
What arethefactorsaffecting the sag?
Anoverheadlineatarivercrossingissupported fromtwotowersofheight50mand80
mabovewaterlevelwithaspanof300m,theworking tensionis2000kg.Determinethe
clearancebetweentheconductorandthewaterlevelmidwaybetweenthetowers.
Weightoftheconductorpermeter=0.844kg.Assumethattheconductortakesthe
shapeofparaboliccurve.
8
(a)
(b)
Brieflydiscuss gradingmethodsusedfor thecables.
A33kvsinglecorecablehasaconductordiameterof10mmandsheathofinside
diameter of40mm. Findthemaximumandminimumstressintheinsulation.