Power System Analysis was a core subject for Electrical & Electronics Engineering, Based On Anna University Syllabus. The Whole Subject was there in this document.
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SRF THEORY BASED STATCOM FOR COMPENSATION OF REACTIVE POWER AND HARMONICSIAEME Publication
The power electronic devices like converters and inverters inject harmonic currents into AC
system due to their non linear characteristics. These devices draw high amount of reactive power
from source. The commencement of Nonlinear Load into the ac power system will have the effect of
harmonics. The presence of harmonics in system it will effected with power quality problems. Due
to this high amount of power losses and disoperation of power electronics devices is caused, along
with this Harmonics have a number of undesirable effects like Voltage disturbances. These
harmonics are needed to mitigate for Power Quality Enhancement in distributed system. Here the
device called STATCOM is one of the FACTS Devices which can be used to mitigate the harmonics
and reactive power compensation. The voltage source converter is core of the STATCOM and the
hysteresis current control is indirect method of controlling of VSC. In this paper we implement with
SRF based STATCOM control. SRF theory is implemented for the generation of controlling
reference current signals for controller of STATCOM. The Matlab\Simulink based model is
developed and simulation results are showed for linear and nonlinear load conditions.
Power System Analysis was a core subject for Electrical & Electronics Engineering, Based On Anna University Syllabus. The Whole Subject was there in this document.
Share with it ur friends & Follow me for more updates.!
SRF THEORY BASED STATCOM FOR COMPENSATION OF REACTIVE POWER AND HARMONICSIAEME Publication
The power electronic devices like converters and inverters inject harmonic currents into AC
system due to their non linear characteristics. These devices draw high amount of reactive power
from source. The commencement of Nonlinear Load into the ac power system will have the effect of
harmonics. The presence of harmonics in system it will effected with power quality problems. Due
to this high amount of power losses and disoperation of power electronics devices is caused, along
with this Harmonics have a number of undesirable effects like Voltage disturbances. These
harmonics are needed to mitigate for Power Quality Enhancement in distributed system. Here the
device called STATCOM is one of the FACTS Devices which can be used to mitigate the harmonics
and reactive power compensation. The voltage source converter is core of the STATCOM and the
hysteresis current control is indirect method of controlling of VSC. In this paper we implement with
SRF based STATCOM control. SRF theory is implemented for the generation of controlling
reference current signals for controller of STATCOM. The Matlab\Simulink based model is
developed and simulation results are showed for linear and nonlinear load conditions.
USING SSSC & STATCOM --IMPROVE TRANSIENT STABILITY--P & Q OSICALLATIONSIJSRD
In a deregulated power system, the electric power demand is extending ordinary which may lead to overloads and loss of generation. Transient stability studies put a fundamental part in power systems, which give information related to the capacity of a power structure to stay in synchronism during major disturbances resulting from either the loss of generation or transmission facilities, sudden or sustained changes. The examination of transient quality is discriminating to work the power structure more secure and this paper focuses on growing the transient relentlessness using FACTS devices like Static Synchronous Series Compensator (SSSC) and static synchronous compensator (STATCOM). These FACTS contraptions are in a perfect world set on transmission structure using Sensitivity approach framework.
Matlab Simulation And Comparison Of Single Phase To Three Phase Converter Fe...IJMER
This paper presents MATLAB simulation and comparison of three phase induction motor drive
supplied from single phase supply with one rectifier and two rectifiers systems. To meet the new
harmonic regulation produced by converters both system incorporates an active input current shaping
feature that results in sinusoidal input current at close to unity power factor. Even with the increase in
the number of switches, the total harmonic distortion in supply current of the parallel connected two
rectifier system is lower than that of a conventional one. The model of the system is developed in
MATLAB software. All simulation results and comparison are presented as well
An electric circuit is a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.
USING SSSC & STATCOM --IMPROVE TRANSIENT STABILITY--P & Q OSICALLATIONSIJSRD
In a deregulated power system, the electric power demand is extending ordinary which may lead to overloads and loss of generation. Transient stability studies put a fundamental part in power systems, which give information related to the capacity of a power structure to stay in synchronism during major disturbances resulting from either the loss of generation or transmission facilities, sudden or sustained changes. The examination of transient quality is discriminating to work the power structure more secure and this paper focuses on growing the transient relentlessness using FACTS devices like Static Synchronous Series Compensator (SSSC) and static synchronous compensator (STATCOM). These FACTS contraptions are in a perfect world set on transmission structure using Sensitivity approach framework.
Matlab Simulation And Comparison Of Single Phase To Three Phase Converter Fe...IJMER
This paper presents MATLAB simulation and comparison of three phase induction motor drive
supplied from single phase supply with one rectifier and two rectifiers systems. To meet the new
harmonic regulation produced by converters both system incorporates an active input current shaping
feature that results in sinusoidal input current at close to unity power factor. Even with the increase in
the number of switches, the total harmonic distortion in supply current of the parallel connected two
rectifier system is lower than that of a conventional one. The model of the system is developed in
MATLAB software. All simulation results and comparison are presented as well
An electric circuit is a path in which electrons from a voltage or current source flow. The point where those electrons enter an electrical circuit is called the "source" of electrons.
Dear student, Cheap Assignment Help, an online tutoring company, provides students with a wide range of online assignment help services for students studying in classes K-12, and College or university. The Expert team of professional online assignment help tutors at Cheap Assignment Help .COM provides a wide range of help with assignments through services such as college assignment help, university assignment help, homework assignment help, email assignment help and online assignment help. Our expert team consists of passionate and professional assignment help tutors, having masters and PhD degrees from the best universities of the world, from different countries like Australia, United Kingdom, United States, Canada, UAE and many more who give the best quality and plagiarism free answers of the assignment help questions submitted by students, on sharp deadline. Cheap Assignment Help .COM tutors are available 24x7 to provide assignment help in diverse fields - Math, Chemistry, Physics, Writing, Thesis, Essay, Accounting, Finance, Data Analysis, Case Studies, Term Papers, and Projects etc. We also provide assistance to the problems in programming languages such as C/C++, Java, Python, Matlab, .Net, Engineering assignment help and Finance assignment help. The expert team of certified online tutors in diverse fields at Cheap Assignment Help .COM available around the clock (24x7) to provide live help to students with their assignment and questions. We have also excelled in providing E-education with latest web technology. The Students can communicate with our online assignment tutors using voice, video and an interactive white board. We help students in solving their problems, assignments, tests and in study plans. You will feel like you are learning from a highly skilled online tutor in person just like in classroom teaching. You can see what the tutor is writing, and at the same time you can ask the questions which arise in your mind. You only need a PC with Internet connection or a Laptop with Wi-Fi Internet access. We provide live online tutoring which can be accessed at anytime and anywhere according to student’s convenience. We have tutors in every subject such as Math, Chemistry, Biology, Physics and English whatever be the school level. Our college and university level tutors provide engineering online tutoring in areas such as Computer Science, Electrical and Electronics engineering, Mechanical engineering and Chemical engineering. Regards http://www.cheapassignmenthelp.com/ http://www.cheapassignmenthelp.co.uk/
the above PPT will give a brief idea of the measuring device used in the field of Mechanical Engineering with images related to the topics in the field of measurement.
A detailed presentation on Power meters which includes watt meter , poly phase power measurement , VAR meter, Energy (kilo-watt/hour) meter ,power factor meter
Physics Class X Electric Current
Contents
1 Electricity
2 Electric Current
3 Electric Potential & Potential Difference
4 Electromotive Force (emf)
5 Electric Circuit and components
6 Current and Voltage Measurements
7 OHM’s Law
8 Factors Affecting Resistance
9 Combination of Resistors(Series & Parallel)
10 Heating Effect of Electricity and its apps.
Learn the differences between self-contained and transformer or instrument rated meter sites, test switches and CTs, Blondel’s Theorem, meter accuracy testing, site verification, and more! This presentation was given at MEUA Meter School. 03.03.20
This presentation will cover the basics and differences between self-contained and transformer or instrument rated meter sites. Also discussed are transformer rated meter forms, test switches and CT's, Blondel's Theorem and why this matters to metering, meter accuracy testing in the field, checking the health of your CT's and PT's, and Site Verification (and not just meter testing).
Similar to Unit I - Basic Electrical and Electronics Engineering (20)
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
TOP 10 B TECH COLLEGES IN JAIPUR 2024.pptxnikitacareer3
Looking for the best engineering colleges in Jaipur for 2024?
Check out our list of the top 10 B.Tech colleges to help you make the right choice for your future career!
1) MNIT
2) MANIPAL UNIV
3) LNMIIT
4) NIMS UNIV
5) JECRC
6) VIVEKANANDA GLOBAL UNIV
7) BIT JAIPUR
8) APEX UNIV
9) AMITY UNIV.
10) JNU
TO KNOW MORE ABOUT COLLEGES, FEES AND PLACEMENT, WATCH THE FULL VIDEO GIVEN BELOW ON "TOP 10 B TECH COLLEGES IN JAIPUR"
https://www.youtube.com/watch?v=vSNje0MBh7g
VISIT CAREER MANTRA PORTAL TO KNOW MORE ABOUT COLLEGES/UNIVERSITITES in Jaipur:
https://careermantra.net/colleges/3378/Jaipur/b-tech
Get all the information you need to plan your next steps in your medical career with Career Mantra!
https://careermantra.net/
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Water billing management system project report.pdfKamal Acharya
Our project entitled “Water Billing Management System” aims is to generate Water bill with all the charges and penalty. Manual system that is employed is extremely laborious and quite inadequate. It only makes the process more difficult and hard.
The aim of our project is to develop a system that is meant to partially computerize the work performed in the Water Board like generating monthly Water bill, record of consuming unit of water, store record of the customer and previous unpaid record.
We used HTML/PHP as front end and MYSQL as back end for developing our project. HTML is primarily a visual design environment. We can create a android application by designing the form and that make up the user interface. Adding android application code to the form and the objects such as buttons and text boxes on them and adding any required support code in additional modular.
MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software. It is a stable ,reliable and the powerful solution with the advanced features and advantages which are as follows: Data Security.MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
4. ELECTRIC CURRENT
Electric current is the time rate of flow of
Electric charge. It is measured in amperes(A).
Mathematical Relationship between current i, charge q
and time t is
1 ampere= 1 coulomb/Second
dt
dq
i
5. • A direct current(dc) is a current that remains
constant with time
• An alternating current (ac) is a current that
varies sinusoidally with the time.
6. ELECTRIC VOLTAGE
The voltage vab between two points a and b in
an electric circuit is the energy (or work) needed
to move a unit charge from a to b.
Or
Voltage or potential difference is the energy
required to move a unit charge through an
element. It is measured in volts(V)
Mathematically
1 volt= 1 joule/coulomb
dq
dw
vab
7. ELECTRIC POWER
Power is the time rate of expending or
absorbing energy. It is measured in watts(W).
Mathematically
P=VI or p=vi
dt
dw
p
8. ELECTRIC ENERGY
Energy is the capacity to do work. It is
measured in Joules(J).
Mathematically
Energy=P*t
1 Wh =3600 J
Que: How much energy does a 100 W electric
bulb will consume in two hours?
12. Resistor
• The resistance R of an element denoted its
ability to resist the flow of electric current.
• It is measured in ohms.
R- resistivity of the material is ohm-meter
l- length of the material in meter
A-cross section area of the material in meter
A
l
R
13. OHM’S LAW
Ohm’s law states that the voltage V across a
resistor is directly proportional to the current i,
flowing through the resistor.
iv
iRv
14. Limitations of Ohm’s law
• Ohm’s law does not applicable for all the non-metallic
conductors.
• It is not applicable to non-linear devices such as zener diode,
Vacuum tubes etc.
• Ohm’s law is true for metal conductors at constant
temperature. If the temperature changes, the law is not
applicable.
15. NETWORK DEFINITION
BRANCH: A branch represents a single element
such as a voltage source or a resistor.
Node: A node is the point of connection
between two or more branches.
Loop: A loop is any closed path in a circuit.
Fundamental theorem of network topology
A nework with b branches,n nodes, and l
independent loops will satisfy the fundamental
theorem of network topology
b=l+n-1
16. Problem 1 : What will be the current drawn by a lamp
rated at 230 V, 60 W connected to the
230 V supply?
Problem 2 : What is amount of current, if the lamp is
connected to 250 V and 415 V?
Problem 3 : What is the value of resistance of the
lamp given in Problem 1?
17. Problem 4 :
A circuit consists of three resistors 3Ω, 4Ω and 6Ω in parallel and
a fourth resistor 4Ω in series. A battery of emf 12 V and internal
resistance 6Ω is connected across the circuit. Find the total
current in the circuit and terminal voltage across the battery.
18. KIRCHHOFF’S LAWS
Kirchhoff’s Voltage Law states that the algebraic
sum of all voltages around the closed path or loop is
zero.
Sum of voltage rises = sum of voltage drops
M= Number of voltages(Number of branches) in
the loop
M
m
m
v
1
0
20. Kirchhoff’s Current Law states that the algebraic
sum of currents entering at a node (or a closed is
zero.
Sum of Currents = Sum of Currents
entering at a node leaving at a node
N= Number of branches connected to the node
N
n
n
i
1
0
22. Problem 6
For the circuit shown in figure, determine the
unknown voltage drop V1
(ANS: V1=19 V)
23. Problem 7
In the circuit of figure find using “krichhoff’s
laws” the currents in the various elements.
Find also the power delivered by the battery.
(Ans: 3 A, 2 A & 1 A, 54 W)
24. Problem 8
Calculate the currents supplied by the batteries
in the network shown in figure.
(Ans: I1=5 A, I2=-1 A & I3=4 A)
30. Problem 11
Using nodal analysis, determine the current in
the 20 Ω resistor.
(Ans:I=0.6 A)
31. Problem 12
Using nodal analysis, obtain the currents
flowing in all the resistors of the circuit shown
in figure.
(Ans:I=4.25 A, 6.38 A, 8.51 A)
32. Problem 13
Using nodal analysis, obtain the current
flowing in the 15 ohm resistor of the circuit
shown in figure.
(Ans:I=2.78A)
33. Electrical Measurements
• Operating Principles of moving iron
instruments (Ammeters and voltmeters)
• Dynamometer type watt meters and energy
meters
24-Dec-20 33
34. Measurement
• Measurement is an act or the result of
quantitative comparison between an unknown
magnitude and pre defined standard. Since two
quantities are compared the results is expressed
in numerical values.
• If the result is to be meaningful two requirements
must be met viz.
1. The standard which is used for comparison must
be accurately known and commonly accepted.
2. The procedure and equipment used for
obtaining this comparison must be provable.
36. Methods of Measurements
Direct comparison method:
• In this method, the unknown quantity
(measurand) is directly compared against a
standard. The result is expressed as a numerical
value and a unit. It is common for the
measurement of physical quantities like mass and
time.
• This method is not always possible, feasible and
practicable. It is inaccurate because they involve
human factors and less sensitive. Hence direct
methods are not preferred and are rarely used.
37. Methods of Measurements
Indirect comparison method:
• In this method, the parameter to be measured
is compared with the standard through the
use of a calibrated system. These methods are
mostly used in industries.
39. Types of Measurements
• Primary measurements:
In this case the sought value of a parameter is
determined by comparing it directly with
reference standard. This type of measurement is
called primary measurements.
Example:
• Measuring the length of a line with a scale.
• Judging the weight of unknown mass.
• Matching of two colours and light intensities
40. Types of Measurements
• Secondary measurements:
This type of measurements involves one conversion since
the measured quantity is not observable (like the
temperature of fluid). It is necessary to make indirect
comparison using the calibrated system. The following
requirements are satisfied by this method.
a) It should be converted temperature changes into length
changes.
b) A length scale calibrated interms of known changes in
temperature.
Example:
In a mercury thermometer the primary signal
(temperature) is transmitted to a transducer (mercury)
and the secondary signal (length) is read by observer)
41. Types of Measurements
• Tertiary measurements:
This type of measurements involves two
conversion. This measurements involves the
conversion of the measured quantity into another
quantity which is again converted into length and
thus involves two conversion of the quantity to
be measured. Measurement of temperature by
thermocouple is an example of this type of
measurements.
42. Types of Measurements
• Tertiary measurements:
• The primary signal is sensed by the transducer which
generates a voltage directly proportional to the
temperature difference. It is the first conversion
(temperature into voltage). This voltage is then
converted into length (second conversion) by means
of suitable meter which is transmitted to observer’s
eye.
43. Types of instruments
• An instrument is a device for measuring the
values or magnitude of a quantity or variable.
1. Mechanical instruments
2. Electrical instruments
3. Electronic instruments
44. Types of instruments
• Mechanical instruments:
The mechanical instruments were the first
instruments in nature and the principles on which
they worked are even used today.
Advantage:
These instruments are very reliable for static and
stable operation.
Disadvantages:
1. It is unable to response rapidly to measurement of
dynamic and transient conditions. This is because of
the rigid, heavy and bulk moving parts and
consequently have a large mass.
2. These instruments are potential source of noise and
hence cause pollution of silence.
45. Types of instruments
• Electrical instruments:
These instruments are more rapid in indicating
the output of detector than mechanical
instruments. Unfortunately electrical
instruments have to depend on mechanical
instruments (i.e., meter) as indicating device.
Since mechanical instruments have some inertia,
they have limited time and hence frequency
response.
46. Types of instruments
Electronic Instruments:
• The requirements to step up response time and also the
direction of dynamic changes in certain parameters,
requires the monitoring time of the order of milliseconds
and quite often microseconds, have led to the development
of electronic instruments.
• For example a CRO can follow dynamic and transient
changes of the order of nanoseconds
• Advantages:
1. More reliable, Light weight, compact, very fast response,
power consumption is very low
• Disadvantages:
1. High cost
2. Complex circuit
48. Classification of Instruments
• Absolute instruments:
It measures the quantity in terms of physical
constants of the instruments. Use of these
instruments is time consuming since every time a
measurement is made, it takes lot of time to
complete the magnitude of measurand.
Examples of absolute instruments are:
1. Tangent galvanometer.
2. Rayleigh’s current balance.
49. Classification of Instruments
• Secondary instruments:
This type of instruments are designed in such a
manner that measurand can be measured by
observing the output indicated by the instrument.
The examples of secondary instruments are
voltmeter, ammeter, glass thermometer and
pressure gauge etc.
Secondary instruments are mainly used in every
sphere of measurement while absolute
instruments are rarely used for examples in
standard institutions.
51. Functional classification of instruments
Indicating instruments:
• These instruments indicate the magnitude of
the quantity being measured, with the help of
dial and pointer. The moving system of such
an instrument is filled with a pointer that
moves over a calibrated scale to indicate the
reading. Examples of this instruments are
voltmeter, ammeters, wattmeter's etc.
52. Functional classification of instruments
Recording instruments:
• They give a continuous record of the quantity
being measured over a specified period. The
moving part connected to a pen, records the
variation in the quantity being measured on a
paper (e.g. X-Y recorders).
53. Functional classification of instruments
Controlling instruments:
• In these instruments, the information is used
by the instruments to control the original
measured quantity. For example thermostat
for temperature control and floats for liquid
level control.
54. Classification of analog instruments
• Direct current instrument
• Alternating current instrument
• Universal instruments ( both DC and AC measurements)
some other classification
• Indicating instrument
• Recording instrument
• Integrating instrument
24-Dec-20 54
55. Principles of operation of analog
instruments
• Magnetic effect
• Thermal effect
• Electrostatic effect
• Induction effect
• Hall effect
24-Dec-20 55
56. • Force of Attraction or Repulsion ( Moving iron instruments)
• Force between a current carrying coil and a permanent
magnet (moving coil instruments)
• Force between two current carrying coil (dynamometer
type instruments)
24-Dec-20 56
57. Operating forces needed for indicating
instruments
• Deflecting force
• Controlling force
• Damping force
24-Dec-20 57
58. Operating system
• Deflecting system
The system or device which produces
deflecting force to move the pointer from it
zero position is known as deflecting system.
The effects used to produce deflecting force
are
1. Magnetic effect – generally for ammeter and
voltmeter
24-Dec-20 58
59. 2.Heating effect – for ammeters and voltmeters
3.Electrodynamic effect – for ammeter,
voltmeters and wattmeters
4.Chemical effect – for DC ampere hour meters
5.Electromagnetic effect – for ammeters,
voltmeters, wattmeters and watthour meter
6 . Electrostatic effect – for voltmeters only
24-Dec-20 59
60. • Controlling system
The system that produces a force equal and
opposite to deflecting force. Controlling forces
are applied in two ways
1. Spring control (used in modern instruments)
2. Gravity control ( not popularly used)
24-Dec-20 60
61. Spring control
• A hair spring attached to the moving system
produces a controlling torque.
• Requirements for spring are
1. They should be non-magnetic (phosphor bronze)
2. They should be free from mechanical fatigue
3. They should have a small resistance, where
springs are used to lead the current into
moving system.
24-Dec-20 61
69. Permanent Magnet Moving Coil
Instruments (PMMC)
• Operating principle
• When a current carrying conductor is placed in a magnetic field, a force
acts upon the conductor which tends to move it.
• If the strength of the magnetic field is constant, force exerted on the
conductor will be proportional to the current carried by it.
• Hence deflecting force will be proportional to the current to be measured.
Deflecting torque = N.B.A.I
= K.I
Where,
K = NBA – constant
I – current flowing through the meter
N – No. of turns in the coil
B – flux density in wb/m2
A – Area of the coil in m2
24-Dec-20 69
70. • Controlling Torque is provided by spiral
springs. This Torque is proportional to the
angular deflection.
T c = Cθ
T c = controlling torque
C = spring constant
θ = angular deflection
• For steady state deflection
KI = C θ
θ = KI/C
current I = (C/K) θ
24-Dec-20 70
73. Advantages of moving coil Instruments
• The scale is uniform
• The power consumption is very low as 20μW to 200 μW
• The torque/weight ratio is high which gives a high accuracy
( 2% of full scale deflection)
• A single instrument can be used for many different current,
voltage ranges
• Errors due to stray magnetic fields are small, because of the
large operating forces
24-Dec-20 73
74. Disadvantages of moving coil
Instruments
• These instruments are useful only for DC. If
the instrument is used in AC, the deflecting
torque reverses when the current reverses;
the pointer cannot follow such rapid reversals
• The cost of the moving coil instrument is
higher than that of moving iron instrument
24-Dec-20 74
75. Errors in PMMC instruments
The main sources of errors are due to
• Weakening of permanent magnet due to
ageing and temperature effect
• Weakening of springs due to ageing and
temperature effect
• Change of moving coil with temperature
24-Dec-20 75
76. Applications of the PMMC instrument
• These instruments can be used as voltmeter
and ammeter with multiranges
• Self shielding magnets make the core magnet
mechanism particularly useful in aircrafts and
other aerospace applications where more
number of instruments are mounted in one
case to form a unified display. Thereby
considerable amount of weight is reduced.
24-Dec-20 76
77. Moving iron instrument
• The most common ammeter and voltmeter
are the moving iron instrument. These type of
instruments are generally used for laboratory
or switch-board power frequencies.
• There are two types of MI instruments
1. Attraction type
2. Repulsion type
24-Dec-20 77
79. Repulsion type
• In this type of MI instrument, there are two
vanes inside the coil. These vanes are similarly
magnetized when the current flows through
the coil and there is a force of repulsion
between the two vanes resulting in the
movement of moving vane.
• There are two types of vanes
1. Radial vane type
2. Co-axial vane type
24-Dec-20 79
82. Torque equation
• Expression for the torque of a moving iron instrument can be
derived by considering a small increment in the current, di supplied
to the coil in the instrument. Because of this, there will be a small
deflection, 𝑑Ө and some mechanical work will be done. If 𝑇𝑑 is the
deflection torque, then
• Mechanical work done = 𝑇𝑑 .𝑑Ө
• As the vane tries to occupy the position of minimum reluctance
either by the principle as in repulsion type instrument, there will be
a change in the energy stored in the magnetic field due to the change
in inductance.
• Let I = initial current in A
L = Instrument inductance in H
Ө = deflection in radians
dI = increase in current in A
dL= change in inductance in H
24-Dec-20 82
83. Torque equation
• If the current increases by dI, the deflection
changes by dӨ which changes the inductance by
dL. In order to increase the current by dI, there
must be an increase in the applied voltage given
by e =
𝑑
𝑑𝑡
(LI)
Since , both L and I are variables,
e = I
𝑑𝐿
𝑑𝑡
+ L
𝑑𝐼
𝑑𝑡
Where, e is the applied voltage.
Electrical energy supplied is given by
24-Dec-20 83
84. Torque equation
eI dt = 𝐼
𝑑𝐿
𝑑𝑡
+ L
𝑑𝐼
𝑑𝑡
𝐼 𝑑𝑡
eI dt = 𝐼2 𝑑𝐿 + 𝐿𝐼 𝑑𝐼
The stored energy due to inductance changes from
1
2
𝐿𝐼2
𝑡𝑜
1
2
(L + dL) (𝐼 + 𝑑𝐼)2
Hence, change in stored energy
1
2
(𝐿 + 𝑑𝐿)(𝐼2 + 2𝐼 𝑑𝐼 + (𝑑𝐼2) −
1
2
𝐼2 𝐿
=
1
2
𝐼2 𝐿 + 𝐼𝐿 𝑑𝐼 +
1
2
L (𝑑𝐼)2 +
1
2
𝐼2 𝑑𝐿 + IdIdL +
1
2
(𝑑𝐼)2dL -
1
2
𝐼2L
Neglecting the higher order terms,
Change in stored energy = 𝐼𝐿 𝑑𝐼 +
1
2
𝐼2 𝑑𝐿
24-Dec-20 84
85. Torque equation
From the principle of conversion of energy
Electrical energy supplied = change in stored energy + Mechanical
work done
𝐼2 𝑑𝐿 + 𝐼𝐿 𝑑𝐼 = 𝐼𝐿 𝑑𝐼 + +
1
2
𝐼2 𝑑𝐿 + 𝑇𝑑 𝑑Ө
𝑇𝑑 𝑑Ө =
1
2
𝐼2 𝑑𝐿
𝑇𝑑 =
1
2
𝐼2 𝒅𝑳
𝒅Ө
Where, Td is the deflecting torque in N-m.
I is the current through the coil in A.
Controlling torque, 𝑻 𝒅 = 𝑲 𝑺 𝜽 𝒊𝒏 𝑁 − 𝑀
Where Ks = control spring constant in N-M/rad.
Ө = deflection in radians.
24-Dec-20 85
86. Torque equation
At equilibrium, 𝑇𝑐 = 𝑇𝑑
𝐾𝑆 𝜃 =
1
2
𝐼2 𝑑𝐿
𝑑𝜃
𝜃 =
1
2
𝐼2
𝐾 𝑆
𝑑𝐿
𝑑Ө
𝜃α𝐼2
From above equation, we can infer that the
deflection of pointer is directly proportional to the
square of the current to be measured. Hence the
deflection torque is unidirectional whatever may
be the polarity of the current. Hence, the moving
iron instruments can be used for both AC and DC.
24-Dec-20 86
87. Errors in MI instruments
• Errors with both DC and AC
1. Hysteresis error
2. Temperature error
3. Stray magnetic fields
• Errors with AC only
1. Frequency errors
24-Dec-20 87
88. Advantages of MI instruments
• Universal instruments
• Less friction errors
• Less cost
• Robustness
• Accuracy
24-Dec-20 88
89. Disadvantages of MI instruments
• Due to hysteresis effect, an appreciable error
in DC measurements
• The scale of MI instruments is not uniform
and is compared at the lower end and
therefore readings are inaccurate at this end
• The instruments are subjected to serious
errors due to frequency changes, hysteresis
and stray magnetic effects
24-Dec-20 89
90. Applications of MI instruments
• Used in multiranges ammeter and voltmeter
• Used as inexpensive indicators such as
charging and discharging current indicators in
automobiles
• Extensively used in industries for
measurement of AC voltage and current
where errors of the order of 5% to 10% are
acceptable.
24-Dec-20 90
91. Wattmeter
• Types of wattmeter
1. Dynamometer type wattmeter
2. Induction type wattmeter
3. Electrostatic type wattmeter
24-Dec-20 91
96. Disadvantages of dynamometer type
instruments
Dynamometer ammeters and voltmeters are not in
common use, especially in DC circuits, due to
following reasons.
• The magnetic field strength obtainable is small,
owing to the absence of iron. This means that a large
number of ampere turns must be used
• The scale is not uniform, since the deflecting torque
varies as the square of the current (T α I2).
• Such instruments are more expensive than the
permanent magnet type ammeter and voltmeter.
24-Dec-20 96
97. Power measurements in single phase AC circuits
using dynamometer type wattmeter
24-Dec-20 97
99. Principle:
The operation of the energy meter is based on
the passage of alternating current through
two coils (current coil and pressure coil). This
coils produce the rotating magnetic field
which interacts with a aluminium disc
suspended near to the coils and makes the
disc rotates.
24-Dec-20 99
100. Construction
• A single phase induction type energy meter
consists of
1. Moving system
2. Operating mechanism
3. Recording mechanism
24-Dec-20 100
101. Advantages of induction type energy meter
• Simple in operation
• High torque/weight ratio
• Unaffected by temperature variations
24-Dec-20 101