These study materials are designed for undergraduate students of electrical engineering and
computing to complement the coursebook that is studied in class. We try to supply students
with additional texts and exercises believing that a larger language, especially lexical, input
can be nothing but useful for their further education.
The scope of this electrical installation handbook is to provide the designer and
user of electrical plants with a quick reference, immediate-use working tool.
This is not intended to be a theoretical document, nor a technical catalogue,
but, in addition to the latter, aims to be of help in the correct definition of
equipment, in numerous practical installation situations.
semiconductors.In the first category are substances which provide an easy path for an electric current. All metals are conductors, however some metals do not conduct well. Manganin, for example, is a poor conductor. Copper is a good conductor, therefore it is widely used for cables. A non-metal which conducts well is carbon. Salt water is an example of a liquid conductor.
A material which does not easily release electrons is called an insulator. Rubber, nylon, porcelain and air are all insulator. There are no perfect insulators.
Electricity is an invisible force that is used to transfer
energy into heat, light, intelligence, or motion. Electricity
is explained in terms of electrical charge, potential differ-
ence (or voltage), electrical charge flow (or current), and
resistance to current flow. Figure 1-1 graphically illus-
trates electron flow through a conductor by comparing it
with water flow through a pipe. The normal unit of current
measurement is the ampere, whereas the normal unit of
voltage measurement is the volt. The unit of opposition to
current flow, or resistance, is the ohm...
1.1 The balance of charges on conductors:
In conductors there are charged particles which can be freely
move under any small force. Therefore the balance of charges on
conductors can be observed under these circumstances:
The electric field equals zero everywhere inside the conductor
E = 0
The electric potential is constant inside the conductor
V = const
The electric field vector on the surface of conductors direct along the
normal of the surface at each point
E = En
The surface of conductors is equipotential
Inside conductors there is no charge.
4.1 Concept of Energy Transmission and Distribution 4.2 Transmission Line Structures Joe C. Pohlman George G. Karady 4.3 Insulators and Accessories George G. Karady and R.G. Farmer 4.4 Transmission Line Construction and Maintenance Wilford Caulkins and Kristine Buchholz 4.5 Insulated Power Cables for High-Voltage Applications Carlos V. Núñez-Noriega and Felimón Hernandez 4.6 Transmission Line Parameters Manuel Reta-Hernández 4.7 Sag and Tension of Conductor D.A. Douglass and Ridley Thrash
4.8 Corona and Noise Giao N. Trinh 4.
The invention of scanning tunneling microscope (STM) by Binnig and his colleagues in
1982 opened up the possibility of imaging material surfaces with spatial resolution much
superior to the conventional microscopy techniques. The STM is the first instrument
capable of directly obtaining three-dimensional images of solid surfaces with atomic
resolution. Even though STM is capable of achieving atomic resolution, it can only be
used on electrical conductors. This limitation has led to the invention of atomic force
microscope (AFM) by Binnig and his co-workers in 1986.
A semiconductor material has a resistivity lying between that of a conductor and that of an
insulator. However, in contrast to the granular materials used for resistors, a semiconductor
establishes its conduction properties through a complex quantum mechanical behavior within
a periodic array of semiconductor atoms, i.e., within a crystalline structure.
Any electromagnetic phenomenon capable of impairing the performance of a device, equipment or system, etc.
An electromagnetic disturbance can be electromagnetic noise, an unwanted signal or a change in the
propagation medium itself.
If each voltage is connected to a circuit with the same power factor and the three currents return along the
same conductor, then the vector sum of the three return currents is zero. Thus instead of three full sized
return cables, only one of smaller size is needed. If none of the load is single phase, then the neutral is not
needed at all. High voltage supplies are nearly always three phase without a neutral conductor. There is a
great economy in distribution costs if the electricity can be supplied in three phases. ...
Technology is often a consequence of science and engineering — although technology as a human activity precedes the two fields. For example, science might study the flow of electrons in electrical conductors, by using already-existing tools and knowledge. This new-found knowledge may then be used by engineers to create new tools and machines, such as semiconductors, computers, and other forms of advanced technology. In this sense, scientists and engineers may both be considered technologists; the three fields are often considered as one for the purposes of research and reference....
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Developing a theoretical relationship between electrical resistivity, temperature, and film thickness for conductors
Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí sinh học đề tài : Developing a theoretical relationship between electrical resistivity, temperature, and film thickness for conductors
Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Developing a theoretical relationship between electrical resistivity, temperature, and film thickness for conductors
If we connect a battery across a body, there is a movement of free electrons towards the positive end. This movement of electrons is an electric current. All materials can be classified into three groups according to how readily they permit an electric current to flow. These are: conductors, insulators, and semiconductors.
In the first category are substances which provide an easy path for an electric current. All metals are conductors, however some metals do not conduct well. Manganin, for example, is a poor conductor. Copper is a good conductor, therefore it is widely used for cables.
The age of electricity began with the work of Hans
ChristianOersted (1777-1851), whodemonstratedin 1819 that a current-caving conductor could produce a magnetic field. This was the first time that a relationship between electricity and magnetism had been established. Oersted’s work started a chain of experiments across Europe that culminated in the discovery of electromagnetic induction by Michael Faraday (1791-1867) in 1831.
Power Quality Considerations
Harmonics • What Are Harmonics? • Harmonic Sequence • Where Do Harmonics Come From? • Effects of Harmonics on the System Voltage • Notching • Effects of Harmonics on Power System Components • Conductors • Three-Phase Neutral Conductors • Transformers • Effects of Harmonics on System Power Factor • Power Factor Correction Capacitors • IEEE Standard 519
Badrul H. Chowdhury
University of Missouri–Rolla
Tokyo Institute of Technology
Arizona State University
A lightning rod (AUS) or lightning conductor (UK) is a metal rod or conductor mounted on top of a building and electrically connected to the ground through a wire, to protect the building in the event of lightning. If lightning strikes the building it will preferentially strike the rod, and be conducted harmlessly to ground through the wire, instead of passing through the building, where it could start a fire or cause electrocution. A lightning rod is a single component in a lightning protection system. ...
AC motors convert AC electrical energy to Mechanical energy. AC motors:
the armature of rotor is a magnet (different to DC motors).
the stator is formed by electromagnets (like in DC motors). Effects of AC Supply on Magnetic Poles Consider the rotor to be a permanent magnet.
Current flowing through conductors energize the magnets and develop N and S poles.
The strength of electromagnets depends on current.
First half cycle current flows in one direction.
Second half cycle it flows in opposite direction...
We have known how can describe the electric field in vacuum.
How is the electric field in a matter environment?
In this chapter we consider the case that the environment is a
Recall that in a conducting body (conductor) the charges move freely in
respond to an electric field, but in nonconducting bodies the charges can
not move freely.
Nonconducting bodies are called dielectrics or insulators.