Electrical engineering
Electrical engineers design complex power systems ...
... and electronic circuits.
Electrical engineering is a field of
engineering that generally deals with the study and application of
electricity,
electronics, and
electromagnetism.
This field first became an identifiable occupation in the latter half
of the 19th century after commercialization of the electric
telegraph, the
telephone, and
electric power distribution and use. Subsequently,
broadcasting and
recording media made electronics part of daily life. The invention of the
transistor and, subsequently, the
integrated circuit brought down the cost of electronics to the point where they can be used in almost any household object. The
personal computer and
information technology are the most complex electronics yet to be used in everyday life.
Electrical engineering has now subdivided into a wide range of subfields including
electronics,
digital computers,
power engineering,
telecommunications,
control systems,
RF engineering,
signal processing,
instrumentation, and
microelectronics. The subject of
electronic engineering is often treated as its own subfield but it intersects with all the other subfields, including the
power electronics of power engineering.
Electrical engineers typically hold a
degree in electrical engineering or electronic engineering. Practicing engineers may have
professional certification and be members of a
professional body. Such bodies include the
Institute of Electrical and Electronic Engineers (IEEE) and the
Institution of Engineering and Technology (IET).
Electrical engineers work in a very wide range of industries and the
skills required are likewise variable. These range from basic circuit
theory to the management skills required of
project manager. The tools and equipment that an individual engineer may need are similarly variable, ranging from a simple
voltmeter to a top end analyzer to sophisticated design and manufacturing software.
History
The discoveries of
Michael Faraday formed the foundation of electric motor technology.
Electricity has been a subject of scientific interest since at least the early 17th century. The first electrical engineer was probably
William Gilbert who designed the
versorium:
a device that detected the presence of statically charged objects. He
was also the first to draw a clear distinction between magnetism and
static electricity and is credited with establishing the term
electricity. In 1775
Alessandro Volta's scientific experimentations devised the
electrophorus, a device that produced a static electric charge, and by 1800 Volta developed the
voltaic pile, a forerunner of the electric battery.
19th century
However, it was not until the 19th century that research into the
subject started to intensify. Notable developments in this century
include the work of
Georg Ohm, who in 1827 quantified the relationship between the
electric current and
potential difference in a
conductor,
Michael Faraday, the discoverer of
electromagnetic induction in 1831, and
James Clerk Maxwell, who in 1873 published a unified
theory of electricity and
magnetism in his treatise
Electricity and Magnetism.
Beginning in the 1830s, efforts were made to apply electricity to practical use in the
telegraph.
By the end of the 19th century the world had been forever changed by
the rapid communication made possible by engineering development of
land-lines,
submarine cables, and, from about 1890,
wireless telegraphy.
Practical applications and advances in such fields created an
increasing need for standardized units of measure. They led to the
international standardization of the units
volt,
ampere,
coulomb,
ohm,
farad, and
henry. This was achieved at an international conference in Chicago 1893.
The publication of these standards formed the basis of future advances
in standardisation in various industries, and in many countries the
definitions were immediately recognised in relevant legislation.
Thomas Edison built the world's first large-scale electrical supply network.
During these years, the study of electricity was largely considered to be a subfield of
physics. It was not until about 1885 that
universities and
institutes of technology such as
Massachusetts Institute of Technology (MIT) and
Cornell University started to offer
bachelor's degrees in electrical engineering. The
Darmstadt University of Technology
founded the first department of electrical engineering in the world in
1882. In that same year, under Professor Charles Cross at MIT began
offering the first option of electrical engineering within its
physics department. In 1883,
Darmstadt University of Technology
and Cornell University introduced the world's first bachelor's degree
courses of study in electrical engineering, and in 1885 the
University College London founded the first chair of electrical engineering in
Great Britain.
[7] The
University of Missouri established the first department of electrical engineering in the United States in 1886. Several other schools soon followed suit, including Cornell and the
Georgia School of Technology in
Atlanta, Georgia.
During these decades use of electrical engineering increased dramatically. In 1882,
Thomas Edison switched on the world's first large-scale electric power network that provided 110 volts —
direct current (DC) — to 59 customers on
Manhattan Island in
New York City. In 1884,
Sir Charles Parsons invented the
steam turbine.
Turbines now provide the mechanical power for about 80 percent of the
electric power in the world using a variety of heat sources. The
alternating current power system developed rapidly after 1886 with efficient, practical,
transformer and
AC motor designs, including
induction motors independently invented by
Galileo Ferraris and
Nikola Tesla and further developed into a practical
three-phase form by
Mikhail Dolivo-Dobrovolsky and
Charles Eugene Lancelot Brown. AC had the ability to transmit power more efficiently over long distances via the use of
transformers to increase and decrease voltages (not possible with DC). The spread in the use of AC set off what has been called the
War of Currents between the backers of AC and DC based power systems, with AC being adopted as the overall standard.
More modern developments
During the
development of radio, many scientists and
inventors contributed to
radio technology and electronics. In his classic physics experiments of 1888,
Heinrich Hertz transmitted
radio waves with a
spark-gap transmitter, and detected them by using simple electrical devices. The mathematical work of
James Clerk Maxwell during the 1850s had shown the possibility of radio waves but
Heinrich Hertz was the first to demonstrate their existence in 1888.
In 1897,
Karl Ferdinand Braun introduced the
cathode ray tube as part of an
oscilloscope, a crucial enabling technology for
electronic television.
John Fleming invented the first radio tube, the
diode, in 1904. Two years later,
Robert von Lieben and
Lee De Forest independently developed the amplifier tube, called the
triode. In 1895,
Guglielmo Marconi
furthered the art of hertzian wireless methods. Early on, he sent
wireless signals over a distance of one and a half miles. In December
1901, he sent wireless waves that were not affected by the curvature of
the Earth. Marconi later transmitted the wireless signals across the
Atlantic between Poldhu, Cornwall, and St. John's, Newfoundland, a
distance of 2,100 miles (3,400 km).
[13] In 1920
Albert Hull developed the
magnetron which would eventually lead to the development of the
microwave oven in 1946 by
Percy Spencer.
[14][15] In 1934 the British military began to make strides toward
radar (which also uses the magnetron) under the direction of Dr Wimperis, culminating in the operation of the first radar station at
Bawdsey in August 1936.
[16]
In 1941
Konrad Zuse presented the
Z3, the world's first fully functional and programmable computer using electromechanical parts. In 1943
Tommy Flowers designed and built the
Colossus, the world's first fully functional, electronic, digital and programmable computer.
[17] In 1946 the
ENIAC (Electronic Numerical Integrator and Computer) of
John Presper Eckert and
John Mauchly
followed, beginning the computing era. The arithmetic performance of
these machines allowed engineers to develop completely new technologies
and achieve new objectives, including the
Apollo program which culminated in
landing astronauts on the Moon.
[18]
Solid-state transistors
The invention of the
transistor in late 1947 by
William B. Shockley,
John Bardeen, and
Walter Brattain of the
Bell Telephone Laboratories opened the door for more compact devices and led to the development of the
integrated circuit in 1958 by
Jack Kilby and independently in 1959 by
Robert Noyce.
[19] Starting in 1968,
Ted Hoff and a team at the
Intel Corporation invented the first commercial
microprocessor, which foreshadowed the
personal computer. The
Intel 4004 was a four-bit processor released in 1971, but in 1973 the
Intel 8080, an eight-bit processor, made the first personal computer, the
Altair 8800, possible.
[20]
Subdisciplines
Electrical engineering has many subdisciplines, the most common of
which are listed below. Although there are electrical engineers who
focus exclusively on one of these subdisciplines, many deal with a
combination of them. Sometimes certain fields, such as electronic
engineering and
computer engineering, are considered separate disciplines in their own right.
Power
Power engineering deals with the
generation,
transmission and
distribution of
electricity as well as the design of a range of related devices. These include
transformers,
electric generators,
electric motors, high voltage engineering, and
power electronics. In many regions of the world, governments maintain an electrical network called a
power grid
that connects a variety of generators together with users of their
energy. Users purchase electrical energy from the grid, avoiding the
costly exercise of having to generate their own. Power engineers may
work on the design and maintenance of the power grid as well as the
power systems that connect to it.
[22] Such systems are called
on-grid
power systems and may supply the grid with additional power, draw power
from the grid or do both. Power engineers may also work on systems that
do not connect to the grid, called
off-grid power systems, which
in some cases are preferable to on-grid systems. The future includes
Satellite controlled power systems, with feedback in real time to
prevent power surges and prevent blackouts.
Control
Control engineering focuses on the
modeling of a diverse range of
dynamic systems and the design of
controllers that will cause these systems to behave in the desired manner. To implement such controllers electrical engineers may use
electrical circuits,
digital signal processors,
microcontrollers and
PLCs (Programmable Logic Controllers).
Control engineering has a wide range of applications from the flight and propulsion systems of
commercial airliners to the
cruise control present in many modern
automobiles. It also plays an important role in
industrial automation.
Control engineers often utilize
feedback when designing
control systems. For example, in an
automobile with
cruise control the vehicle's
speed is continuously monitored and fed back to the system which adjusts the
motor's power output accordingly. Where there is regular feedback,
control theory can be used to determine how the system responds to such feedback.
Electronics
Electronic engineering involves the design and testing of
electronic circuits that use the properties of
components such as
resistors,
capacitors,
inductors,
diodes and
transistors to achieve a particular functionality.
[22] The
tuned circuit, which allows the user of a
radio to
filter
out all but a single station, is just one example of such a circuit.
Another example (of a pneumatic signal conditioner) is shown in the
adjacent photograph.
Prior to the Second World War, the subject was commonly known as
radio engineering and basically was restricted to aspects of communications and
radar,
commercial radio and
early television.
[22]
Later, in post war years, as consumer devices began to be developed,
the field grew to include modern television, audio systems,
computers and
microprocessors. In the mid-to-late 1950s, the term
radio engineering gradually gave way to the name
electronic engineering.
Before the invention of the
integrated circuit in 1959,
electronic circuits were constructed from discrete components that
could be manipulated by humans. These discrete circuits consumed much
space and
power and were limited in speed, although they are still common in some applications. By contrast,
integrated circuits packed a large number—often millions—of tiny electrical components, mainly
transistors, into a small chip around the size of a
coin. This allowed for the powerful
computers and other electronic devices we see today.
Microelectronics
Microelectronics engineering deals with the design and
microfabrication of very small electronic circuit components for use in an
integrated circuit or sometimes for use on their own as a general electronic component. The most common microelectronic components are
semiconductor transistors, although all main electronic components (
resistors,
capacitors etc.) can be created at a microscopic level.
Nanoelectronics is the further scaling of devices down to
nanometer levels. Modern devices are already in the nanometer regime, with below 100 nm processing having been standard since about 2002.
Microelectronic components are created by chemically fabricating
wafers of semiconductors such as silicon (at higher frequencies,
compound semiconductors
like gallium arsenide and indium phosphide) to obtain the desired
transport of electronic charge and control of current. The field of
microelectronics involves a significant amount of chemistry and material
science and requires the electronic engineer working in the field to
have a very good working knowledge of the effects of
quantum mechanics.
Signal processing
A
Bayer filter on a
CCD requires signal processing to get a red, green, and blue value at each pixel.
Signal processing deals with the analysis and manipulation of
signals. Signals can be either
analog, in which case the signal varies continuously according to the information, or
digital,
in which case the signal varies according to a series of discrete
values representing the information. For analog signals, signal
processing may involve the
amplification and
filtering of audio signals for audio equipment or the
modulation and
demodulation of signals for
telecommunications. For digital signals, signal processing may involve the
compression,
error detection and
error correction of digitally sampled signals.
Signal Processing is a very mathematically oriented and intensive area forming the core of
digital signal processing
and it is rapidly expanding with new applications in every field of
electrical engineering such as communications, control, radar,
audio engineering,
broadcast engineering,
power electronics and bio-medical engineering as many already existing
analog systems are replaced with their digital counterparts.
Analog signal processing is still important in the design of many
control systems.
DSP processor ICs are found in every type of modern electronic systems and products including,
SDTV |
HDTV sets,
[33] radios and mobile communication devices,
Hi-Fi audio equipment,
Dolby noise reduction algorithms,
GSM mobile phones,
mp3 multimedia players, camcorders and digital cameras, automobile control systems,
noise cancelling headphones, digital
spectrum analyzers, intelligent missile guidance,
radar,
GPS based cruise control systems and all kinds of
image processing,
video processing,
audio processing and
speech processing systems.
Telecommunications
Satellite dishes are a crucial component in the analysis of satellite information.
Telecommunications engineering focuses on the
transmission of
information across a
channel such as a
coax cable,
optical fiber or
free space. Transmissions across free space require information to be encoded in a
carrier wave to shift the information to a carrier frequency suitable for transmission, this is known as
modulation. Popular analog modulation techniques include
amplitude modulation and
frequency modulation.
[36]
The choice of modulation affects the cost and performance of a system
and these two factors must be balanced carefully by the engineer.
Once the transmission characteristics of a system are determined, telecommunication engineers design the
transmitters and
receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a
transceiver. A key consideration in the design of transmitters is their
power consumption as this is closely related to their
signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by
noise.
Instrumentation
Instrumentation engineering deals with the design of devices to measure physical quantities such as
pressure,
flow and
temperature. The design of such instrumentation requires a good understanding of
physics that often extends beyond
electromagnetic theory. For example,
flight instruments measure variables such as
wind speed and
altitude to enable pilots the control of aircraft analytically. Similarly,
thermocouples use the
Peltier-Seebeck effect to measure the temperature difference between two points.
Often instrumentation is not used by itself, but instead as the
sensors
of larger electrical systems. For example, a thermocouple might be used
to help ensure a furnace's temperature remains constant.
[41] For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
Computers
Computer engineering deals with the design of
computers and
computer systems. This may involve the design of new
hardware, the design of
PDAs, tablets and
supercomputers or the use of computers to control an
industrial plant. Computer engineers may also work on a system's
software. However, the design of complex software systems is often the domain of
software engineering, which is usually considered a separate discipline.
Desktop computers
represent a tiny fraction of the devices a computer engineer might work
on, as computer-like architectures are now found in a range of devices
including
video game consoles and
DVD players.
Related disciplines
Mechatronics is an engineering discipline which deals with the convergence of electrical and
mechanical systems. Such combined systems are known as
electromechanical systems and have widespread adoption. Examples include
automated manufacturing systems,
heating, ventilation and air-conditioning systems and various subsystems of
aircraft and
automobiles.
The term
mechatronics is typically used to refer to
macroscopic systems but
futurists have predicted the emergence of very small electromechanical devices. Already such small devices, known as
Microelectromechanical systems (MEMS), are used in automobiles to tell
airbags when to deploy, in
digital projectors to create sharper images and in
inkjet printers
to create nozzles for high definition printing. In the future it is
hoped the devices will help build tiny implantable medical devices and
improve
optical communication.
Biomedical engineering is another related discipline, concerned with the design of
medical equipment. This includes fixed equipment such as
ventilators,
MRI scanners and
electrocardiograph monitors as well as mobile equipment such as
cochlear implants,
artificial pacemakers and
artificial hearts.
Education
Electrical engineers typically possess an
academic degree with a major in electrical engineering,
electronics engineering, or electrical and electronic engineering.
[51]
The same fundamental principles are taught in all programs, though
emphasis may vary according to title. The length of study for such a
degree is usually four or five years and the completed degree may be
designated as a
Bachelor of Engineering,
Bachelor of Science,
Bachelor of Technology, or
Bachelor of Applied Science depending on the university. The
bachelor's degree generally includes units covering
physics,
mathematics,
computer science,
project management, and a
variety of topics in electrical engineering.
[52]
Initially such topics cover most, if not all, of the subdisciplines of
electrical engineering. At some schools, the students can then choose to
emphasize one or more subdisciplines towards the end of their courses
of study. At many schools, electronic engineering is included as part of
an electrical award, sometimes explicitly, such as a Bachelor of
Engineering (Electrical and Electronic), but in others electrical and
electronic engineering are both considered to be sufficiently broad and
complex that separate degrees are offered.
[53]
Some electrical engineers choose to study for a postgraduate degree such as a
Master of Engineering/
Master of Science (M.Eng./M.Sc.), a Master of
Engineering Management, a
Doctor of Philosophy (Ph.D.) in Engineering, an
Engineering Doctorate (Eng.D.), or an
Engineer's degree. The master's and engineer's degrees may consist of either
research,
coursework
or a mixture of the two. The Doctor of Philosophy and Engineering
Doctorate degrees consist of a significant research component and are
often viewed as the entry point to
academia.
In the United Kingdom and some other European countries, Master of
Engineering is often considered to be an undergraduate degree of
slightly longer duration than the Bachelor of Engineering rather than
postgraduate.
[54]
Practicing engineers
Belgian electrical engineers inspecting the rotor of a 40,000 kilowatt turbine of the
General Electric Company in New York City
In most countries, a Bachelor's degree in engineering represents the first step towards
professional certification and the degree program itself is certified by a
professional body.
[55]
After completing a certified degree program the engineer must satisfy a
range of requirements (including work experience requirements) before
being certified. Once certified the engineer is designated the title of
Professional Engineer (in the United States, Canada and South Africa),
Chartered Engineer or
Incorporated Engineer (in India, Pakistan, the United Kingdom, Ireland and
Zimbabwe), Chartered Professional Engineer (in Australia and New Zealand) or
European Engineer (in much of the
European Union).
The advantages of certification vary depending upon location. For
example, in the United States and Canada "only a licensed engineer may
seal engineering work for public and private clients".
[56] This requirement is enforced by state and provincial legislation such as
Quebec's Engineers Act.
[57] In other countries, no such legislation exists. Practically all certifying bodies maintain a
code of ethics that they expect all members to abide by or risk expulsion.
[58]
In this way these organizations play an important role in maintaining
ethical standards for the profession. Even in jurisdictions where
certification has little or no legal bearing on work, engineers are
subject to
contract law. In cases where an engineer's work fails he or she may be subject to the
tort of negligence and, in extreme cases, the charge of
criminal negligence. An engineer's work must also comply with numerous other rules and regulations such as
building codes and legislation pertaining to
environmental law.
Professional bodies of note for electrical engineers include the
Institute of Electrical and Electronics Engineers (IEEE) and the
Institution of Engineering and Technology
(IET). The IEEE claims to produce 30% of the world's literature in
electrical engineering, has over 360,000 members worldwide and holds
over 3,000 conferences annually.
[59]
The IET publishes 21 journals, has a worldwide membership of over
150,000, and claims to be the largest professional engineering society
in Europe.
[60][61]
Obsolescence of technical skills is a serious concern for electrical
engineers. Membership and participation in technical societies, regular
reviews of periodicals in the field and a habit of continued learning
are therefore essential to maintaining proficiency. MIET(Member of the
Institution of Engineering and Technology) is recognised in Europe as
Electrical and computer (technology) engineer.
[62]
In Australia, Canada and the United States electrical engineers make up around 0.25% of the labor force (see
note).
Outside of Europe and North America, engineering graduates per-capita,
and hence probably electrical engineering graduates also, are most
numerous in Taiwan, Japan, and South Korea.
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