Electrical engineering: Difference between revisions
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The [[workplace]]s of electrical engineers are just as varied as the types of work they do. Electrical engineers may be found in the pristine lab environment of a [[fabrication plant]], the offices of a [[consulting firm]] or on site at a [[mine]]. |
The [[workplace]]s of electrical engineers are just as varied as the types of work they do. Electrical engineers may be found in the pristine lab environment of a [[fabrication plant]], the offices of a [[consulting firm]] or on site at a [[mine]]. |
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As in every other engineering discipline, [[project management]] skills are essential to the practice of professional electrical engineering. Other than the most junior level of practice, engineers must be familiar with preparation of |
As in every other [[Professional Engineer|engineering discipline]], [[project management]] skills are essential to the practice of professional electrical engineering. Other than the most junior level of practice, engineers must be familiar with preparation of [[budget]]s and [[Schedule (project management)|schedules]], and with formal project procedures for communication within the design group and with external clients, and with good business practices for document control and filing. [[Technical Writing|Strong written communication]] skills are essential for preparation of documentation and for communication with clients. |
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While [[CAD|computer-aided drafting]] is a staple of engineering design, and software to interactively produce schematic diagrams and layouts is common, a basic ability to visualize and sketch objects in three dimensions is invaluable for an electrical engineer, and essential for communicating design concepts to the technological staff who will produce the final graphic representations. |
While [[CAD|computer-aided drafting]] is a staple of engineering design, and software to interactively produce schematic diagrams and layouts is common, a basic ability to visualize and sketch objects in three dimensions is invaluable for an electrical engineer, and essential for communicating design concepts to the technological staff who will produce the final graphic representations. |
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Revision as of 21:25, 22 July 2005
Electrical engineering is an engineering discipline that deals with the study and application of electricity and electromagnetism. Its practitioners are called electrical engineers. Electrical engineering is a broad field that encompasses many subfields including those that deal with power, control systems, electronics and telecommunications.
History
Electrical engineering as a professional discipline advanced rapidly in parallel with the growing applications of electrical technology for power utilities, communication, and later, computation. By 1890 several institutions in the United States and Canada offered degree programs in electrical engineering. Masters and doctorate programs in electrical engineering were not common until well into the 20th century. Previously electrical studies had been part of the mechanical program, or affiliated with the department of physics.
MIT offered the first course in electrical engineering in the U.S. in 1882. This course was organized by Professor Charles R. Cross who was head of the Physics department, and who later became a founder of the American Institute of Electrical Engineers which later became the Institute of Electrical and Electronics Engineers. In 1886 the University of Missouri established the first department of electrical engineering in the U.S. [1]
Even in the early days of engineering education, conflicts existed between education directed toward practical hands-on skills and application of mathematical and physical theory. This range of opportunities persists to this day; someone educated as an electrical engineer may be found supervising electricians in an industrial plant or may be researching fundamental problems in semiconductor physics or mathematical analysis.
Applied mathematics proved well-suited to the practical problems of electrical engineering, and engineers developed some mathematical techniques applicable to other disciplines (such as Oliver Heaviside's formulation of Maxwell's Equations in the modern vector form).
An early example of the application of mathematics to electrical engineering arose in 1883 when Thomas Edison's company undertook the installation of an overhead electrical distribution in Sunbury, Pennsylvania. To establish the most economic wire size for the distribution system that Edison had a miniature model laboriously constructed, with each customer's load modelled by turns of resistance wire. Miniature models of feeders and branch circuits were constructed, and tested with various wire sizes until a satisfactory size was found. An engineer working for Edison, Frank Sprague, demonstrated to Edison that the proper sizes could be calculated mathematically in a single afternoon. [2]
Training and certification
Electrical engineers typically possess a university degree with a major in electrical engineering. The length of study for such a degree is usually three or four years and the completed degree may be designated as a Bachelor of Engineering, Bachelor of Science or Bachelor of Applied Science depending upon the university.
The degree generally includes units covering physics, mathematics, project management and specific topics in electrical engineering. Initially such topics cover most, if not all, of the subfields of electrical engineering. Students then choose to specialize in one or more subfields towards the end of the degree.
Some electrical engineers also choose to pursue a postgraduate degree such as a Master of Engineering, a Doctor of Philosophy in Engineering or an Engineer's degree. The Master and Engineer's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy consists of a significant research component and is often viewed as the entry point to academia. In the United Kingdom, the Master of Engineering is often considered an undegraduate degree of slightly longer duration than the Bachelor of Engineering.
In most countries, a Bachelor's degree in engineering represents the first step towards certification and the degree program itself is certified by a professional body. 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 and Canada), Chartered Engineer (in the United Kingdom, Ireland and India), Chartered Professional Engineer (in Australia) or European Engineer (in much of the European Union).
The advantages of certification vary depending upon location. For example, in the United States "only a licensed engineer may prepare, sign and seal, and submit engineering plans and drawings to a public authority for approval, or seal engineering work for public and private clients" however this is not the case in other countries such as Australia. [3]
Professional bodies of note for electrical engineers include the Institute of Electrical and Electronics Engineers (IEEE) and the Institution of Electrical Engineers (IEE). The IEEE claims to produce 30 percent of the world's literature in electrical engineering, has over 360,000 members worldwide and holds over 300 conferences anually. [4] The IEE publishes 14 journals, has a worldwide membership of 120,000, certifies Chartered Engineers in the United Kingdom and claims to be the largest professional engineering society in Europe. [5] [6]
Tools and work
From the global positioning system to electric power generation, electrical engineers are responsible for a wide range of technologies. They design, develop, test and supervise the deployment of electrical systems and electronic devices. For example, they may work on the design of telecommunication systems, the operation of electric power stations, the lighting and wiring of buildings, the design of household appliances or the control of industrial machinary. [7]
Fundamental to the discipline are the sciences of physics and mathematics as these help to obtain both a qualitative and quantitative description of how such systems will work. Today most engineering work involves the use of computers and it is commonplace to use computer-aided design programs when designing electrical systems.
Although most engineers will understand basic circuit theory, the work of electrical engineers is so varied that it is difficult to specify particular theories that are common to most electrical engineering work. Quantum mechanics and solid state physics might be relevant to an engineer working on VLSI but are largely irrelevant to engineers working with macroscopic electrical systems. Even circuit theory may not be relevant to a person designing telecommunication systems that use off-the-shelf components. Perhaps the most critical technical skills for electrical engineers are reflected in university programs, which emphasize strong numerical skills, computer literacy and the ability to understand the technical language and concepts that relate to electrical engineering. For most engineers, technical work accounts for only a fraction of the work they do. A lot of time is also spent on tasks such as discussing proposals with clients or dividing engineering tasks amongst team members. [8]
The workplaces of electrical engineers are just as varied as the types of work they do. Electrical engineers may be found in the pristine lab environment of a fabrication plant, the offices of a consulting firm or on site at a mine.
As in every other engineering discipline, project management skills are essential to the practice of professional electrical engineering. Other than the most junior level of practice, engineers must be familiar with preparation of budgets and schedules, and with formal project procedures for communication within the design group and with external clients, and with good business practices for document control and filing. Strong written communication skills are essential for preparation of documentation and for communication with clients.
While computer-aided drafting is a staple of engineering design, and software to interactively produce schematic diagrams and layouts is common, a basic ability to visualize and sketch objects in three dimensions is invaluable for an electrical engineer, and essential for communicating design concepts to the technological staff who will produce the final graphic representations.
Also as for other engineering disciplines, usually electrical engineers will at some point in their careers will be responsible for supervision of other technical professionals. One might observe that management skills can become more important to senior engineers than their initial technical skills.
Obsolescence of technical skills is a serious concern to electrical engineers. Membership and participation in technical societies, regular review of periodicals in the field, and a habit of continued learning are essential to maintaining proficiency in the rapidly-developing field.
Subfields
Electrical engineering has many subfields, all of which center around electromagnetism. This section describes seven of the most popular subfields in electrical engineering as well as the type of work that engineers in each subfield do. Although there are engineers who focus exclusively on one subfield, there also many who focus on a combination of subfields.
Power
Power engineering is a subfield of electrical engineering that deals with electricity generation, transmission and distribution. These three areas make up a power grid that is used to provide industry, commerce and residents with electrical power.
Today, most power distribution is done using an alternating current with many grids choosing to adopt three-phase electric power. The power is then split before it reaches residential customers whose low-power appliances generally rely upon single-phase electric power. Many industries prefer to receive three-phase power though because it allows them to drive electric motors with greater efficiency. High-voltage direct current may be used for long distance transmission or interconnections between grids.
Many sites will choose to have their own generators to either complement or replace power from the main grid. Hospitals often have such systems in case of a power outage and some industries, especially those in remote areas, may find it more economical to generate their own power.
Transformers play an important role in power transmission because they allow power to be converted to and from higher voltages. This is important because higher voltages suffer less power loss during transmission. Electrical substations exist throughout grids to convert power to high voltages before transmission and to low voltages suitable for appliances after transmission.
As well as the design of such systems, a key focus of power engineering is the operation of such systems. Since electric power cannot be efficiently stored, power engineers must also make sure that the power supply closely matches the demand. This can be achieved through mathematical modelling. If a grid is undersupplied users may experience brownouts or blackouts.
Control systems
Control engineering is the engineering discipline that focuses on the modelling of a diverse range of dynamic systems and the design of controllers that will cause these systems to behave in the desired manner. Although such controllers need not be electrical many are and hence control engineering is often viewed as a subfield of electrical engineering.
Electrical circuits, digital signal processors and microcontrollers can all be used to implement control systems. 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.
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 speed accordingly. Where there is regular feedback, control theory can be used to determine how the system responds to such feedback. In practically all such systems stability is important and control theory can help ensure stability is achieved.
Although feedback is an important aspect of control engineering, control engineers may also work on the control of systems without feedback. This is known as open loop control. A classic example of open loop control is a washing machine that runs through a pre-determined cycle without the use of sensors.
Electronics
In the subfield of electronic engineering, engineers design and test electrical networks (more commonly known as circuits) that use the electromagnetic properties of electrical components such as resistors, capacitors, inductors, diodes and transistors to achieve a particular functionality. The tuner circuit, which allows the user of a radio to filter out all but a single station, is just one example of such a circuit.
Electronics is often considered to have begun when Lee De Forest invented the vacuum tube in 1907. Within 10 years, his device was used by radio transmitters and receivers as well as systems for long distance telephone calls. Vacuum tubes remained the preferred amplifying device for 40 years, until researchers working for William Shockley at Bell Labs invented the transistor in 1947. In the following years, transistors made small portable radios, or transistor radios, possible as well as allowing more powerful mainframe computers to be built. Transistors were cooler, smaller and required lower voltages than vacuum tubes to work.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by hand. These non-integrated circuits consumed much space and power, were prone to failure and were limited in speed although they are still common in simple 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 electrical devices we see today.
In designing an integrated circuit, electronic engineers first construct circuit schematics that specify the electrical components and describe the interconnections between them. When completed, VLSI engineers convert the schematics into actual layouts, which map the layers of various conductor and semiconductor materials needed to construct the circuit. The conversion from schematics to layouts can be done by software (see electronic design automation) but very often requires human fine-tuning decrease space and power consumption. Once the layout is complete, it can be sent to a fabrication plant for manufacturing.
Integrated circuits and other electrical components can then assembled on printed circuit boards to form more complicated circuits. Today, printed circuit boards are found in most electronic devices including televisions, computers and audio players.
Signal processing
Signal processing is a subfield of electrical engineering that 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.
Digital signals can be recreated perfectly despite the presence of noise. They can be analysed or manipulated using a microprocessor, dedicated digital signal processor or specialized digital circuit. Analog signals are important for real world interactions. For example, loudspeakers require analog signals to produce meaningful sounds and many sensors such as resistance thermometers output analog signals. They can be analysed or manipulated using circuit elements such as resistors, capacitors, inductors and operational amplifiers.
The advantages of digital signals and the uses of analog signals mean it is often desirable to convert between the two. This can be done using either a digital-to-analog converter or an analog-to-digital converter. For this the engineer must decide on the sampling interval and resolution needed to suitably represent the information. For example, the audio of compact discs is resolved to 65,536 levels every 23 microseconds corresponding to 16-bits at 44.1kHz.
In the analog world, signal processing engineers may work on the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications. In the digital world, signal processing engineers may work on the compression, error checking and error detection of digital signals.
Telecommunications
Telecommunications engineering is a subfield of electrical engineering that focuses on the transmission of information across a channel such as a coax cable, optical fiber or free space. Telecommunications is closely related to signal processing as signal processing is essential for the transmission of information.
Transmissions across free space require information to be encoded in a carrier wave in order 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 where the amplitude or frequency of the carrier wave is varied according to the information. The digital equivalents of these techniques are amplitude-shift keying and frequency-shift keying. There are also more sophisticated modulation techniques including vestigial sideband modulation (used for analog television broadcasts) and coded orthogonal frequency division multiplexing (used for digital television broadcasts outside the United States and Canada). The choice of modulation affects the cost and performance of a system and the two must be balanced carefully by the engineer. For digital cable transmissions, modulation may not be necessary however an appropriate line code must be chosen.
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.
Telecommunication engineers also play an important role in the overall design and implementation of communication systems. This includes determining the optimal placement of radio masts and towers, the arrangement of elements in a computer network and the required strength of transmitters.
Instrumentation
Instrumentation engineering, when considered as a subfield of electrical engineering, deals with the design of devices to measure physical quantities such as pressure, flow and temperature. These devices are known as instrumentation.
The design of such instrumentation requires a good understanding of physics that often extends beyond electromagnetic theory. For example, radar guns use the Doppler effect to measure the speed of oncoming vehicles. Similarly, thermocouples use the Peltier-Seebeck effect to measure the temperature difference between two points.
Thermocouples are a good example of the challenges faced by instrumentation engineers. Although the design of an arbitrary thermocouple is not difficult, instrumentation engineers must make a decision about the types of materials used by the thermocouple based upon an application's requirements. There are other issues to consider too, including whether the accuracy of the thermocouple is sufficient or whether a resistance thermometer might be more appropriate.
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. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
Computers
Computer engineering is a subfield of electrical engineering that deals with the design of computers and computer systems. This may involve the design of new hardware, the design of PDAs 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.
Computer engineers typically have a sound understanding of digital systems theory and computer architecture as well as an understanding of VLSI, computer networks and computer science. In this sense, computer engineers are qualified to work on a wide variety of digital systems, not just computers.
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
Perhaps the most notable discipline related to electrical engineering is that of mechatronics. Mechatronics is an engineering discipline, which deals with the convergence of electrical and mechanical systems. Such combined systems are known a electromechanical systems and have widespread adoption. Examples include automated manufacturing systems, heating, ventilation and air-conditioning (HVAC) systems and various subsystems of aircrafts 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 micro electromechanical systems (MEMS), are used in automobile airbag systems, digital projectors, and inkjet printers. Specifically, micro electromechanical accelerometers tell airbags when to deploy, micro electromechanical mirror arrays create sharper images on modern projectors and micro electromechanical nozzles allows inkjet printers to create high-definition prints. Predictions for future uses include yaw-control systems for automobiles and aircraft, tiny implantable medical devices and improved systems for optical communications. [9]
A final related discipline is that of biomedical engineering, which is 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.
References
- ^ . ISBN 087942172X.
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{{cite book}}: Missing or empty|title=(help); Unknown parameter|Author=ignored (|author=suggested) (help); Unknown parameter|Publisher=ignored (|publisher=suggested) (help); Unknown parameter|Title=ignored (|title=suggested) (help); Unknown parameter|Year=ignored (|year=suggested) (help)CS1 maint: extra punctuation (link) - ^ "Why Should You Get Licensed?". National Society of Professional Engineers. July 11.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ "About the IEEE". IEEE. July 11.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ "About the IEE". The IEE. July 11.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ "Journal and Magazines". The IEE. July 11.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ "Electrical and Electronics Engineers, except Computer". Occupational Outlook Handbook. July 16.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) (see here regarding copyright) - ^ Trevelyan, James; (2005). What Do Engineers Really Do?. University of Western Australia. (seminar with slides)
- ^ "MEMS the world!". IntelliSense Software Corporation. July 17.
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See also
- List of electrical engineering topics
- List of electrical engineers
- Broadcast engineering
- Electronic design automation
- Computer engineering
External links
- History of the IEEE Electrical Engineering Professional Society at its website
- All About Circuits Learn the nuts and bolts about building electrical circuits, and to build appliances based on electrical circuits
- IEEE Virtual Museum A virtual museum that illustrates many of the basic electrical engineering and electricity concepts through examples, figures, and interviews.
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