Power Transformers

Transformer, device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage. Transformers are employed for widely varying purposes; e.g., to reduce the voltage of conventional power circuits to operate low-voltage devices, such as doorbells and toy electric trains, and to raise the voltage from electric generators so that electric power can be transmitted over long distances

Transformers change voltage through electromagnetic induction; i.e., as the magnetic lines of force (flux lines) build up and collapse with the changes in current passing through the primary coil, current is induced in another coil, called the secondary. The secondary voltage is calculated by multiplying the primary voltage by the ratio of the number of turns in the secondary coil to the number of turns in the primary coil, a quantity called the turns ratio

Air-core transformers are designed to transfer radio-frequency currents—i.e., the currents used for radio transmission; they consist of two or more coils wound around a solid insulating substance or on an insulating coil form. Iron-core transformers serve analogous functions in the audio-frequency range.

Impedance-matching transformers are used to match the impedance of a source and that of its load, for most efficient transfer of energy. Isolation transformers are usually employed for reasons of safety to isolate a piece of equipment from the source of power

Public utility, enterprise that provides certain classes of services to the public, including common carrier transportation (buses, airlines, railroads, motor freight carriers, pipelines, etc.); telephone and telegraph; power, heat, and light; and community facilities for water, sanitation, and similar services. In most countries such enterprises are state-owned and state-operated, but in the United States they are mainly privately owned and are operated under close governmental regulation

The classic explanation for the need to regulate public utilities is that they are enterprises in which the technology of production, transmission, and distribution almost inevitably leads to complete or partial monopoly—that they are, in a phrase, natural monopolies. The monopolistic tendency arises from economies of scale in the particular industry, from the large capital costs typical of such enterprises, from the inelasticity of demand among consumers of the service, from considerations of the excess capacity necessary to meet demand peaks, and other considerations. It is often also the case that the existence of competing parallel systems—of local telephones or natural gas, for example—would be inordinately expensive, wasteful, and inconvenient. Given the tendency to monopoly and the potential therefore of monopolistic pricing practices, public regulation has for more than a century been applied to certain classes of business

Rural electrification, project implemented in the United States in the second quarter of the 20th century by the Rural Electrification Administration (REA), a federal agency established in 1935, under the New Deal, in an effort to raise the standard of rural living and to slow the extensive migration of rural Americans to urban centres; more than 98 percent of the United States’ farms were equipped with electric power under the program

The REA provided low-interest loans to farm cooperatives for the construction and operation of power plants and power lines in rural areas. Rural electrification brought city conveniences, such as electric lighting and radio, to areas of low population density and allowed for the automation of a number of farm operations.

Although rural electrification did contribute to bridging the gap between urban and rural life, it did not succeed in checking the movement of farm workers to cities; the application of technical innovations, in fact, acted to increase productivity per man-hour and to replace hand labour with automation and mechanization

Tesla coil, an electrical transformer that uses high-frequency alternating current (AC) to increase voltage. Because of its extremely high voltage, the electricity in a Tesla coil can travel through the air, powering—or damaging—nearby electronic devices, often with arcs of lightninglike electricity. Though the Tesla coil produces extremely high voltage, the high frequency of the current generally makes it possible for most people to approach the device and even be struck by the arcs without suffering injury. The spectacular effects created by the Tesla coil make the device popular for scientific exhibitions, but the principles underlying the coil were also important to the development of radio technology.

The Tesla coil was invented by Serbian American inventor Nikola Tesla in 1891. Tesla was primarily interested in its potential to wirelessly transmit electricity, particularly for lighting. He hoped to build large coils scattered across Earth, each of which would provide power to any device with a receiver coil. However, he had little success with this plan. In 1893 Tesla gave a lecture and demonstration on wireless transmission in which he proposed signal transmission in conjunction with power transmission. He also obtained a patent describing the same principles, which is considered the first radio patent

A Tesla coil is an electrical transformer, or a device that raises or lowers voltage, which is a measure of electrical potential. A Tesla coil generates very high voltage, often in excess of one million volts. It uses AC electricity, meaning that the voltage of the circuit changes at a particular frequency. A modern Tesla coil usually consists of an initial transformer that boosts voltage from the power source and sends it to a capacitor attached to the primary coil, which absorbs the high-voltage power. When the capacitor reaches a sufficiently high voltage, electricity flows across a spark gap, or a space between two high-conducting terminals, at a high frequency, creating an AC current in the primary coil