Electrification

Electrification is the process of powering by electricity and, in many contexts, the introduction of such power by changing over from an earlier power source.

The broad meaning of the term, such as in the history of technology, economic history, and economic development, usually applies to a region or national economy. Broadly speaking, electrification was the build-out of the electricity generation and electric power distribution systems that occurred in Britain, the United States, and other now- developed countries from the mid-1880s until around 1950 and is still in progress in rural areas in some developing countries. This included the transition in manufacturing from line shaft and belt drive using steam engines and water power to electric motors.

The electrification of particular sectors of the economy is called by terms such as ''factory electrification'', ''household electrification'', ''rural electrification'', ''aviation electrification'' or ''railway electrification''. It may also apply to changing industrial processes such as smelting, melting, separating or refining from coal or coke heating, or chemical processes to some type of electric process such as electric arc furnace, electric induction or resistance heating, or electrolysis or electrolytic separating.

Electrification was called "the greatest engineering achievement of the 20th Century" by the National Academy of Engineering, and it continues in both rich and poor countries.

History of electrification

The earliest commercial uses of electricity were electroplating and the telegraph.

Development of magnetos, dynamos and generators

In the years 1831–1832, Michael Faraday discovered the operating principle of electromagnetic generators. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor that is subjected to a varying magnetic flux, as for example, a wire moving through a magnetic field. He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.

Around 1832, Hippolyte Pixii improved the magneto by using a wire wound horseshoe, with the extra coils of conductor generating more current, but it was AC. André-Marie Ampère suggested a means of converting current from Pixii's magneto to DC using a rocking switch. Later segmented commutators were used to produce direct current.

William Fothergill Cooke and Charles Wheatstone developed a telegraph around 1838-40. In 1840 Wheatstone was using a magneto that he developed to power the telegraph. Wheatstone and Cooke made an important improvement in electrical generation by using a battery-powered electromagnet in place of a permanent magnet, which they patented in 1845. The self-excited magnetic field dynamo did away with the battery to power electromagnets. This type of dynamo was made by several people in 1866.

The first practical generator, the Gramme machine, was made by Z. T. Gramme, who sold many of these machines in the 1870s. British engineer R. E. B. Crompton improved the generator to allow better air cooling and made other mechanical improvements. Compound winding, which gave more stable voltage with load, improved the operating characteristics of generators.

The improvements in electrical generation technology in the 19th century increased its efficiency and reliability greatly. The first magnetos only converted a few percent of mechanical energy to electricity. By the end of the 19th century the highest efficiencies were over 90%.

Electric lighting

Arc lighting

Sir Humphry Davy invented the carbon arc lamp in 1802 upon discovering that electricity could produce a light arc with carbon electrodes. However, it was not used to any great extent until a practical means of generating electricity was developed.

Carbon arc lamps were started by making contact between two carbon electrodes, which were then separated to within a narrow gap. Because the carbon burned away, the gap had to be constantly readjusted. Several mechanisms were developed to regulate the arc. A common approach was to feed a carbon electrode by gravity and maintain the gap with a pair of electromagnets, one of which retracted the upper carbon after the arc was started and the second controlled a brake on the gravity feed.

Arc lamps of the time had very intense light output – in the range of 4,000 candlepower (candelas) – and released a lot of heat, and they were a fire hazard, all of which made them inappropriate for lighting homes.

In the 1850s, many of these problems were solved by the arc lamp invented by William Petrie and William Staite. The lamp used a magneto-electric generator and had a self-regulating mechanism to control the gap between the two carbon rods. Their light was used to light up the National Gallery in London and was a great novelty at the time. These arc lamps and designs similar to it, powered by large magnetos, were first installed on English lighthouses in the mid 1850s, but the power limitations prevented these models from being a proper success.

The first successful arc lamp (the Yablochkov candle) was developed by Russian engineer Pavel Yablochkov using the Gramme generator. Its advantage lay in the fact that it did not require the use of a mechanical regulator like its predecessors. It was first exhibited at the Paris Exposition of 1878 and was heavily promoted by Gramme. The arc light was installed along the half mile length of Avenue de l'Opéra, Place du Theatre Francais and around the Place de l'Opéra in 1878.

R. E. B. Crompton developed a more sophisticated design in 1878 which gave a much brighter and steadier light than the Yablochkov candle. In 1878, he formed Crompton & Co. and began to manufacture, sell and install the Crompton lamp. His concern was one of the first electrical engineering firms in the world.

Incandescent light bulbs

Various forms of incandescent light bulbs had numerous inventors; however, the most successful early bulbs were those that used a carbon filament sealed in a high vacuum. These were invented by Joseph Swan in 1878 in Britain and by Thomas Edison in 1879 in the US. Edison’s lamp was more successful than Swan’s because Edison used a thinner filament, giving it higher resistance and thus conducting much less current. Edison began commercial production of carbon filament bulbs in 1880. Swan's light began commercial production in 1881.

Swan's house, in Low Fell, Gateshead, was the world's first to have working light bulbs installed. The Lit & Phil Library in Newcastle, was the first public room lit by electric light, and the Savoy Theatre was the first public building in the world lit entirely by electricity.Burgess, Michael. "Richard D'Oyly Carte", ''The Savoyard'', January 1975, pp. 7–11

Central power stations and isolated systems

The first central station providing public power is believed to be one at Godalming, Surrey, U.K. autumn 1881. The system was proposed after the town failed to reach an agreement on the rate charged by the gas company, so the town council decided to use electricity. The system lit up arc lamps on the main streets and incandescent lamps on a few side streets with hydroelectric power. By 1882 between 8 and 10 households were connected, with a total of 57 lights. The system was not a commercial success and the town reverted to gas.

The first large scale central distribution supply plant was opened at Holborn Viaduct in London in 1882. Equipped with 1000 incandescent lightbulbs that replaced the older gas lighting, the station lit up Holborn Circus including the offices of the General Post Office and the famous City Temple church. The supply was a direct current at 110 V; due to power loss in the copper wires, this amounted to 100 V for the customer.

Within weeks, a parliamentary committee recommended passage of the landmark 1882 Electric Lighting Act, which allowed the licensing of persons, companies or local authorities to supply electricity for any public or private purposes.

The first large scale central power station in America was Edison's Pearl Street Station in New York, which began operating in September 1882. The station had six 200 horsepower Edison dynamos, each powered by a separate steam engine. It was located in a business and commercial district and supplied 110 volt direct current to 85 customers with 400 lamps. By 1884 Pearl Street was supplying 508 customers with 10,164 lamps.

By the mid-1880s, other electric companies were establishing central power stations and distributing electricity, including Crompton & Co. and the Swan Electric Light Company in the UK, Thomson-Houston Electric Company and Westinghouse in the US and Siemens in Germany. By 1890 there were 1000 central stations in operation. The 1902 census listed 3,620 central stations. By 1925 half of power was provided by central stations.

Load factor and isolated systems

One of the biggest problems facing the early power companies was the hourly variable demand. When lighting was practically the only use of electricity, demand was high during the first hours before the workday and the evening hours when demand peaked. As a consequence, most early electric companies did not provide daytime service, with two-thirds providing no daytime service in 1897.

The ratio of the average load to the peak load of a central station is called the load factor. For electric companies to increase profitability and lower rates, it was necessary to increase the load factor. The way this was eventually accomplished was through motor load. Motors are used more during daytime and many run continuously. Electric street railways were ideal for load balancing. Many electric railways generated their own power and also sold power and operated distribution systems.

The load factor adjusted upward by the turn of the 20th century—at Pearl Street the load factor increased from 19.3% in 1884 to 29.4% in 1908. By 1929, the load factor around the world was greater than 50%, mainly due to motor load.

Before widespread power distribution from central stations, many factories, large hotels, apartment and office buildings had their own power generation. Often this was economically attractive because the exhaust steam could be used for building and industrial process heat, which today is known as cogeneration or combined heat and power (CHP). Most self-generated power became uneconomical as power prices fell. As late as the early 20th century, isolated power systems greatly outnumbered central stations. Cogeneration is still commonly practiced in many industries that use large amounts of both steam and power, such as pulp and paper, chemicals and refining. The continued use of private electric generators is called microgeneration.

Direct current electric motors

The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832. The crucial advance that this represented over the motor demonstrated by Michael Faraday was the incorporation of a commutator. This allowed Sturgeon's motor to be the first capable of providing continuous rotary motion.

Frank J. Sprague improved on the DC motor in 1884 by solving the problem of maintaining a constant speed with varying load and reducing sparking from the brushes. Sprague sold his motor through Edison Co. It is easy to vary speed with DC motors, which made them suited for a number of applications such as electric street railways, machine tools and certain other industrial applications where speed control was desirable.

Alternating current

Although the first power stations supplied direct current, the distribution of alternating current soon became the most favored option. The main advantages of AC were that it could be transformed to high voltage to reduce transmission losses and that AC motors could easily run at constant speeds.

Alternating current technology was rooted in Faraday's 1830–31 discovery that a changing magnetic field can induce an electric current in a circuit.

The first person to conceive of a rotating magnetic field was Walter Baily who gave a workable demonstration of his battery-operated polyphase motor aided by a commutator on June 28, 1879 to the Physical Society of London. Nearly identical to Baily’s apparatus, French electrical engineer Marcel Deprez in 1880 published a paper that identified the rotating magnetic field principle and that of a two-phase AC system of currents to produce it. In 1886, English engineer Elihu Thomson built an AC motor by expanding upon the induction-repulsion principle and his wattmeter.

It was in the 1880s that the technology was commercially developed for large scale electricity generation and transmission. In 1882 the British inventor and electrical engineer Sebastian de Ferranti, working for the company Siemens collaborated with the distinguished physicist Lord Kelvin to pioneer AC power technology including an early transformer.

A power transformer developed by Lucien Gaulard and John Dixon Gibbs was demonstrated in London in 1881, and attracted the interest of Westinghouse. They also exhibited the invention in Turin in 1884, where it was adopted for an electric lighting system. Many of their designs were adapted to the particular laws governing electrical distribution in the UK.

Sebastian Ziani de Ferranti went into this business in 1882 when he set up a shop in London designing various electrical devices. Ferranti believed in the success of alternating current power distribution early on, and was one of the few experts in this system in the UK. With the help of Lord Kelvin, Ferranti pioneered the first AC power generator and transformer in 1882. John Hopkinson, a British physicist, invented the three-wire (three-phase) system for the distribution of electrical power, for which he was granted a patent in 1882.

The Italian inventor Galileo Ferraris invented a polyphase AC induction motor in 1885. The idea was that two out-of-phase, but synchronized, currents might be used to produce two magnetic fields that could be combined to produce a rotating field without any need for switching or for moving parts. Other inventors were the American engineers Charles S. Bradley and Nikola Tesla