1.
London Underground 1972 Stock
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The London Underground 1972 Stock is a type of rolling stock used on the London Underground. The 1972 Stock was ordered to make up the shortfall in trains on the Northern lines 1959 Tube Stock fleet and it is, however, currently used on the Bakerloo line. A total of 252 cars were ordered from Metro-Cammell and later refurbished by Tickford, in 2016, the 1972 stock started to have life extension work done to ensure the trains could remain in service. In the early 1970s the 1938 Tube stock on the Bakerloo and Northern lines was life-expired, tentative designs for a new Northern line fleet were abandoned when the go-ahead was given for the Piccadilly line to be extended to Heathrow Airport. That required a new fleet of trains to replace the 1959 stock then in use. Originally it was planned to refurbish some 301938 trains, the 1972 Tube stock was ordered in a hurry, so there was no time to create a new design, the trains were based on the 1967 Tube stock on the Victoria line. Although almost identical looking, the 1972 trains had a guard and door controls in the rear car, a further 33 trains of 1972 Tube stock were ordered to provide service on the Jubilee line. The 1972 Mk2 stock had slightly different interiors, such as dark blue seating moquette, externally the biggest difference was that the doors were painted red, with an LT roundel on the side of the carriages, rather than the Johnston lettering. The train number plates on the 1972 Mk2 trains operated on the Northern, the earlier 1972 stock on the Northern line was replaced by 1995 Tube Stock in 1999. The 1972 Mark 2 stock was refurbished in the 1990s. After being withdrawn from the Northern line, a few cars of 1972 Mark 1 stock were converted to run with 1967 stock in service on the Victoria line. A further two trains were converted to be compatible with the MkII type, and these now run on the Bakerloo line, one ex-Northern line Trainset is also permanently based at the now-closed Aldwych tube station, for use in films. The 1972 trains are formed of seven-car sets, and have a total of 268 passenger seats, the EVO tube concept design, a lighter articulated train with walk-through cars, was introduced early in 2011. In early 2014 the Bakerloo, Piccadilly, Central and Waterloo & City line rolling-stock replacement project was renamed New Tube for London and moved to the design and specification stage. The proposal introduces fully automated trains and signalling to increase capacity first on the Piccadilly line in 2025, followed by the Central, Waterloo & City, and Bakerloo lines by 2033. The fully automated trains may not have drivers, however, the ASLEF and RMT trade unions representing drivers strongly oppose this, middle two car are 67DM vehicles -3079,3179. Front 2 and rear two are 72 MK1 stock Front two 3313-4313 Rear two 4213-3213 Unit 3079 &3179 have recently been overhauled in Eastleigh, with no cab windows and new cables leading into each other. The AIT will replace the Track Recording Train which is currently in use, transport for London - Rolling Stock -1972 Tubeprune -1972 Tube Stock
2.
Northern line
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The Northern line is a London Underground line, coloured black on the Tube map. The section between Stockwell and Borough opened in 1890, and is the oldest section of deep-level tube line on the network, for most of its length it is a deep-level tube line. There were about 252,310,000 passenger journeys in 2011/12 on the Northern line, making it the second-busiest line on the Underground. Despite its name, it does not serve the northernmost stations on the network, though it does serve the southernmost station, there are 50 stations on the line, of which 36 have platforms below ground. An extension in the 1920s used a route planned by a fourth company. Abandoned plans from the 1920s to extend the line further southwards, from the 1930s to the 1970s, the tracks of a seventh company were also managed as a branch of the Northern line. The C&SLR, Londons first deep-level tube railway, was built under the supervision of James Henry Greathead and it was the first of the Undergrounds lines to be constructed by boring deep below the surface and the first to be operated by electric traction. The railway opened in November 1890 from Stockwell to a station at King William Street. This was inconveniently placed and unable to cope with the traffic so, in 1900. By 1907 the C&SLR had been extended at both ends to run from Clapham Common to Euston. The CCE&HR was opened in 1907 and ran from Charing Cross via Euston and Camden Town to Golders Green and it was extended south by one stop to Embankment in 1914 to form an interchange with the Bakerloo and District lines. In 1913 the Underground Electric Railways Company of London, owner of the CCE&HR, took over the C&SLR, during the early 1920s, a series of works was carried out to connect the C&SLR and CCE&HR tunnels to enable an integrated service to be operated. The first of new tunnels, between the C&SLRs Euston station and the CCE&HRs station at Camden Town, had originally been planned in 1912 but had been delayed by World War I. The second connection linked the CCE&HRs Embankment and C&SLRs Kennington stations and provided a new station at Waterloo to connect to the main line station there. The smaller-diameter tunnels of the C&SLR were expanded to match the diameter of the CCE&HR. In conjunction with the works to integrate the two lines, two extensions were undertaken, northwards to Edgware in Middlesex and southwards to Morden in Surrey. The Edgware extension used plans dating back to 1901 for the Edgware and it extended the CCE&HR line from its terminus at Golders Green to Edgware in two stages, to Hendon Central in 1923 and to Edgware in 1924. The line crossed open countryside and ran on the surface, apart from a tunnel north of Hendon Central
3.
Variable-frequency drive
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A variable-frequency drive is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage. VFDs are used in applications ranging from small appliances to the largest of mine mill drives and that lack of penetration highlights significant energy efficiency improvement opportunities for retrofitted and new VFD installations. VFDs are available in a number of different low- and medium-voltage AC-AC and DC-AC topologies, a variable-frequency drive is a device used in a drive system consisting of the following three main sub-systems, AC motor, main drive controller assembly, and drive/operator interface. The AC electric motor used in a VFD system is usually three-phase induction motor, motors that are designed for fixed-speed operation are often used. The VFD controller is a power electronics conversion system consisting of three distinct sub-systems, a rectifier bridge converter, a direct current link, and an inverter. Voltage-source inverter drives are by far the most common type of drives, most drives are AC-AC drives in that they convert AC line input to AC inverter output. However, in applications such as common DC bus or solar applications. The most basic rectifier converter for the VSI drive is configured as a three-phase, six-pulse, in a VSI drive, the DC link consists of a capacitor which smooths out the converters DC output ripple and provides a stiff input to the inverter. This filtered DC voltage is converted to quasi-sinusoidal AC voltage output using the active switching elements. VSI drives provide higher power factor and lower distortion than phase-controlled current-source inverter. The drive controller can also be configured as a phase converter having single-phase converter input, controller advances have exploited dramatic increases in the voltage and current ratings and switching frequency of solid-state power devices over the past six decades. Introduced in 1983, the bipolar transistor has in the past two decades come to dominate VFDs as an inverter switching device. For example, for 460 V,60 Hz motors, this linear V/Hz relationship is 460/60 =7.67 V/Hz, some V/Hz control drives can also operate in quadratic V/Hz mode or can even be programmed to suit special multi-point V/Hz paths. Although space vector pulse-width modulation is becoming popular, sinusoidal PWM is the most straightforward method used to vary drives motor voltage. Operation of the motors above rated nameplate speed is possible, but is limited to conditions that do not require more power than the rating of the motor. This is sometimes called field weakening and, for AC motors, means operating at less than rated V/Hz, permanent magnet synchronous motors have quite limited field-weakening speed range due to the constant magnet flux linkage. Wound-rotor synchronous motors and induction motors have much wider speed range, for example, a 100 HP,460 V,60 Hz,1775 RPM induction motor supplied with 460 V,75 Hz, would be limited to 60/75 = 80% torque at 125% speed = 100% power. At higher speeds, the motor torque has to be limited further due to the lowering of the breakaway torque of the motor
4.
Current collector
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Those for overhead wires are roof-mounted devices, those for third rails are mounted on the bogies. Typically, they have one or more spring-loaded arms that permit the working engagement with the rail or overhead wire, the collector arm pushes the contact shoe against the contact wire or rail. As the vehicle moves, the shoe slides along the wire or rail to draw the electricity needed to run the vehicles motor. The current collector arms are electrically conductive but mounted insulated on the vehicles roof, an insulated cable connects the collector with the switch, transformer or motor. The steel rails of the act as the electrical return. Electric vehicles that collect their current from an overhead line system use different forms of one- or two-arm pantograph collectors, the current collection device presses against the underside of the lowest wire of an overhead line system, which is called a contact wire. Most overhead supply systems are either DC or single phase AC, three phase AC systems use a pair of overhead wires, and paired trolley poles. Electric railways with third rails, or fourth rails, in tunnels carry collector shoes projecting laterally, or vertically, the contact shoe may slide on top of the third rail, on the bottom or on the side. The side running contact shoe is used against the bars on rubber-tired metros. A vertical contact shoe is used on power supply systems, stud contact systems. A pair of shoes was used on underground current collection systems. The contact shoe on a contact system is called a ski collector. The ski collector moves vertically to accommodate variations in the height of the studs. Contact shoes may also be used on overhead conductor rails, on bars or on trolley wires. Most railways use three rails, while the London Underground uses four rails
5.
Bogie
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A bogie is a chassis or framework carrying wheels, attached to a vehicle, thus serving as a modular subassembly of wheels and axles. Bogies take various forms in various modes of transport, while bogie is the preferred spelling and first-listed variant in various dictionaries, bogey and bogy are also used. A bogie in the UK, or a truck, wheel truck. In Indian English, bogie may also refer to a railway carriage. In South Africa, the bogie is often alternatively used to refer to a freight or goods wagon. The first standard gauge British railway to build coaches with bogies, an alternate configuration often is used in articulated vehicles, which places the bogies under the connection between the carriages or wagons. Most bogies have two axles, but some cars designed for heavy loads have more axles per bogie, heavy-duty cars may have more than two bogies using span bolsters to equalize the load and connect the bogies to the cars. Suspension to absorb shocks between the frame and the rail vehicle body, Common types are coil springs, or rubber airbags. At least one wheelset, composed of an axle with bearings and a wheel at each end The bolster, the railway car is supported at the pivot point on the bolster. Axle box suspensions absorb shocks between the bearings and the bogie frame. The axle box suspension usually consists of a spring between the frame and axle bearings to permit up-and-down movement, and sliders to prevent lateral movement. A more modern design uses solid rubber springs, brake equipment, Two main types are used, brake shoes that are pressed against the tread of the wheel, and disc brakes and pads. More modern, bolsterless bogie designs omit these features, instead taking advantage of the movement of the suspension to permit rotational movement. The Commonwealth bogie, manufactured by the English Steel Corporation under licence from the Commonwealth Steel Company in Illinois, fitted with SKF or Timken bearings, it was introduced in the late 1950s for all BR Mark 1 vehicles. It was a heavy, cast-steel design weighing about 6.5 long tons, with sealed roller bearings on the axle ends, the leaf springs were replaced by coil springs running vertically rather than horizontally. The advanced design gave a better quality than the BR1. The side frame of the bogie was usually of bar construction, with simple horn guides attached, the axle boxes had a cast-steel equaliser beam or bar resting on them. The bar had two steel coil springs placed on it and the bogie frame rested on the springs, the effect was to allow the bar to act as a compensating lever between the two axles and to use both springs to soften shocks from either axle
6.
Adtranz
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ABB Daimler-Benz Transportation, commonly known under its brand Adtranz, was a multi-national rail transport equipment manufacturer with facilities concentrated in Europe and the US. The company was created in 1996 in the merger of Daimler-Benzs, in 1999, DaimlerChrysler bought ABBs shares and changed its official name to DaimlerChrysler Rail Systems. Bombardier Transportation acquired the company in 2001, at which time Adtranz was the second largest manufacturer of such equipment. The acquisition significantly increased the size of Bombardiers rail industry holdings making Bombardier the largest rail equipment manufacturer in the world, Adtranz manufactured mainline locomotives, high-speed, regional, metro and underground passenger trains, trams and people movers as well as freight wagons. Non rolling stock businesses included railway electrification and signalling infrastructure, in the EU, outside Germany, the merger would have meant no significant market share increase, including Scandinavia, where ABB had a dominant market share. The merger came into force on 1 January 1996, however the company continued to be loss making, losing $111 million in 1997. Polish manufacturer Pafawag was acquired in 1997 and the facility modernised, controlling interests in MÁV Dunakeszi, Hungary, a new diesel locomotive design with engine and electrical traction system provided by General Electric was introduced, named Blue Tiger. Adtranz intended to consolidate its product range around these families once on-going deliveries are finished, Adtranz continued to make an operating loss in 1998, attributed to earlier contracts with underestimated costs, as well as technical problems with products. The same year brought an order for 400 locomotives for Deutsche Bahn, in 2000 Adtranz finally achieved profitability. In preparation for a sale from DaimlerChrysler buyers for non-core rolling stock manufacturing businesses were sought, in January 2000 The Greenbrier Companies acquired the freight wagon business based in Siegen. The electrical installations business was sold to Balfour Beatty in late 2000 for €153million, no buyer was found for the railway signalling division. In August 2000 Bombardier Inc. announced that it was to buy Adtranz for $711million, the takeover came into legal effect on 1 May 2001 with a final price of $725million. The brand Adtranz was created by Landor Associates as part of the identity of ABB Daimler Benz Transportation. It was capitalised by the companies with a capital D as ADtranz, following the standard English text formatting, above the text ADtranz, the company logo included a green dot, symbolizing a signal set on green, as well as the environmental friendliness of railways. In addition to the company registered the slogan ADtranz - we speak railways. Rights on the brand and slogan were deleted in 2008 and 2007 respectively, westinghouse Transportation - via AEG acquisition 1988 Archive of Adranz homepage Welcome to Adtranz. Archived from the original on 28 December 1996
7.
London Underground infrastructure
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The infrastructure of the London Underground includes 11 lines, with 270 stations. Most of the lines emerge onto the surface outside the central area, the oldest train running on the Underground was introduced in 1972. The Underground is electrified using a system, the DC traction supply being independent of the running rails. Planned improvements include new stations, line extensions and more lines with automatic train operation, the total length of railway on London Underground is 250 miles and made up of the sub-surface network and the deep-tube lines. In 1971/72 it was remeasured in kilometres using Ongar as the zero point, the tunnels and trains are of a similar size to those on British main lines. The Hammersmith & City and Circle lines share all their stations and it is these that were the tube lines, although since the 1950s the term tube has come to be used to refer to the whole London Underground system. Many of the central London deep-tube line stations, such as the Central and Piccadilly lines, are higher than the lines to assist deceleration when arriving. There are 20 miles of tunnel and 93 miles of tube tunnel. Trains generally run on the track, although in some places, for example the Central line east of St Pauls station. Seven of the 32 London boroughs are not served by the Underground, six of these are south of the River Thames, Bexley, Bromley, Croydon, Kingston, Lewisham and Sutton. The seventh unserved borough is Hackney, although Manor House and Old Street stations lie just outside its boundary, the borough is served by the London Overgrounds North London Line and its East London Line extension. Greenwich borough was unserved until North Greenwich station opened on the Jubilee line extension in 1999, the borough of Lewisham used to be served by the Underground on the East London line - now part of London Overground - at New Cross and New Cross Gate. The lines are electrified with a four-rail DC system, a rail between the rails is energised at −210 V and a rail outside the running rails at +420 V. The traction current has no direct earth point, but there are two resistors connected across the traction supply, the centre tap of the resistors is earthed, establishing the reference point between the positive and negative rails by voltage division. The resistors are large enough to prevent large currents flowing through the earthed infrastructure, the positive resistor is twice as large as the negative resistor, since the positive rail carries twice the voltage of the negative rail. The Metropolitan Railways first line was built in the belief it would be operated by smokeless locomotives and this led to an 1897 Board of Trade report that reported a pharmacist was treating people in distress after having travelled on the railway with his Metropolitan Mixture. The report recommended more openings be authorised but the sections of the Metropolitan. Forced ventilation was not considered when the deep-tube Central London Railway opened in 1900, however, soon after opening there were complaints about a smell that the company couldnt explain, and by 1911 they had installed a system of fans injecting filtered air and ozone
8.
London Underground
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The London Underground is a public rapid transit system serving London and some parts of the adjacent counties of Buckinghamshire, Essex and Hertfordshire in the United Kingdom. The network has expanded to 11 lines, and in 2015–16 carried 1.34 billion passengers, the 11 lines collectively handle approximately 4.8 million passengers a day. The system has 270 stations and 250 miles of track, despite its name, only 45% of the system is actually underground in tunnels, with much of the network in the outer environs of London being on the surface. In addition, the Underground does not cover most southern parts of Greater London, the current operator, London Underground Limited, is a wholly owned subsidiary of Transport for London, the statutory corporation responsible for the transport network in Greater London. As of 2015, 92% of operational expenditure is covered by passenger fares, the Travelcard ticket was introduced in 1983 and Oyster, a contactless ticketing system, in 2003. Contactless card payments were introduced in 2014, the LPTB was a prominent patron of art and design, commissioning many new station buildings, posters and public artworks in a modernist style. Other famous London Underground branding includes the roundel and Johnston typeface, to prepare construction, a short test tunnel was built in 1855 in Kibblesworth, a small town with geological properties similar to London. This test tunnel was used for two years in the development of the first underground train, and was later, in 1861, the worlds first underground railway, it opened in January 1863 between Paddington and Farringdon using gas-lit wooden carriages hauled by steam locomotives. It was hailed as a success, carrying 38,000 passengers on the opening day, the Metropolitan District Railway opened in December 1868 from South Kensington to Westminster as part of a plan for an underground inner circle connecting Londons main-line termini. The Metropolitan and District railways completed the Circle line in 1884, built using the cut and this opened in 1890 with electric locomotives that hauled carriages with small opaque windows, nicknamed padded cells. The Waterloo and City Railway opened in 1898, followed by the Central London Railway in 1900, the Metropolitan Railway protested about the change of plan, but after arbitration by the Board of Trade, the DC system was adopted. When the Bakerloo was so named in July 1906, The Railway Magazine called it an undignified gutter title, by 1907 the District and Metropolitan Railways had electrified the underground sections of their lines. In January 1913, the UERL acquired the Central London Railway, the Bakerloo line was extended north to Queens Park to join a new electric line from Euston to Watford, but World War I delayed construction and trains reached Watford Junction in 1917. During air raids in 1915 people used the stations as shelters. An extension of the Central line west to Ealing was also delayed by the war, the Metropolitan promoted housing estates near the railway with the Metro-land brand and nine housing estates were built near stations on the line. Electrification was extended north from Harrow to Rickmansworth, and branches opened from Rickmansworth to Watford in 1925, the Piccadilly line was extended north to Cockfosters and took over District line branches to Harrow and Hounslow. In 1933, most of Londons underground railways, tramway and bus services were merged to form the London Passenger Transport Board, the Waterloo & City Railway, which was by then in the ownership of the main line Southern Railway, remained with its existing owners. In the same year that the London Passenger Transport Board was formed, in the following years, the outlying lines of the former Metropolitan Railway closed, the Brill Tramway in 1935, and the line from Quainton Road to Verney Junction in 1936
9.
Jubilee line
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The Jubilee line is a London Underground line. Opened in 1979, it is the newest line on the network, although sections of track date back to 1932. The later stations are larger and have special safety features, both aspects being attempts to future-proof the line, the Jubilee line is coloured silver/grey on the Tube map, to mark the Silver Jubilee of Elizabeth II after which the line was named. Between Finchley Road and Wembley Park, the Jubilee line shares its route with the Metropolitan line, between Canning Town and Stratford, the line runs parallel to the Stratford International branch of the Docklands Light Railway. In 1932, the Metropolitan Railway built a branch from its line at Wembley Park to Stanmore. The line, as many others in the northwest London area, was designed to absorb commuter traffic from the new. At first, the Metropolitan had advocated a new line roughly following the line of the Edgware Road between the tube station and a point near Willesden Green. Indeed, construction advanced as far as the rebuilding of Edgware Road station to accommodate 4 platforms of 8-car length, things changed, though, with the formation of the London Passenger Transport Board and the subsequent absorption of the Metropolitan. The solution was now a new branch of the Bakerloo line from Baker Street to serve new stations at St, the new line rose between the Metropolitan tracks at Finchley Road, providing cross-platform interchange with the Metropolitan line. At Wembley Park, the new Bakerloo would run on to serve Kingsbury, Queensbury, Canons Park and Stanmore, the Bakerloo extension, built as above, opened in 1939. The planning for the Tube network immediately before and after World War II considered several new routes, Line C opened as the Victoria line, in stages, from 1968 to 1972. Work on the northeast–southwest route continued, the new line was to have been called the Fleet line after the River Fleet. In 1971, construction began on the new Fleet line, economic pressure and doubt over the final destination of the line had led to a staged approach. Under the first stage, the Baker Street-to-Stanmore branch of the Bakerloo line was joined at Baker Street to a new 2, the new tube was to offer cross-platform interchange between the Bakerloo and Fleet at Baker Street, as pioneered on the Victoria line. The work was completed in 1979, as part of the works, Trafalgar Square and Strand stations were combined into a single station complex, Charing Cross. The existing Charing Cross station on the sub-surface District and Circle lines was renamed Embankment, another part of the works included a section of test tunnel, built near New Cross. When the planned route was altered, this section was abandoned as it was effectively useless. However, this idea was rejected because of the costs involved
10.
Power inverter
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A power inverter, or inverter, is an electronic device or circuitry that changes direct current to alternating current. The input voltage, output voltage and frequency, and overall power handling depend on the design of the device or circuitry. The inverter does not produce any power, the power is provided by the DC source, a power inverter can be entirely electronic or may be a combination of mechanical effects and electronic circuitry. Static inverters do not use moving parts in the conversion process, a typical power inverter device or circuit requires a relatively stable DC power source capable of supplying enough current for the intended power demands of the system. The input voltage depends on the design and purpose of the inverter, examples include,12 VDC, for smaller consumer and commercial inverters that typically run from a rechargeable 12 V lead acid battery or automotive electrical outlet. 24,36 and 48 VDC, which are standards for home energy systems. 200 to 400 VDC, when power is from solar panels. 300 to 450 VDC, when power is from electric vehicle battery packs in vehicle-to-grid systems, hundreds of thousands of volts, where the inverter is part of a high-voltage direct current power transmission system. An inverter can produce a wave, modified sine wave, pulsed sine wave. The two dominant commercialized waveform types of inverters as of 2007 are modified sine wave and sine wave, the second method converts DC to AC at battery level and uses a line-frequency transformer to create the output voltage. This is one of the simplest waveforms an inverter design can produce and is best suited to low-sensitivity applications such as lighting and heating, square wave output can produce humming when connected to audio equipment and is generally unsuitable for sensitive electronics. A power inverter device which produces a multiple step sinusoidal AC waveform is referred to as a sine wave inverter, to more clearly distinguish the inverters with outputs of much less distortion than the modified sine wave inverter designs, the manufacturers often use the phrase pure sine wave inverter. However, this is not critical for most electronics as they deal with the quite well. Where power inverter devices substitute for standard power, a sine wave output is desirable because many electrical products are engineered to work best with a sine wave AC power source. The standard electric utility provides a sine wave, typically with minor imperfections, switch-mode power supply devices, such as personal computers or DVD players, function on quality modified sine wave power. AC motors directly operated on non-sinusoidal power may produce extra heat, may have different speed-torque characteristics, the modified sine wave output of such an inverter is the sum of two square waves one of which is phase shifted 90 degrees relative to the other. The result is three level waveform with equal intervals of zero volts, peak positive volts, zero volts, peak negative volts, the resultant wave very roughly resembles the shape of a sine wave. Most inexpensive consumer power inverters produce a sine wave rather than a pure sine wave
11.
British Rail Class 465
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The British Rail Class 465 Networker electric multiple units were built by GEC Alsthom and BREL between 1991 and 1993, and by ABB Rail between 1993 and 1994. They were brought into service from 1992 and operated by British Rail until 1997, then by Connex until 2003, South Eastern Trains until 2006 and then Southeastern to the present day. Network SouthEast began the planning for the development of the Class 465 Networker in 1988, the Class 465 was introduced in order to replace the 41-year-old Class 415 EMUs. All trains were supplied in Network SouthEast livery and branded Kent Link Networker. Some units were re-liveried in the first Connex South Eastern livery, all 465/0, 465/1, 465/2, 465/9 and 466 trains are now in the white and charcoal livery of Southeastern with blue doors. There are other visible but minor differences in door switches and audible chimes, window shapes, in addition, the two units employ different traction motors, which sound different. Despite the differences though, the units can be used interchangeably, particularly during peak times when longer trains are used, it is quite common to see a train comprising two four car units, one from each batch. Both classes share many similarities with the later dual-voltage Class 365, when first introduced, all seating was standard class only. Although the units are interoperable, the parts for the different units are different. The maximum speed of a Class 465 Networker is 75 mph, a Solid State Traction Converter package controls 3-phase AC Traction motors, which allows for Rheostatic or Regenerative Dynamic braking. Primary braking system is Electro-pneumatically actuated disc brakes, which is blended with the Dynamic brakes, tachometers on every axle of the unit provide for Wheel Slip/Slide Protection. A solid state Auxiliary Converter provides 110 V DC and 240 V AC supplies, on a BREL the Aux Converter is located on the TSO, whereas on the GEC Alsthom there is one each on the TSO and TSOL. In 2007, plans were drawn up to improve reliability of the BREL, brush, the suppliers / manufacturers of the original traction equipment worked as consultants to assist in retro-fitting the new equipment. The first example to re-enter service was 465181, which rolled out in March 2009, the units with the new equipment are easily recognisable, because they sound similar to the Class 395. In 2005,34 465/2 units were given an extensive refurbishment and this included new interior panelling, new flooring, new lighting, new seat moquette, and the addition of a new first class seating area at the front and rear of the units, amongst other changes. This was done with the intention that they would be cascaded to the outer-suburban routes alongside the Class 375s, from 2010, the whole of the class 465/466 saw another refresh, with new seating covers and Advertisement posters. It wasnt until 465151 was returned in early 2011 that we saw the livery which now seems to be standard. Since December 2010, the 465s have been returned to Slade Green Depot on a weekly basis and this process was finished on 21 May 2012 once all the 465/0/1s had been repainted
12.
Light-emitting diode
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A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated, when a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the band gap of the semiconductor. LEDs are typically small and integrated optical components may be used to shape the radiation pattern, appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still used as transmitting elements in remote-control circuits. The first visible-light LEDs were also of low intensity and limited to red, modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. Early LEDs were often used as indicator lamps for electronic devices and they were soon packaged into numeric readouts in the form of seven-segment displays and were commonly seen in digital clocks. Recent developments in LEDs permit them to be used in environmental, LEDs have allowed new displays and sensors to be developed, while their high switching rates are also used in advanced communications technology. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, as of 2017, LED lights home room lighting are as cheap or cheaper than compact fluorescent lamp sources of comparable output. They are also more energy efficient and, arguably, have fewer environmental concerns linked to their disposal. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide, russian inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide and other semiconductor alloys in 1955. Braunstein observed infrared emission generated by simple diode structures using gallium antimonide, GaAs, indium phosphide, in 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein …had set up a simple optical communications link, the emitted light was detected by a PbS diode some distance away. This signal was fed into an amplifier and played back by a loudspeaker. Intercepting the beam stopped the music and we had a great deal of fun playing with this setup. This setup presaged the use of LEDs for optical communication applications, by October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector
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