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Split-phase electric power

A split-phase or single-phase three-wire system is a type of single-phase electric power distribution. It is the AC equivalent of the original Edison three-wire direct-current system. Its primary advantage is that it saves conductor material over a single-ended single-phase system, while only requiring a single phase on the supply side of the distribution transformer.[1]

Fig. 3. Pole-mounted single-phase transformer with three-wire center-tapped "split-phase" secondary.One side of the primary is connected to ground. On the three secondary terminals, the center tap is also grounded with a short strap to the transformer case.

Fig. 1
Fig. 2

A transformer supplying a three-wire distribution system has a single-phase input (primary) winding. The output (secondary) winding is center-tapped and the center tap connected to a grounded neutral. As shown in Fig. 1. either end to center has half the voltage of end-to-end. Fig. 2 illustrates the phasor diagram of the output voltages for a split-phase transformer. Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system.

In the United States, the practice originated with the DC distribution system developed by Thomas Edison. By connecting pairs of lamps or groups of lamps on the same circuit in series, and doubling the supply voltage, the size of conductors was reduced substantially.

The line to neutral voltage is half the line-to-line voltage. Lighting and small appliances are connected between a line wire and the neutral. Large appliances, such as cooking equipment, space heating, water pumps, clothes dryers, and air conditioners are connected across the two line conductors, requiring less current and smaller conductors than would be needed if the appliances were designed for the lower voltage. [2]

Fig. 4
Fig. 5

If the load were guaranteed to be balanced, then the neutral conductor would not carry any current and the system would be equivalent to a single-ended system of twice the voltage with the line wires taking half the current. This would not need a neutral conductor at all, but would be wildly impractical for varying loads; just connecting the groups in series would result in excessive voltage and brightness variation as lamps are switched on and off.

By connecting the two lamp groups to a neutral, intermediate in potential between the two live legs, any imbalance of the load will be supplied by a current in the neutral, giving substantially constant voltage across both groups. The total current carried in all three wires (including the neutral) will always be twice the supply current of the most heavily loaded half.

For short wiring runs limited by conductor ampacity, this allows three half-sized conductors to be substituted for two full-sized ones, using 75% of the copper of an equivalent single-phase system.

Longer wiring runs are more limited by voltage drop in the conductors. Because the supply voltage is doubled, a balanced load can tolerate double the voltage drop, allowing quarter-sized conductors to be used; this uses 3/8 the copper of an equivalent single-phase system.

In practice, some intermediate value is chosen. For example, if the imbalance is limited to 25% of the total load (half of one half) rather than the absolute worst-case 50%, then conductors 3/8 of the single-phase size will guarantee the same maximum voltage drop, totalling 9/8 of one single-phase conductor, 56% of the copper of the two single-phase conductors.

Balanced power

In a so-called balanced power system, an isolation transformer with a center tap is used to create a separate supply with conductors at a balanced Vnom/2 with respect to ground. The purpose of a balanced power system is to minimize the noise coupled into sensitive equipment from the power supply.

Unlike a three-wire distribution system, the grounded neutral is not distributed to the loads; only line-to-line connections at 120 V are used. A balanced power system is only used for specialized distribution in audio and video production studios, sound and television broadcasting, and installations of sensitive scientific instruments.

The U.S. National Electrical Code provides rules for technical power installations.[3] The systems are not to be used for general-purpose lighting or other equipment, and may use special sockets to ensure only approved equipment is connected to the system. Additionally, technical power systems pay special attention to the way the distribution system is grounded.

A risk of using a balanced power system, in an installation that also uses "conventional" power in the same rooms, is that a user may inadvertently interconnect the power systems together via an intermediate system of audio or video equipment, elements of which might be connected to different power systems.


In Europe, three-phase 230/400 V is most commonly used. However, 230/460 V, three-wire, single-phase systems are used to run farms and small groups of houses when only one (or sometimes two) of the three-phase high-voltage conductors are available. A split-phase final step-down transformer is often used, with the centre-tap earthed and the two halves usually supplying different buildings.

In the UK, electric tools and portable lighting at construction sites are required to be fed from a centre-tapped system with only 55 V between live conductors and the earth. This system is used with 110 V equipment and therefore no neutral conductor is needed. The intention is to reduce the electrocution hazard that may exist when using electrical equipment at a wet or outdoor construction site. Portable transformers that transform single-phase 240 V to this 110 V system are a common piece of construction equipment. Generator sets used for construction sites are equipped to supply it directly.

An incidental benefit is that the filaments of 110 V incandescent lamps used on such systems are thicker and therefore mechanically more rugged than those of 240 V lamps.


In Australia and New Zealand, remote loads are connected to the grid using SWER (single-wire earth return) transmission lines, since it is cheapest to run only one wire. The primary of the transformer is connected between the high voltage line and earth, the secondary is a three-wire single-phase system as described here, the secondary voltage being 230/460 V. Single phase loads are split between the two circuits. Hot water services use both circuits.

North America

This three-wire single phase system is common in North America for residential and light commercial applications. In this case, the voltages are 120 V line to neutral (grounded center tap of transformer) and 240 V line to line. This system allows 120 volts to be supplied for lighting and convenience outlets, and 240 volts for higher-demand appliances such as space heating, air conditioning, kitchen stoves or water heaters. Wiring regulations govern the application of split-phase circuits; since the neutral (return) conductor is not protected by a fuse or circuit breaker, a neutral wire can be shared only by circuits fed from opposite lines of the supply system. Two circuits from opposing lines may share a neutral if both breakers are connected by a bar so that both trip simultaneously ([4] NEC 210.4), this prevents 120 V from feeding across 240 V circuits.


In Sweden split-phase electric power is also used on some railways. The center tap is grounded, one pole is fed with an overhead wire section, while the other wire is used for another section.

Amtrak's 60 Hz traction power system in the Northeast Corridor between New York and Boston also uses split-phase power distribution. Two separate wires are run along the track, the contact wire for the locomotive and an electrically separate feeder wire. Each wire is fed with 25 kV with respect to ground, with 50 kV between them. Autotransformers along the track balance the loads between the contact and feeder wires, reducing resistive losses.

In the UK Network Rail are using autotransformers on all new 50 Hz electrification, and (as of 2014) are converting many old booster transformer [1] installations to autotransformers, to reduce energy losses [2] and exported electromagnetic interference, both of which increase when longer, heavier, or faster trains are introduced, drawing higher peak current from the supply. Note that booster transformers only "boost" the return of traction current through its intended path, the "return conductor", rather than randomly through the earth, and do not boost, but rather reduce, the available voltage at the train, and introduce additional losses. The autotransformer system enforces the traction return current taking its intended path, while reducing the transmission losses, and therefore achieves both required objectives, of controlling return current leakage to earth and ensuring low energy loss, simultaneously. There is an initial cost penalty, because the previous return conductor, insulated to a fairly modest voltage, must be replaced by an anti-phase feeder, insulated to 25 kV, and the autotransformers themselves are larger and more expensive than the previous booster transformers.

See also
  1. Terrell Croft and Wilford Summers (ed), American Electricians' Handbook, Eleventh Edition, McGraw Hill, New York (1987) ISBN 0-07-013932-6, chapter 3, pages 3-10, 3-14 to 3-22.
  2. Gonen, Turan. Electric Power Distribution System Engineering, 2nd ed. CRC Press, 2007, p. 284.
  3. NFPA 70, National Electrical Code 2005, National Fire Protection Association, Inc., Quincy, Massachusetts USA, (2005). no ISBN , articles 640 and 647
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Circular polarization on rubber thread, converted to linear polarization Polarization ( also polarisation ) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations . In a transverse wave, the direction of the oscillation is transverse to the direction of motion of the wave, so the oscillations can have different directions perpendicular to the wave direction. A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical instrument like a guitar string . Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves , such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic wav ...more...

Global Hybrid Cooperation


Global Hybrid Cooperation (formerly called Advanced Hybrid System 2 or AHS2 ) is a set of hybrid vehicle technologies jointly developed by General Motors , Daimler , and Chrysler LLC , with BMW joining in 2005. It uses 2 or 3 planetary gearsets in an automatic transmission : one on the internal combustion engine side (input split) paired with a second (output split), forming the compound split, and possibly one third additional planetary gearset to multiply the number of fixed gear ratios (up to 4). General Motors has stopped using the "AHS2" name as of 2006, preferring to call it simply a "two-mode hybrid system". This technology was named as "Technology of the Year" for 2007 by Automobile Magazine . While Toyota 's Hybrid Synergy Drive may appear similar in that it also combines the power from an Internal combustion engine (ICE) and a pair of electric motor-generators ; however in its current form, Toyota uses only one planetary gearset providing only single mode functionality (i.e. input split only) using ...more...

Coherence (physics)


In physics , two wave sources are perfectly coherent if they have a constant phase difference and the same frequency , and the same waveform . Coherence is an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference . It contains several distinct concepts, which are limiting cases that never quite occur in reality but allow an understanding of the physics of waves, and has become a very important concept in quantum physics. More generally, coherence describes all properties of the correlation between physical quantities of a single wave, or between several waves or wave packets. Interference is nothing more than the addition, in the mathematical sense, of wave functions. A single wave can interfere with itself, but this is still an addition of two waves (see Young's slits experiment ). Constructive or destructive interferences are limit cases, and two waves always interfere, even if the result of the addition is complicated or not remarkable. When interfering, two ...more...

Andhra Pradesh Power Generation Corporation


Andhra Pradesh Power Generation Corporation Limited is power generating organization in Andhra Pradesh . It undertakes operation and maintenance of the power plants and also setting up new power projects alongside upgrading the project's capacity. Under the recommendations of Hittenbhayya committee setup by TDP Govt.. History The government reforms in power sector led to the formation of APGENCO on 28 December 1998 and commenced operations from 1 February 1999. The imbalance of the revenues against the cost of production, no significant reduction in technical losses and energy thefts, high cost purchases from IPP's, other SEB's gradually worsened the financial position of APSEB. APSEB division Government of Andhra Pradesh realizing the declining tendency of the financial position of APSEB and considering the recommendations made by committee it was unbundled into Andhra Pradesh Power Generation Corporation (APGENCO) & Transmission Corporation of Andhra Pradesh Limited (APTRANSCO) on 1 February 1999 by A ...more...

Online Electric Vehicle


OLEV bus in service The Online Electric Vehicle (OLEV) is an electric vehicle that charges wirelessly while moving using electromagnetic induction (the wireless transfer of power through magnetic fields ). It functions by using a segmented "recharging" road that induces a current in "pick-up" modules on the vehicle. OLEV is the first public transport system that used a "recharging" road and was first launched on March 9, 2010 by The Korea Advanced Institute of Science and Technology (KAIST). Mechanical Description The OLEV system is split into two main parts: the segmented "recharging" road and the "pick-up" modules on the vehicle. In the Road In the "recharging" road, slim W-shaped ferrite cores (magnetic cores used in induction) are buried 30 cm underground in a fish bone like structure. Power cables are wrapped around the center of the fish bone structures to make the "primary coils". This design combines the magnetic fields of the two sides of the cables and shapes the fields in a way that maximizes induc ...more...



MainPower New Zealand Limited is an electricity distribution company, based in Rangiora , New Zealand , responsible for electricity distribution to over 37,000 customers in the Canterbury Region north of the Waimakariri River . MainPower was formed in 1994, after the Energy Companies Act 1992 required the North Canterbury Electric Power Board to reform into a commercial power company. More reforms in 1998 required electricity companies nationally to split their lines and retail businesses, with MainPower retaining its lines business and selling its retail business to Contact Energy . MainPower has initiated a number of local generation projects, including the Mount Cass Wind Farm . Electricity network MainPower has a total service area of 11,180 square kilometres (4,320 sq mi), covering the Waimakariri , Hurunui and Kaikoura districts. The area includes the towns of Kaiapoi , Rangiora , Oxford , Woodend , Pegasus , Amberley , Waipara , Culverden , Cheviot , Hanmer Springs and Kaikoura . MainPower takes elect ...more...

Internal combustion engine


Diagram of a cylinder as found in 4-stroke gasoline engines.: C  –  crankshaft . E  – exhaust camshaft . I  – inlet camshaft . P  –  piston . R  –  connecting rod . S  –  spark plug . V  –  valves . red: exhaust, blue: intake. W  –  cooling water jacket .gray structure –  engine block . Diagram describing the ideal combustion cycle by Carnot An internal combustion engine ( ICE ) is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high- temperature and high- pressure gases produced by combustion applies direct force to some component of the engine. The force is applied typically to pistons , turbine blades , rotor or a nozzle . This force moves the component over a distance, transforming chemical energy into useful mechanical energy . The first commercially successful internal combustion engine was created by Étienne Lenoir around 1859 and ...more...

Index of electrical engineering articles


This is an alphabetical list of articles pertaining specifically to electrical and electronics engineering . For a thematic list, please see List of electrical engineering topics . For a broad overview of engineering, see List of engineering topics . For biographies, see List of engineers . A 866A – 15 kV AC – 2D computer graphics – 3Com – Abrasion (mechanical) – AC adapter – AC power plugs and sockets – AC power – AC/AC converter – AC/DC receiver design – AC/DC conversion – Active rectification – Actuator – Adaptive control – Adjustable-speed drive – Advanced Z-transform – Affinity law – Agbioeletric – AIEE – All American Five – Alloy – ALOHAnet – Alpha–beta transformation – Altair 8800 – Alternating current – Alternator (auto) – Alternator synchronization -- Alternator – Altitude – Aluminium smelting – AIEE – Ammeter – Amorphous metal transformer – Ampacity – Ampere – Ampère's circuital law – Ampère's force law – Ampère's law – Amplidyne – Amplifier – Amplitude modulation – Analog circuit – Analog filter – ...more...

Electrical wiring in North America


Electrical wiring in North America follows regulations and standards for installation of building wiring. Terminology Although much of the electrician 's field terminology matches that of the electrical codes , usages can vary: Neutral wire is the return conductor of a circuit; in building wiring systems, the neutral wire is connected to earth ground at least at one point. North American standards state that the neutral is neither switched nor fused except in very narrowly defined circumstances. The neutral is connected to the center tap of the power company transformer of a split-phase system, or the center of the wye connection of a polyphase power system. Hot is any conductor (wire or otherwise) connected with an electrical system that has electric potential relative to electrical ground or neutral. Ground is a safety conductor with a low impedance path to earth. It is often called the "ground wire," or safety ground. It is either bare or has green insulation. Leg as in “hot leg” refers to one of multiple ...more...

Low-voltage network


A low-voltage network or secondary network is a part of electric power distribution which carries electric energy from distribution transformers to electricity meters of end customers. Secondary networks are operated at a low voltage level, which is typically equal to the mains voltage of electric appliances. Most modern secondary networks are operated at AC rated voltage of 100–120 or 230–240  volts , at the frequency of 50 or 60  hertz (see mains electricity by country ). Operating voltage, required number of phases ( three-phase or single-phase ) and required reliability dictate topology and configuration of the network. The simplest form are radial service drop lines from the transformer to the customer premises. Low-voltage radial feeders supply multiple customers. For increased reliability, so-called spot networks and grid networks provide supply of customers from multiple distribution transformers and supply paths. Electric wiring can be realized by overhead power lines , aerial or underground power ca ...more...

Thyristor switched capacitor


A thyristor switched capacitor (TSC) is a type of equipment used for compensating reactive power in electrical power systems. It consists of a power capacitor connected in series with a bidirectional thyristor valve and, usually, a current limiting reactor ( inductor ). The thyristor switched capacitor is an important component of a Static VAR Compensator (SVC), where it is often used in conjunction with a thyristor controlled reactor (TCR). Static VAR compensators are a member of the Flexible AC transmission system (FACTS) family. Circuit diagram A TSC is usually a three-phase assembly, connected either in a delta or a star arrangement. Unlike the TCR, a TSC generates no harmonics and so requires no filtering. For this reason, some SVCs have been built with only TSCs . This can lead to a relatively cost-effective solution where the SVC only requires capacitive reactive power, although a disadvantage is that the reactive power output can only be varied in steps. Continuously variable reactive power output ...more...

Mobile office


Mobile Office on the Streets of London. A mobile office is an office built within a truck, motorhome , trailer or purpose built shipping container . Most common are towable offices built on an axled iron frame for easy relocation. Mobile field offices are often found on construction sites , or at disaster scenes where a temporary office space is needed. Typically, mobile offices in North America feature a single phase split (240 volt center-tapped) electric service that is connected to a nearby source of power, to run small window-unit air conditioners, and the like. There are many types of companies that sell, lease, rent new and used storage containers , portable buildings or modular buildings . This type of construction shortens the construction period as the building can be built in a factory in as little as six weeks and the site and utility work can be done in conjunction with the construction of the building. The term " mobile office " is also used for the workspace of salespeople or similar, working o ...more...

DC-to-DC converter


A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter . Power levels range from very low (small batteries) to very high (high-voltage power transmission). History Before the development of power semiconductors and allied technologies, one way to convert the voltage of a DC supply to a higher voltage, for low-power applications, was to convert it to AC by using a vibrator , followed by a step-up transformer and rectifier . For higher power an electric motor was used to drive a generator of the desired voltage (sometimes combined into a single "dynamotor" unit, a motor and generator combined into one unit, with one winding driving the motor and the other generating the output voltage). These were relatively inefficient and expensive procedures used only when there was no alternative, as to power a car radio (which then used thermionic valves/tubes requiring much higher ...more...

Power over Ethernet


In this configuration, an Ethernet connection includes power over Ethernet (gray cable looping below), and a PoE splitter provides a separate data cable (gray, looping above) and power cable (black, also looping above) for a wireless access point . The splitter is the silver and black box in the middle between the wiring junction box (left) and the WAP (right). The PoE connection eliminates the need for a nearby power outlet . In another common configuration, the WAP or other connected device includes internal PoE splitting and the external splitter is not used. Power over Ethernet or PoE describes any of several standard or ad-hoc systems which pass electric power along with data on twisted pair Ethernet cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points , IP cameras , and VoIP phones . There are several common techniques for transmitting power over Ethernet cabling. Two of them have been standardized by IEEE 802.3 since 2003. Thes ...more...

Nevada Power Company


Nevada Power Company was a Las Vegas -based company that produced, distributed, and sold electricity in the southern part of the state of Nevada . In 2005, it had over 700,000 electric customers in parts of three Nevada counties — a service area of more than 4,000 square miles (10,000 km ). In 1998, Nevada Power merged with Nevada's other major utility, Sierra Pacific Resources . It continued as a subsidiary of Sierra Pacific until 2005, when the company changed its name to NV Energy . History Nevada Power was founded on March 20, 1906 as Consolidated Power and Telephone , the electric and telephone company for the year-old town of Las Vegas. It split into two companies in 1929. The telephone company, Southern Nevada Telephone Company , eventually was acquired by Centel . It was later owned by Sprint and Embarq , and is now part of CenturyLink . The power company became Southern Nevada Power . In 1937, it became the first utility to receive power from the Hoover Dam . As the Las Vegas Valley boomed in the 195 ...more...

Phase-shift keying


Phase-shift keying ( PSK ) is a digital modulation process which conveys data by changing (modulating) the phase of a reference signal (the carrier wave ). The modulation occurs by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs , RFID and Bluetooth communication. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits . Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator , which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal – such a system is termed coherent (and referred to as CPSK). Alternatively, ...more...

ER9 electric trainset


For servicing suburban commuter lines, electrified on 25 kV, AC, the Railcar Manufacturing Plant of Riga produced ER9, then ER9p electric trainsets in the 1966-1975 period. The mass production of these trains had begun in 1964. Railcar types Three types of cars were manufactured for these trains, which were motor, trailer, and cab-trailer. The minimal quantity of cars is four (2 motor & 2 cab-trailer cars). The maximal quantity was twelve (6 motor cars, 4 trailers, and 2 cab-trailers.) The trains could be controlled and/or operated only from cab cars. Design and construction Railcar bodies The railcar bodies utilise a frameless construction similar to the ER2 series trainsets, with a number of modifications due to the different equipment arrangement, such as AC transformers and rectifiers. The car entrances are fitted for both high and low platforms. Like most Soviet rollingstock, the cars have SA-3 automatic couplers . The bodies are supported by two twin-axle bogies. The bogie frames are of a H-shaped ...more...

Antenna (radio)


In radio an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver . In transmission , a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception , an antenna intercepts some of the power of an electromagnetic wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified . Antennas are essential components of all radio equipment, and are used in radio broadcasting , broadcast television , two-way radio , communications receivers , radar , cell phones , satellite communications and other devices. An antenna is an array of conductors ( elements ), electrically connected to the receiver or transmitter. During transmission, the oscillating current applied to the antenna by a transmitter creates an oscillating electric field and magnetic field a ...more...

High-voltage direct current


A high-voltage, direct current ( HVDC ) electric power transmission system (also called a power super highway or an electrical super highway ) uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current (AC) systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. For underwater power cables , HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may still be justified, due to other benefits of direct current links. HVDC allows power transmission between unsynchronized AC transmission systems. Since the power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power. HVDC also allows transfer of power between grid systems running at differ ...more...

Earth leakage circuit breaker


An Earth-leakage circuit breaker ( ELCB ) is a safety device used in electrical installations with high Earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected. Once widely used, more recent installations instead use residual current circuit breakers which instead detect leakage current directly. Purpose The main purpose of Earth leakage protectors is to prevent injury to humans and animals due to electric shock. History This is a category of devices, which are used to protect instruments, circuits and operators, while Earth leakage. Early ELCBs are voltage sensing devices, which are now replaced by current sensing devices (RCD/RCCB). Usually voltage sensing devices are called ELCB and current sensing devices are called RCCB. Voltage sensing ELCBs were first introduced about sixty years ago. Current sensing ELCBs were first introduced about forty years ago. For many years, the voltage opera ...more...

Baldwin-Westinghouse electric locomotives


Baldwin , the locomotive manufacturer, and Westinghouse , the promoter of AC (alternating current) electrification, joined forces in 1895 to develop AC railway electrification . Soon after the turn of the century, they marketed a single-phase high-voltage system to railroads. From 1904-05 they supplied locomotives carrying a joint builder's plate to a number of American railroads, particularly for the New Haven (the New York, New Haven and Hartford Railroad ) line from New York to New Haven, and other New Haven lines. A New Haven EP-1 electric locomotive, circa 1907. Note the small DC pantograph between the two larger AC pantographs. Baldwin-Westinghouse electric locomotives Experimental locomotives In 1895 a box-cab locomotive 32 feet (9.8 m) long with two four-wheel trucks and weighing 46 short tons (41.1 long tons; 41.7 t) was built at the East Pittsburg ( Pennsylvania ) works of Westinghouse. It was used for more than a decade of AC and DC experimentation. Sold in 1906 to the Lackawanna & Wyoming Val ...more...



R-410A , sold under the trademarked names Suva 410A , Forane 410A , Puron , EcoFluor R410 , Genetron R410A , and AZ-20 , is a zeotropic , but near- azeotropic mixture of difluoromethane (CHF, called R-32) and pentafluoroethane (CHFCF, called R-125), which is used as a refrigerant in air conditioning applications. R-410A cylinders are colored pink . Environmental effects Unlike alkyl halide refrigerants that contain bromine or chlorine, R-410A (which contains only fluorine) does not contribute to ozone depletion , and is therefore becoming more widely used, as ozone-depleting refrigerants like R-22 are phased out. However, it has a high global warming potential (500 times the effect of carbon dioxide ), similar to that of R-22. Since R-410A allows for higher SEER ratings than an R-22 system, by reducing power consumption, the overall impact on global warming of R-410A systems will be substantially lower than that of R-22 systems due to reduced greenhouse gas emissions from power plants. History R-410A was in ...more...

Guitar wiring


Guitar wiring refers to the electrical components, and interconnections thereof, inside an electric guitar (and, by extension, other electric instruments like the bass guitar or mandolin ). It most commonly consists of pickups , potentiometers to adjust volume and tone, a switch to select between different pickups (if the instrument has more than one), and the output socket . There may be additional controls for specific functions; the most common of these are described below. Electrical components Underside of a 1981 Fender Lead I pickguard, showing the wiring. The following section describes the most common components found inside an electric guitar. Pickups Pickups convert the mechanical energy of a vibrating string to an electrical signal, allowing it to be amplified, processed and reproduced. Pickups vary greatly in construction, size, types of materials used, as well as various electrical properties, but are generally divided into two categories – single-coil and double-coil (also known as humbucker ). ...more...

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