1.
Alternating current
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Alternating current, is an electric current which periodically reverses direction, whereas direct current flows only in one direction. A common source of DC power is a cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, the usual waveform of alternating current in most electric power circuits is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves, audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information encoded onto the AC signal and these currents typically alternate at higher frequencies than those used in power transmission. Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer, use of a higher voltage leads to significantly more efficient transmission of power. The power losses in a conductor are a product of the square of the current and this means that when transmitting a fixed power on a given wire, if the current is halved, the power loss will be four times less. Power is often transmitted at hundreds of kilovolts, and transformed to 100–240 volts for domestic use, high voltages have disadvantages, such as the increased insulation required, and generally increased difficulty in their safe handling. In a power plant, energy is generated at a convenient voltage for the design of a generator, near the loads, the transmission voltage is stepped down to the voltages used by equipment. Consumer voltages vary somewhat depending on the country and size of load, the voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate. Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world, high-voltage direct-current electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. HVDC systems, however, tend to be expensive and less efficient over shorter distances than transformers. Three-phase electrical generation is very common, the simplest way is to use three separate coils in the generator stator, physically offset by an angle of 120° to each other. Three current waveforms are produced that are equal in magnitude and 120° out of phase to each other, if coils are added opposite to these, they generate the same phases with reverse polarity and so can be simply wired together. In practice, higher pole orders are commonly used, for example, a 12-pole machine would have 36 coils. The advantage is that lower rotational speeds can be used to generate the same frequency, for example, a 2-pole machine running at 3600 rpm and a 12-pole machine running at 600 rpm produce the same frequency, the lower speed is preferable for larger machines. If the load on a system is balanced equally among the phases. Even in the worst-case unbalanced load, the current will not exceed the highest of the phase currents
2.
Electric power
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Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second, Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes by the power industry through an electric power grid. Electric power is sold by the kilowatt hour which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using an electricity meter, which keeps a total of the electric energy delivered to a customer. Electrical power provides a low form of energy and can be carried long distances and converted into other forms of energy such as motion. Electric power, like power, is the rate of doing work, measured in watts. The term wattage is used colloquially to mean electric power in watts, the potential energy of the charges due to the voltage between the terminals is converted to kinetic energy in the device. These devices are called passive components or loads, they consume electric power from the circuit, converting it to other forms of such as mechanical work, heat, light. Examples are electrical appliances, such as bulbs, electric motors. In alternating current circuits the direction of the voltage periodically reverses, devices in which this occurs are called active devices or power sources, such as electric generators and batteries. Some devices can be either a source or a load, depending on the voltage, for example, a rechargeable battery acts as a source when it provides power to a circuit, but as a load when it is connected to a battery charger and is being recharged. Since electric power can flow either into or out of a component, Electric power flowing out of a circuit into a component is arbitrarily defined to have a positive sign, while power flowing into a circuit from a component is defined to have a negative sign. Thus passive components have positive power consumption, while power sources have negative power consumption and this is called the passive sign convention. In alternating current circuits, energy storage such as inductance and capacitance may result in periodic reversals of the direction of energy flow. The portion of power flow that, averaged over a cycle of the AC waveform. That portion of power due to stored energy, that returns to the source in each cycle, is known as reactive power. Real power is represented as a vector and reactive power is represented as a vertical vector
3.
Voltage
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Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential energy between two points per unit electric charge. The voltage between two points is equal to the work done per unit of charge against an electric field to move the test charge between two points. This is measured in units of volts, voltage can be caused by static electric fields, by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these three. A voltmeter can be used to measure the voltage between two points in a system, often a reference potential such as the ground of the system is used as one of the points. A voltage may represent either a source of energy or lost, used, given two points in space, x A and x B, voltage is the difference in electric potential between those two points. Electric potential must be distinguished from electric energy by noting that the potential is a per-unit-charge quantity. Like mechanical potential energy, the zero of electric potential can be chosen at any point, so the difference in potential, i. e. the voltage, is the quantity which is physically meaningful. The voltage between point A to point B is equal to the work which would have to be done, per unit charge, against or by the electric field to move the charge from A to B. The voltage between the two ends of a path is the energy required to move a small electric charge along that path. Mathematically this is expressed as the integral of the electric field. In the general case, both an electric field and a dynamic electromagnetic field must be included in determining the voltage between two points. Historically this quantity has also called tension and pressure. Pressure is now obsolete but tension is used, for example within the phrase high tension which is commonly used in thermionic valve based electronics. Voltage is defined so that negatively charged objects are pulled towards higher voltages, therefore, the conventional current in a wire or resistor always flows from higher voltage to lower voltage. Current can flow from lower voltage to higher voltage, but only when a source of energy is present to push it against the electric field. This is the case within any electric power source, for example, inside a battery, chemical reactions provide the energy needed for ion current to flow from the negative to the positive terminal. The electric field is not the only factor determining charge flow in a material, the electric potential of a material is not even a well defined quantity, since it varies on the subatomic scale. A more convenient definition of voltage can be found instead in the concept of Fermi level, in this case the voltage between two bodies is the thermodynamic work required to move a unit of charge between them
4.
Utility frequency
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The utility frequency, line frequency or mains frequency is the nominal frequency of the oscillations of alternating current in an electric power grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas, current usage by country or region is given in the list of mains power around the world. During the development of electric power systems in the late 19th and early 20th centuries. Large investment in equipment at one frequency made standardization a slow process, however, as of the turn of the 21st century, places that now use the 50 Hz frequency tend to use 220–240 V, and those that now use 60 Hz tend to use 100–127 V. Both frequencies coexist today with no technical reason to prefer one over the other. Unless specified by the manufacturer to operate on both 50 and 60 Hz, appliances may not operate efficiently or even if used on anything other than the intended frequency. In practice, the frequency of the grid varies around the nominal frequency, reducing when the grid is heavily loaded. However, most utilities will adjust the frequency of the grid over the course of the day to ensure a constant number of cycles occur and this is used by some clocks to accurately maintain their time. Several factors influence the choice of frequency in an AC system, lighting, motors, transformers, generators and transmission lines all have characteristics which depend on the power frequency. All of these factors interact and make selection of a power frequency a matter of considerable importance, the best frequency is a compromise between contradictory requirements. When large central generating stations became practical, the choice of frequency was made based on the nature of the intended load, eventually improvements in machine design allowed a single frequency to be used both for lighting and motor loads. A unified system improved the economics of electricity production, since system load was more uniform during the course of a day, the first applications of commercial electric power were incandescent lighting and commutator-type electric motors. Both devices operate well on DC, but DC could not be changed in voltage. Commutator-type motors do not operate well on high-frequency AC, because the changes of current are opposed by the inductance of the motor field. Though commutator-type universal motors are common in AC household appliances and power tools, they are small motors, less than 1 kW. The induction motor was found to work well on frequencies around 50 to 60 Hz, once AC electric motors became common, it was important to standardize frequency for compatibility with the customers equipment. Generators operated by slow-speed reciprocating engines will produce lower frequencies, for a number of poles, than those operated by, for example. For very slow prime mover speeds, it would be costly to build a generator with enough poles to provide a high AC frequency, as well, synchronizing two generators to the same speed was found to be easier at lower speeds
5.
AC power plugs and sockets
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AC power plugs and sockets are devices that allow electrically operated equipment to be connected to the primary alternating current power supply in a building. Electrical plugs and sockets differ in voltage and current rating, shape, size, Plugs and sockets for portable appliances started becoming available in the 1880s, to replace connections to light sockets with easier to use wall-mounted outlets. A proliferation of types developed to address the issues of convenience, today there are approximately 20 types in common use around the world, and many obsolete socket types are still found in older buildings. The International Electrotechnical Commission publishes IEC60050, the International Electrotechnical Vocabulary, the plug has protruding pins or, in US terminology, blades that fit into matching slots or holes in the sockets. In this article, the plug is used in the sense defined by IEC60050. Sockets are designed to prevent exposure of bare energised contacts, sockets may also have protruding exposed contacts, but these are used exclusively for grounding. These may include plugs with insulated sleeves, recessed sockets, sockets with blocking shutters, the term plug is in general and technical use in all forms of English, common alternatives being power plug, electric plug, and plug top. The normal technical term for an AC power socket is socket-outlet, in British English the general term is socket, but there are numerous common alternatives, including power point, plug socket, wall socket, and wall plug. In American English receptacle is used in official standards and codes such as the NEMA connector standard, there is also colloquial use of socket in American English. A socket may be surrounded by a decorative or protective cover called a plate, face plate, outlet cover, socket cover. In some designs this is a piece with the socket itself, bought. Electrical sockets for single phase domestic, commercial and light industrial purposes generally provide two or three electrical connections to the supply conductors. Two-pin sockets normally provide neutral and line connections, both of which carry current and are defined as live parts, Neutral is usually very near to earth potential, usually being earthed either at the distribution board or at the substation. Line carries the full supply voltage relative to the neutral, three-pin sockets provide, in addition, a protective earth connection for exposed metal parts of an appliance. An adaptor is defined in IEC60050 as a portable accessory constructed as an integral unit incorporating both a plug portion and one or more socket-outlet portions, when electricity was first introduced into houses, it was primarily used for lighting. At that time, many electricity companies operated a system where the cost of electricity for lighting was lower than that for other purposes. This led to portable appliances being connected to light bulb sockets using lampholder plugs, as electricity became a common method of operating labour-saving appliances, a safe means of connection to the electric system other than using a light socket was needed. Smith subsequently received US patent 311,616 for the device in 1885
6.
Electrical grid
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An electrical grid is an interconnected network for delivering electricity from suppliers to consumers. Power stations may be located near a source, at a dam site, or to take advantage of renewable energy sources. They are usually large to take advantage of the economies of scale. The electric power which is generated is stepped up to a voltage at which it connects to the electric power transmission network. The bulk power transmission network will move the power long distances, sometimes across international boundaries, on arrival at a substation, the power will be stepped down from a transmission level voltage to a distribution level voltage. As it exits the substation, it enters the distribution wiring, finally, upon arrival at the service location, the power is stepped down again from the distribution voltage to the required service voltage. Electrical grids vary in size covering an single building through national grids which cover whole countries. Early electric energy was produced near the device or service requiring that energy, in the 1880s, electricity competed with steam, hydraulics, and especially coal gas. Coal gas was first produced on premises but later evolved into gasification plants that enjoyed economies of scale. In the industrialized world, cities had networks of piped gas, but gas lamps produced poor light, wasted heat, made rooms hot and smoky, and gave off hydrogen and carbon monoxide. In the 1880s electric lighting soon became advantageous compared to gas lighting, Electric utility companies took advantage of economies of scale and moved to centralized power generation, distribution, and system management. With long distance power transmission it became possible to interconnect stations to balance load, merz was appointed head of a Parliamentary Committee and his findings led to the Williamson Report of 1918, which in turn created the Electricity Supply Bill of 1919. The bill was the first step towards an integrated electricity system, the Electricity Act of 1926 led to the setting up of the National Grid. The Central Electricity Board standardized the nations electricity supply and established the first synchronized AC grid and this started operating as a national system, the National Grid, in 1938. In the United States in the 1920s, utilities formed joint-operations to share peak load coverage, no longer were electric utilities built as vertical monopolies, where generation, transmission and distribution were handled by a single company. Now, the three stages could be split among various companies, in an effort to provide accessibility to high voltage transmission. The Energy Policy Act of 2005 allowed incentives and loan guarantees for energy production. In France, electrification began in the 1900s, with 700 communes in 1919, and 36,528 in 1938
7.
Mains electricity by country
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Every country has differing rules regarding distribution of electricity for portable appliances and lighting. Voltage, frequency, and plug type vary widely, but large regions may use common standards, physical compatibility of receptacles may not ensure compatibility of voltage, frequency, or connection to earth ground. This article lists the type, voltage and frequency commonly expected for many territories. In some areas, older standards may still exist, foreign enclaves or buildings frequented by tourists may support plugs not otherwise used in a country, for the convenience of travellers. The International Electrotechnical Commission publishes a web microsite World Plugs which provides the source for this page. World Plugs includes some history, a description of plug types, and a list of countries giving the type used, in this article, the term plug is used in the sense defined by IEC60050. IEC 60884-1 para 9.2 does stipulate that, it not be possible, within a given system. IEC 60884-1 para 6.1 defines the preferred voltage ratings for single phase plugs, any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. The lettering system used here is from World Plugs, which defines the names and gives a list of what plug types are used where. Type A makes specific reference to American and Japanese plugs, as does Type B, Type C is specifically identified as the Europlug and described as a plug which fits into any socket that accepts 4. 0–4.8 mm round contacts on 19 mm centres. Type D is specifically rated at 5 A, Type E and Type F are specifically rated at 16 A and defined as having 4.8 mm pins on 19 mm centres. Type G is identified as the fused British plug, the Type H plug is described as unique to Israel. Type I is described as having both 10 A and 15 A ratings, Type J is rated at 10 A and is differentiated from Type N. The Type K rating is not shown, the Type L description includes both ratings and pin sizes. Type M is described as looking similar to Type D, the Type N description is of the two variations of Brazilian plug, however, the original plug and socket is defined in IEC 60906-1 and has been adopted as a South African national Standard. The Brazilian version is non-compliant with the IEC standard, not all plugs are included in the letter system, for example, there is no designation for the plug defined by the Thai National Standard TIS116-2549. IEC World Plugs is ambiguous in some areas, it does not reference national technical standards that define the dimensions, Plugs will usually mate with sockets which are intended to accept plugs classified under the same letter type, but there is no guarantee of this. Despite this, World Plugs lists seven territories as using only Type C and this may be for a number of reasons, for instance the Thai standard TIS 166-2549 includes a socket which will also accept Types A, B and C plugs as well as the Thai plug
8.
Earthing system
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The point of reference is the Earths conductive surface, or on ships, the surface of the sea. The choice of earthing system can affect the safety and electromagnetic compatibility of the installation and this article only concerns grounding for electrical power. As part of an earth return power and signal lines, such as were used for low wattage power delivery. In radio, as a plane for large monopole antenna. As ancillary voltage balance for other kinds of antennas, such as dipoles. As the feed-point of a dipole antenna for VLF and ELF radio. A protective conductor avoids electric shock hazard by keeping the surface of connected devices close to earth potential in fault conditions. In the event of a fault, a current is allowed to flow to earth by the earthing system, if this is excessive the overcurrent protection of a fuse or circuit breaker will operate, thereby protecting the circuit and removing any fault-induced voltages from the exposed-conductive surfaces. This disconnection is a tenet of modern wiring practice and is referred to as the Automatic Disconnection of Supply. Protection is therefore by limiting the elevation of voltage and its duration, the alternative is defense in depth – such as reinforced or double insulation – where multiple independent failures must occur to expose a dangerous condition. A functional earth connection serves a purpose other than electrical safety, other examples of devices that use functional earth connections include surge suppressors and electromagnetic interference filters. On electricity networks with a voltage of 240 V to 1. In the United States and Canada,120 V power outlets installed before the mid-1960s generally did not include a ground pin, in the developing world, local wiring practice may not provide a connection to an earthing pin of an outlet. In the absence of an earth, devices needing an earth connection often used the supply neutral. Many 110 V appliances have polarized plugs to maintain a distinction between line and neutral, but using the neutral for equipment earthing can be highly problematical. Line and neutral might be reversed in the outlet or plug. Even normal load currents in the neutral might generate hazardous voltage drops, for these reasons, most countries have now mandated dedicated protective earth connections that are now almost universal. In such case a residual current detector is installed to detect the current leaking to ground, international standard IEC60364 distinguishes three families of earthing arrangements, using the two-letter codes TN, TT, and IT
9.
Volt
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The volt is the derived unit for electric potential, electric potential difference, and electromotive force. One volt is defined as the difference in potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It is also equal to the difference between two parallel, infinite planes spaced 1 meter apart that create an electric field of 1 newton per coulomb. Additionally, it is the difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can also be expressed as amperes times ohms, watts per ampere, or joules per coulomb, for the Josephson constant, KJ = 2e/h, the conventional value KJ-90 is used, K J-90 =0.4835979 GHz μ V. This standard is typically realized using an array of several thousand or tens of thousands of junctions. Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc. in the water-flow analogy sometimes used to explain electric circuits by comparing them with water-filled pipes, voltage is likened to difference in water pressure. Current is proportional to the diameter of the pipe or the amount of water flowing at that pressure. A resistor would be a reduced diameter somewhere in the piping, the relationship between voltage and current is defined by Ohms Law. Ohms Law is analogous to the Hagen–Poiseuille equation, as both are linear models relating flux and potential in their respective systems, the voltage produced by each electrochemical cell in a battery is determined by the chemistry of that cell. Cells can be combined in series for multiples of that voltage, mechanical generators can usually be constructed to any voltage in a range of feasibility. High-voltage electric power lines,110 kV and up Lightning, Varies greatly. Volta had determined that the most effective pair of metals to produce electricity was zinc. In 1861, Latimer Clark and Sir Charles Bright coined the name volt for the unit of resistance, by 1873, the British Association for the Advancement of Science had defined the volt, ohm, and farad. In 1881, the International Electrical Congress, now the International Electrotechnical Commission and they made the volt equal to 108 cgs units of voltage, the cgs system at the time being the customary system of units in science. At that time, the volt was defined as the difference across a conductor when a current of one ampere dissipates one watt of power. The international volt was defined in 1893 as 1/1.434 of the emf of a Clark cell and this definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of reproducible units was abandoned in 1948. Prior to the development of the Josephson junction voltage standard, the volt was maintained in laboratories using specially constructed batteries called standard cells
10.
Root mean square
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In statistics and its applications, the root mean square is defined as the square root of mean square. The RMS is also known as the mean and is a particular case of the generalized mean with exponent 2. RMS can also be defined for a continuously varying function in terms of an integral of the squares of the values during a cycle. For a cyclically alternating electric current, RMS is equal to the value of the current that would produce the same average power dissipation in a resistive load. In Estimation theory the mean square error of an estimator is a measure of the imperfection of the fit of the estimator to the data. The RMS value of a set of values is the root of the arithmetic mean of the squares of the values. In Physics, the RMS current is the value of the current that dissipates power in a resistor. In the case of a set of n values, the RMS x r m s =1 n, the RMS over all time of a periodic function is equal to the RMS of one period of the function. The RMS value of a function or signal can be approximated by taking the RMS of a sequence of equally spaced samples. Additionally, the RMS value of various waveforms can also be determined without calculus, in the case of the RMS statistic of a random process, the expected value is used instead of the mean. If the waveform is a sine wave, the relationships between amplitudes and RMS are fixed and known, as they are for any continuous periodic wave. However, this is not true for a waveform which may or may not be periodic or continuous. For a zero-mean sine wave, the relationship between RMS and peak-to-peak amplitude is, Peak-to-peak =22 × R M S ≈2.8 × R M S, for other waveforms the relationships are not the same as they are for sine waves. Waveforms made by summing known simple waveforms have an RMS that is the root of the sum of squares of the component RMS values, if the component waveforms are orthogonal. R M S Total = R M S12 + R M S22 + ⋯ + R M S n 2 A special case of this, another special case, useful in statistics, is given in #Relationship to other statistics. Electrical engineers often need to know the power, P, dissipated by an electrical resistance and it is easy to do the calculation when there is a constant current, I, through the resistance. Average power can also be using the same method that in the case of a time-varying voltage, V, with RMS value VRMS. This equation can be used for any waveform, such as a sinusoidal or sawtooth waveform
11.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
12.
Single-phase electric power
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In electrical engineering, single-phase electric power is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, single phase AC power systems peak in voltage at 90° and 270°. Because of the rises and falls in voltage, power is not delivered at a constant rate, the waveforms of the three supply conductors are offset from one another in time by one-third of their period. When the three phases are connected to windings around the interior of a motor stator, they produce a magnetic field. The primary difference between phase and three phase AC power is the constancy of delivery. Standard frequencies of single-phase power systems are either 50 or 60 Hz, special single-phase traction power networks may operate at 16.67 Hz or other frequencies to power electric railways. In some countries such as the United States, single phase is divided in half to create split-phase electric power for household appliances. No arrangement of transformers can convert a single-phase load into a load on a polyphase system. A single-phase load may be powered from a distribution system either by connection between a phase and neutral or by connecting the load between two phases. The load device must be designed for the voltage in each case, in North America, a typical three-phase system will have 208 volts between the phases and 120 volts between phase and neutral. If heating equipment designed for the 240-volt three-wire single phase system is connected to two phases of a 208 volt supply, it will only produce 75% of its heating effect. Single-phase motors may have taps to allow their use on either 208 V or 240 V supplies, on higher voltage systems where a single phase transformer is in use to supply a low voltage system, the method of splitting varies. In North American utility distribution practice, the primary of the transformer is wired across a single high voltage feed wire and neutral. Rural distribution may be a single phase at a medium voltage, in Britain the step-down primary is wired phase-phase. Single-phase power distribution is used especially in rural areas, where the cost of a three-phase distribution network is high and motor loads are small. High power systems, say hundreds of kVA or larger, are always three phase. The largest supply normally available as single phase varies according to the standards of the electrical utility, in the UK a single-phase household supply may be rated 100 A or even 125 A, meaning that there is little need for 3 phase in a domestic or small commercial environment. Much of the rest of Europe has traditionally had much smaller limits on the size of single phase supplies resulting in houses being supplied with 3 phase
13.
Three-phase electric power
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Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of system and is the most common method used by electrical grids worldwide to transfer power. It is also used to large motors and other heavy loads. The three-phase system was invented by Galileo Ferraris, Mikhail Dolivo-Dobrovolsky, Jonas Wenström. The common reference is usually connected to ground and often to a current-carrying conductor called the neutral. Due to the difference, the voltage on any conductor reaches its peak at one third of a cycle after one of the other conductors. This phase delay gives constant power transfer to a linear load. It also makes it possible to produce a magnetic field in an electric motor. In a three-phase system feeding a balanced and linear load, the sum of the currents of the three conductors is zero. In other words, the current in each conductor is equal in magnitude to the sum of the currents in the two, but with the opposite sign. The return path for the current in any phase conductor is the two phase conductors.5 times as many wires. Thus, the ratio of capacity to conductor material is doubled, the same ratio of capacity to conductor material can also be attained with a center-grounded single-phase system. However, two-phase power results in a smooth torque in a generator or motor. Three-phase systems may also have a wire, particularly in low-voltage distribution. The neutral allows three separate single-phase supplies to be provided at a constant voltage and is used for supplying groups of domestic properties which are each single-phase loads. The connections are arranged so that, as far as possible in each group, further up the distribution system, the currents are usually well balanced. Transformers may be wired in a way that they have a secondary but a three-wire primary while allowing unbalanced loads. This makes it possible to reduce the size of the neutral conductor because it carries little or no current, with a balanced load, all the phase conductors carry the same current and so can be the same size
14.
Libya
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The three traditional parts of the country are Tripolitania, Fezzan and Cyrenaica. With an area of almost 1.8 million square kilometres, Libya is the fourth largest country in Africa, Libya has the 10th-largest proven oil reserves of any country in the world. The largest city and capital, Tripoli, is located in western Libya, the other large city is Benghazi, which is located in eastern Libya. Libya has been inhabited by Berbers since the late Bronze Age, the Phoenicians established trading posts in western Libya, and ancient Greek colonists established city-states in eastern Libya. Libya was variously ruled by Carthaginians, Persians, Egyptians and Greeks before becoming a part of the Roman Empire, Libya was an early center of Christianity. After the fall of the Western Roman Empire, the area of Libya was mostly occupied by the Vandals until the 7th century, in the 16th century, the Spanish Empire and the Knights of St John occupied Tripoli, until Ottoman rule began in 1551. Libya was involved in the Barbary Wars of the 18th and 19th centuries, Ottoman rule continued until the Italian occupation of Libya resulted in the temporary Italian Libya colony from 1911 to 1943. During the Second World War Libya was an important area of warfare in the North African Campaign, the Italian population then went into decline. Libya became an independent kingdom in 1951, a military coup in 1969 overthrew King Idris I, beginning a period of sweeping social reform. Since then, Libya has experienced a period of instability, the European Union is involved in an operation to disrupt human trafficking networks exploiting refugees fleeing from wars in Africa for Europe. At least two political bodies claim to be the government of Libya, the Council of Deputies is internationally recognized as the legitimate government, but it does not hold territory in the capital, Tripoli, instead meeting in the Cyrenaica city of Tobruk. Parts of Libya are outside of either governments control, with various Islamist, rebel, the United Nations is sponsoring peace talks between the Tobruk and Tripoli-based factions. An agreement to form an interim government was signed on 17 December 2015. Under the terms of the agreement, a nine-member Presidency Council, the leaders of the new government, called the Government of National Accord, arrived in Tripoli on 5 April 2016. Since then the GNC, one of the two governments, has disbanded to support the new GNA. The name Libya was introduced in 1934 for Italian Libya, reviving the name for Northwest Africa. The name was based on use in 1903 by Italian geographer Federico Minutilli. It was intended to supplant terms applied to Ottoman Tripolitania, the region of what is today Libya having been ruled by the Ottoman Empire from 1551 to 1911
15.
Anarchy
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Anarchy is the condition of a society, entity, group of people, or a single person that rejects hierarchy. The term originally meant leaderlessness, but in 1840, Pierre-Joseph Proudhon adopted the term in his treatise What Is Property, to refer to a new political philosophy, anarchism, which advocates stateless societies based on voluntary associations. In practical terms, anarchy can refer to the curtailment or abolition of traditional forms of government and it could also mean a nation or anywhere on earth that is inhabited, that has no system of government or central rule. The word anarchy comes from the ancient Greek ἀναρχία, which combines ἀ, not, without and ἀρχή, ruler, leader, thus, the term refers to a person or society without rulers or without leaders. The German philosopher Immanuel Kant treated anarchy in his Anthropology from a Pragmatic Point of View as consisting of Law and Freedom without Force. Thus, for Kant, anarchy falls short of being a civil state because the law is only an empty recommendation if force is not included to make this law efficacious. For there to be such a state, force must be included while law and freedom are maintained, Kant identified four kinds of government, Law and freedom without force. Anarchism is a philosophy that advocates self-governed societies based on voluntary institutions. These are often described as stateless societies, although several authors have defined them more specifically as institutions based on non-hierarchical free associations, Anarchism holds the state to be undesirable, unnecessary, or harmful. While anti-statism is central, anarchism entails opposing authority or hierarchical organisation in the conduct of all relations, including, but not limited to. There are many types and traditions of anarchism, not all of which are mutually exclusive, Anarchist schools of thought can differ fundamentally, supporting anything from extreme individualism to complete collectivism. Strains of anarchism have been divided into the categories of social, some individualist anarchists are also socialists or communists while some anarcho-communists are also individualists or egoists. Anarchism as a movement has regularly endured fluctuations in popularity. Since the 1890s, the term libertarianism has been used as a synonym for anarchism and was used almost exclusively in this sense until the 1950s in the United States, right-libertarians are divided into minarchists and anarcho-capitalists or voluntarists. Outside the English-speaking world, libertarianism generally retains its association with left-wing anarchism, many of these societies can be considered to be anarchic in the sense that they explicitly reject the idea of centralized political authority. The egalitarianism typical of human hunter-gatherers is interesting when viewed in an evolutionary context, one of humanitys two closest primate relatives, the chimpanzee, is anything but egalitarian, forming hierarchies that are dominated by alpha males. In Society Against the State Pierre Clastres examines stateless societies where cultural practices and attitudes avert the development of hierarchy. He dismisses the notion that the state is the outcome of the evolution of human societies
16.
Direct current
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Direct current is a flow of electrical charge carriers that always takes place in the same direction. The current need not always have the magnitude, but if it is to be defined as dc. This contrasts with alternating current which varies the direction of flow, sources of direct current include power supplies, electrochemical cells and batteries, and photovoltaic cells and panels. The intensity, or amplitude, of a direct current might fluctuate with time, in some such cases the dc has an ac component superimposed on it. An example of this is the output of a cell that receives a modulated light communications signal. A source of dc is sometimes called a dc generator, batteries and various other sources of dc produce a constant voltage. This is called pure dc and can be represented by a straight, the peak and effective values are the same. The peak to peak value is zero because the instantaneous amplitude never changes, in some instances the value of a dc voltage pulsates or oscillates rapidly with time, in a manner similar to the changes in an ac wave. The unfiltered output of a wave or a full wave rectifier. In 1820, Hans Christian Orsted discovered that electrical current creates a magnetic field and this discovery made scientists relate magnetism to the electric phenomena. In 1879, Thomas Edison invented the light bulb. He improved a 50-year-old idea using lower current electricity, a vacuum inside the globe and a small carbonized filament. At that time, the idea of lightning was not new. Edison not only invented an incandescent electric light, but an electric lighting system contained all the necessary elements to make the incandescent light safe, economical. Prior to 1879, direct current electricity had been used in lighting for the outdoors and it was in the 1880s when the modern electric utility industry began. It was an evolution from street lighting systems and from gas and it was located in Lower Manhattan, on Pearl Street. This station provided light and electricity to customers in a one square mile range, the station was called Thomas Edisons Pearl Street Electricity Generating Station. This station introduced four elements of an electric utility system, Efficient distribution, competitive price, reliable central generation
17.
Energy Information Administration
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The U. S. Energy Information Administration is a principal agency of the U. S. EIA programs cover data on coal, petroleum, natural gas, electric, renewable and nuclear energy. EIA is part of the U. S. Department of Energy, the EIA disseminates its data products, analyses, reports, and services to customers and stakeholders primarily through its website and the customer contact center. Located in Washington, D. C. the EIA has about 325 federal employees, by law, the EIA’s products are prepared independently of policy considerations. The EIA neither formulates nor advocates any policy conclusions. ”More than 2 million people use the EIA’s information online each month, some of the EIA’s products include, General Interest Energy Information Energy Explained, Energy information written for a general, non-technical audience. A nonpartisan guide to the range of energy topics from biodiesel to uranium. Energy Kids Page, A very popular product from the EIA is its “Kid’s Page”, which students, citizens. Energy Glossary, Common energy terms defined in plain language and this Week in Petroleum, Weekly summary and explanation of events in U. S. and world petroleum markets, including weekly data. Natural Gas Weekly Update, Weekly summary and discussion of events, Data and Surveys Gasoline and Diesel Fuel Update, Weekly price data for U. S. national and regional averages. Monthly Energy Review, Provides statistics on monthly and annual U. S. national energy consumption going back in some cases to 1949, the figures are given in units of quads Annual Energy Review, EIAs primary report of historical annual energy statistics. For many series, data begin with the year 1949 and this report has been superseded by the Monthly Energy Review and was not produced for 2012. Country Energy Profiles, Data by country, region, and commercial group for 219 countries with additional country analysis notes for 87 of these, country Analysis Briefs, EIAs in-depth analyses of energy production, consumption, imports, and exports for 36 individual countries and regions. Residential Energy Consumption Survey, EIAs comprehensive survey and analysis of energy consumption, household characteristics. Projections and Outlooks Short-Term Energy Outlook, Energy projections for the next 13-24 months, Annual Energy Outlook, Projection and analysis of U. S. energy supply, demand, and prices through 2040 based on EIAs National Energy Modeling System. Projections are currently based on existing legislation, without assumption of any future Congressional action or technological advancement, international Energy Outlook, EIAs assessment of the outlook for international energy markets through 2040. It also provided the FEA with data collection enforcement authority for gathering data from energy producing, Section 205 of this law established the Energy Information Administration as the primary federal government authority on energy statistics and analysis to carry out a. The same law established that EIA’s processes and products are independent from review by Executive Branch officials, the majority of EIA energy data surveys are based on the general mandates set forth above. However, there are some surveys specifically mandated by law, including, EIA-28, eIA-1605 and 1605EZ, Voluntary Reporting of Greenhouse Gases - Section 1605 of the Energy Policy Act of 1992. EIA-886, Annual Survey of Alternative Fueled Vehicle Suppliers and Users - Section 503 of the Energy Policy Act of 1992, eIA-858, Uranium Marketing Annual Survey - Section 1015 of the Energy Policy Act of 1992
18.
AC adapter
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An AC adapter, AC/DC adapter, or AC/DC converter is a type of external power supply, often enclosed in a case similar to an AC plug. Other common names include plug pack, plug-in adapter, adapter block, domestic mains adapter, line power adapter, wall wart, power brick, adapters for battery-powered equipment may be described as chargers or rechargers. AC adapters are used with devices that require power but do not contain internal components to derive the required voltage. The internal circuitry of a power supply is very similar to the design that would be used for a built-in or internal supply. Size and weight of the device was largely determined by the transformer, ratings over a few watts made the devices too large and heavy to be physically supported by a wall outlet. The output voltage of these adapters varied with load, for equipment requiring a stable voltage. Losses in the transformer and the regulator were considerable, efficiency was relatively low. In the early twenty-first century, switched-mode power supplies became almost ubiquitous for this purpose, mains voltage is rectified to a high direct voltage driving a switching circuit, which contains a transformer operating at a high frequency and outputs direct current at the desired voltage. The high-frequency ripple is more easily filtered out than mains-frequency, the high frequency allows the transformer to be small, which reduces its losses, and the switching regulator can be much more efficient than a linear regulator. The result is a more efficient, smaller, and lighter device. Safety is ensured, as in the linear circuit, because there is still a transformer which electrically isolates the output from the mains. However, unless very carefully designed and using suitable components, switching adapters are more likely to fail than the type, due in part to complex circuitry. Unless designed well, these adapters may be damaged by overloads, even transient ones. A very common mode of failure is due to the use of electrolytic capacitors whose equivalent series resistance increases with age, well-designed circuits pay attention to the ESR, ripple current rating, pulse operation, and temperature rating of capacitors. External AC adapters are used to power small or portable electronic devices. The advantages include, Safety – External power adapters can free product designers from worrying about some safety issues, much of this style of equipment uses only voltages low enough not to be a safety hazard internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used, the equipment need not be designed with concern for hazardous voltages inside the enclosure and this is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts. Heat reduction – Heat reduces reliability and longevity of electronic components, a separate power supply removes a source of heat from the apparatus
19.
Electrical wiring
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Electrical wiring is commonly understood to be an electrical installation for operation by end users within a building, an engineered structure or a designated outdoor location. It includes the cabling and associated such as switches, distribution boards, sockets and light fittings. Such wiring is subject to safety standards for design and installation. Associated circuit protection, control and distribution devices within a buildings wiring system are subject to voltage, current, the International Electrotechnical Commission is attempting to harmonise wiring standards amongst member countries, but significant variations in design and installation requirements still exist. Wiring installation codes and regulations are intended to protect people and property from electrical shock and they are usually based on a model code produced by a national or international standards organisation, such as the IEC. The standard is mandatory in both New Zealand and Australia, therefore, all electrical work covered by the standard must comply, in European countries, an attempt has been made to harmonise national wiring standards in an IEC standard, IEC60364 Electrical Installations for Buildings. Hence national standards follow a system of sections and chapters. However, this standard is not written in language that it can readily be adopted as a national wiring code. Neither is it designed for use by electrical tradesmen and inspectors for testing compliance with national wiring standards. In Germany, DKE is the responsible for the promulgation of electrical standards. DIN VDE0100 is the German wiring regulations document harmonised with IEC60364, the first electrical codes in the United States originated in New York in 1881 to regulate installations of electric lighting. Since 1897 the US National Fire Protection Association, a private non-profit association formed by insurance companies, has published the National Electrical Code, States, counties or cities often include the NEC in their local building codes by reference along with local differences. The NEC is modified every three years and it is a consensus code considering suggestions from interested parties. The proposals are studied by committees of engineers, tradesmen, manufacturer representatives, fire fighters, since 1927, the Canadian Standards Association has produced the Canadian Safety Standard for Electrical Installations, which is the basis for provincial electrical codes. The Canadian code reprints Chapter 13 of IEC60364, but there are no numerical criteria listed in that chapter to assess the adequacy of any electrical installation. Although the US and Canadian national standards deal with the physical phenomena and broadly similar objectives. As part of the North American Free Trade Agreement program, US and Canadian standards are slowly converging toward each other, the 17th edition includes new sections for microgeneration and solar photovoltaic systems. The first edition was published in 1882, to enable wires to be easily and safely identified, all common wiring safety codes mandate a colour scheme for the insulation on power conductors
20.
Electrical potential
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An electric potential is the amount of work needed to move a unit positive charge from a reference point to a specific point inside the field without producing any acceleration. Typically, the point is Earth or a point at Infinity. By dividing out the charge on the particle a remainder is obtained that is a property of the field itself. This value can be calculated in either a static or an electric field at a specific time in units of joules per coulomb. The electric potential at infinity is assumed to be zero, a generalized electric scalar potential is also used in electrodynamics when time-varying electromagnetic fields are present, but this can not be so simply calculated. The electric potential and the vector potential together form a four vector. Classical mechanics explores concepts such as force, energy, potential etc, force and potential energy are directly related. A net force acting on any object will cause it to accelerate, as it rolls downhill its potential energy decreases, being translated to motion, inertial energy. It is possible to define the potential of certain force fields so that the energy of an object in that field depends only on the position of the object with respect to the field. Two such force fields are the field and an electric field. Such fields must affect objects due to the properties of the object. Objects may possess a property known as charge and an electric field exerts a force on charged objects. If the charged object has a charge the force will be in the direction of the electric field vector at that point while if the charge is negative the force will be in the opposite direction. The magnitude of the force is given by the quantity of the charge multiplied by the magnitude of the field vector. The electric potential at a point r in an electric field E is given by the line integral where C is an arbitrary path connecting the point with zero potential to r. When the curl ∇ × E is zero, the integral above does not depend on the specific path C chosen. The concept of electric potential is linked with potential energy. A test charge q has a potential energy UE given by U E = q V
21.
Ground (electricity)
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Electrical circuits may be connected to ground for several reasons. In mains powered equipment, exposed parts are connected to ground to prevent user contact with dangerous voltage when electrical insulation fails. In electrical power systems, a protective ground conductor is an essential part of the safety Earthing system. Connection to ground also limits the build-up of static electricity when handling flammable products or electrostatic-sensitive devices, in some telegraph and power transmission circuits, the earth itself can be used as one conductor of the circuit, saving the cost of installing a separate return conductor. For measurement purposes, the Earth serves as a constant potential reference against which other potentials can be measured, an electrical ground system should have an appropriate current-carrying capability to serve as an adequate zero-voltage reference level. In electronic circuit theory, a ground is usually idealized as a source or sink for charge. Where a real ground connection has a significant resistance, the approximation of zero potential is no longer valid, stray voltages or earth potential rise effects will occur, which may create noise in signals or if large enough will produce an electric shock hazard. This is usually a large conductor attached to one side of the power supply which serves as the return path for current from many different components in the circuit. Long-distance electromagnetic telegraph systems from 1820 onwards used two or more wires to carry the signal and return currents. During dry weather, the ground connection often developed a high resistance, an electrical connection to earth can be used as a reference potential for radio frequency signals for certain kinds of antennas. The part directly in contact with the earth - the earth electrode - can be as simple as a rod or stake driven into the earth. Because high frequency signals can flow to earth due to capacitative effects, because of this, a complex system of buried rods and wires can be effective. An ideal signal ground maintains a fixed potential regardless of how much current flows into ground or out of ground. Some types of transmitting antenna systems in the VLF, LF, MF, sometimes a counterpoise is used as a ground plane, supported above the ground. Electrical power distribution systems are connected to ground to limit the voltage that can appear on distribution circuits. A distribution system insulated from ground may attain a high potential due to transient voltages caused by arcing, static electricity, a ground connection of the system dissipates such potentials and limits the rise in voltage of the grounded system. In a mains electricity wiring installation, the ground conductor typically refers to three different conductors or conductor systems as listed below. Equipment earthing conductors provide a connection between non-current-carrying metallic parts of equipment and the earth
22.
Kitchen stove
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A kitchen stove, usually called a gas range, range, cooker, or oven is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of heat for the cooking process and may also contain an oven. When homes began to be heated with heating systems, there was less need for an appliance that served as both heat source and cooker and stand-alone cookers replaced them. Cooker and stove are often used interchangeably, the fuel-burning stove is the most basic design of kitchen stove. Nearly half of the people in the world, burn biomass, more fuel efficient and environmentally sound biomass cook stoves are being developed for use there. Modern kitchen stoves may use alternative methods for heating food, natural gas and electric stoves are the most common today in western countries. In particular, professional chefs often prefer gas cooktops, for they allow them to control the more finely. On the other hand, some chefs often prefer electric stoves because they tend to heat more evenly. Todays major brands offer both gas and electric stoves, and many also offer dual-fuel stoves combining gas and electric cooktops Modern kitchen stoves have both burners on the top as well as an oven. A cooktop can refer to the top of a stove or burners built into a countertop, many newer cooktops are made of glass-ceramic. A drop-in range a combination unit that installs in a kitchens lower cabinets flush with the countertop. Most modern stoves come in a unit with built-in extractor hoods, early clay stoves that enclosed the fire completely, were known from the Chinese Qin Dynasty, and a similar design known as kamado appeared in the Kofun period in Japan. These stoves were fired by wood or charcoal through a hole in the front, in both designs, pots were placed over or hung into holes at the top of the knee-high construction. Raised kamados were developed in Japan during the Edo period, prior to the 18th century in Europe, people cooked over open fires fueled by wood. In the Middle Ages, waist-high brick-and-mortar hearths and the first chimneys appeared, the fire was built on top of the construction, the cooking done mainly in cauldrons hung above the fire or placed on trivets. The heat was regulated by placing the cauldron higher or lower above the fire, attempts were made to enclose the fire to make better use of the heat that it generated and thus reduce the wood consumption. An early step was the chamber, the fire was enclosed on three sides by brick-and-mortar walls and covered by an iron plate. This technique also caused a change in the used for cooking
23.
Log splitter
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A log splitter is a piece of machinery or equipment used for splitting firewood from softwood or hardwood logs that have been pre-cut into sections, usually by chainsaw or on a saw bench. Many log splitters consist of a hydraulic or electrical rod and piston assembly, the higher the pressure rating, the greater the thickness or length of the rounds that can be split. The log splitter consists of all four major hydraulic components, most log splitter models for home use have a rating around 10 tons, but professional hydraulic models may exert 25 tons of force or more. A simple log splitter may be powered by a motor driving a hydraulic pump or by gasoline or diesel engine with or without a tractor. The non-electric versions can be used remotely where the splitter can be moved to the location of the cut wood source, split logs can then be loaded into trucks, trailers or bulk bags. No matter what the source, a log splitter either uses a hydraulic piston to drive the log through a stationary blade or a rotating cone shaped screw mandrel that pulls the log up over a wedge. Some models have attachments that prevent the split logs from falling to the ground allowing the operator to reposition the logs quickly for a pass on the log splitter. Some cone or screw splitters are mounted on platforms mounted on a 3-point linkage that allow the log to be repeatedly split into smaller pieces without putting the wood down. Although smaller firewood splitters are intended for home, there are now many commercial units available, specialty producers such as those producing maple syrup use units that split 4 foot lengths. Machines that split and point wood for fence post also exist though they are few in number as it is generally safer, the rising cost of domestic heating gas oil has reawakened a desire for alternative fuel sources and burning wood is carbon neutral. Modern wood burning stoves are efficient and safe, many consumers that would not have considered splitting their own logs a few years ago are now burning wood fuel for both ecological and economical reasons. Although a good log splitter can save the operator hours of labor, only trained adults should operate a log splitter, since anything caught between the log and the splitting blade will receive at least 10 tons of pressure. Most hydraulic machines now have two handed operation for safety which means both of the operators hands are needed to actuate the splitter thus keeping them out of the way of the moving blade. The behavior of each log can not be predicted, so a safety zone should be established around the splitter to prevent injury from flying splinters of wood. Helpers can pick up the pieces of firewood, but should not stand near the log splitter while it is in operation
24.
Split-phase electric power
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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 and its primary advantage is that it saves conductor material over a single-ended single-phase system, while only requiring single phase on the supply side of the distribution transformer. A transformer supplying a three-wire distribution system has a single-phase input winding, the output winding is center-tapped and the center tap connected to a grounded neutral. 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 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 dividing a lighting load into two equal groups of lamps connected in series, the total supply voltage can be doubled and the size of conductors reduced substantially. The line to ground voltage is half the line-to-line voltage, lighting and small appliances are connected between a line wire and the neutral. The total current carried in all three wires will always be twice the 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. In practice, some intermediate value is chosen, in a so-called technical power system, an isolation transformer with a center tap is used to create a separate supply with conductors at a balanced 60 V with respect to ground. The purpose of a power system is to minimize the noise coupled into sensitive equipment from the power supply. Unlike a three-wire distribution system, the neutral is not distributed to the loads. A balanced power system is used for specialized distribution in audio and video production studios, sound and television broadcasting. The U. S. National Electrical Code provides rules for power installations. The systems are not to be used for lighting or other equipment. Additionally, technical power systems pay special attention to the way the system is grounded. 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 of the three-phase high-voltage conductors are available. A split-phase final step-down transformer is used, with the centre-tap earthed
25.
Air conditioning
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Air conditioning is the process of removing heat from a confined space, thus cooling the air, and removing humidity. Air conditioning can be used in domestic and commercial environments. Air conditioners often use a fan to distribute the air to an occupied space such as a building or a car to improve thermal comfort. The cooling is achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can also be based on desiccants and subterraneous pipes that can distribute the heated refrigerant to the ground for cooling. In the most general sense, air conditioning can refer to any form of technology that modifies the condition of air, in common usage, though, air conditioning refers to systems which cool air. In construction, a system of heating, ventilation, and air conditioning is referred to as heating, ventilation. Since prehistoric times, snow and ice were used for cooling, the business of harvesting ice during winter and storing for use in summer became popular towards the late 17th century. This practice was replaced by mechanical ice-making machines, the basic concept behind air conditioning is said to have been applied in ancient Egypt, where reeds were hung in windows and were moistened with trickling water. The evaporation of water cooled the air blowing through the window and this process also made the air more humid, which can be beneficial in a dry desert climate. In Ancient Rome, water from aqueducts was circulated through the walls of houses to cool them. Other techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. The 2nd-century Chinese inventor Ding Huan of the Han Dynasty invented a fan for air conditioning, with seven wheels 3 m in diameter. During the subsequent Song Dynasty, written sources mentioned the air conditioning rotary fan as even more widely used, in the 17th century, Cornelis Drebbel demonstrated Turning Summer into Winter for James I of England by adding salt to water. The introduction of air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States. In 1758, Benjamin Franklin and John Hadley, a professor at Cambridge University. Franklin and Hadley confirmed that evaporation of volatile liquids could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and they lowered the temperature of the thermometer bulb down to −14 °C while the ambient temperature was 18 °C
26.
Industrial and multiphase power plugs and sockets
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Industrial and multiphase plugs and sockets provide a connection to the electrical mains rated at higher voltages and currents than household plugs and sockets. They are generally used in systems, with high currents. Industrial outlets may have weatherproof covers, waterproofing sleeves, or may be interlocked with a switch to prevent accidental disconnection of an energized plug, some types of connectors are approved for hazardous areas such as coal mines or petrochemical plants, where flammable gas may be present. Almost all three-phase power plugs have a connection, but may not have a neutral because three-phase loads such as motors do not need the neutral. Such plugs have only four prongs, an example of a socket with neutral is the L21-30 and the L21-20 both of which have five pins. While some forms of power plugs and sockets are set by standards, countries may have their own different standards. For example, the colour-coding of wires may not be the same as for small mains plugs, the plug has protruding pins or, in US terminology, blades that fit into matching slots or holes in the sockets. In this article, the plug is used in the sense defined by IEC60050. Sockets are designed to prevent exposure of bare energised contacts and these may include plugs with insulated sleeves, recessed sockets, sockets with blocking shutters, and sockets designed to accept only compatible plugs inserted in the correct orientation. The term plug is in general and technical use in all forms of English, common alternatives being power plug, electric plug, the normal technical term for an AC power socket is socket-outlet, but in non-technical common use a number of other terms are used. In British English the general term is socket, but there are common alternatives, including power point, plug socket, wall socket. Electrical sockets for industrial, commercial and domestic purposes generally provide two or more current carrying connections to the supply conductors and these connections are classified as poles. A pole will be either a neutralconnection or a line Neutral is usually very near to earth potential, Line carries the full supply voltage relative to the neutral. Single phase sockets are classified as two pole and provide a line contact and a neutral contact. In addition, an earth contact is usually, but not always, present. Three phase sockets provide three line contacts, they may include either or both of a neutral and protective earth contact. The designations of the three contacts may vary, the IEC standards use the Line designations L1, L2 and L3. They may also include an earth contact
27.
Circuit breaker
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A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current, typically resulting from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected, unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset to resume normal operation. The generic function of a breaker, RCD or a fuse. An early form of circuit breaker was described by Thomas Edison in an 1879 patent application and its purpose was to protect lighting circuit wiring from accidental short circuits and overloads. A modern miniature circuit breaker similar to the now in use was patented by Brown. Hugo Stotz, an engineer who had sold his company to BBC, was credited as the inventor on DRP458392, stotzs invention was the forerunner of the modern thermal-magnetic breaker commonly used in household load centers to this day. All circuit breaker systems have features in their operation, but details vary substantially depending on the voltage class, current rating. The circuit breaker must firstly detect a fault condition, in small mains and low voltage circuit breakers, this is usually done within the device itself. Typically, the heating and/or magnetic effects of current are employed. Circuit breakers for large currents or high voltages are usually arranged with protective relay pilot devices to sense a fault condition, Circuit breakers may also use the higher current caused by the fault to separate the contacts, such as thermal expansion or a magnetic field. The circuit breaker contacts must carry the current without excessive heating. Contacts are made of copper or copper alloys, silver alloys, service life of the contacts is limited by the erosion of contact material due to arcing while interrupting the current. Miniature and molded-case circuit breakers are usually discarded when the contacts have worn, when a high current or voltage is interrupted, an arc is generated. The length of the arc is generally proportional to the voltage while the intensity is proportional to the current and this arc must be contained, cooled and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating gas, or oil as the medium the arc forms in, finally, once the fault condition has been cleared, the contacts must again be closed to restore power to the interrupted circuit. Low-voltage miniature circuit breaker uses air alone to extinguish the arc and these circuit breakers contain so-called arc chutes, a stack of mutually insulated parallel metal plates which divide and cool the arc. By splitting the arc into smaller arcs the arc is cooled down while the arc voltage is increased, the number of plates in the arc chute is dependent on the short-circuit rating and nominal voltage of the circuit breaker. In larger ratings, oil circuit breakers rely upon vaporization of some of the oil to blast a jet of oil through the arc
28.
Fuse (electrical)
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In electronics and electrical engineering, a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit including the source of power and the load. Its essential component is a wire or strip that melts when too much current flows through it. It is a device and once a fuse has operated it is an open circuit. The time and current operating characteristics of fuses are chosen to provide adequate protection without needless interruption, wiring regulations usually define a maximum fuse current rating for particular circuits. Short circuits, overloading, mismatched loads, or device failure are the reasons for fuse operation. A fuse is a means of removing power from a faulty system. Circuit breakers can be used as a design solution to fuses. Breguet recommended the use of conductors to protect telegraph stations from lightning strikes, by melting. A variety of wire or foil fusible elements were in use to protect telegraph cables, a fuse was patented by Thomas Edison in 1890 as part of his electric distribution system. The fuse is arranged in series to carry all the current passing through the protected circuit, the resistance of the element generates heat due to the current flow. The size and construction of the element is determined so that the heat produced for a current does not cause the element to attain a high temperature. If too high a current flows, the element rises to a temperature and either directly melts, or else melts a soldered joint within the fuse. The fuse element is made of zinc, copper, silver, aluminum, the fuse ideally would carry its rated current indefinitely, and melt quickly on a small excess. The element must not be damaged by minor harmless surges of current, the fuse elements may be shaped to increase heating effect. In large fuses, current may be divided between multiple strips of metal, fuse elements may be supported by steel or nichrome wires, so that no strain is placed on the element, but a spring may be included to increase the speed of parting of the element fragments. The fuse element may be surrounded by air, or by materials intended to speed the quenching of the arc, silica sand or non-conducting liquids may be used. A maximum current that the fuse can continuously conduct without interrupting the circuit, the speed at which a fuse blows depends on how much current flows through it and the material of which the fuse is made. The operating time is not a fixed interval, but decreases as the current increases, Fuses have different characteristics of operating time compared to current, characterized as, according to time required to respond to an overcurrent condition
29.
Short circuit
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A short circuit is an electrical circuit that allows a current to travel along an unintended path with no or a very low electrical impedance. The electrical opposite of a circuit is an open circuit. It is common to misuse short circuit to describe any electrical malfunction, a short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages. This results in an electric current limited only by the Thévenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, in circuit analysis, a short circuit is a connection between two nodes that forces them to be at the same voltage. In an ideal circuit, this means there is no resistance. In real circuits, the result is a connection with almost no resistance, in such a case, the current is limited by the rest of the circuit. A common type of short circuit occurs when the positive and negative terminals of a battery are connected with a low-resistance conductor, with low resistance in the connection, a high current exists, causing the cell to deliver a large amount of energy in a short time. Overloaded wires can also overheat, sometimes causing damage to the wires insulation, in mains circuits, short circuits may occur between two phases, between a phase and neutral or between a phase and earth. Such short circuits are likely to result in a high current. However, it is possible for circuits to arise between neutral and earth conductors, and between two conductors of the same phase. Such short circuits can be dangerous, particularly as they may not immediately result in a current and are therefore less likely to be detected. Possible effects include unexpected energisation of a circuit presumed to be isolated, to help reduce the negative effects of short circuits, power distribution transformers are deliberately designed to have a certain amount of leakage reactance. The leakage reactance helps limit both the magnitude and rate of rise of the fault current, a short circuit may lead to formation of an electric arc. The arc, a channel of hot ionized plasma, is highly conductive, surface erosion is a typical sign of electric arc damage. Even short arcs can remove significant amount of materials from the electrodes, a short circuit fault current can, within milliseconds, be thousands of times larger than the normal operating current of the system. Damage from short circuits can be reduced or prevented by employing fuses, circuit breakers, or other overload protection, overload protection must be chosen according to the current rating of the circuit. Circuits for large home appliances require protective devices set or rated for higher currents than lighting circuits, wire gauges specified in building and electrical codes are chosen to ensure safe operation in conjunction with the overload protection
30.
Residual-current device
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A residual-current device, or residual-current circuit breaker, is a device that instantly breaks an electric circuit to prevent serious harm from an ongoing electric shock. Injury may still occur in cases, for example if a human falls after receiving a shock. In the United States and Canada, the device is commonly known as a ground fault circuit interrupter. In the United Kingdom, these are known by their initials RCD. In Australia, they are known as safety switches or an RCD. An earth leakage circuit breaker may be a residual-current device, although an older type of voltage-operated earth leakage circuit breaker also exists, in German-speaking countries the device is sometimes known as FI where the F stands for fault and I for the symbol that represents electric current. Under normal circumstances, these two wires are expected to carry matching currents, and any difference can indicate a short circuit or other electrical anomaly is present, Leakage can indicate a shock hazard which is a potential danger to a person. Current leakage can result in harm or death due to electric shock, a current of around 30 mA is potentially sufficient to cause cardiac arrest or serious harm if it persists for more than a small fraction of a second. RCDs are designed to disconnect the conducting wires quickly enough to prevent serious injury from such shocks, RCDs are usually testable and resettable devices. Commonly they include a button that when pressed, safely creates a small leakage condition, the former are commonly known as double-pole designs, the latter as single-pole designs. RCDs are designed to disconnect the circuit if there is a leakage current, by detecting small leakage currents and disconnecting quickly enough, they may prevent electrocution. By contrast, conventional circuit breakers or fuses only break the circuit when the current is excessive. RCDs operate by measuring the current balance between two conductors using a current transformer. This measures the difference between current flowing through the conductor and that returning through the neutral conductor. If these do not sum to zero, there is a leakage of current to somewhere else, automatic disconnection and a measure of shock protection is therefore still provided even if the earth wiring of the installation is damaged or incomplete. Residual-current detection is complementary to over-current detection, residual-current detection cannot provide protection for overload or short-circuit currents, except for the special case of a short circuit from live to ground. For a RCD used with power, all three live conductors and the neutral must pass through the current transformer. The diagram depicts the internal mechanism of a residual-current device, the device is designed to be wired in-line in an appliance power cord
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Europe
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Europe is a continent that comprises the westernmost part of Eurasia. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, yet the non-oceanic borders of Europe—a concept dating back to classical antiquity—are arbitrary. Europe covers about 10,180,000 square kilometres, or 2% of the Earths surface, politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a population of about 740 million as of 2015. Further from the sea, seasonal differences are more noticeable than close to the coast, Europe, in particular ancient Greece, was the birthplace of Western civilization. The fall of the Western Roman Empire, during the period, marked the end of ancient history. Renaissance humanism, exploration, art, and science led to the modern era, from the Age of Discovery onwards, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at times the Americas, most of Africa, Oceania. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to economic, cultural, and social change in Western Europe. During the Cold War, Europe was divided along the Iron Curtain between NATO in the west and the Warsaw Pact in the east, until the revolutions of 1989 and fall of the Berlin Wall. In 1955, the Council of Europe was formed following a speech by Sir Winston Churchill and it includes all states except for Belarus, Kazakhstan and Vatican City. Further European integration by some states led to the formation of the European Union, the EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The European Anthem is Ode to Joy and states celebrate peace, in classical Greek mythology, Europa is the name of either a Phoenician princess or of a queen of Crete. The name contains the elements εὐρύς, wide, broad and ὤψ eye, broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. For the second part also the divine attributes of grey-eyed Athena or ox-eyed Hera. The same naming motive according to cartographic convention appears in Greek Ανατολή, Martin Litchfield West stated that phonologically, the match between Europas name and any form of the Semitic word is very poor. Next to these there is also a Proto-Indo-European root *h1regʷos, meaning darkness. Most major world languages use words derived from Eurṓpē or Europa to refer to the continent, in some Turkic languages the originally Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa
32.
Africa
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Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities, cultures and languages. In the late 19th century European countries colonized most of Africa, Africa also varies greatly with regard to environments, economics, historical ties and government systems. However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which also included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2. Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
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Asia
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Asia covers an area of 44,579,000 square kilometres, about 30% of Earths total land area and 8. 7% of the Earths total surface area. The continent, which has long been home to the majority of the population, was the site of many of the first civilizations. Asia is notable for not only its large size and population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, the western boundary with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains, China and India alternated in being the largest economies in the world from 1 to 1800 A. D. The accidental discovery of America by Columbus in search for India demonstrates this deep fascination, the Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties, the boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia, the border between Asia and Europe was historically defined by European academics. In Sweden, five years after Peters death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia, the Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg, the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century, the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is usually placed along the crest of the Caucasus Mountains, the border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the possessions of the various empires there. Lewis and Wigen assert, The narrowing of Southeast Asia to its present boundaries was thus a gradual process, Asia is larger and more culturally diverse than Europe. It does not exactly correspond to the borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds there is no or is no substantial physical separation between them
34.
Australia
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Australia, officially the Commonwealth of Australia, is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the worlds sixth-largest country by total area, the neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north, the Solomon Islands and Vanuatu to the north-east, and New Zealand to the south-east. Australias capital is Canberra, and its largest urban area is Sydney, for about 50,000 years before the first British settlement in the late 18th century, Australia was inhabited by indigenous Australians, who spoke languages classifiable into roughly 250 groups. The population grew steadily in subsequent decades, and by the 1850s most of the continent had been explored, on 1 January 1901, the six colonies federated, forming the Commonwealth of Australia. Australia has since maintained a liberal democratic political system that functions as a federal parliamentary constitutional monarchy comprising six states. The population of 24 million is highly urbanised and heavily concentrated on the eastern seaboard, Australia has the worlds 13th-largest economy and ninth-highest per capita income. With the second-highest human development index globally, the country highly in quality of life, health, education, economic freedom. The name Australia is derived from the Latin Terra Australis a name used for putative lands in the southern hemisphere since ancient times, the Dutch adjectival form Australische was used in a Dutch book in Batavia in 1638, to refer to the newly discovered lands to the south. On 12 December 1817, Macquarie recommended to the Colonial Office that it be formally adopted, in 1824, the Admiralty agreed that the continent should be known officially as Australia. The first official published use of the term Australia came with the 1830 publication of The Australia Directory and these first inhabitants may have been ancestors of modern Indigenous Australians. The Torres Strait Islanders, ethnically Melanesian, were originally horticulturists, the northern coasts and waters of Australia were visited sporadically by fishermen from Maritime Southeast Asia. The first recorded European sighting of the Australian mainland, and the first recorded European landfall on the Australian continent, are attributed to the Dutch. The first ship and crew to chart the Australian coast and meet with Aboriginal people was the Duyfken captained by Dutch navigator, Willem Janszoon. He sighted the coast of Cape York Peninsula in early 1606, the Dutch charted the whole of the western and northern coastlines and named the island continent New Holland during the 17th century, but made no attempt at settlement. William Dampier, an English explorer and privateer, landed on the north-west coast of New Holland in 1688, in 1770, James Cook sailed along and mapped the east coast, which he named New South Wales and claimed for Great Britain. The first settlement led to the foundation of Sydney, and the exploration, a British settlement was established in Van Diemens Land, now known as Tasmania, in 1803, and it became a separate colony in 1825. The United Kingdom formally claimed the part of Western Australia in 1828. Separate colonies were carved from parts of New South Wales, South Australia in 1836, Victoria in 1851, the Northern Territory was founded in 1911 when it was excised from South Australia
35.
New Zealand
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New Zealand /njuːˈziːlənd/ is an island nation in the southwestern Pacific Ocean. The country geographically comprises two main landmasses—the North Island, or Te Ika-a-Māui, and the South Island, or Te Waipounamu—and around 600 smaller islands. New Zealand is situated some 1,500 kilometres east of Australia across the Tasman Sea and roughly 1,000 kilometres south of the Pacific island areas of New Caledonia, Fiji, because of its remoteness, it was one of the last lands to be settled by humans. During its long period of isolation, New Zealand developed a distinct biodiversity of animal, fungal, the countrys varied topography and its sharp mountain peaks, such as the Southern Alps, owe much to the tectonic uplift of land and volcanic eruptions. New Zealands capital city is Wellington, while its most populous city is Auckland, sometime between 1250 and 1300 CE, Polynesians settled in the islands that later were named New Zealand and developed a distinctive Māori culture. In 1642, Dutch explorer Abel Tasman became the first European to sight New Zealand, in 1840, representatives of Britain and Māori chiefs signed the Treaty of Waitangi, which declared British sovereignty over the islands. In 1841, New Zealand became a colony within the British Empire, today, the majority of New Zealands population of 4.7 million is of European descent, the indigenous Māori are the largest minority, followed by Asians and Pacific Islanders. Reflecting this, New Zealands culture is derived from Māori and early British settlers. The official languages are English, Māori and New Zealand Sign Language, New Zealand is a developed country and ranks highly in international comparisons of national performance, such as health, education, economic freedom and quality of life. Since the 1980s, New Zealand has transformed from an agrarian, Queen Elizabeth II is the countrys head of state and is represented by a governor-general. In addition, New Zealand is organised into 11 regional councils and 67 territorial authorities for local government purposes, the Realm of New Zealand also includes Tokelau, the Cook Islands and Niue, and the Ross Dependency, which is New Zealands territorial claim in Antarctica. New Zealand is a member of the United Nations, Commonwealth of Nations, ANZUS, Organisation for Economic Co-operation and Development, Pacific Islands Forum, and Asia-Pacific Economic Cooperation. Dutch explorer Abel Tasman sighted New Zealand in 1642 and called it Staten Landt, in 1645, Dutch cartographers renamed the land Nova Zeelandia after the Dutch province of Zeeland. British explorer James Cook subsequently anglicised the name to New Zealand, Aotearoa is the current Māori name for New Zealand. It is unknown whether Māori had a name for the country before the arrival of Europeans. Māori had several names for the two main islands, including Te Ika-a-Māui for the North Island and Te Waipounamu or Te Waka o Aoraki for the South Island. Early European maps labelled the islands North, Middle and South, in 1830, maps began to use North and South to distinguish the two largest islands and by 1907, this was the accepted norm. The New Zealand Geographic Board discovered in 2009 that the names of the North Island and South Island had never been formalised and this set the names as North Island or Te Ika-a-Māui, and South Island or Te Waipounamu
36.
South America
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South America is a continent located in the western hemisphere, mostly in the southern hemisphere, with a relatively small portion in the northern hemisphere. It may also be considered a subcontinent of the Americas, which is the used in nations that speak Romance languages. The reference to South America instead of other regions has increased in the last decades due to changing geopolitical dynamics. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean, North America and it includes twelve sovereign states, a part of France, and a non-sovereign area. In addition to this, the ABC islands of the Kingdom of the Netherlands, Trinidad and Tobago, South America has an area of 17,840,000 square kilometers. Its population as of 2005 has been estimated at more than 371,090,000, South America ranks fourth in area and fifth in population. Brazil is by far the most populous South American country, with more than half of the population, followed by Colombia, Argentina, Venezuela. In recent decades Brazil has also concentrated half of the regions GDP and has become a first regional power, most of the population lives near the continents western or eastern coasts while the interior and the far south are sparsely populated. Most of the continent lies in the tropics, the continents cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the majority of South Americans speak Portuguese or Spanish. South America occupies the portion of the Americas. The continent is delimited on the northwest by the Darién watershed along the Colombia–Panama border. Almost all of mainland South America sits on the South American Plate, South Americas major mineral resources are gold, silver, copper, iron ore, tin, and petroleum. These resources found in South America have brought high income to its countries especially in times of war or of rapid growth by industrialized countries elsewhere. However, the concentration in producing one major export commodity often has hindered the development of diversified economies and this is leading to efforts to diversify production to drive away from staying as economies dedicated to one major export. South America is one of the most biodiverse continents on earth, South America is home to many interesting and unique species of animals including the llama, anaconda, piranha, jaguar, vicuña, and tapir. The Amazon rainforests possess high biodiversity, containing a proportion of the Earths species. Brazil is the largest country in South America, encompassing around half of the land area
37.
United Kingdom
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The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is also the 21st-most populous country, with an estimated 65.1 million inhabitants, together, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Leeds, Glasgow, Liverpool and Manchester. The United Kingdom consists of four countries—England, Scotland, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language, culture and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index. It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, cultural, military, scientific and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland, Wales and Northern Ireland have devolved self-government
38.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
39.
Japan
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Japan is a sovereign island nation in Eastern Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asia Mainland and stretches from the Sea of Okhotsk in the north to the East China Sea, the kanji that make up Japans name mean sun origin. 日 can be read as ni and means sun while 本 can be read as hon, or pon, Japan is often referred to by the famous epithet Land of the Rising Sun in reference to its Japanese name. Japan is an archipelago consisting of about 6,852 islands. The four largest are Honshu, Hokkaido, Kyushu and Shikoku, the country is divided into 47 prefectures in eight regions. Hokkaido being the northernmost prefecture and Okinawa being the southernmost one, the population of 127 million is the worlds tenth largest. Japanese people make up 98. 5% of Japans total population, approximately 9.1 million people live in the city of Tokyo, the capital of Japan. Archaeological research indicates that Japan was inhabited as early as the Upper Paleolithic period, the first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other regions, mainly China, followed by periods of isolation, from the 12th century until 1868, Japan was ruled by successive feudal military shoguns who ruled in the name of the Emperor. Japan entered into a period of isolation in the early 17th century. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the bombings of Hiroshima and Nagasaki. Japan is a member of the UN, the OECD, the G7, the G8, the country has the worlds third-largest economy by nominal GDP and the worlds fourth-largest economy by purchasing power parity. It is also the worlds fourth-largest exporter and fourth-largest importer, although Japan has officially renounced its right to declare war, it maintains a modern military with the worlds eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a country with a very high standard of living. Its population enjoys the highest life expectancy and the third lowest infant mortality rate in the world, in ancient China, Japan was called Wo 倭. It was mentioned in the third century Chinese historical text Records of the Three Kingdoms in the section for the Wei kingdom, Wa became disliked because it has the connotation of the character 矮, meaning dwarf. The 倭 kanji has been replaced with the homophone Wa, meaning harmony, the Japanese word for Japan is 日本, which is pronounced Nippon or Nihon and literally means the origin of the sun. The earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, at the start of the seventh century, a delegation from Japan introduced their country as Nihon
40.
Taiwan
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Taiwan, officially the Republic of China, is a state in East Asia. Neighbours include China to the west, Japan to the northeast, Taiwan is the most populous state that is not a member of the United Nations, and the one with the largest economy. The island of Taiwan, also known as Formosa, was inhabited by Taiwanese aborigines before the 17th century. After a brief rule by the Kingdom of Tungning, the island was annexed by the Qing dynasty, the Qing ceded Taiwan to Japan in 1895 after the Sino-Japanese War. While Taiwan was under Japanese rule, the Republic of China was established on the mainland in 1912 after the fall of the Qing dynasty, following the Japanese surrender to the Allies in 1945, the ROC took control of Taiwan. However, the resumption of the Chinese Civil War led to the ROCs loss of the mainland to the Communists, and the flight of the ROC government to Taiwan in 1949. As a founding member of the United Nations, the ROC continued to represent China at the United Nations until 1971, in the early 1960s, Taiwan entered a period of rapid economic growth and industrialization, creating a stable industrial economy. In the 1980s and early 1990s, it changed from a one-party military dictatorship dominated by the Kuomintang to a multi-party democracy with universal suffrage, Taiwan is the 22nd-largest economy in the world, and its high-tech industry plays a key role in the global economy. It is ranked highly in terms of freedom of the press, health care, public education, economic freedom, the PRC has consistently claimed sovereignty over Taiwan and asserted the ROC is no longer in legitimate existence. Under its One-China Policy the PRC refused diplomatic relations with any country that recognizes the ROC, the PRC has threatened the use of military force in response to any formal declaration of independence by Taiwan or if PRC leaders decide that peaceful unification is no longer possible. There are various names for the island of Taiwan in use today, the former name Formosa dates from 1542, when Portuguese sailors sighted the main island of Taiwan and named it Ilha Formosa, which means beautiful island. The name Formosa eventually replaced all others in European literature and was in use in English in the early 20th century. This name was adopted into the Chinese vernacular as the name of the sandbar. The modern word Taiwan is derived from this usage, which is seen in forms in Chinese historical records. Use of the current Chinese name was formalized as early as 1684 with the establishment of Taiwan Prefecture, through its rapid development, the entire Formosan mainland eventually became known as Taiwan. The official name of the state is the Republic of China and it was a member of the United Nations representing China until 1971, when it lost its seat to the Peoples Republic of China. Over subsequent decades, the Republic of China has become known as Taiwan. In some contexts, especially ones from the ROC government
41.
Saudi Arabia
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Saudi Arabia is bordered by Jordan and Iraq to the north, Kuwait to the northeast, Qatar, Bahrain and the United Arab Emirates to the east, Oman to the southeast and Yemen to the south. It is separated from Israel and Egypt by the Gulf of Aqaba and it is the only nation with both a Red Sea coast and a Persian Gulf coast and most of its terrain consists of arid desert and mountains. The area of modern-day Saudi Arabia formerly consisted of four regions, Hejaz, Najd and parts of Eastern Arabia. The Kingdom of Saudi Arabia was founded in 1932 by Ibn Saud and he united the four regions into a single state through a series of conquests beginning in 1902 with the capture of Riyadh, the ancestral home of his family, the House of Saud. Saudi Arabia has since been a monarchy, effectively a hereditary dictatorship governed along Islamic lines. The ultraconservative Wahhabi religious movement within Sunni Islam has been called the predominant feature of Saudi culture, with its global spread largely financed by the oil and gas trade. Saudi Arabia is sometimes called the Land of the Two Holy Mosques in reference to Al-Masjid al-Haram and Al-Masjid an-Nabawi, the state has a total population of 28.7 million, of which 20 million are Saudi nationals and 8 million are foreigners. The states official language is Arabic, petroleum was discovered on 3 March 1938 and followed up by several other finds in the Eastern Province. Saudi Arabia has since become the worlds largest oil producer and exporter, controlling the second largest oil reserves. The kingdom is categorized as a World Bank high-income economy with a high Human Development Index and is the only Arab country to be part of the G-20 major economies. However, the economy of Saudi Arabia is the least diversified in the Gulf Cooperation Council, the state has attracted criticism for its treatment of women and use of capital punishment. Saudi Arabia is an autocracy, has the fourth highest military expenditure in the world. Saudi Arabia is considered a regional and middle power, in addition to the GCC, it is an active member of the Organisation of Islamic Cooperation and OPEC. Following the unification of the Hejaz and Nejd kingdoms, the new state was named al-Mamlakah al-ʻArabīyah as-Suʻūdīyah by royal decree on 23 September 1932 by its founder, Abdulaziz Al Saud. Although this is translated as the Kingdom of Saudi Arabia in English it literally means the Saudi Arab kingdom. Its inclusion expresses the view that the country is the possession of the royal family. Al Saud is an Arabic name formed by adding the word Al, meaning family of or House of, in the case of the Al Saud, this is the father of the dynastys 18th century founder, Muhammad bin Saud. There is evidence that human habitation in the Arabian Peninsula dates back to about 125,000 years ago
42.
North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
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Central America
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Central America is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. Central America is bordered by Mexico to the north, Colombia to the southeast, the Caribbean Sea to the east, Central America consists of seven countries, Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. The combined population of Central America is between 41,739,000 and 42,688,190, Central America is a part of the Mesoamerican biodiversity hotspot, which extends from northern Guatemala through to central Panama. Due to the presence of several active faults and the Central America Volcanic Arc. Volcanic eruptions and earthquakes occur frequently, these disasters have resulted in the loss of many lives. In the Pre-Columbian era, Central America was inhabited by the peoples of Mesoamerica to the north and west. Soon after Christopher Columbuss voyages to the Americas, the Spanish began to colonize the Americas, the seven states finally became independent autonomous states, beginning with Nicaragua, Honduras, Costa Rica, and Guatemala, followed by El Salvador, then Panama, and finally Belize. Middle America is usually thought to comprise Mexico to the north of the 7 states of Central America as well as Colombia, usually the whole of the Caribbean to the north-east and sometimes the Guyanas are also included. According to one source, the term Central America was used as a synonym for Middle America as recently as 1962, in Brazil, Central America comprises all countries between Mexico and Colombia, including those in the Caribbean. Mexico, in whole or in part, is included by British people. For the people living in the 5 countries formerly part of the Federal Republic of Central America there is a distinction between the Spanish language terms América Central and Centroamérica, in the Pre-Columbian era, the northern areas of Central America were inhabited by the indigenous peoples of Mesoamerica. Most notable among these were the Mayans, who had built numerous cities throughout the region, and the Aztecs, following Christopher Columbuss voyages to the Americas, the Spanish sent many expeditions to the region, and they began their conquest of Maya territory in 1523. Soon after the conquest of the Aztec Empire, Spanish conquistador Pedro de Alvarado commenced the conquest of northern Central America for the Spanish Empire. Beginning with his arrival in Soconusco in 1523, Alvarados forces systematically conquered and subjugated most of the major Maya kingdoms, including the Kiche, Tzutujil, Pipil, and the Kaqchikel. By 1528, the conquest of Guatemala was nearly complete, with only the Petén Basin remaining outside the Spanish sphere of influence, the last independent Maya kingdoms – the Kowoj and the Itza people – were finally defeated in 1697, as part of the Spanish conquest of Petén. In 1538, Spain established the Real Audiencia of Panama, which had jurisdiction over all land from the Strait of Magellan to the Gulf of Fonseca. This entity was dissolved in 1543, and most of the territory within Central America then fell under the jurisdiction of the Audiencia Real de Guatemala. This area included the current territories of Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and the Mexican state of Chiapas, the president of the Audiencia, which had its seat in Antigua Guatemala, was the governor of the entire area
