1.
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
2.
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
3.
D54 (protocol)
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D54 is an analogue lighting communications protocol used to control stage lighting. It was developed by Strand Lighting in the late 70s and originally designed to handle 384 channels, D54 is still supported, and is available on the Strand 500 series consoles alongside DMX. One of the significant problems in controlling dimmers is getting the signal from a lighting control unit to the dimmer units. In about 1976, to deal with the bulky cable requirements of analog control, originally developed for use on the Strand Galaxy and Strand Gemini control desks. The refresh period would also have been slow on such a long dimmer update cycle, instead, multiple D54 streams were supported by some later consoles. D54 was developed in the United Kingdom at approximately the time as AMX192 was developed in the United States. Article Authors Note, Little information is available regarding this protocol, electrical Parameters 1) Outputs to be short-circuit proof to 0 V to unlimited periods. 2) Every thing works fine when the sync pulse >=10 us, 3) Unlike DMX512 you cannot shorten the frame to the no. of channels you use, the whole 384 channels + the start 0 valued channel must be sent. Again these remarks are gained from a project with Strand EC90 dimmer
4.
DMX512
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DMX512 is a standard for digital communication networks that are commonly used to control stage lighting and effects. It was originally intended as a method for controlling light dimmers. It soon became the method for linking controllers to dimmers and special effects devices such as fog machines. DMX has also expanded to uses in interior and architectural lighting. DMX can now be used to control almost anything, reflecting its popularity in theaters, DMX512 employs EIA-485 differential signaling at its physical layer, in conjunction with a variable-size, packet-based communication protocol. DMX512 does not include automatic error checking and correction, and so is not a control for hazardous applications. False triggering may be caused by interference, static electricity discharges, improper cable termination, excessively long cables. Developed by the Engineering Commission of United States Institute for Theatre Technology, in 1998 the Entertainment Services and Technology Association began a revision process to develop the standard as an ANSI standard. It was revised again in 2008, and is the current standard known as E1.11 –2008, USITT DMX512-A, in January 2011 ESTA merged with PLASA, a similar organization in the UK. The new organization is called Plasa, all ESTA standards are now maintained by Plasa. A DMX512 network employs a multi-drop bus topology with nodes strung together in what is called a daisy chain. A network consists of a single DMX512 controller – which is the master of the network —, for example, a lighting console is frequently employed as the controller for a network of slave devices such as dimmers, fog machines and intelligent lights. Each slave device has a DMX512 IN connector and usually an OUT connector as well, the controller, which has only an OUT connector, is connected via a DMX512 cable to the IN connector of the first slave. A second cable then links the OUT or THRU connector of the first slave to the IN connector of the slave in the chain. For example, the diagram below shows a simple network consisting of a controller. The specification requires a terminator to be connected to the final OUT or THRU connector of the last slave on the daisy chain, which would otherwise be unconnected. A terminator is a male connector with an integral 120 Ω resistor connected across the primary data signal pair. If a secondary data pair is used, a resistor is connected across it as well
5.
Fluorescent lamp
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A fluorescent lamp or a fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor which produces ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than incandescent lamps, the typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. Compact fluorescent lamps are now available in the same sizes as incandescents and are used as an energy-saving alternative in homes. Because they contain mercury, many fluorescent lamps are classified as hazardous waste, the United States Environmental Protection Agency recommends that fluorescent lamps be segregated from general waste for recycling or safe disposal, and some jurisdictions require recycling of them. Fluorescence of certain rocks and other substances had been observed for hundreds of years before its nature was understood, by the middle of the 19th century, experimenters had observed a radiant glow emanating from partially evacuated glass vessels through which an electric current passed. The explanation relied on the nature of electricity and light phenomena as developed by the British scientists Michael Faraday in the 1840s and James Clerk Maxwell in the 1860s. Little more was done with this phenomenon until 1856 when German glassblower Heinrich Geissler created a vacuum pump that evacuated a glass tube to an extent not previously possible. Geissler invented the first gas-discharge lamp, the Geissler tube, consisting of an evacuated glass tube with a metal electrode at either end. When a high voltage was applied between the electrodes, the inside of the lit up with a glow discharge. By putting different chemicals inside, the tubes could be made to produce a variety of colors, more important, however, was its contribution to scientific research. One of the first scientists to experiment with a Geissler tube was Julius Plücker who systematically described in 1858 the luminescent effects that occurred in a Geissler tube and he also made the important observation that the glow in the tube shifted position when in proximity to an electromagnetic field. Alexandre Edmond Becquerel observed in 1859 that certain substances gave off light when they were placed in a Geissler tube and he went on to apply thin coatings of luminescent materials to the surfaces of these tubes. Fluorescence occurred, but the tubes were very inefficient and had an operating life. Inquiries that began with the Geissler tube continued as even better vacuums were produced, the most famous was the evacuated tube used for scientific research by William Crookes. That tube was evacuated by the highly effective mercury vacuum pump created by Hermann Sprengel, Research conducted by Crookes and others ultimately led to the discovery of the electron in 1897 by J. J. Thomson and X-rays in 1895 by Wilhelm Roentgen. While Becquerel was interested primarily in conducting research into fluorescence. Although Edison lost interest in fluorescent lighting, one of his employees was able to create a gas-based lamp that achieved a measure of commercial success
6.
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
7.
Electrical connector
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An electrical connector, is an electro-mechanical device used to join electrical terminations and create an electrical circuit. Electrical connectors consist of plugs and jacks, the connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or devices. An adapter can be used to bring together dissimilar connectors. There are hundreds of types of electrical connectors, connectors may join two lengths of flexible copper wire or cable, or connect a wire or cable to an electrical terminal. In computing, a connector can also be known as a physical interface. Cable glands, known as cable connectors in the US, connect wires to devices rather than electrically and are distinct from quick-disconnects performing the latter. It is usually desirable for a connector to be easy to visually, rapid to assemble, require only simple tooling. In some cases an equipment manufacturer might choose a connector specifically because it is not compatible with those other sources. No single connector has all the properties, the proliferation of types is a reflection of differing requirements. Fretting is a failure mode in electrical connectors that have not been specifically designed to prevent it. Many connectors are keyed, with some mechanical component which prevents mating except with a correctly oriented matching connector, some connector housings are designed with locking mechanisms to prevent inadvertent disconnection or poor environmental sealing. Locking mechanism designs include locking levers of various sorts, screw locking, a terminal is a simple type of electrical connector that connects two or more wires to a single connection point. Wire nuts are another type of single point connector, terminal blocks provide a convenient means of connecting individual electrical wires without a splice or physically joining the ends. They are usually used to connect wiring among various items of equipment within an enclosure or to make connections among individually enclosed items. Since terminal blocks are available for a wide range of wire sizes and terminal quantity. One type of terminal block accepts wires that are prepared only by removing a short length of insulation from the end, another type accepts wires that have ring or spade terminal lugs crimped onto the wires. Printed circuit board mounted terminal blocks allow individual wires to be connected to the circuit board, a general type of connector that simply screws or clamps bare wire to a post, such connectors are frequently used in electronic test equipment and audio. Many, but not all binding posts will also accept a banana connector plug, since stripping the insulation from wires is time-consuming, many connectors intended for rapid assembly use insulation-displacement connectors so that insulation need not be removed from the wire
