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Ignitron
An ignitron is a type of gas-filled tube used as a controlled rectifier and dating from the 1930s. Invented by Joseph Slepian while employed by Westinghouse, Westinghouse was the original manufacturer and owned trademark rights to the name "Ignitron". Ignitrons are closely related to mercury-arc valves but differ in the way the arc is ignited. They function similarly to thyratrons; a triggering pulse to the igniter electrode turns the device "on", allowing a high current to flow between the cathode and anode electrodes. After it is turned on, the current through the anode must be reduced to zero to restore the device to its nonconducting state. They are used to switch high currents in heavy industrial applications. Construction and operation An ignitron is usually a large steel container with a pool of mercury in the bottom that acts as a cathode during operation. A large graphite or refractory metal cylinder, held above the pool by an insulated electrical connection, serves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ignitron
An ignitron is a type of gas-filled tube used as a controlled rectifier and dating from the 1930s. Invented by Joseph Slepian while employed by Westinghouse, Westinghouse was the original manufacturer and owned trademark rights to the name "Ignitron". Ignitrons are closely related to mercury-arc valves but differ in the way the arc is ignited. They function similarly to thyratrons; a triggering pulse to the igniter electrode turns the device "on", allowing a high current to flow between the cathode and anode electrodes. After it is turned on, the current through the anode must be reduced to zero to restore the device to its nonconducting state. They are used to switch high currents in heavy industrial applications. Construction and operation An ignitron is usually a large steel container with a pool of mercury in the bottom that acts as a cathode during operation. A large graphite or refractory metal cylinder, held above the pool by an insulated electrical connection, serves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PRR E44
The PRR E44 was an electric, rectifier-equipped locomotive built by General Electric for the Pennsylvania Railroad between 1960 and 1963. The PRR used them for freight service on the Northeast Corridor. They continued in service under Penn Central and Conrail until Conrail abandoned its electric operations in the early 1980s. They were then acquired by Amtrak and NJ Transit, where they lived short lives; all were retired by the mid-1980s. One is preserved at the Railroad Museum of Pennsylvania. Design By the late 1950s, with its P5a fleet aging, the Pennsylvania Railroad needed new electric freight locomotives. In fact, the PRR had never really had a successful electric freight locomotive. The P5a was originally built to haul passengers, being bumped from that duty by the more powerful GG1. The GG1s were best at hauling passenger trains; while also adequate for fast, time-sensitive freights, they were not as efficient on heavy freights (especially coal and ore trains) at a tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury-arc Valve
A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-current alternating current (AC) into direct current (DC). It is a type of cold cathode gas-filled tube, but is unusual in that the cathode, instead of being solid, is made from a pool of liquid mercury and is therefore self-restoring. As a result mercury-arc valves, when used as intended, are far more robust and durable and can carry much higher currents than most other types of gas discharge tube. Some examples have been in continuous service, rectifying 50 ampere currents for decades. Invented in 1902 by Peter Cooper Hewitt, mercury-arc rectifiers were used to provide power for industrial motors, electric railways, streetcars, and electric locomotives, as well as for radio transmitters and for high-voltage direct current (HVDC) power transmission. They were the primary method of high power rectification before the advent of se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas-filled Tube
A gas-filled tube, also commonly known as a discharge tube or formerly as a Plücker tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Gas-filled tubes exploit phenomena related to electric discharge in gases, and operate by ionizing the gas with an applied voltage sufficient to cause electrical conduction by the underlying phenomena of the Townsend discharge. A gas-discharge lamp is an electric light using a gas-filled tube; these include fluorescent lamps, metal-halide lamps, sodium-vapor lamps, and neon lights. Specialized gas-filled tubes such as krytrons, thyratrons, and ignitrons are used as switching devices in electric devices. The voltage required to initiate and sustain discharge is dependent on the pressure and composition of the fill gas and geometry of the tube. Although the envelope is typically glass, power tubes often use ceramics, and military tubes often use glass-lined metal. Both hot cathode and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulsed Power
Pulsed power is the science and technology of accumulating energy over a relatively long period of time and releasing it instantly, thus increasing the instantaneous power. They can be used in some applications such as food processing, water treatment, weapon, and medical applications. Overview Energy is typically stored within electrostatic fields (capacitors), magnetic fields (inductors), as mechanical energy (using large flywheels connected to special-purpose high-current alternators), or as chemical energy (high-current lead-acid batteries, or explosives). By releasing the stored energy over a very short interval (a process that is called energy compression), a huge amount of peak power can be delivered to a load. For example, if one joule of energy is stored within a capacitor and then evenly released to a load over one second, the average power delivered to the load would only be 1 watt. However, if all of the stored energy were released within one microsecond, the average pow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Westinghouse Electric Corporation
The Westinghouse Electric Corporation was an American manufacturing company founded in 1886 by George Westinghouse. It was originally named "Westinghouse Electric & Manufacturing Company" and was renamed "Westinghouse Electric Corporation" in 1945. The company acquired the CBS television network in 1995 and was renamed "CBS Corporation" until being acquired by Viacom in 1999, a merger completed in April 2000. The CBS Corporation name was later reused for one of the two companies resulting from the split of Viacom in 2006. The Westinghouse trademarks are owned by Westinghouse Electric Corporation, and were previously part of Westinghouse Licensing Corporation. The nuclear power business, Westinghouse Electric Company, was spun off from the Westinghouse Electric Corporation in 1999. History Westinghouse Electric was founded by George Westinghouse in Pittsburgh, Pennsylvania, on January 8, 1886. The firm became active in developing electric infrastructure throughout ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity towa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overcurrent
In an electric power system, overcurrent or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessive generation of heat, and the risk of fire or damage to equipment. Possible causes for overcurrent include short circuits, excessive load, incorrect design, an arc fault, or a ground fault. Fuses, circuit breakers, and current limiters are commonly used overcurrent protection (OCP) mechanisms to control the risks. Circuit breakers, relays, and fuses protect circuit wiring from damage caused by overcurrent. Related standards * IEC 60364-4-43: Electrical installations of buildings – Part 4-43: Protection for safety – Protection against overcurrent See also * Current limiting * Electrical fault * Electrical safety * Overvoltage When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage. The conditions may be hazardous. Depending on its duration, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rectifier
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation (converting DC to AC) is performed by an inverter. The process is known as ''rectification'', since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes, wet chemical cells, mercury-arc valves, stacks of copper and selenium oxide plates, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motor-generator sets have been used. Early radio receivers, called crystal radios, used a " cat's whisker" of fine wire pressing on a crystal of galena (lead sulfide) to serve as a point-contact rectifier or "crystal detector". Rectifiers have many uses, but are often found serving as components of DC power supplies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traction Motors
A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric or hydrogen vehicles, elevators or electric multiple unit. Traction motors are used in electrically powered rail vehicles (electric multiple units) and other electric vehicles including electric milk floats, elevators, roller coasters, conveyors, and trolleybuses, as well as vehicles with electrical transmission systems (diesel-electric locomotives, electric hybrid vehicles), and battery electric vehicles. Motor types and control Direct-current motors with series field windings are the oldest type of traction motors. These provide a speed-torque characteristic useful for propulsion, providing high torque at lower speeds for acceleration of the vehicle, and declining torque as speed increases. By arranging the field winding with multiple taps, the speed characteristic can be varied, allowing relatively smooth operator control of acceleration. A further measure of control is pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overhead Lines
An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, trolleybuses or trams. It is known variously as: * Overhead catenary * Overhead contact system (OCS) * Overhead equipment (OHE) * Overhead line equipment (OLE or OHLE) * Overhead lines (OHL) * Overhead wiring (OHW) * Traction wire * Trolley wire This article follows the International Union of Railways in using the generic term ''overhead line''. An overhead line consists of one or more wires (or rails, particularly in tunnels) situated over rail tracks, raised to a high electrical potential by connection to feeder stations at regular intervals. The feeder stations are usually fed from a high-voltage electrical grid. Overview Electric trains that collect their current from overhead lines use a device such as a pantograph, bow collector or trolley pole. It presses against the underside of the lowest overhead wire, the contact wire. Current collector ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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