|
15 KV AC Railway Electrification
Railway electrification using at are used on transport railways in Rail transport in Germany, Germany, Rail transport in Austria, Austria, Rail transport in Switzerland, Switzerland, Rail transport in Sweden, Sweden, and Rail transport in Norway, Norway. The high voltage enables high power transmission with the lower frequency reducing the losses of the traction motors that were available at the beginning of the 20th century. Globally, railway electrification in late 20th century tends to use 25 kV AC railway electrification, AC systems which has become the preferred standard for new railway electrifications. Nevertheless, local extensions of the existing network is commonplace. In particular, the Gotthard Base Tunnel (opened on 1 June 2016) uses 15 kV, 16.7 Hz electrification. Due to high conversion costs, it is unlikely that existing systems will be converted to despite the fact that this would reduce the weight of the on-board step-down transformers to one t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe Rail Electrification En
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east. Europe shares the landmass of Eurasia with Asia, and of Afro-Eurasia with both Africa and Asia. Europe is commonly considered to be Boundaries between the continents#Asia and Europe, separated from Asia by the Drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea, and the waterway of the Bosporus, Bosporus Strait. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and Europe ... is formed by the Ural Mountains, Ural River, Caspian Sea, Caucasus Mountains, and the Black Sea with its outlets, the Bosporus and Dardanelles." Europe covers approx. , or 2% of Earth#Surface, Earth's surface (6.8% of Earth's land area), making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
600VDC
This is a list of the power supply systems that are, or have been, used for railway electrification. Note that the voltages are nominal and vary depending on load and distance from the substation. , many trams and trains use on-board solid-state electronics to convert these supplies to run three-phase electric power, three-phase AC traction motors. Tram electrification systems are listed List of tram systems by gauge and electrification, here. Key to the tables below * Volts: voltage or volt * Current: ** DC = direct current ** # Hz = frequency in hertz (alternating current (AC)) *** AC supplies are usually single-phase electric power, single-phase (1φ) except where marked three-phase (3φ). * Conductors: ** overhead line or ** conductor rail, usually a third rail to one side of the running rails. Conductor rail can be: *** top contact: oldest, least safe, most affected by ice, snow, rain and leaves. Protection boards are installed on most top contact systems, which increases sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the Inverse second, reciprocal of one second. It is used only in the case of periodic events. It is named after Heinrich Hertz, Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in metric prefix, multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Arc
An electric arc (or arc discharge) is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (physics), plasma, which may produce visible light. An arc discharge is initiated either by thermionic emission or by field emission. After initiation, the arc relies on thermionic emission of electrons from the electrodes supporting the arc. An arc discharge is characterized by a lower voltage than a glow discharge. An archaic term is voltaic arc, as used in the phrase "voltaic arc lamp". Techniques for arc suppression can be used to reduce the duration or likelihood of arc formation. In the late 19th century, Arc lamp, electric arc lighting was in wide use for Street light#Arc lamps, public lighting. Some low-pressure electric arcs are used in many applications. For example, fluorescent lamp, fluorescent tubes, mercury, sodium, and met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commutator (electric)
A commutator is a rotary switch, electrical switch in certain types of electric motors and electrical generators that periodically reverses the Current (electricity), current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature (electrical engineering), armature of the machine. Two or more electrical contacts called "brush (electric), brushes" made of a soft conductive material like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings (coils of wire) on the armature (electrical engineering), armature are connected to the commutator segments. Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Reactance
In electrical circuits, reactance is the opposition presented to alternating current by inductance and capacitance. It's measured in Ohm, Ω (Ohms). Along with resistance, it is one of two elements of Electrical impedance, impedance; however, while both elements involve transfer of electrical energy, no Joule heating, dissipation of electrical energy as heat occurs in reactance; instead, the reactance stores energy until a quarter-cycle later when the energy is returned to the circuit. Greater reactance gives smaller current for the same applied voltage. Reactance is used to compute amplitude and Phase (waves), phase changes of Sine wave, sinusoidal alternating current going through a circuit element. Like resistance, reactance is measured in ohms, with positive values indicating ''inductive'' reactance and negative indicating ''capacitive'' reactance. It is denoted by the symbol X. An ideal resistor has zero reactance, whereas ideal reactors have no shunt conductance and no ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Universal Motor
The universal motor is a type of electric motor that can operate on either AC or DC power and uses an electromagnet as its stator to create its magnetic field. It is a commutated series-wound motor where the stator's field coils are connected in series with the rotor windings through a commutator. It is often referred to as an AC series motor. The universal motor is very similar to a DC series motor in construction, but is modified slightly to allow the motor to operate properly on AC power. This type of electric motor can operate well on AC because the current in both the field coils and the armature (and the resultant magnetic fields) will alternate (reverse polarity) synchronously with the supply. Hence the resulting mechanical force will occur in a consistent direction of rotation, independent of the direction of applied voltage, but determined by the commutator and polarity of the field coils.Herman, Stephen L. ''Delmar's Standard Textbook of Electricity, 3rd Edition.'' Cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
War Of The Currents
The war of the currents was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s. It grew out of two lighting systems developed in the late 1870s and early 1880s: arc lamp street lighting running on high-voltage alternating current (AC), and large-scale low-voltage direct current (DC) indoor incandescent lighting being marketed by Thomas Edison's company. In 1886, the Edison system was faced with new competition: an alternating current system initially introduced by George Westinghouse's company that used transformers to step down from a high voltage so AC could be used for indoor lighting. Using high voltage allowed an AC system to transmit power over longer distances from more efficient large central generating stations. As the use of AC spread rapidly with other companies deploying their own systems, the Edison Electric Light Company claimed in early 1888 that high voltages used in an alternating cur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Power Distribution
Electric power distribution is the final stage in the Power delivery, delivery of electricity. Electricity is carried from the Electric power transmission, transmission system to individual consumers. Distribution Electrical substation, substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between and with the use of transformers. ''Primary'' distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment and household appliances. Often several customers are supplied from one transformer through ''secondary'' distribution lines. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtrans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transformer
In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force, electromotive force (EMF) across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil. Transformers are used to change Alternating current, AC voltage levels, such transformers being termed step-up or step-down type to increase or decrease voltage level, respectively. Transformers can also be used to provide galvanic isolation between circuits as well as to couple stages of signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joule Heating
Joule heating (also known as resistive heating, resistance heating, or Ohmic heating) is the process by which the passage of an electric current through a conductor (material), conductor produces heat. Joule's first law (also just Joule's law), also known in countries of the former Soviet Union, USSR as the Joule–Lenz law, Assuming the element behaves as a perfect resistor and that the power is completely converted into heat, the formula can be re-written by substituting Ohm's law, V = I R , into the generalized power equation: P = IV = I^2R = V^2/R where ''R'' is the electrical resistance and conductance, resistance. Voltage can be increased in DC circuits by connecting batteries or solar panels in series. Alternating current When current varies, as it does in AC circuits, P(t) = U(t) I(t) where ''t'' is time and ''P'' is the instantaneous active power being converted from electrical energy to heat. Far more often, the ''average'' power is of more interest than the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
