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30-717: DE1 is a Ukrainian series of DC electric locomotives . It is the first electric locomotive developed by Ukraine since the end of the Soviet Union . The DE1 was produced for service in the Near-Dnieper and the Donets Basin regional divisions of the Ukrainian Railways . All of them were produced by the Dnepropetrovsk research-and-production association for electric locomotive engineering. By

60-510: A rectifier , which contains electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alternating current via an inverter . Direct current has many uses, from the charging of batteries to large power supplies for electronic systems, motors, and more. Very large quantities of electrical energy provided via direct-current are used in smelting of aluminum and other electrochemical processes. It

90-543: A DC circuit. However, most such circuits have a DC solution. This solution gives the circuit voltages and currents when the circuit is in DC steady state . Such a circuit is represented by a system of differential equations . The solution to these equations usually contain a time varying or transient part as well as constant or steady state part. It is this steady state part that is the DC solution. There are some circuits that do not have

120-407: A DC solution. Two simple examples are a constant current source connected to a capacitor and a constant voltage source connected to an inductor. In electronics, it is common to refer to a circuit that is powered by a DC voltage source such as a battery or the output of a DC power supply as a DC circuit even though what is meant is that the circuit is DC powered. In a DC circuit, a power source (e.g.

150-453: A battery system to ensure power is maintained for subscriber lines during power interruptions. Other devices may be powered from the telecommunications DC system using a DC-DC converter to provide any convenient voltage. Many telephones connect to a twisted pair of wires, and use a bias tee to internally separate the AC component of the voltage between the two wires (the audio signal) from

180-423: A battery, capacitor, etc.) has a positive and negative terminal, and likewise, the load also has a positive and negative terminal. To complete the circuit, positive charges need to flow from the power source to the load. The charges will then return to the negative terminal of the load, which will then flow back to the negative terminal of the battery, completing the circuit. If either the positive or negative terminal

210-493: A catalyst to produce electricity and water as byproducts) also produce only DC. Light aircraft electrical systems are typically 12 V or 24 V DC similar to automobiles. NorNed NorNed is a 580-kilometre (360 mi) long high-voltage direct current submarine power cable between Feda, Norway and the seaport of Eemshaven in the Netherlands , which interconnects both countries' electrical grids . It

240-524: A direct current source . The DC solution of an electric circuit is the solution where all voltages and currents are constant. Any stationary voltage or current waveform can be decomposed into a sum of a DC component and a zero-mean time-varying component; the DC component is defined to be the expected value, or the average value of the voltage or current over all time. Although DC stands for "direct current", DC often refers to "constant polarity". Under this definition, DC voltages can vary in time, as seen in

270-554: Is also used for some railways , especially in urban areas . High-voltage direct current is used to transmit large amounts of power from remote generation sites or to interconnect alternating current power grids. Direct current was produced in 1800 by Italian physicist Alessandro Volta 's battery, his Voltaic pile . The nature of how current flowed was not yet understood. French physicist André-Marie Ampère conjectured that current travelled in one direction from positive to negative. When French instrument maker Hippolyte Pixii built

300-482: Is an AC device which uses a rectifier to produce DC for battery charging. Most highway passenger vehicles use nominally 12  V systems. Many heavy trucks, farm equipment, or earth moving equipment with Diesel engines use 24 volt systems. In some older vehicles, 6 V was used, such as in the original classic Volkswagen Beetle . At one point a 42 V electrical system was considered for automobiles, but this found little use. To save weight and wire, often

330-435: Is commonly found in many extra-low voltage applications and some low-voltage applications, especially where these are powered by batteries or solar power systems (since both can produce only DC). Most electronic circuits or devices require a DC power supply . Domestic DC installations usually have different types of sockets , connectors , switches , and fixtures from those suitable for alternating current. This

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360-427: Is disconnected, the circuit will not be complete and the charges will not flow. In some DC circuit applications, polarity does not matter, which means you can connect positive and negative backwards and the circuit will still be complete and the load will still function normally. However, in most DC applications, polarity does matter, and connecting the circuit backwards will result in the load not working properly. DC

390-412: Is distributed to a substation, which utilizes a rectifier to convert the power to direct current. The term DC is used to refer to power systems that use only one electrical polarity of voltage or current, and to refer to the constant, zero-frequency, or slowly varying local mean value of a voltage or current. For example, the voltage across a DC voltage source is constant as is the current through

420-447: Is mostly due to the lower voltages used, resulting in higher currents to produce the same amount of power . It is usually important with a DC appliance to observe polarity, unless the device has a diode bridge to correct for this. Most automotive applications use DC. An automotive battery provides power for engine starting, lighting, the ignition system, the climate controls, and the infotainment system among others. The alternator

450-568: Is then artificially limited. The cable had a fault in 2011, causing 7 weeks out of operation. A fault was discovered in May 2022, causing a shutdown of operations. Operations are expected to resume in October 2022. Although classed as a "bipolar" HVDC scheme, the NorNed scheme is unusual for a Line-Commutated ( thyristor -based) HVDC scheme since there is just one 12-pulse converter at each end of

480-448: The DC component of the voltage between the two wires (used to power the phone). High-voltage direct current (HVDC) electric power transmission systems use DC for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. Applications using fuel cells (mixing hydrogen and oxygen together with

510-545: The cable generated revenues of approximately €50 million. In the business case drawn up for the NorNed cable, annual revenues were estimated at €64 million. NorNed has been included in European Market Coupling Company operations as of 12 January 2011. The internal grid in Norway is sometimes not capable of handling enough power for NorNed and Cross-Skagerrak , and capacity for these cables

540-407: The circuit voltages and currents are independent of time. A particular circuit voltage or current does not depend on the past value of any circuit voltage or current. This implies that the system of equations that represent a DC circuit do not involve integrals or derivatives with respect to time. If a capacitor or inductor is added to a DC circuit, the resulting circuit is not, strictly speaking,

570-517: The design. They were both retired in 2007 and 2013, respectively. By 2008, a total of 40 units of the DE1 were produced. The series was succeeded by the DS3 locomotives. Direct current The abbreviations AC and DC are often used to mean simply alternating and direct , as when they modify current or voltage . Direct current may be converted from an alternating current supply by use of

600-654: The first dynamo electric generator in 1832, he found that as the magnet used passed the loops of wire each half turn, it caused the flow of electricity to reverse, generating an alternating current . At Ampère's suggestion, Pixii later added a commutator , a type of "switch" where contacts on the shaft work with "brush" contacts to produce direct current. The late 1870s and early 1880s saw electricity starting to be generated at power stations . These were initially set up to power arc lighting (a popular type of street lighting) running on very high voltage (usually higher than 3,000 volts) direct current or alternating current. This

630-487: The first sections started in early 2006 and the final section was laid by the end of 2007. On the Dutch shore, TenneT has connected the cable to the 380 kV Dutch high‑voltage grid. In Feda, Statnett has done the same for the 300 kV Norwegian transmission grid. Commercial operation started on 5 May 2008 with a capacity auction. The first commercial power transfer took place on 6 May 2008. After two months of operation,

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660-512: The highest voltage rating of any HVDC converter in the world. The connection has a loss of 4.2% (95.8% efficiency). NorNed is the first power link between the Nordic electrical transmission system Nordel and the continent that is planned to be open to the power market. The main trading over the link is presumed to be one day ahead spot market trading based on the price difference between the markets. In spite of quite equal average spot market prices,

690-512: The metal frame of the vehicle is connected to one pole of the battery and used as the return conductor in a circuit. Often the negative pole is the chassis "ground" connection, but positive ground may be used in some wheeled or marine vehicles. In a battery electric vehicle , there are usually two separate DC systems. The "low voltage" DC system typically operates at 12V, and serves the same purpose as in an internal combustion engine vehicle. The "high voltage" system operates at 300-400V (depending on

720-590: The middle of the 1990s there was a need to replace the ageing VL8 locomotives, which had stopped operating in Russia were only being used by that point on the Near-Dnieper and Donets territorial railways in southeastern Ukraine. The Dnepropetrovsk electric locomotive factory was tasked with developing a new electric locomotive. The first two units produced, numbered DE1-001 (made in 1995) and DE1-002 (in 1997), became test prototypes that were used to further develop

750-428: The raw output of a rectifier or the fluctuating voice signal on a telephone line. Some forms of DC (such as that produced by a voltage regulator ) have almost no variations in voltage , but may still have variations in output power and current. A direct current circuit is an electrical circuit that consists of any combination of constant voltage sources, constant current sources, and resistors . In this case,

780-430: The scheme, midpoint-grounded at Eemshaven. With voltage-source converter-based HVDC systems, this arrangement with the two high voltage cables at equal and opposite voltages but only a single converter at each end is referred to as a Symmetrical monopole . Consequently, with a DC voltage of ±450 kV, the converter for the NorNed project has a terminal to terminal DC voltage rating of 900 kV, making it (as of 2012)

810-464: The vehicle), and provides the power for the traction motors . Increasing the voltage for the traction motors reduces the current flowing through them, increasing efficiency. Telephone exchange communication equipment uses standard −48 V DC power supply. The negative polarity is achieved by grounding the positive terminal of power supply system and the battery bank. This is done to prevent electrolysis depositions. Telephone installations have

840-406: Was followed by the widespread use of low voltage direct current for indoor electric lighting in business and homes after inventor Thomas Edison launched his incandescent bulb based electric " utility " in 1882. Because of the significant advantages of alternating current over direct current in using transformers to raise and lower voltages to allow much longer transmission distances, direct current

870-502: Was once the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the NorNed cable is a bipolar HVDC link with a voltage of ±450 kV and a capacity of 700 MW. NorNed is a joint project of the Norwegian transmission system operator Statnett and its Dutch counterpart TenneT . The cable system itself and the two converter stations were produced by ABB . Installation of

900-477: Was replaced over the next few decades by alternating current in power delivery. In the mid-1950s, high-voltage direct current transmission was developed, and is now an option instead of long-distance high voltage alternating current systems. For long distance undersea cables (e.g. between countries, such as NorNed ), this DC option is the only technically feasible option. For applications requiring direct current, such as third rail power systems, alternating current

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