What is the voltage and how does electric plug look like in Russia?
Resistance is a measure of the opposition to current flow in an electrical circuit. a German physicist who studied the relationship between voltage, current and. Electric power basic formulas calculator voltage current mathematical equation formula for power law watts resistance understanding. There are only two types of electrical voltage used in the household network: the European type is V and the American type is
Southwick to seek some application for the curious phenomenon. Fell and the Buffalo ASPCA, electrocuting hundreds of stray dogs, to come up with a method to euthanize animals via electricity. An commission appointed by New York governor David B. Hillwhich including Southwick, recommended in that executions be carried out by electricity using the electric chair. As part of their fact-findingthe commission sent out surveys to hundreds of experts on law and medicine, seeking their opinions, as well as contacting electrical experts, including Elihu Thomson and Thomas Edison.
After further prompting, Edison hit out at his chief electric power competitor, George Westinghouse, in what may have been the opening salvo in the war of currents, stating in a December letter to Southwick that it would be best to use current generated by "'alternating machines,' manufactured principally in this country by Geo. The press in New York seemed to switch overnight from stories about electric lights vs gas lighting to "death by wire" incidents, with each new report seeming to fan public resentment against high voltage AC and the dangerously tangled overhead electrical wires in the city.
At this point an electrical engineer named Harold P.
War of the currents - Wikipedia
Brownwho at that time seemed to have no connection to the Edison company,  sent a June 5, letter to the editor of the New York Post claiming the root of the problem was the alternating current AC system being used.
Brown argued that the AC system was inherently dangerous and "damnable" and asked why the "public must submit to constant danger from sudden death" just so utilities could use a cheaper AC system. At the beginning of attacks on AC, Westinghouse, in a June 7, letter, tried to defuse the situation. He invited Edison to visit him in Pittsburgh and said "I believe there has been a systemic attempt on the part of some people to do a great deal of mischief and create as great a difference as possible between the Edison Company and The Westinghouse Electric Co.
Edison thanked him but said "My laboratory work consumes the whole of my time". There were many rebuttals to Browns claims in the newspapers and letters to the board, with people pointing out he was showing no scientific evidence that AC was more dangerous than DC. Westinghouse pointed out in letters to various newspapers the number of fires caused by DC equipment and suggested that Brown was obviously being controlled by Edison, something Brown continually denied.
At this meeting, supporters of AC provided anecdotal stories from electricians on how they had survived shocks from AC at voltages up to volts and argued that DC was the more dangerous of the two.
Brown paid local children to collect stray dogs off the street for his experiments with direct and alternating current. Brown then applied volts of alternating current which killed the dog.
Four days later he held a second demonstration to answer critics' claims that the DC probably weakened the dog before it died. In this second demonstration, three dogs were killed in quick succession with volts of AC. Brown's campaign to restrict AC to volts went nowhere but legislation did come close to passing in Ohio and Virginia. Hastings who came up with the idea of using Brown and several New York physicians to attack Westinghouse and the other AC companies in retaliation for what Hastings thought were unscrupulous bids by Westinghouse for lighting contracts in Denver and Minneapolis.
In addition, Thomas Edison himself sent a letter to the city government of Scranton, Pennsylvania recommending Brown as an expert on the dangers of AC. Patents and mergers[ edit ] Nikola Tesla 's induction motor patent was acquired by Westinghouse in July with plans to incorporate it in a completely integrated AC system.
During this period Westinghouse continued to pour money and engineering resources into the goal of building a completely integrated AC system. He bought the Waterhouse Electric Light Company in and the United States Illuminating Company ingiving Westinghouse their own arc lighting systems as well as control over all the major incandescent lamp patents not controlled by Edison.
Shallenberger developed an induction meter that used a rotating magnetic field for measuring alternating current giving the company a way to calculate how much electricity a customer used. Morgan to take over Westinghouse Electric. Several of the business deals between Thomson-Houston and Westinghouse fell apart and in April a judge rolled back part of Westinghouse's original Gaulard Gibbs patent, stating it only covered transformers linked in series.
Morgan and the Vanderbilt family for Edison's lighting experiments, merged. The peak of the war[ edit ] Through the fall of a battle of words with Brown specifically attacking Westinghouse continued to escalate. The magazine investigated the claim and found at most only two of the deaths could be attributed to Westinghouse installations.
During this time they sought the advice of Harold Brown as a consultant. This ended up expanding the war of currents into the development of the chair and the general debate over capital punishment in the US.
The claims that AC was more deadly than DC and was the best current to use was questioned with some committee members, pointing out that Brown's experiments were not scientifically carried out and were on animals smaller than a human being.
At their November meeting the committee recommended volts although the type of electricity, direct current or alternating currentwas not determined.
Hastings to arrange the use of the West Orange laboratory. Brown used alternating current for all of his tests on animals larger than a human, including 4 calves and a lame horse, all dispatched with volts of AC.
Westinghouse criticized these tests as a skewed self-serving demonstration designed to be a direct attack on alternating current. Brown's December 18 letter refuted the claims and Brown even challenged Westinghouse to an electrical duel, with Brown agreeing to be shocked by ever-increasing amounts of DC power if Westinghouse submitted himself to the same amount of increasing AC power, first to quit loses.
In March when members of the Medico-Legal Society embarked on another series of tests to work out the details of electrode composition and placement they turned to Brown for technical assistance. Also in March, Superintendent of Prisons Austin Lathrop asked Brown if he could supply the equipment needed for the executions as well as design the electric chair. Brown turned down the job of designing the chair but did agree to fulfill the contract to supply the necessary electrical equipment.
This became another behind-the-scenes maneuver to acquire Westinghouse AC generators to supply the current, apparently with the help of the Edison company and Westinghouse's chief AC rival, Thomson-Houston.
The term "Westinghoused" was put forward as well as "Gerrycide" after death penalty commission head Elbridge Gerryand "Browned". William Kemmler was sentenced to die in the electric chair around June 24,but before the sentence could be carried out an appeal was filed on the grounds that it constituted cruel and unusual punishment under the US Constitution. It became obvious to the press and everyone involved that the politically connected and expensive lawyer who filed the appeal, William Bourke Cockranhad no connection to the case but did have connection to the Westinghouse company, obviously paying for his services.
His strategy was to show that Brown had falsified his test on the killing power of AC and to prove that electricity would not cause certain death and simply lead to torturing the condemned. In cross examination he questioned Brown's lack of credentials in the electrical field and brought up possible collusion between Brown and Edison, which Brown again denied.
Many witnesses were called by both sides to give firsthand anecdotal accounts about encounters with electricity and evidence was given by medical professionals on the human body's nervous system and the electrical conductivity of skin. Brown was accused of fudging his tests on animals, hiding the fact that he was using lower current DC and high-current AC.
After the first jolt of electricity Kemmler was found to be still breathing. Three-phase electrical generation is very common. In practice, higher "pole orders" are commonly used. The advantage is that lower rotational speeds can be used to generate the same frequency. If the load on a three-phase system is balanced equally among the phases, no current flows through the neutral point.
Even in the worst-case unbalanced linear load, the neutral current will not exceed the highest of the phase currents.
War of the currents
Harmonics can cause neutral conductor current levels to exceed that of one or all phase conductors. For three-phase at utilization voltages a four-wire system is often used. When stepping down three-phase, a transformer with a Delta 3-wire primary and a Star 4-wire, center-earthed secondary is often used so there is no need for a neutral on the supply side. For smaller customers just how small varies by country and age of the installation only a single phase and neutral, or two phases and neutral, are taken to the property.
- Alternating current
- What is the voltage and how does electric plug look like in Russia?
For larger installations all three phases and neutral are taken to the main distribution panel. From the three-phase main panel, both single and three-phase circuits may lead off.
Three-wire single-phase systems, with a single center-tapped transformer giving two live conductors, is a common distribution scheme for residential and small commercial buildings in North America. This arrangement is sometimes incorrectly referred to as "two phase". A similar method is used for a different reason on construction sites in the UK. A third wirecalled the bond or earth wire, is often connected between non-current-carrying metal enclosures and earth ground. This conductor provides protection from electric shock due to accidental contact of circuit conductors with the metal chassis of portable appliances and tools.
Bonding all non-current-carrying metal parts into one complete system ensures there is always a low electrical impedance path to ground sufficient to carry any fault current for as long as it takes for the system to clear the fault. This low impedance path allows the maximum amount of fault current, causing the overcurrent protection device breakers, fuses to trip or burn out as quickly as possible, bringing the electrical system to a safe state.Voltage, Current, Resistance & Power
AC power supply frequencies[ edit ] Further information: A low frequency eases the design of electric motors, particularly for hoisting, crushing and rolling applications, and commutator-type traction motors for applications such as railways. However, low frequency also causes noticeable flicker in arc lamps and incandescent light bulbs.
The use of lower frequencies also provided the advantage of lower impedance losses, which are proportional to frequency. Effects at high frequencies[ edit ] Play media A Tesla coil producing high-frequency current that is harmless to humans, but lights a fluorescent lamp when brought near it A direct current flows uniformly throughout the cross-section of a uniform wire.
An alternating current of any frequency is forced away from the wire's center, toward its outer surface. This is because the acceleration of an electric charge in an alternating current produces waves of electromagnetic radiation that cancel the propagation of electricity toward the center of materials with high conductivity.
This phenomenon is called skin effect. At very high frequencies the current no longer flows in the wire, but effectively flows on the surface of the wire, within a thickness of a few skin depths. For example, the skin depth of a copper conductor is approximately 8. Since the current tends to flow in the periphery of conductors, the effective cross-section of the conductor is reduced.
This increases the effective AC resistance of the conductor, since resistance is inversely proportional to the cross-sectional area. The AC resistance often is many times higher than the DC resistance, causing a much higher energy loss due to ohmic heating also called I2R loss.
Techniques for reducing AC resistance[ edit ] For low to medium frequencies, conductors can be divided into stranded wires, each insulated from one another, and the relative positions of individual strands specially arranged within the conductor bundle.
Wire constructed using this technique is called Litz wire.
This measure helps to partially mitigate skin effect by forcing more equal current throughout the total cross section of the stranded conductors.