War of Currents

In the "War of Currents" era in the late 1880s, Nikola Tesla and Thomas Edison became adversaries due to Edison's promotion of direct current (DC) for electric power distribution over the more efficient alternating current (AC) advocated by Tesla. During the initial years of electricity distribution, Edison's direct current was the standard for the United States and Edison was not disposed to lose all his patent royalties. Direct current worked well for the incandescent lamps that were the principal load of the day. From his wo ...

Including:

• War of Currents - Electric power transmission
• War of Currents - AC vs. DC
• War of Currents - Niagara Falls
• War of Currents - Edison's propaganda
• War of Currents - Westinghouse the condemned
• War of Currents - The Falls to Buffalo
• War of Currents - Outcome
• War of Currents - Recent innovations

Read more here: » War of Currents: Encyclopedia - War of Currents

The direct current electric power transmission system had limitations that were recognized and solved by Tesla's alternating current. High loads of direct current often melted copper wires and DC could rarely be transmitted for distances of greater than one mile without introducing excessive voltage drops. The three-wire distribution system provided some improvement in voltage drop and conductor sizes, but did not eliminate the problem. Edison's response to the DC system limitations was to generate power close to where it was consumed (distr ...

See also:

War of Currents, War of Currents - Electric power transmission, War of Currents - AC vs. DC, War of Currents - Niagara Falls, War of Currents - Edison's propaganda, War of Currents - Westinghouse the condemned, War of Currents - The Falls to Buffalo, War of Currents - Outcome, War of Currents - Recent innovations

Read more here: » War of Currents: Encyclopedia II - War of Currents - Electric power transmission

Transformer - Cores. Transformers for use at power or audio frequencies have cores made of many thin laminations of silicon steel. By concentrating the magnetic flux, more of it is usefully linked by both primary and secondary windings. Since the steel core is conductive, it, too, has currents induced in it by the changing magnetic flux. Each layer is insulated from the adjacent layer to reduce the energy lost to eddy current heating of the core. A typical laminated core is made from E-shaped and I-shaped p ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - An analogy, Transformer - Flux coupling laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classifications, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Enclosure, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Audio transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Construction

A transformer usually has: two or more insulated windings, to carry current a core, in which the mutual magnetic field couples the windings. In transformers designed to operate at low frequencies, the windings are usually formed around an iron or steel core. This helps to confine the magnetic field within the transformer and increase its efficiency, although the presence of the core causes energy losses. Transformers made to operate at high frequencies may use other l ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - Flux coupling, Transformer - Electrical laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classification, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Construction

In 1875, Thomas Edison had been a virtual unknown. He had achieved some success with a "multiplex telegraph" system that allowed multiple telegraph signals to be sent over a single wire, but had not yet obtained the recognition he wanted. He was working on a telephone system but was upstaged by Bell. Edison bounced back quickly from the setback to invent the phonograph, which was a public sensation nobody had dreamed possible and made him famous. Edison's next step, in 1878, was to invent an improved incandescent light bulb, and more ...

See also:

George Westinghouse, George Westinghouse - Early years, George Westinghouse - Electricity and the War of Currents, George Westinghouse - Later years, George Westinghouse - Death and legacy

Read more here: » George Westinghouse: Encyclopedia II - George Westinghouse - Electricity and the War of Currents

George Westinghouse was born in Central Bridge, New York, on October 6 1846. In the mid-1850s, his father, George Westinghouse Senior, established a factory in Schenectady, New York, where young George learned about mechanics, manufacturing, management, and business. After the outbreak of the American Civil War in 1861, the 15-year-old George ran away with two of his brothers to fight for the Union cause. One of the brothers was killed in action. George transfe ...

See also:

George Westinghouse, George Westinghouse - Early years, George Westinghouse - Electricity and the War of Currents, George Westinghouse - Later years, George Westinghouse - Death and legacy

Read more here: » George Westinghouse: Encyclopedia II - George Westinghouse - Early years

Transformer - Flux coupling. A simple single phase transformer consists of two electrical conductors called the primary winding and the secondary winding. The primary is fed with a varying (alternating or pulsed continuous) electric current which creates a varying magnetic field around the conductor and in the magnetic core (shaded grey). The secondary, which is placed in this varying magnetic flux, develops an electromotive force or EMF. If the ends of the secondary are connected toge ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - Flux coupling, Transformer - Electrical laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classification, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Basic principles

Direct current (DC or "continuous current") is the constant flow of electric charge from high to low potential. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams. In direct current, the electric charges flow in the same direction, distinguishing it from alternating current (AC). A term formerly used f ...

Including:

• Direct current - Various definitions
• Direct current - Applications

Read more here: » Direct current: Encyclopedia - Direct current

An alternating current (AC) is an electrical current where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However in certain applications different waveforms are used, such as triangular or square waves. Used generically, AC refers to the form in which electricity is delivered to businesses and residences. Ho ...

Including:

• Alternating current - History
• Alternating current - Distribution and domestic power supply
• Alternating current - AC power supply frequencies by country
• Alternating current - Mathematics of AC voltages

Read more here: » Alternating current: Encyclopedia - Alternating current

An electric shock can occur upon contact of a human or animal body with any source of voltage high enough to cause sufficient current flow through the muscles or nerves. The minimum detectable current in humans is thought to be about 1 mA. The current may cause tissue damage or heart fibrillation if it is sufficiently high. Electric shock - Description. An electric shock is usually painful and can be lethal. The level of voltage is not a direct guide to the level of injury or danger of death, despite the co ...

Including:

• Electric shock - Description
• Electric shock - 'Let go' current
• Electric shock - Shock effects
• Electric shock - Psychological
• Electric shock - Physiological
• Electric shock - Issues affecting lethality
• Electric shock - Avoiding danger of shock
• Electric shock - Shock due to differing ground potentials
• Electric shock - First aid
• Electric shock - Deliberate uses
• Electric shock - Electric shock as medical treatment
• Electric shock - Torture
• Electric shock - Capital punishment
• Electric shock - Games

Read more here: » Electric shock: Encyclopedia - Electric shock

In 1893, in a significant coup, the Westinghouse company was awarded the contract to set up an AC network to power the World's Columbian Exposition in Chicago, Illinois, giving the company and the technology widespread positive publicity. Westinghouse also received a contract to set up the first long-range power network, with AC generators at Niagara Falls producing electricity for distribution i ...

See also:

George Westinghouse, George Westinghouse - Early years, George Westinghouse - Electricity and the War of Currents, George Westinghouse - Later years, George Westinghouse - Death and legacy

Read more here: » George Westinghouse: Encyclopedia II - George Westinghouse - Later years

Transformer - Classification. Transformers may be roughly classified by the power handled in the circuit, in watts (or, more accurately, VA (volt amperes)): Up to 1 watt: Signal transformers, interstage coupling 1 - 1000 watts: Small power transformers, filament transformers, audio output transformers 1 kilowatt - 1 megawatt: Power transformers; larger units in this range may be oil filled 1 megawatt and over: Large power transformers, used for substations, large electrical ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - Flux coupling, Transformer - Electrical laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classification, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Practical considerations

Transformer - Classifications. Transformers are adapted to numerous engineering applications and may be classified in many ways: By power level (from fraction of a watt to many megawatts), By application (power supply, impedance matching, circuit isolation), By frequency range (power, audio, RF) By voltage class (a few volts to about 750 kilovolts) By cooling type (air cooled, oil filled, fan cooled, water cooled, etc.) By purpose (rectifier, arc furnace, ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - An analogy, Transformer - Flux coupling laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classifications, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Enclosure, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Audio transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Practical considerations

Transformer - An analogy. The transformer may be considered as a simple two wheel 'gearbox' for electrical voltage and current. The primary winding is analogous to the input shaft and the secondary winding to the output shaft. In this comparison, voltage is equivalent to shaft speed, current to shaft torque. In a gearbox, mechanical power (speed multiplied by torque) is constant (neglecting losses) and is equivalent to electrical power (voltage multiplied by current) which is also constant. The gear ratio is equivalent to the transformer step up or down ratio. See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - An analogy, Transformer - Flux coupling laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classifications, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Enclosure, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Audio transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Basic principles

The transformer is one of the simplest of electrical devices. A good mechanical analogy is that of a gearbox. Its design and principles have changed little over the last one hundred years, yet the transformer still plays a substantial role in the continuing development of high-voltage power transmission. It permits the economical transmission of power over large distances, allowing generating stations to be located physically further from sites of electricity demand and nearer to their sources of fuel. The simplicity, reliability, and econom ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - Flux coupling, Transformer - Electrical laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classification, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Introduction

The transformer is one of the simplest of electrical devices. Its basic design, materials, and principles have changed little over the last one hundred years, yet transformer designs and materials continue to be improved. Transformers are essential in high voltage power transmission providing an economical means of transmitting power over large distances. The simplicity, reliability, and economy of conversion of voltages by transformers was the principal factor in the selection of alternating current power transmission in the "War of Current ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - An analogy, Transformer - Flux coupling laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classifications, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Enclosure, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Audio transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Introduction

Transformer - Autotransformers. Main article: Autotransformer An autotransformer has only a single winding, which is tapped at some point along the winding. AC or pulsed voltage is applied across a portion of the winding, and a higher (or lower) voltage is produced across another portion of the same winding. For voltage ratios not exceeding about 3:1, an autotransformer is less costly, lighter, smaller and more efficient ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - An analogy, Transformer - Flux coupling laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classifications, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Enclosure, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Audio transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Transformer designs

Transformer - Autotransformers. An autotransformer has only a single winding, which is tapped at some point along the winding. AC or pulsed DC power is applied across a portion of the winding, and a higher (or lower) voltage is produced across another portion of the same winding. Autotransformers are used to compensate for voltage drop in a distribution system or for matching two transmission voltages, for example 115 kV and 138 kV. For voltage ratios not exceeding about 3:1, an autotransformer is less costly, lighter, smaller and more efficient than a t ...

See also:

Transformer, Transformer - Introduction, Transformer - Basic principles, Transformer - Flux coupling, Transformer - Electrical laws, Transformer - Invention, Transformer - Practical considerations, Transformer - Classification, Transformer - Losses, Transformer - High frequency operation, Transformer - Construction, Transformer - Cores, Transformer - Windings, Transformer - Insulation, Transformer - Shielding, Transformer - Coolant, Transformer - Terminals, Transformer - Transformer designs, Transformer - Autotransformers, Transformer - Polyphase transformers, Transformer - Resonant transformers, Transformer - Instrument transformers, Transformer - Pulse transformers, Transformer - RF transformers, Transformer - Uses of transformers

Read more here: » Transformer: Encyclopedia II - Transformer - Transformer designs

Electrical engineering has many subfields. This section describes seven of the most popular subfields in electrical engineering. Although there are electrical engineers who focus exclusively on one subfield, there are also many who focus on a combination of subfields. Some fields such as electronics engineering and computer engineering are not always considered subfields of electrical engineering b ...

See also:

Electrical engineering, Electrical engineering - Terminology, Electrical engineering - History, Electrical engineering - Early developments in electricity, Electrical engineering - The emergence of radio and electronics, Electrical engineering - Education, Electrical engineering - Training and certification, Electrical engineering - Demographics, Electrical engineering - Tools and work, Electrical engineering - Subfields, Electrical engineering - Other related disciplines

Read more here: » Electrical engineering: Encyclopedia II - Electrical engineering - Subfields

AC voltage can be stepped up or down by a transformer to a different voltage. High-voltage, direct current electric power transmission systems contrast with the more common alternating-current systems as a means for the bulk transmission of electrical power. However, these tend to be more expensive and less efficient than transformers, or did not exist when Edison, Westinghouse and Tesla were designing their power systems. Use of a higher voltage leads to more efficient transmission of power. The power losses in a conductor are a prod ...

See also:

Alternating current, Alternating current - History, Alternating current - Distribution and domestic power supply, Alternating current - AC power supply frequencies, Alternating current - Mathematics of AC voltages

Read more here: » Alternating current: Encyclopedia II - Alternating current - Distribution and domestic power supply