Transcript

A A transformertransformer is a device that transfers is a device that transfers electrical energy from one circuit to electrical energy from one circuit to another.another.

It is done by changing current in the first It is done by changing current in the first circuit (primary) creating a magnetic field circuit (primary) creating a magnetic field that induces voltage in the second voltage that induces voltage in the second voltage (secondary).(secondary).

HISTORYHISTORY

18311831 – transformer principle was – transformer principle was demonstrated by Michael Faradaydemonstrated by Michael Faraday

18361836 – first widely used transformer – first widely used transformer (induction coil) was invented by Nicholas (induction coil) was invented by Nicholas CallanCallan

1830’s-1870’s1830’s-1870’s – efforts were made to build – efforts were made to build better induction coilsbetter induction coils

1880’s1880’s – efficient induction coils were – efficient induction coils were introducedintroduced

1876 1876 – lighting system based on induction – lighting system based on induction coils was invented by Pavel Yablochkovcoils was invented by Pavel Yablochkov

18851885 – the commmercial transformer was – the commmercial transformer was built by William Stanleybuilt by William Stanley

18891889 – first three-phase transformer was – first three-phase transformer was developed by Russian engineer Mikhail developed by Russian engineer Mikhail Dolivo-Dobrovolsky.Dolivo-Dobrovolsky.

18911891 – the Tesla coil, a resonant – the Tesla coil, a resonant transformer for generating very high transformer for generating very high voltages at high frequency was invented voltages at high frequency was invented by Nikola Tesla.by Nikola Tesla.

PresentPresent – some transformers are used in – some transformers are used in many electronic devicesmany electronic devices

AutotransformerAutotransformer

has only a single winding with has only a single winding with two end terminals, plus a third two end terminals, plus a third at an intermediate tap point. at an intermediate tap point. The primary voltage is The primary voltage is applied across two of the applied across two of the terminals, and the secondary terminals, and the secondary voltage taken from one of voltage taken from one of these and the third terminal. these and the third terminal. The primary and secondary The primary and secondary circuits therefore have a circuits therefore have a number of windings turns in number of windings turns in common.common.

Polyphase TransformerPolyphase Transformer

three individual single-three individual single-phase transformers phase transformers incorporated as a single incorporated as a single three-phase transformer three-phase transformer and is used for three-and is used for three-phase supplies. In this phase supplies. In this case, the magnetic case, the magnetic circuits are connected circuits are connected together, the core thus together, the core thus containing a three-phase containing a three-phase flow of flux.flow of flux.

Leakage TransformersLeakage Transformers

also called a stray-field also called a stray-field transformer, has a transformer, has a significantly higher significantly higher leakage inductance than leakage inductance than other transformer. other transformer. Leakage transformers Leakage transformers are used for arc welding are used for arc welding and high voltage and high voltage discharge lamps. It acts discharge lamps. It acts then both as a voltage then both as a voltage transformer and as a transformer and as a magnetic ballast. magnetic ballast.

Resonant TransformerResonant Transformer

a kind of the leakage a kind of the leakage transformer that uses transformer that uses the leakage inductance the leakage inductance of its secondary of its secondary windings in windings in combination with combination with external capacitors, to external capacitors, to create one or more create one or more resonant circuits that resonant circuits that can generate very high can generate very high voltages.voltages.

Instrument TransformersInstrument Transformers

is a measurement device is a measurement device designed to provide a designed to provide a current in its secondary current in its secondary coil proportional to the coil proportional to the current flowing in its current flowing in its primary. They are primary. They are designed to present designed to present negligible load to the negligible load to the supply being measured supply being measured and to have a precise and to have a precise voltage ratio to voltage ratio to accurately step down accurately step down high voltages.high voltages.

ClassificationClassification

Transformers can be classified in different ways:Transformers can be classified in different ways:

By power levelBy power level: from a fraction of a volt-ampere (VA) to : from a fraction of a volt-ampere (VA) to over a thousand MVA; over a thousand MVA;

By frequency rangeBy frequency range: power-, audio-, or radio frequency; : power-, audio-, or radio frequency; By voltage classBy voltage class: from a few volts to hundreds of : from a few volts to hundreds of

kilovolts; kilovolts; By cooling typeBy cooling type: air cooled, oil filled, fan cooled, or water : air cooled, oil filled, fan cooled, or water

cooled; cooled; By application functionBy application function: such as power supply, : such as power supply,

impedance matching, output voltage and current impedance matching, output voltage and current stabilizer, or circuit isolation; stabilizer, or circuit isolation;

By end purposeBy end purpose: distribution, rectifier, arc furnace, : distribution, rectifier, arc furnace, amplifier output; amplifier output;

By winding turns ratioBy winding turns ratio: step-up, step-down, isolating : step-up, step-down, isolating (near equal ratio), variable.(near equal ratio), variable.

ApplicationsApplications

used to increase voltage before used to increase voltage before transmitting electrical energy over long transmitting electrical energy over long distances through wires.distances through wires.

enable economic transmission of power enable economic transmission of power over long distances.over long distances.

used extensively in electronic products to used extensively in electronic products to step down the supply voltage to a level step down the supply voltage to a level suitable for the low voltage circuits they suitable for the low voltage circuits they contain. contain.

electrically isolates the end user from electrically isolates the end user from contact with the supply voltage contact with the supply voltage

Sources :Sources :

http://en.wikipedia.org/wiki/Transformer#Applicationshttp://en.wikipedia.org/wiki/Transformer#Applications

http://images.search.yahoo.com/search/images?p=resonant+transformer&js=1&ei=utf-8&fr=sfp&xargs=0&pstart=1&b=21&ni=20http://images.search.yahoo.com/search/images?p=resonant+transformer&js=1&ei=utf-8&fr=sfp&xargs=0&pstart=1&b=21&ni=20

http://images.search.yahoo.com/search/images;_http://images.search.yahoo.com/search/images;_


Top Related