EMTR

• Transformers


  • They either increase or decrease AC voltage
• The property of induction was discovered

  1830s
• William Stanley built the first reliable commercial transformer


  1886
• Electromagnetic induction


  The phenomena of electrical voltage generated when a coil of wire was wrapped around an iron core
• Inventors of transformers


  • Ottó Bláthy, Miksa Déri, Károly Zipernowsky
  • Lucien Gaulard, Sebstian Ferranti, William Stanley
  • Nikola Tesla
• First forms of transformers used in Austro-Hungary


  1878-1880s
• First forms of transformers used in England

  1882 onward
• Lucien Gaulard used his AC system for the Lanzo to Turin electrical exposition in Northern Italy


  1884
• Mikhail Dobrovsky designed and demonstrated his 3 phase transformers in the Electro-Technical Exposition at Frankfurt, Germany


  1891
• First AC power system that used the modern transformer was in Great Barrington, Massachusetts


  1886
• The AC demonstration system built in Great Barrington in 1886 by William Stanley, financed by Westinghouse was the greatest achievement in AC power until that point
• This event caught the attention of the entire electrical industry as it used the first modern transformer
• Lanzo to Turin electrical exposition in Northern Italy

  1884
• Electro-Technical Exposition at Frankfurt, Germany

  1891
• Lard (Frenchman) used his AC system for the revolutionary Lanzo to Turin electrical exposition in 1884
• Mikhail Dobrovsky designed and demonstrated his 3 phase transformers in the Electro-Technical Exposition at Frankfurt, Germany in 1891
• This single event inspired George Westinghouse to dive into AC current system development with significant resources
• This led to Westinghouse's great achievements a few years later, which in turn led to the formation of General Electric as an opposition to Westinghouse's success
• Stanley's big contributions were the design of an E-shaped core in the transformer and designing the induction coils in parallel instead of in series
• Stanley got valuable experience from this to help him advance the field of AC generators and full AC system design
• Many engineers after this studied the Great Barrington experiment and learned from it
• Transformer


  An electrical device that transfers energy between two or more circuits through electromagnetic induction
• Transformer


  • It is a static machine used for transforming power from one circuit to another without changing frequency
  • It transfers electrical power from one alternating current (ac) circuit to another without change in frequency
• Transformer working principle


  1. Changing current in primary coil creates changing magnetic field

  2. Changing magnetic field induces changing voltage in secondary coil

  3. If load is connected to secondary, electric charge will flow and transfer energy
• General types of transformer

  • Step-up transformer
  • Step-down transformer
• Types according to construction of iron core

  • Core type transformer
  • Shell type transformer
• Types according to construction of windings

  • Two winding transformer
  • Autotransformer
• Types according to location of installation

  • Indoor transformer
  • Outdoor transformer
• Types according to use

  • Power transformer
  • Distribution transformer
  • Instrument transformer
• Types according to number of phases

  • Single phase transformer
  • Three phase transformer
• Mutual flux


  The changing magnetic field that induces a changing voltage in the secondary winding
• Ratio of transformation


  The ratio of primary to secondary turns
• The 2,300/230-volt, 60-cycle transformer has 4800 turns in the primary. The mutual flux is 179,867.67 maxwells, the ratio of transformation is 10, and the number of secondary coil turns is 480
• The secondary winding of a 4,600/230-volt transformer has 36 turns, so the number of turns in the primary winding is 720
• The secondary load current of a 2,300/115-volt transformer is 46 amperes, so the primary current is 2.3 amperes
• Transformer connections


  • Wye-wye
  • Delta-delta
  • Wye-delta
  • Delta-wye
  • Open delta
• Wye-wye connection


  • Suitable for transformer applications that do not need a neutral on the primary side
  • Three-wire configuration can be used on three-phase and single-phase circuits
  • If one transformer fails, the entire system could become compromised
• Delta-delta connection


  • Provides a closed path for circulation of third harmonic component of current
  • Flux remains sinusoidal which results in sinusoidal voltages
  • Suitable for unbalanced loading
• Wye-delta connection


  • Delta connection assures balanced line-to-neutral voltages on the wye side
  • Provides a path for the third harmonic components in the exciting current independent of the neutral conductor
• Delta-wye connection


  • The most commonly used three-phase transformer connection
  • Wye-connected secondary allows single-phase load to be distributed among the three phases to neutral