. A device that transfers electrical energy from one circuit to another circuit.
 . Used to step up and step down AC voltages.
 . Uses principle of mutual induction.
 . Mutual Induction: Production of electromotive force in circuit by current changing in second circuit which is linked magnetically to the first.
 . William Stanley built the first commercial transformer in 1886.


  . Input connections: Input source is connected - Primary side.
  . Output connections: Transformed power is sent to load - Secondary Side.
  . Windings: Primary- draws power from source.
                     Secondary- delivers transformed voltage to load.
  . Core: Provides controlled path for magnetic flux generated.


  . Primary coil is connected to AC supply.
  . An alternating current passes through primary coil wrapped around soft iron core.
  . Changing current produces changing magnetic filed.
  . This induces alternating voltage in secondary coil.
  . This induces AC in circuit connected to secondary coil.

  . No electric connection between primary and secondary.
  . Only AC is supplied to primary.
  . If DC is supplied, no current is induced in secondary.

Types of Transformers:

  Based on Voltage levels:
  1. Step-Up Transformer: Secondary voltage is stepped up by increasing number of windings in secondary coil.
  2. Step-Down Transformer: Secondary voltage is stepped down by decreasing number of windings in primary coil.

  Based on Core:
  1. Core: Winding surrounds laminated core.
  2. Shell: Laminated core surrounds Winding.

  Based on Winding:
  1. Standard: Primary and Secondary winding placed in different regions.
  2. Auto Transformer: Windings connected to each other in series.

  Based on Usage:
  1. Power Transformer: Bigger in size.
                                  Suitable for high voltage power transfer.
                                  Used in power generation stations and transmission substation.
  2. Distribution Transformer: Smaller in size.
                                           Works with 50-70% efficiency.
                                           Used to distribute power generated from plant to remote locations.
  3. Measurement Transformer: Used to measure electrical quantity like voltage, current, power.
  4. Protection Transformer: Used in component protection purpose.

Usage of Transformers:

 . Used everywhere like from home appliances to large systems.
 . Adapters and chargers of mobile phones.
 . To step up voltage level at power plant and at substation, step down voltage level.