Transformers

 . 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.

 Construction:

  . 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.

Working:

  . 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.

Note: 

  . 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.