Transformer introduction and construction

Transformer introduction and construction

Introduction:- Transformer is an static electrical machine. It is used to increase or decrease  voltage, Basically a transformer has two winding and a magnetic core. Winding are Known as primary winding and secondary winding.Primary winding is connected to supply and secondary winding is connected to load.When alternating voltage is applied to primary winding an alternating magnetic flux setsup in core. Due to that flux in core alternating voltage is induced in secondary winding which causes current to flow through load circuit.

Basically transformer are of two type

1. Step up transformer:- It is used to increase the voltage in secondary side.

2. Step down transformer:- It is used to decrease the voltage in secondary side.

Transformation ratio- It is the ratio of number of turns in secondary winding to number of turns in primary winding.
K = N2/N1 also K=V2/V1 and K= I1/I2 with this formula we can find the number of turns in secondary winding if primary winding turns are known.

In Electronics generally step down transformer are used for power supplies. for example 230/12v 2A, 230/18v 3A etc. Example of step up transformer is ignition coil of bike, EHT transformer in TV, high voltage transformer in microwave oven etc.

Transformers are classified on the basis of their use

1. Power transformer used in power supplies.
2. Driver transformer used in driver circuit of audio amplifiers.
3. Output transformer used in output circuit of audio amplifiers.
4. Impedance matching transformer used inside moving coil microphones.
5. Multiple secondary winding:- these transformer have multiple secondary windings for different          voltages.
6. Auto transformer:- these transformers have single winding with tapping for primary and secondary      windings.

Transformers are also classified on the basis of core material used.

1. Iron core:-  Power transformer, battery charger transformer, input/output transformer etc.

2. Ferite core transformer-   Driver transformer, EHT transformer in TV. SMPS transformer etc. these transformer works at frequency of 15 KHz. there size is also small due to high frequency working.

3. Air core coils:- used in radio and tv circuit.

In addition to this very large transformers are used in power system.