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Transformers and Different Voltages 

What is it?

  • Set of coils wound around a core, usually made of iron generating a magnetic field, that creates energy between the coils. 

  • The electrical power transformer is a static device which transforms electrical energy from one circuit to another without any direct electrical connection and with the help of mutual induction between two windings.

  • The Voltage Transformer can be thought of as an electrical component rather than an electronic component.

A transformer operates on the principals of electromagnetic induction. 

  • The three main parts of a transformer are:

  • Primary winding

  • Secondary winding

  • Magnetic core

Primary winding: Which produces magnetic flux when it is connected to the electrical source.

Secondary winding: The flux, produced by primary winding, passes through the core, will link with the secondary winding. This winding also wounds on the same core and gives the desired output of the transformer.

Magnetic core: The magnetic flux produced by the primary winding, that will pass through this low reluctance path linked with secondary winding and create a closed magnetic circuit.​

Two types of transformer:

Step-down transformer

Step-up transformer

How does it work?

  • The working principle of the transformer is very simple.

  • It depends upon Faraday's law of electromagnetic induction.

  • Actually, mutual induction between two or more winding is responsible for transformation action in an electrical transformer.

e.m.f produce at primary winding (E1)= - Np

dΦ

dt

___

Power on both sides is equal.

Vp Ip = Vs Is

Frequency on both sides is equal.

Fp = Fs (50Hz)

  • If alternating current (Ip) supply to the primary winding.

  • The magnetic flux Φ is set up in laminated core.

  • This magnetic flux Φ cuts secondary winding.

  • According to Faraday's law of electromagnetic induction, it produces mutual-induction emf at secondary.

A transformer works with AC supply to the primary winding.

A transformer can not produce flux with a DC supply in the coil at the primary winding.

Why Transformer?

  • The longer the wires, the higher their resistance.

  • The higher their resistance, the more they cause some of the energy flowing through them to be converted into heat.

  • Voltage drop across resistor : Current x Resistance

  • Power lost as heat in resistor : Current x Voltage drop

: Current x Current x Resistance

  • We can reduce the amount of energy that is converted into heat in the wires by reducing the amount of current flowing through them.

  • And we can accomplish this by adding the two transformers as given below.

  • But, the current flowing in between the two transformers is much smaller than the current we ever had flowing through the circuit before.

  • This is the principle by which electric utilities use transformers to deliver electricity to people's home more efficiently. 

  • Transformers are used to step-up or step-down electrical currents and are the heart of computer power supplies.

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