Transformers

Transformers

BY MOHAMMAD IBRAHIM

Introduction to transformersWhat are they made up ofTheir working processTypes of transformersExplaining themImportant keynotesImportant equations regarding transformersThe national Grid

What is a transformer?1)Atransformeris a device that changes potential difference (voltage) from one value to another value making it smaller or greater using the principle of electromagnetic induction. 2) A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A transformer may increase or decrease voltage depending on the number of turns of coils that you include.

What does it consist of?A transformer consists of two coils wound on a soft iron core. One of the coils is connected to a mains power supply (gets supplied alternating current) is known as primary coil while the other is connected to any load (component Eg. Lamp) is known as secondary coil. These coils must be separated from each other.

Here is a diagram illustrating this

Working Process of a Transformer:The changing alternating current in primary coil produces a changing (alternating) magnetic field which link through the soft iron core from primary to secondary coil.

There are two main types of transformers:

Step up TransformerStep down transformer

Step up transformer:A step up transformer is a type of transformer that increases voltage from primary to secondary (more secondary winding turns than primary winding turns) is called astep up transformer.

Step-down transformer:A step down transformer is a type of transformer that decreases voltage from primary to secondary (less secondary winding turns than primary winding turns) is called astep up transformer.

A.C GRAPH:

If the input in the primary coil is A.C then the output must beA.C

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Dell (D) -

A video illustrating A.C in a transformer

THE FOLLOWING IS THE SYMBOL FOR A TRANSFORMER

The following are real pictures of transformers

Transformers are very efficient devices, if we assume they are 100% efficient (no energy wasted), then the electrical input power will equal the electrical output power.CALCULATING THE POWER OF A TRANSFORMER.

Efficiency is never 100%, although it can be 99%. Energy is lost if some of the primary magnetic field does not pass through the secondary.Energy is also lost because some eddy currents are induced in the soft iron core as well as in the coil. These eddy currents can by reduced by making the core laminated from thin metal strips.

SOLID CORE LAMINATED CORE

With no laminations with laminationsHigh eddy currents low eddy currents

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The equation for finding the voltage or the number of turns of coil in the primary/secondary coil.

Solving equations:A transformer has 100 turns in the secondary coil. It steps up a voltage from 50 to 240 volts. Calculate the number of turns in the primary coil.

After rearranging the formula

Answer=100 turns in the primary coil

A keypoint :Increasing the turns of coil results in:More VoltageLess current

Decreasing the turns of coil results in:Less VoltageMore current

What is The National Grid?

The national grid consists of transformers and high voltage cables. The national grid connects the power stations to the homes. Energy is always lost in the power cables, the bigger the distance between the power stations and the homes, the greater the energy loss. We can use electricity to transform energy from the power cables to the homes with less energy loss. First the electricity passes through step up transformers which increase the voltage, therefore the current will be less, less heat will be produced, and the energy loss will decrease. However, the voltage will be so high and that cant pass in our homes, so we use step down transformers which decrease the voltage.

BY8-D