What is a Power transformer? Its construction, working, advantages, disadvantages & Applications

A power transformer is a device that is used to transfer electrical energy from one circuit to another circuit by means of electromagnetic induction. It is an essential component of the electrical power system and is used to step up or step down the voltage level of the electrical power.

Construction of Power Transformer:

A typical power transformer consists of two coils, namely, primary and secondary coils, wound around a laminated core made up of magnetic material such as iron. The two coils are separated from each other and are electrically insulated from each other. The primary coil is connected to the input voltage source, and the secondary coil is connected to the load.

Working of Power Transformer:

When an alternating current is passed through the primary coil, it produces a magnetic flux in the core, which in turn induces a voltage in the secondary coil. The voltage induced in the secondary coil is proportional to the turn ratio of the transformer. Hence, if the number of turns in the secondary coil is greater than the number of turns in the primary coil, the output voltage will be higher than the input voltage.

Power transformer working

Advantages of Power Transformer:

  1. Power transformers are highly efficient and can transfer large amounts of power with minimum loss.
  2. They provide isolation between the input and output circuits, thereby providing protection against electrical shocks.
  3. They are highly reliable and have a long life span.
  4. They can be designed for different voltage levels and power ratings, making them suitable for a wide range of applications.

Disadvantages of Power Transformer:

  1. Power transformers are bulky and heavy, making them difficult to transport and install.
  2. They generate heat during operation, which can affect their efficiency and life span.
  3. They require regular maintenance and monitoring to ensure proper operation.


  1. Power transformers are used in electrical power generation and transmission systems to step up or step down the voltage level of the electrical power.
  2. They are used in electrical substations to distribute electrical power to different areas.
  3. They are used in industrial applications to power heavy machinery and equipment.
  4. They are also used in consumer electronics such as televisions, radios, and computers to provide the required voltage level.

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