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

A voltage transformer is an electrical device that is used to convert high voltage power into a low voltage that can be easily measured, monitored, or used for various applications. It is commonly known as a potential transformer (PT) and is used in power systems for a variety of applications such as protective relaying, metering, and control.

Construction of voltage transformer:

A typical voltage transformer consists of a primary winding, a secondary winding, and a magnetic core. The primary winding is connected to the high voltage source, and the secondary winding is connected to a low voltage device. The magnetic core is made up of high permeability magnetic material and is used to transfer the voltage from the primary winding to the secondary winding.

Working of voltage transformer:

When a high voltage is applied to the primary winding, an alternating magnetic flux is generated in the core. This flux induces a voltage in the secondary winding that is proportional to the number of turns in the winding. Since the secondary winding has fewer turns than the primary winding, the output voltage is lower than the input voltage. The ratio of the primary voltage to the secondary voltage is known as the turns ratio, and it determines the output voltage.

Advantages of voltage transformer:

  1. Provides isolation between the high voltage and low voltage circuits, thereby protecting the low voltage circuit from the high voltage circuit.
  2. The voltage transformer operates at a lower voltage, which makes it safe for metering and other low voltage applications.
  3. The voltage transformer provides accurate voltage measurement and regulation.
  4. The voltage transformer has a high efficiency and is reliable in operation.

Disadvantages of voltage transformer:

  1. The voltage transformer is relatively bulky and heavy.
  2. The voltage transformer requires periodic maintenance.
  3. The voltage transformer is expensive.


  1. Voltage transformers are used in power transmission and distribution systems for metering, protective relaying, and control applications.
  2. Voltage transformers are used in electronic devices and instruments for voltage measurement and regulation.
  3. Voltage transformers are used in testing and calibration laboratories for accurate voltage measurement.
  4. Voltage transformers are used in industrial applications for voltage regulation and control.

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