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

A single phase transformer is a type of transformer that converts alternating current (AC) power at one voltage level to another voltage level with the same frequency. It is used in a wide range of applications, from small electronic devices to large power distribution systems.

Single Phase Transformer Types

The following types of transformer are typically constructed to receive and output single-phase AC power.

Audio Transformer

This type removes ground noise from audio signals by supplying the device with magnetic shielding.


They are commonly employed in low power systems to connect circuits with various voltage classes. It consists of only one winding, cannot isolate networks, and is typically lighter, smaller, and cheaper than other types. The voltage supply and electrical load are joined to two taps, and voltages are specified by tapping the winding at several points. An autotransformer with a regulated tap is introduced as a variable transformer or a variac.


In this type, the transformer regulates a voltage rating to device specifications. They are generally utilized as circuit isolators.

Constant-Voltage Transformer (CVT)

This type creates a relatively constant output voltage, despite practically great variances in the input voltage.

Constant-Current Transformer (CCT)

They are also called a regulator; it includes a self-regulating secondary section that supplies a consistent output current for any load through its dynamic level. It is usual for streetlight cases.

Distribution Transformer

This is the pole-mounted, oft-seen device that steps down current for light-duty electrical cases.

Flyback Transformer

This type can be used to create a high-voltage output, and the transformer saves power in its magnetic sections for a short time.

Construction of single phase transformer:

A transformer consists of two windings wrapped around a common core. The core is typically made of laminated steel to reduce energy losses due to eddy currents. The primary winding is connected to the input voltage source, while the secondary winding is connected to the load.

Working of single phase transformer:

When an AC voltage is applied to the primary winding, it creates a magnetic field around the core. This magnetic field induces a voltage in the secondary winding, which is proportional to the number of turns in the secondary winding. The voltage ratio between the primary and secondary windings is determined by the number of turns in each winding.

Advantages of single phase transformer:

  • Simple construction and easy to maintain
  • Low cost
  • High efficiency
  • Reliable operation


  • Limited power output compared to three-phase transformers
  • Not suitable for high voltage or high current applications


  • Power supplies for electronic devices
  • Lighting ballasts
  • AC voltage regulators
  • Isolation transformers for safety purposes
  • Audio transformers for impedance matching in audio equipment

Overall, this type of transformer are widely used in a variety of applications due to their simplicity, reliability, and low cost.

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