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

A core type transformer is a type of transformer where the windings are wound around a magnetic core. The core is usually made of laminated sheets of steel to reduce eddy current losses. Core type transformers are one of the most common types of transformers used in power systems.

The construction of a core type transformer

  1. Core selection: The type and size of the core are selected based on the transformer’s specifications, including the power rating and frequency.
  2. Winding: The primary and secondary windings are wound around the core. The number of turns in each winding is determined based on the desired voltage ratio.
  3. Insulation: The windings are insulated from each other and from the core to prevent short circuits and reduce losses.
  4. Termination: The ends of the windings are brought out and connected to terminals for external connections.
  5. Enclosure: The transformer is enclosed in a protective casing to protect it from environmental factors such as moisture and dust.
  6. Testing: The transformer is tested to ensure that it meets the specifications and functions properly.

Working of core type transformer:

Core type transformers work based on the principle of electromagnetic induction. When an alternating current is passed through the primary winding of the transformer, it creates a magnetic field that induces a voltage in the secondary winding. The amount of voltage induced in the secondary winding depends on the ratio of the number of turns in the primary winding to the number of turns in the secondary winding. The magnetic core helps to concentrate the magnetic field and reduce losses.

Advantages of core type transformer:

  1. High efficiency: Core type transformers have a high efficiency due to the magnetic core which helps to reduce losses.
  2. Low leakage inductance: The magnetic core provides a closed magnetic circuit, which helps to reduce leakage inductance.
  3. Good voltage regulation: Core type transformers have a good voltage regulation because the magnetic core helps to maintain a constant magnetic flux.

Disadvantages of core typetransformer:

  1. Heavy: Core type transformers are heavier than shell type transformers due to the larger amount of iron in the core.
  2. Expensive: Core type transformers are more expensive to manufacture than shell type transformers due to the larger amount of iron in the core.


  1. Power transmission and distribution systems
  2. Power generation facilities
  3. Industrial applications such as welding, arc furnaces, and motor starting
  4. Lighting applications such as street lighting and neon signs.

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