Electrical Engineering Transformers

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It consists of primary and secondary windings wound around a magnetic core.

A transformer operates on the principle of electromagnetic induction. When an alternating current flows through the primary winding, it creates a varying magnetic field in the core, which induces a voltage in the secondary winding according to Faraday’s Law of Induction.

The main components of a transformer are:

• Primary Winding: Coil connected to the input voltage source.
• Secondary Winding: Coil connected to the output load.
• Magnetic Core: Provides a path for the magnetic flux

• Step-up Transformer: Increases voltage from primary to secondary winding (secondary voltage > primary voltage).
• Step-down Transformer: Decreases voltage from primary to secondary winding (secondary voltage < primary voltage)

The two main types of losses in a transformer are:

• Core (Iron) Losses: Due to hysteresis and eddy currents in the core.
• Copper (Winding) Losses: Due to the resistance of the windings.

A laminated core reduces eddy current losses by increasing the electrical resistance of the core material, which confines the eddy currents to smaller paths and thereby reduces their magnitude.

Mutual inductance is the ability of one coil to induce a voltage in another coil through a shared magnetic field. In a transformer, the primary winding induces a magnetic field that links with the secondary winding, inducing a voltage according to Faraday’s Law.

• Core-type Transformer: Windings are placed around the core limbs.
• Shell-type Transformer: Core surrounds most of the windings.

• Power Transformers: Used in transmission networks for high voltage applications.
• Distribution Transformers: Used to distribute electricity to end-users at lower voltages.
• Instrument Transformers: Include current transformers (CTs) and potential transformers (PTs) for measuring and protection purposes.

A tap changer is a mechanism in transformers that allows for the adjustment of the turns ratio to regulate the output voltage. It can be either on-load (OLTC) or off-load (de-energized).