What is a Transformer And How Do They Work? | Transformer Working Principle | Electrical4U

Summary

This video provides a comprehensive overview of how transformers work, highlighting their key components: two windings and a metallic core. It explains the principle of electromagnetic induction, where alternating current in the primary winding generates a varying magnetic flux that induces an electromotive force in the secondary winding. The video also discusses the significance of the right-hand grip rule for determining flux direction, and how a low reluctance magnetic core enhances power transfer. It concludes with an explanation of step-up and step-down transformers, emphasizing the relationship between the number of turns in the windings and the resulting voltage transformation.

Takeaways

• 😀 A transformer is a static machine consisting of three main parts: two windings and a metallic core.
• 😀 The windings are coils made of a good conductor that behave as inductors when alternating current flows through them.
• 😀 The magnetic flux produced by the windings is proportional to the current and varies with the direction of the current.
• 😀 The right-hand grip rule helps determine the direction of the magnetic flux in the windings.
• 😀 Self-induced EMF across the windings is caused by the continually varying magnetic flux, following Faraday's laws of electromagnetic induction.
• 😀 Lenz's law states that the induced voltage in the windings is opposite in polarity to the supply voltage.
• 😀 The voltage induced per turn in the windings increases with the number of turns, while the total induced EMF depends on the supply voltage.
• 😀 A second winding experiences an induced EMF due to the varying flux linkage from the first winding, allowing for power transfer.
• 😀 Using a low reluctance magnetic core, like steel, maximizes the magnetic flux linkage between the two windings.
• 😀 The voltage across the secondary winding can be either greater or less than that of the primary winding, classifying the transformer as either step-up or step-down.

Q & A

What is a transformer and how is it classified?

A transformer is a static machine that transfers electrical energy between two or more circuits through electromagnetic induction. It has no moving parts and is classified based on its function as either a step-up transformer (increases voltage) or a step-down transformer (decreases voltage).

What are the main components of a transformer?

The main components of a transformer are two windings (primary and secondary) and a metallic core. The windings are coils made of a good conductor, and the core is typically made of a low reluctance magnetic material like steel.

What role do the windings play in a transformer?

The windings in a transformer act as inductors. When alternating current flows through the windings, it generates a varying magnetic flux, which is essential for inducing electromotive force (EMF) in the other winding.

How does the right-hand grip rule apply to transformers?

The right-hand grip rule helps determine the direction of the magnetic flux produced by the current flowing through the windings. By gripping the coil with the right hand, with the thumb pointing in the direction of the current, the fingers indicate the direction of the magnetic flux.

What is self-induced EMF in the context of a transformer?

Self-induced EMF is the voltage generated across a winding due to the changing magnetic flux within the winding itself, as described by Faraday's law of electromagnetic induction. This induced voltage opposes the applied voltage according to Lenz's law.

What determines the induced voltage per turn in a transformer winding?

The induced voltage per turn in a transformer winding is determined by the supply voltage and the number of turns in the winding. The total induced EMF across the winding is proportional to the number of turns.

What happens when a secondary winding is placed near a primary winding in a transformer?

When a secondary winding is placed near a primary winding, it experiences induced EMF due to the varying magnetic flux produced by the primary winding. This induced EMF is typically small due to limited flux linkage.

Why is a low reluctance magnetic core used in transformers?

A low reluctance magnetic core, such as steel, is used in transformers to maximize the magnetic flux linkage between the primary and secondary windings. This increases the efficiency of power transfer from the primary to the secondary winding.

How does the number of turns in the primary and secondary windings affect voltage?

The relationship between the number of turns in the primary (N1) and secondary (N2) windings determines the voltage transformation. If N2 is greater than N1, the secondary voltage (V2) will be greater than the primary voltage (V1), resulting in a step-up transformer. Conversely, if N2 is less than N1, V2 will be less than V1, resulting in a step-down transformer.

What is the significance of Faraday's law in transformer operation?

Faraday's law is fundamental to transformer operation as it states that the induced EMF in a coil is directly proportional to the rate of change of magnetic flux linkage. This principle underlies how transformers transfer energy between windings through electromagnetic induction.