How does a Transformer work ?

Summary

This video explains the operation and construction of a three-phase transformer, highlighting its role in improving power transmission efficiency. It covers the basic principle of electromagnetic induction, how it varies magnetic flux to induce EMF in secondary coils. The video also discusses transformer configurations, including delta and star connections, and the use of disc type windings for high power ratings. It concludes with insights on core construction, energy loss, and cooling mechanisms.

Takeaways

• 🔌 Transformers operate on the principle of electromagnetic induction to transfer power efficiently over long distances.
• 🧲 A varying magnetic flux is created by a coil carrying an alternating current, which induces an electromotive force (EMF) in the secondary coil.
• 🔗 The core of a transformer is made of ferromagnetic material to effectively link the magnetic flux to the secondary winding.
• 🔄 The EMF induced in the secondary coil is proportional to the number of turns in the coil, allowing for voltage transformation.
• 🔄 A lower voltage can be achieved with fewer turns in the secondary coil compared to the primary, and vice versa for higher voltages.
• ⚙️ Three-phase transformers consist of three single-phase transformers with a concentric coil configuration.
• 🌀 High-power transformers often use disc type windings, where separate disk windings are connected in series.
• ⚡ The low voltage windings are connected in a delta configuration, and the high voltage windings in a star configuration, increasing the line voltage by a factor of √3.
• 🏭 A three-phase step-up transformer can provide three-phase power and a neutral wire, requiring high-voltage insulated bushings.
• 🛠 The transformer core is made of thin, insulated steel laminations to reduce energy loss due to eddy currents.
• 🌡️ Transformers are often immersed in oil for cooling, with a conservator tank to accommodate volume changes as the oil heats and expands.

Q & A

What is the primary function of a transformer?

A transformer's primary function is to receive AC power at one voltage and deliver it at another voltage, which helps achieve better transmission efficiency while transferring power over longer distances.

What is the basic working principle of a transformer?

The basic working principle of a transformer is electromagnetic induction, where a varying magnetic flux associated with a loop induces an electromotive force across it.

How does a current-carrying conductor contribute to the operation of a transformer?

A current-carrying conductor produces a magnetic field around it, which, when associated with a coil in an alternating EMF system, creates a fluctuating magnetic field that can induce an EMF in secondary coils.

What role does a ferromagnetic core play in a transformer?

A ferromagnetic core in a transformer helps to effectively link the fluctuating magnetic field to the secondary winding, allowing for the induction of EMF in the secondary coils.

How is the induced EMF in the secondary coil related to the primary coil?

The induced EMF in the secondary coil is directly proportional to the number of turns in the secondary coil and the magnetic flux, which is the same for both primary and secondary coils, resulting in the same EMF per turn.

What is the relationship between the turns in the primary and secondary coils and the voltage transformation?

Fewer turns in the secondary coil compared to the primary coil will lower the voltage, while more turns will increase the voltage, following the principle that EMF per turn is the same for both coils.

How does a three-phase transformer differ from a single-phase transformer?

A three-phase transformer uses three single-phase transformers with a concentric coil configuration, where the primary and secondary coils sit concentrically, and two more windings are employed.

What is a Disc type winding and why is it used in high-power transformers?

A Disc type winding is a special kind of winding where separate disk windings are connected in series through outer and inner crossovers. It is used in high-power transformers to improve efficiency and reduce energy loss.

What is the purpose of the delta and star configurations in the windings of a three-phase transformer?

The low voltage windings are connected in a delta configuration, and the high voltage windings are connected in a star configuration. This setup increases the line voltage to 3.5 times at the high voltage side.

Why are high-voltage insulated bushings necessary in transformers?

High-voltage insulated bushings are required to safely bring out the electrical energy from the transformer, protecting against electrical discharges at high voltages.

How do thin insulated steel laminations in the core of a transformer reduce energy loss?

Thin insulated steel laminations reduce energy loss due to eddy current formation by minimizing the path for current flow within the core, thus reducing the resistive heating effect.

What is the role of the cooling system in a transformer?

The cooling system, often involving oil, dissipates heat generated by various energy losses during power transfer from the primary to secondary coil, preventing overheating and maintaining the transformer's efficiency.