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.

Outlines

00:00

🔌 Understanding Transformers

This paragraph explains the basic function of transformers, which is to receive AC power at one voltage and deliver it at another to improve transmission efficiency over long distances. It introduces the concept of a three-phase transformer and its working principle based on electromagnetic induction. The principle involves a varying magnetic flux inducing an electromotive force (EMF) across a loop. The transformer uses a coil and alternating EMF system to create a fluctuating magnetic field, which is linked to a secondary winding through a ferromagnetic core. The induced EMF in the secondary coils is the sum of individual EMFs in each turn, and the EMF per turn is the same for both primary and secondary coils due to the same magnetic flux passing through them. The induced EMF at the secondary coil is inversely proportional to the number of turns in the primary coil, allowing for voltage transformation. The paragraph also discusses the relationship between primary and secondary currents due to energy conservation and the special winding configurations used in high-power transformers, such as disc type windings and delta and star configurations for low and high voltage windings, respectively.

05:02

🌡️ Cooling and Energy Loss in Transformers

The second paragraph focuses on the energy losses that occur during power transfer in transformers, which are dissipated as heat. To manage this, transformers are often immersed in a cooling coil filled with oil that dissipates heat through natural convection. As the oil absorbs heat, it expands, and a conservator tank is used to accommodate this volume change. The paragraph concludes by encouraging viewers to explore other videos for more information on different types of transformer cores and windings.

Keywords

💡Transformer

A transformer is an electrical device that transfers electrical energy from one circuit to another through electromagnetic induction. In the video, transformers are discussed as devices that can receive AC power at one voltage and deliver it at another voltage, which is crucial for efficient power transmission over long distances. The script explains that transformers operate on the principle of electromagnetic induction, where a varying magnetic field induces an electromotive force (EMF) in a secondary coil.

💡AC Power

AC power, or alternating current power, refers to electrical energy that reverses direction periodically. The video mentions that transformers are capable of receiving AC power at one voltage, which is a fundamental aspect of their operation. The fluctuating nature of AC current is what allows transformers to function by creating a varying magnetic field.

💡Electromagnetic Induction

Electromagnetic induction is the production of an electromotive force across a conductor that is exposed to a varying magnetic field. The video script describes this principle as the basic working principle of a transformer, where a fluctuating magnetic field induces an EMF in the secondary coils. This is the core mechanism that allows transformers to change voltage levels.

💡Ferromagnetic Material

Ferromagnetic materials are substances that strongly attract iron, nickel, and cobalt, and are used in transformers to create a magnetic path for the induction process. The script mentions that the core of a transformer is made of a ferromagnetic material, which helps link the fluctuating magnetic field to the secondary winding, enhancing the induction process.

💡EMF

Electromotive force (EMF) is the energy provided by an electric source to push electric charge through a circuit. In the context of the video, EMF is induced in the secondary coils due to electromagnetic induction. The script explains that the EMF per turn for both primary and secondary coils is the same, which is a key factor in determining the output voltage of the transformer.

💡Three-Phase Transformer

A three-phase transformer is a type of transformer that can handle three-phase AC power, which is commonly used in power distribution systems. The video script describes how three-phase transformers use three single-phase transformers with a concentric coil configuration, which is essential for maintaining the balance and efficiency of power transmission in three-phase systems.

💡Disc Type Winding

Disc type winding is a special kind of winding used in high-power transformers, where separate disk windings are connected in series through outer and inner crossovers. The video script mentions that high-power transformers often employ disc type windings, which are designed to reduce energy loss and improve the efficiency of the transformer.

💡Delta Configuration

A delta configuration is a type of electrical connection in which the three windings of a transformer are connected end-to-end, forming a closed loop. The video script explains that low voltage windings in transformers are connected in a delta configuration, which is used to increase the line voltage and is common in three-phase systems.

💡Star Configuration

A star configuration is an electrical connection where one end of each winding is connected together at a common point, and the other ends are connected to the supply lines. The video script mentions that high voltage windings are connected in a star configuration, which helps in reducing the voltage and is also used in three-phase systems.

💡Eddy Current

Eddy currents are circular electric currents induced within conductors by a changing magnetic field. The video script discusses how thin insulated steel laminations are used in the core of the transformer to reduce energy loss due to eddy current formation, which is a significant factor in the efficiency of the transformer.

💡Cooling Coil

A cooling coil is a component used to dissipate heat generated within electrical equipment such as transformers. The video script describes how transformers are often immersed in a cooling coil filled with oil, which helps to dissipate the heat generated by energy losses during power transfer, ensuring the transformer operates efficiently.

Highlights

Transformers receive AC power at one voltage and deliver it at another, improving transmission efficiency over long distances.

The basic principle of transformers is electromagnetic induction.

A varying magnetic flux in a loop induces an electromotive force across it.

A current-carrying conductor produces a magnetic field that can be manipulated by a coil.

The magnetic field associated with a coil fluctuates with the alternating current.

A ferromagnetic core links the magnetic flux to a secondary winding.

The induced EMF in the secondary coils is due to electromagnetic induction.

The net EMF induced across the winding is the sum of individual EMFs in each turn.

EMF per turn for both primary and secondary coils is the same due to the same magnetic flux.

The induced EMF at the secondary coil is proportional to the number of turns in the coil.

Transformers can lower or increase voltage by adjusting the number of turns in the secondary coil.

Energy conservation dictates the relationship between primary and secondary currents.

Three-phase transformers use three single-phase transformers with a concentric coil configuration.

High power transformers use a special Disc type winding connected in series.

Low voltage windings are connected in a delta configuration, and high voltage windings in a star configuration.

From a three-phase step-up transformer, four output wires can be drawn: three-phase power wires and one neutral.

High-voltage insulated bushings are required to bring out the electrical energy.

The transformer core is made of thin insulated steel laminations to reduce energy loss from eddy currents.

The transformer is immersed in a cooling coil to dissipate heat generated by energy losses.

A conservator tank helps accommodate volume changes in oil due to heat absorption.

Transcripts

Transformers are capable of receiving AC power at one voltage

and delivering it at another voltage.

In this way they help achieve better transmission efficiency,

while transferring the power over longer distances.

In this video we will go through the working and construction of a

three-phase transformer,

by starting from its simplest form.

The basic working principle a transformer is simple,

Electromagnetic induction.

According to this principle

a varying magnetic flux associated with the loop

will induce an electromotive force across it.

Such a fluctuating magnetic field can easily be produced by a coil

and alternating EMF system.

A current-carrying conductor produces a magnetic field around it.

The magnetic field produced by a coil

will be as shown in the figure.

With the fluctuating nature of the alternating current,

the magnetic field associated with the coil will also fluctuate.

This magnetic flux can be effectively linked to a secondary winding,

with the help of a core

made up a ferromagnetic material.

This fluctuating magnetic field will induce an EMF in the secondary coils

due to electromagnetic induction.

Since the turns are arranged in a series,

the net EMF induced across the winding

will be the sum of the individual EMFs

induced in each turn.

Since the same magnetic flux is

passing through the primary and secondary coils,

the EMF per turn for both the primary and secondary coils will be the same.

The EMF per turn for the primary coil

is related to the applied input voltage as shown.

As a result the induced EMF at the secondary coil

is expressed as follows:

This simply means that with fewer turns in the secondary

than in primary one can lower the voltage.

For the reverse case one can increase the voltage.

But since energy is conserved,

the primary and secondary currents have to

obey the following relationship:

Three-phase transformers use three such

single-phase transformers,

but with a slightly different coil configuration.

Here the primary and secondary coils sit concentrically.

Two more such windings are employed in a three-phase transformer.

Transformers with high power ratings generally employ

a special kind of winding known as a Disc type winding,

Where separate disk windings are connected in series

through outer and inner crossovers.

The low voltage windings are connected

in a delta configuration.

And the high voltage linings are

connected in a star configuration.

Thus the line voltage further rises to

3^.5 times at high voltage side.

This also means that,

from a three-phase step up transformer

we can draw four output wires,

three-phase power wires and one neutral.

High-voltage insulated bushings are required

to bring out the electrical energy.

The core of the transformer is made of thin insulated steel laminations.

Such steel laminations are stacked together

as shown to form a three-phase limbs.

The purpose of thin laminations is to reduce

energy lost due to eddy current formation.

The low voltage winding usually sit near the core.

Various kinds of energy loss happens

while transferring power from the primary to secondary coil.

All these energy losses are dissipated as heat.

So usually the transformer is immersed in a cooling coil,

to dissipate the heat.

The oil dissipates the heat via natural convection.

Oil in the tank will expand

as it absorbs the heat.

A conservator tank helps to accommodate for this volume change.

To know more on

different types a transformer cores and windings

please check out our other videos.

Thank you !