How Power Transformers work ? | Epic 3D Animation #transformers

Summary

This video explores the workings of power transformers, key devices in electrical energy transmission and distribution. It explains the basic principles of transformers, including electromagnetic induction, mutual induction, and the difference between step-up and step-down transformers. The video also covers transformer components such as windings, laminated cores, and bushings, and discusses efficiency improvements like minimizing eddy currents. Additionally, the video explains transformer types, the importance of transformer oil, and the role of tap changers in adjusting voltage levels during variable loads.

Takeaways

• ⚡ Transformers revolutionized the field of electrical energy transmission and distribution by enabling constant voltage AC supply systems.
• 🔌 Transformers work on the principle of electromagnetic induction, which occurs when a changing magnetic flux induces voltage in a nearby coil.
• 🔄 Transformers are static machines that increase or decrease voltage levels of an AC supply with a corresponding change in current.
• 💡 The primary winding of a transformer is connected to the supply, while the secondary winding delivers the output voltage.
• 🛠️ Transformers use ferromagnetic cores to improve efficiency by providing a low reluctance path for magnetic flux and minimizing leakage flux.
• 🔥 Laminated cores are employed in transformers to reduce energy losses caused by eddy currents, improving overall efficiency.
• 🔋 Step-up transformers increase voltage while lowering current, whereas step-down transformers decrease voltage and raise current.
• 🌐 Transformers do not change the frequency of the AC supply; the input and output frequency remain the same.
• ⚙️ On-load tap changers allow transformers to adjust voltage ratios to maintain stable output under varying load conditions.
• 🌡️ Transformers are filled with insulating oil for cooling and insulation, and a conservator tank is used to store excess oil.

Q & A

What is the primary function of a transformer?

A transformer is used for increasing or decreasing the voltage levels of an AC supply with a corresponding change in current. It transfers electrical energy from one circuit to another through mutual induction.

Why do transformers not incur frictional or windage losses?

Transformers do not have any moving parts, except for the on-load tap changer (OLTC) and motor drive unit, which minimizes frictional or windage losses. This makes them one of the most efficient electrical machines.

What principle does a transformer operate on?

A transformer operates on the principle of mutual induction. When an alternating current (AC) flows through the primary coil, it produces a varying magnetic field that induces a voltage in the secondary coil.

Why doesn't electromagnetic induction work with a DC supply in transformers?

Electromagnetic induction requires a change in magnetic flux to induce voltage. Since a DC supply generates a constant magnetic field without flux changes, no voltage is induced in the secondary coil.

What is the purpose of the transformer core?

The transformer core provides a low reluctance path for the magnetic flux between the primary and secondary windings, making the transfer of electrical energy more efficient.

What are eddy currents and how are they minimized in a transformer?

Eddy currents are loops of electric current induced in the transformer core due to the changing magnetic flux. They cause energy loss in the form of heat. To minimize them, laminated cores made of thin, insulated sheets are used.

What is the difference between a step-up and step-down transformer?

A step-up transformer increases the voltage from the primary to the secondary winding, while a step-down transformer decreases the voltage from the primary to the secondary winding.

What role do tappings play in a transformer?

Tappings are connection points along the winding that allow access to different portions of the coil, enabling voltage adjustments. They are used to fine-tune the transformer’s output voltage.

Why are power transformers designed with a laminated core?

Power transformers use a laminated core to reduce eddy current losses. The insulation between the thin sheets of ferromagnetic material blocks the flow of eddy currents, enhancing efficiency.

What is the difference between single-phase and three-phase transformers?

Single-phase transformers operate on single-phase AC supply and are typically used for low power applications like home electricity. Three-phase transformers operate on a three-phase AC supply and are used for high power applications like industrial power distribution.

Outlines

00:00

🔌 The Evolution of Transformers in Electrical Systems

The invention of transformers at the end of the 19th century revolutionized the way electrical energy is transmitted and distributed, making it possible for power stations to be located far from homes. Transformers operate at high voltages and handle large electrical loads. They increase or decrease AC voltage levels, with corresponding changes in current, and are highly efficient because they have no moving parts (except for the On Load Tap Changer). The working principle of transformers is based on electromagnetic induction, which occurs when a changing magnetic flux links with a coil, inducing voltage. This principle is at the core of transformer operation.

05:02

⚙️ The Role of Ferromagnetic Cores in Transformers

To improve the efficiency of energy transfer, transformer coils are wrapped around a ferromagnetic core, made of materials like iron or steel. These cores help link the magnetic flux between the primary and secondary windings. However, alternating magnetic flux also generates eddy currents in the core, causing heat loss. To reduce this, transformers use laminated cores, composed of insulated iron or steel sheets, which minimize eddy currents and energy loss. The transformer efficiently transfers electrical energy between voltage levels without converting it to another form.

10:03

⚡ Step-Up and Step-Down Transformers

Transformers adjust the input and output voltages according to their transformation ratio. If the secondary winding has more turns than the primary, it’s a step-up transformer, increasing voltage and lowering current. If the primary has more turns, it’s a step-down transformer, lowering voltage and increasing current. Importantly, transformers do not change the frequency of the AC supply. They also have tapping points along the windings to adjust the voltage ratio, enabling different output voltages.

15:03

🔄 Differences Between Core-Type and Shell-Type Transformers

While core-type transformers have windings around the core, shell-type transformers place windings within a laminated core. Both operate on the same principle of electromagnetic induction but differ in their structural design. Single-phase transformers are used for residential power, stepping down voltage from high transmission levels to household use. In contrast, three-phase transformers handle larger power loads and are preferred for high-power applications due to their efficiency in distributing power.

20:04

🔋 The Core: Heart of the Transformer

The transformer core, composed of laminated sheets, minimizes energy loss and noise caused by vibration. Windings are carefully insulated and placed to avoid damage from the core’s sharp edges. For large power transformers, the windings are separated by axial and radial spacers, which allow oil to flow for cooling and improve insulation. High-conductivity copper windings, often rectangular in shape, are used due to their stability and efficiency.

🔧 Helical and Continuous Disc Windings in Power Transformers

Low-voltage windings in power transformers often use helical winding for high-current applications, while high-voltage windings use continuous disc windings for uniform voltage distribution. Copper conductors are coated with insulation, and multiple strands of conductors are used to prevent eddy current losses. Transformers can use either star or delta configurations for windings, depending on their design.

⚙️ Adjusting Transformer Voltage: Tappings and On-Load Tap Changers

Transformers use tappings on the high-voltage winding to adjust the voltage ratio for efficient operation under varying loads. On-load tap changers allow switching between different tappings without interrupting the supply. These changers are operated mechanically, usually by a motor drive unit, and include a diverter switch and tap selector.

🏠 Bushings and Insulation in Transformers

Transformer bushings, both low-voltage and high-voltage, allow the safe transfer of current through the transformer tank. Low-voltage bushings are typically porcelain, while high-voltage bushings use more complex designs with oil-impregnated or resin-impregnated insulation. These bushings are vital for preventing electrical and mechanical stresses.

💡 The Role of Transformer Oil and Conservators

Transformer oil serves a dual purpose: providing electrical insulation and cooling the transformer windings. A conservator tank stores excess oil, ensuring that the transformer tank remains filled. This oil is crucial for the safe and efficient operation of power transformers, as a shortage could lead to transformer failure.

Keywords

💡Transformer

A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. In the video, it is discussed as a crucial component in energy transmission and distribution systems, allowing for the adjustment of voltage levels in AC power supplies, which is essential for efficient energy transfer over long distances.

💡Electromagnetic Induction

Electromagnetic induction is the process by which a voltage or current is generated in a conductor due to a changing magnetic field. The video explains this concept as the fundamental principle behind the operation of transformers, as it enables the transfer of electrical energy between primary and secondary windings.

💡Primary and Secondary Windings

These are the two coils in a transformer, where the primary winding receives the input electrical energy, and the secondary winding delivers the transformed output energy. The video describes how these windings are wrapped around a core and explains their roles in increasing or decreasing voltage levels in an AC supply.

💡Ferromagnetic Core

A ferromagnetic core is made of materials like iron or steel and is used in transformers to provide a path for magnetic flux. This core enhances the efficiency of the transformer by ensuring most of the magnetic flux from the primary winding links with the secondary winding. The video highlights its role in improving energy transfer efficiency.

💡Eddy Currents

Eddy currents are loops of electric current induced within conductors by a changing magnetic field. In transformers, these currents cause energy losses as heat. The video discusses how laminated cores are used to minimize eddy currents, improving the transformer's overall efficiency.

💡Step-up Transformer

A step-up transformer increases the voltage from the primary to the secondary winding, allowing for higher voltage transmission. The video explains that this type of transformer is essential for long-distance power transmission, as higher voltages reduce energy loss.

💡Step-down Transformer

A step-down transformer decreases the voltage from the primary to the secondary winding. This type of transformer is used to reduce high transmission voltages to levels suitable for domestic or commercial use, such as the 120 or 240 volts in homes, as explained in the video.

💡Leakage Flux

Leakage flux refers to the portion of magnetic flux that does not link the primary and secondary windings, reducing the transformer's efficiency. The video emphasizes the importance of minimizing leakage flux to improve energy transfer efficiency.

💡On-load Tap Changer

An on-load tap changer is a device used in transformers to adjust the voltage ratio between the primary and secondary windings without interrupting the power supply. The video explains how this mechanism helps maintain a stable output voltage under varying load conditions.

💡Insulating Oil

Insulating oil is used in power transformers to provide cooling and insulation for the windings. The video explains its importance in preventing transformer failure by keeping the windings insulated and maintaining thermal stability under high voltage and temperature conditions.

Highlights

Transformers revolutionized electrical energy transmission, enabling the development of modern AC supply systems.

Transformers operate at high voltages and can handle millions of watts of electrical load.

A transformer increases or decreases AC voltage levels with a corresponding inverse change in current.

Transformers have no moving parts, except for the On Load Tap Changer (OLTC), making them highly efficient.

The principle of electromagnetic induction is key to transformer operation: a changing magnetic flux induces voltage in coils.

AC supply creates alternating magnetic fields, enabling voltage induction through mutual induction between coils.

Ferromagnetic cores improve energy transfer efficiency by providing a low-reluctance path for magnetic flux.

Eddy currents cause energy loss in transformer cores; laminated cores minimize this by reducing eddy current formation.

Step-up transformers increase voltage with a decrease in current, while step-down transformers do the opposite.

Transformer tappings adjust the voltage ratio between primary and secondary windings, providing different output voltages.

Shell-type and core-type transformers have different structural designs but work on the same principle of electromagnetic induction.

Three-phase transformers are used for high-power applications due to their efficiency in transmitting large amounts of power.

Power transformers use a laminated core, insulation materials, and specialized windings to minimize losses and ensure safe operation.

Helical windings are used in low-voltage windings to handle high current in power transformers efficiently.

High-voltage bushings and oil-insulated transformers enhance voltage handling capacity and provide cooling for reliable operation.

Transcripts

Transformers are game changers in the

field of electrical energy transmission

and

distribution the invention of power

Transformers towards the end of the 19th

century made possible the development of

the modern constant voltage AC Supply

systems with power stations located many

miles away from our

homes this incredible machine operates

at hundreds of thousands of volts and

can handle millions of watt of

electrical load

in this video we are going to explore

the working of this incredible piece of

engineering so without further Ado let's

start it a Transformer is used for

increasing or decreasing the voltage

levels of a AC Supply with a

corresponding increase or decrease in

current it is a static machine which

means unlike an electric motor which has

a stationary part called the stator and

a moving part known as the rotor a

Transformer does not have any moving

parts except for the oltc and motor

Drive Unit which we will discuss later

in this video due to having no moving

Parts Transformers do not incur any

frictional or windage losses making them

one of the most efficient electrical

machines before diving into the working

of a power transformer let's first take

a look at the fundamentals of a

transformer when we move a magnet near a

coil a voltage is induced in the coil

this occur due to a change in the number

of magnetic field lines passing through

the coil or alternatively we can say

there is a change in magnetic flux

linking with the coil this phenomenon is

known as electromagnetic

induction the strength of induced

voltage depends upon the number of turns

in the coil the strength of the magnetic

field and how fast we are moving the

magnet or we can say the rate of change

of flux linking with the coil

a change in magnetic flux is absolutely

necessary for electromagnetic induction

if we stop moving the magnet no matter

how strong the magnetic field of the

magnet is or how many turns are there in

the coil no voltage is induced in the

coil let's replace this bar magnet with

another coil if we connect this coil to

a DC Supply the magnetic field produced

by the coil looks very similar to the

magnetic field of the bar

magnet as the magnetic flux linking with

the first coil is not changing with time

no voltage is induced in the first coil

that's why electromagnetic induction

does not work with a DC

Supply now instead of a DC Supply if we

feed an AC Supply to this coil an

alternating magnetic field is formed

this varying magnetic field creates a

change in the magnetic flux of the first

coil and hence hence a voltage is

induced in the first coil this is called

Mutual induction and it is the working

principle of a

transformer similar to this setup a

Transformer is consists of two coils

wrapped around a ferromagnetic

core these coils are made with copper

coated with a thin layer of varnish or

insulation the thickness of this coating

depends upon the desired level of

insulation required

varnish coating serves to insulate each

turn of the coil preventing any bypasses

and ensuring uninterrupted current flow

along the entire length of the

coil when either of the two coils is fed

with an AC Supply the alternating

magnetic field produced by that coil

links with the other coil inducing a

voltage however this transfer of

electrical energy is very inefficient

because only a small part of the

magnetic field from the first coil links

with the other

coil to improve efficiency coils are

wound around a core made of

ferromagnetic materials like iron or

steel the coil connected to the supply

is called the primary winding of the

Transformer and the coil on the output

side or connected to load is called the

secondary

winding the flux produced by the primary

winding which links with the secondary

winding is called linkage flux

while the flux produced by the primary

winding but not linking with a secondary

winding is called leakage flux it's

important to note that leakage flux does

not contribute to the transfer of

electrical energy and therefore should

be minimized to improve the efficiency

of a

transformer a Transformer core acts as a

pathway for magnetic flux providing a

low reluctance path as a result most of

the magnetic flux produced by the

primary coil link with secondary coil

making the transfer of electrical energy

more

efficient as the core is also made up of

conducting material the alternating flux

passing through the core induces Loops

of current inside the core due to

electromagnetic induction these Loops of

electric current are called Edy

currents Edy currents cause energy loss

inside the core in the form of heat

which reduces the efficiency of a

transformer that's why in a Transformer

a laminated core is used instead of a

solid ferromagnetic

core a laminated core is made up of thin

sheets of iron or steel each coated with

insulation these sheets are tightly held

together to minimize the air gap between

them the insulation on the sheets blocks

the flow of Eddie currents by providing

High Resistance thus minimizing their

formation

and that's how a laminated core

minimizes Eddy currents and makes the

transfer of energy more

efficient as we know an electric motor

is used to convert electrical energy

into mechanical

energy however a Transformer is

different it does not convert electrical

energy into any other form instead it

transfer electrical energy from one

voltage level to

another the input and output voltage of

a transformer are related according to

its transformation ratio here NP and ns

are number of turns in the primary and

secondary winding respectively if the

number of turns in the secondary winding

are higher than on the primary winding

the voltage induced in the secondary

winding is higher compared to the

primary input voltage while the current

in the secondary winding is lower

because energy is conserved this type of

Transformer is called a stepup

Transformer and it is used for

increasing the voltage level of an AC

Supply on the other hand if the primary

winding has more turns compared to the

secondary winding the voltage induced in

the secondary winding is lower than the

primary input voltage and the secondary

current is higher this type of

Transformer is called a stepdown

Transformer and it is used for

decreasing the voltage level of an AC

Supply

an important point to note is that a

Transformer does not affect the

frequency of the AC Supply the input and

output of the Transformer have different

voltages but the same

frequency now let's understand what are

Transformer tappings a tapping in a

Transformer is a connection point along

the winding that allow access to a

specific portion of the

coil tappings are used to adjust the

voltage ratio between the primary and

secondary windings enabling the

Transformer to provide different output

voltages based on how the primary and

secondary windings are placed around the

laminated core Transformers are

generally of two types core type

Transformers and shell type

Transformers as we have already

discussed core type Transformers let's

now focus on shell type

Transformers the working principle of a

shell type Transformer is the same as

that of a core type Transformer the only

difference is in their structure a shell

type Transformer also has primary and

secondary windings placed centrically on

a laminated ferromagnetic core in this

design the core surrounds a significant

portion of the

windings both core and shell type

Transformers can produce similar

characteristics the choice between core

and shell type construction is typically

determined by factors such as cost

insulation stress heat distribution and

weight both of these are singlephase

Transformers meaning they operate on a

singlephase AC supply singlephase

distribution Transformers are also a

integral part of power system these are

step down Transformers that reduce the

high voltage AC input from the nearest

substation to 120 or 240 volts which is

the voltage used in your

home high voltage singlephase AC input

is fed through HV bushings we will

discuss high voltage bushings in detail

later in this video it is a pole mounted

singlephase distribution transformer

meaning it is installed on electrical

poles and has a power rating of a few

100 KVA or less in contrast three-phase

Transformers are used for high power

applications a three-phase Transformer

operates on a three-phase AC Supply

which consists of three individual

phases with a phase difference of 120°

between each

phase the power ratings of three-phase

Transformers can reach hundreds of MVA

depending on the specific Transformer

and its design high power rating

Transformers typically work on a

three-phase supply instead of a

singlephase supply why because

three-phase systems are more efficient

for transmitting and distributing large

amount of power compared to a single

phase now that we've covered the basics

of Transformers let's dive into the

specifics of how a power transformer

operates let's start with the heart of a

transformer the core in any efficient

power transformer the core isn't just

important it's absolutely essential to

its operation without it nothing else

would work as it

should a power transformer core is built

from thousands of thin laminated sheets

made of ferromagnetic materials like

Silicon steel the purpose of Transformer

core is to provide a low reluctance path

for the magnetic flux that links primary

and secondary

windings the alternating flux which

links primary and secondary windings

causes vibration in the laminated sheets

generating loud unwanted noise and

leading to energy loss to minimize these

issues the laminated sheets are tightly

secured

together let's now focus on how the

windings are placed on a power

Transformers

core first an insulation sheet and an

insulation cylinder are placed to

insulate the windings from the core and

protect them from damage caused by the

core's sharp

edges this cylinder is made made from

electrical insulation

materials three pairs of low voltage and

high voltage windings are placed

centrically on each limb of the core in

a three-phase Transformer each pair of

low voltage and high voltage winding

corresponds to one phase the low voltage

winding is always placed near the core

because it has a low voltage rating

making it easier to insulate from the

core the winding arrangement of power

transformer also includes axial and

Radial

spacers axial and Radial spacers

typically made from insulating materials

like pressboard epoxy resin or other

high strength insulating

Composites they prevent winding

deformation under mechanical stress

ensuring long-term reliability and

performance these spacers provide proper

gaps or Ducks between different

conductors allowing Transformer oil to

flow and cool the windings

additionally axial and Radial spacers

ensure proper insulation and structural

Integrity Transformer windings are made

of high conductivity copper due to its

excellent mechanical properties and high

electrical conductivity making it an

ideal material for this

application for all Transformers with

ratings larger than a few KVA

rectangular section conductors are used

instead of the normal round

conductors this is because because

windings with rectangular section

conductors have a good space factor and

high mechanical

stability copper conductors are covered

with paper

insulation high power Transformers use

paper insulation instead of varnish or

enamel coating because paper insulation

can better withstand higher temperatures

without degrading provides greater

mechanical and dialectric strength

allowing it to endure high voltages

without

breakdown in a three-phase Transformer

each phase is consist of a pair of low

voltage and high voltage

windings in a low voltage winding the

number of turns are much less compared

to a high voltage winding as the name

suggests the voltage level in the LV

winding is lower than in the HV winding

and the current is very high according

to the transformation

ratio the exact voltage and current

ratings of the LV and HV winding depends

upon the specific

Transformer helical winding is mostly

used for low voltage windings in power

Transformers it's the simplest type of

winding and is ideal for low voltage

High current

applications in a helical winding the

conductor is shaped in the form of a

helix the amount of current in the LV

winding of a power transformer can be

thousands of amps which is why a very

thick conductor is used for the LV

winding however using a single solid

conductor can cause Eddie current losses

to mitigate this a continuously

transposed conductor is used in a low

voltage winding instead of a single

solid

conductor a CTC is consists of multiple

strands each insulated from the others

by varnish

Coating in a CTC the position of each

strand continuously changes along the

length of the cable

this prevents circulating currents

caused by differences in the induced

voltage of each

strand high voltage windings have a

greater number of turns compared to low

voltage windings although the conductor

cross-sectional area is significantly

smaller HV windings are typically wound

using continuous dis

windings in a continuous dis winding

conductors are wound in continuous

spirals alternating from inside to

outside and outside to inside forming

dis- like

structures these discs are connected

through inner and outer

crossovers The Continuous disk design

ensure more uniform voltage distribution

across the winding reducing the risk of

insulation

failure power transformer windings are

connected in either star or Delta

configuration depending on the design of

the

Transformer we will discuss about star

and Delta Connections in a future video

in a power transformer and support

structure made of insulating materials

like press board is used for providing

mechanical support and electrical

insulation crepe paper tubes and srbp

tubes are employed for ensuring secure

and effective

connections almost all power

Transformers require adjustment of their

voltage ratio to operate effectively

under variable load

conditions this is achieved by adjusting

their transformation ratio using

tappings tappings are placed on the high

voltage winding because high voltage

winding is more accessible as it is

positioned outside of the low voltage

winding Additionally the lower current

in the HV winding simplifies the process

of switching between different

tappings an onload tap changer is used

to switch between Taps to maintain the

output voltage of a transformer during

variable load

conditions it is consists of two main

parts a diverter switch and a tap

selector the operation of an onload tap

changer is mechanically operated by a

motor Drive Unit through a bevel gear

mechanism all of these components

including the core windings tappings and

on load tap changer are enclosed within

a sealed chamber known as the

transformer tank the terminals of the

low voltage and high voltage windings

are brought out of the transformer tank

through

bushings Transformer bushings are

essential components designed to

withstand High electrical and mechanical

stresses in a Transformer we have both

low voltage bushings and high voltage

bushings the bushings connected to the

low voltage windings are called Low volt

voltage bushings while those connected

to the high voltage windings are called

high voltage

bushings for low voltage windings simple

porcelain bushings are used a porcelain

bushing mainly consists of a central

conductor surrounded by a weather

resistant insulating structure made from

high dialectric strength ceramic

materials like

porcelain for the high voltage side oil

impregnated or resin impregnated

condenser bushings are used as they are

designed to withstand higher

voltages a condenser bushings consists

of a central conductor surrounded by a

condenser and a porcelain

insulator the condenser is made up of

layers of metal foil and insulation

paper impregnated with oil or resin this

Arrangement acts like numerous

capacitors connected in series this

configuration ensures a uniform

distribution of voltage within the

bushing these types of bushings are

filled with insulating mineral oil to

further enhance their voltage handling

capacity the top of the bushing includes

an oil expansion chamber to accommodate

the expansion and contraction of the oil

due to temperature

changes insulating oil is crucial to the

operation of a power

transformer the main tank of a power

transformer is completely filled with

insulating mineral oil known as

Transformer

oil this oil is stable and high

temperatures and possesses excellent

electrical insulating properties

providing both Cooling and insulation to

the Transformer

windings an additional smaller tank

known as the conservator is used to

store excess Transformer

oil the conservator is connected to the

transformer tank and ensures that it is

is always completely filled with oil

preventing any oil shortage inside the

transformer

tank Transformer oil is extremely

important for the insulation of a power

transformer and a shortage of oil in the

transformer tank can even lead to

Transformer

failure a power transformer is a large

and complex machine and there are still

many Concepts and devices related to it

that I haven't covered in this video If

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