WHAT IS TRANSFORMER?AND ITS TYPES.
· What is a Transformer?
Ans. A
Transformer is a static electrical machine which transfers AC electrical power
from one circuit to the other circuit at the constant frequency, but the
voltage level can be altered that means voltage can be increased or decreased
according to the requirement.
Equation.
E= N dϕ /dt
· What is Types of transformer?
I.
Ans. There are types of transformer.
II.
Based on Voltage Level
a.
Step-Up Transformer
b.
Step-Down Transformer
c.
Isolation Transformer
Step-Up Transformer
A Step Up Transformer is a device which
converts low voltage at primary side to high voltage at secondary side. The
primary winding of a coil has less number of turns than the secondary winding.
Equation:
Vp/Vs = Ns/Np
Advantages:
o
Transmit electricity over long distances at low
cost.
o
Helps in reducing the resistance on the line.
o
Ability to work continuously.
o
start operations immediately after its
installation without any delays.
o
Highly efficient and suffer from very little
losses.
o
Do not involve much time and money for
maintenance.
Limitations:
o
Applications limited to AC operations only.
o
Use a round-the-clock cooling system i.e. makes
the system bulky.
o
Step-Down Transformer
o
A Step Down Transformer is a device which
converts high voltage at primary side to low voltage at secondary side. The
secondary winding of a coil has less number of turns than the primary winding.
Equation:
Vs/Vp = Ns/Np
Advantages:
o
Easy power transmission at low cost.
o
Highly reliable and efficient.
o
Provides varied voltage requirements.
Limitations:
o
Requires a lot of maintenance, which can damage
the transformer.
o
Volatility in feedstock costs.
o
Fault rectification takes more time.
Isolation Transformer
Isolation transformer can be step-up
transformer or step-down transformer but the primary and secondary voltage
values are always equal i.e. turns ratio is always 1. This is obtained with a
same number of turns on the primary and secondary windings. Isolation
transformers are referred to as "insulated".
Equation:
Vs/Vp
= Ns/Np Where Ns=Np
Advantages:
o
Provide safety to electronic components and the
persons against electrical shock.
o
Suppress the electrical noise.
o
Avoids ground loops.
o
Provide available supply even if the device is
broken.
o
Used as instrument transformers
o
Handle any amount of voltage necessary.
Limitations:
o
Produce distortion at secondary side when
operates as pulse transformer.
o
When operating DC pulse signal, saturation of
the core decreases.
o
High cost.
2. Based on Usage
On the basis of usage, transformer types
are listed below.
I.
Power Transformers
II.
Distribution Transformers
Power Transformers
·
Main principle of power transformer is to
convert the Low voltage input to a high voltage output. This transformer acts
as a bridge between the power generator and the primary distribution grid. This
has complex construction due to high power generation and mainly installed at
the generating stations and transmission substations. The power transformers
are employed in the transmission networks of higher voltages.
Advantages:
o
Suitable for high voltage applications (greater
than 33KV).
o
High insulation level.
o
Minimize the power loss.
o
Cost effective.
Limitations:
Loaded for 24 hours at transmission
station, thus, the core and copper loss will occur for the whole day.
Big in size.
Distribution Transformers
o
Distribution transformers are step down
transformer and used in distribution network for industrial and domestic
purpose. These transformers convert High grid voltage to the end customer
required voltage where the electrical energy is distributed and utilized at the
consumer end. In order to distribute the power from power plant to remote
locations, these transformers are used.
Advantages:
o Small size.
o Easy
installation.
o Low
magnetic losses.
o It is not
always fully loaded
Limitations:
o Designed
for 50-70% efficiency.
o Low
flux density as compare to power transformer.
o Regular
load fluctuations.
o Time-dependent.
3. Based on Electrical Supply
On the basis of configuration, transformer types are
listed below.
I.
Single phase transformer
II.
Three phase transformer
Single Phase Transformer
When there is only one coil at
primary side and one coil at secondary side, then the transformer is called
single phase transformer. Here the power supplies through a single conductor.
This type of transformer accepts single-phase alternating current and output
single-phase alternating current, typically at variant voltage level that operates
in a unified time phase. These types of transformer are mostly used in the
household devices.
Advantages:
·
Simple network.
·
Cost effective.
·
Most efficient AC power supply for up to 1000
watts.
Limitations:
·
Supply only 1-ph load.
·
used to light loads and small electric motors.
·
Minimum power transfer capability.
·
Power failure occurs.
Three Phase Transformer
Three phase transformer means
the power flows through three conductors. Three phase transformer contains six
coils, three coils at primary side and three coils at secondary side. This type
of transformer accepts three-phase alternating current and output three-phase
alternating current, typically at variant voltage level that operates in a
unified time phase. These types of transformer are mostly used as a power or
distribution transformers
Advantages:
·
Large motors or heavy loads materials.
·
Transmission of power to long distance through
magnetic field.
·
Maximum power transfer capability.
·
Power failures do not occur.
Limitations:
Required many cooling systems depending on the
transformer rated power.
Complex network.
4. Based on Place of Usage
On the basis of place of usage, transformer types are
listed below.
I.
Indoor Transformers
II.
Outdoor Transformers
Indoor Transformers
Indoor transformers are usually a Dry type transformer.
These transformers use air as cooling medium and usually their primary and
secondary side connections are isolated. Dry type transformers are installed in
buildings and close to buildings because they are environmentally safer i.e.
less flammable. These type of transformers are considered as ideal for shopping
malls, hospitals, residential complexes and other commercial areas.
Advantages:
o Low
maintenance cost.
o Safer
option as compare to oil-filled transformer.
Limitations:
o Higher
operating loss.
o Noise
pollution.
o Expensive.
Outdoor Transformers
Outdoor transformers are usually an Oil filled
transformers. These transformers use oil as cooling medium and are designed to
be utilized in outdoor environments due to the chance of oil leakage and spills
that create a fireplace risk, and must be protected against environmental
conditions.
Advantages:
o Smaller
and more efficient.
o Lower
operational costs.
Limitations:
o High
Maintenance cost.
o Require
periodic sampling of the oil.
5. Based on the Core Medium
On the basis of core medium,
transformer types are listed below.
I.
Air Core Transformer
II.
Iron Core Transformer
III.
Ferrite Core Transformer
Air Core Transformer
Air-core transformers are
designed to transfer radio-frequency currents—i.e., used in radio transmitter
and communication devices etc. As the name suggests, these transformers have no
solid core, which makes them very light in weight, thus making them ideal for
small-sized portable electronic devices. Air core transformers create flux
using the windings and the air passing through them. This help air core
transformer to completely eliminate undesirable characteristics of
ferromagnetic core (eddy current losses, hysteresis, saturation, etc.)
Advantages:
·
Zero distortion.
·
Zero dissipation of signal quality.
·
Noise-free operation.
·
Lack of losses in hysteresis and eddy currents.
·
Lighter in weight.
Limitations:
·
Low degree of coupling (mutual inductance)
·
Unsuitable for use in power distribution.
Iron Core Transformer
In this type of transformer,
primary and secondary windings are wounded on multiple iron plates. These iron
plates provide perfect linkage path to the generated flux and serve analogous
functions in the audio-frequency range. Iron core transformer are widely used
and highly efficient as compare to air core transformer.
Advantages:
·
Handle large loads at a low frequency.
·
Offers less reluctance.
·
Highly efficient.
Limitations:
·
Large eddy current losses.
Ferrite Core Transformer
Ferrite core transformer means
a transformer whose magnetic core is made up of ferrite. Ferrites are
non-conductive, ceramic compounds that are ferromagnetic in nature. The high
magnetic permeability of these transformers makes them ideal for a variety of
high frequency transformers, adjustable inductors, wide band transformers,
common Mode Chokes, switched-mode power supply and radio frequency
applications.
Advantages:
·
Low reluctance magnetic path.
·
High current resistivity.
·
Provides low eddy current losses over many
frequencies.
·
High magnetic permeability, coercivity and
Q-values.
·
Low hysteresis factor, DC sensitivity and signal
distortion.
Limitations:
·
Easily saturated (its saturation flux density is
typically < 0.5 T).
·
Permeability drifts with temperature.
·
Write down the point of
audio transformer and radio transformer?
Ans=Audio transformers can also be used for
matching microphones to amplifier inputs. The main purpose of a
transformer at the amplifier input is matching impedance between
microphones, connecting cables and the amplifier input. This is important to
ensure that there is no signal reduction due to impedance mismatching.
