In this article, we will discuss the definition, construction, working principle, and applications of an electrical transformer. So let us start with the basic definition of the transformer.
What is a Transformer?
A transformer is
an electrical AC machine which is used to transform voltage or current levels
in an electrical power system. This transformation of voltage or current from
one level to another is done without the change of frequency. Transformer
is a static electrical machine because it does not have any moving or rotating
parts like an electric motor.
In an electric power system, the generation, transmission,
distribution, and utilization of electrical power are done at different voltage
levels. This is required due to some economic, safety, and many other technical
reasons.
For example, the generation of electrical power is economical
at the voltage level of about 11 kV to 33 kV. The transmission of electrical
power is economical in the voltage range of 132 kV to 400 kV or at a higher
voltage. The distribution of electrical power requires a voltage level of about
11 kV to 33 kV. Whereas, the utilization of electrical power requires a voltage
level of about 220 V to 3300 V.
Therefore, in an electrical power system, it is required to
step-up and step-down the voltage level at different points. For this purpose,
a device called a transformer is used.
Construction of Transformer
An electrical transformer consists of three important parts
namely, a primary winding, a secondary winding, and a magnetic core. The construction
of a transformer is depicted in figure-1.
The primary winding is one which is connected to the AC source, and the secondary winding is one which is connected to the load. The magnetic core acts as a path for magnetic flux and the primary winding and secondary winding are wound around the magnetic core.
Both primary and secondary windings of the transformer are
made of conducting wire such as copper or aluminium wire. These wires are
insulated and wound on the magnetic core.
The magnetic core of the transformer is made up of silicon-content steel sheets which have high permeability and low hysteresis loss. The
magnetic core is built using thin laminated sheets of silicon steel to reduce
the eddy current loss. Where the laminations are insulated from each other. The
mean thickness of each lamination is around 0.35 mm.
Working Principle of Transformer
The working principle of the transformer is based on Faraday’s law of electromagnetic induction
(mutual inductance).
According to the principle of electromagnetic induction,
when a changing magnetic field is linked with a coil, an emf is induced in the
coil. This phenomenon is called electromagnetic induction.
Therefore, the operation of a transformer is based on the
fact that electrical energy can be efficiently transferred from one coil to
another by means of varying magnetic fields, provided that both of the coils are
placed on a common magnetic circuit.
Working of Transformer
The working of a two-winding transformer is explained as
follows:
When the primary winding of the transformer is connected to
a source of AC supply, an alternating current flows through it. Since the
primary winding is wound around the magnetic core, thus the alternating current
flowing through the primary winding produces an alternating magnetic flux in
the core. This alternating magnetic flux travels to the secondary winding and
links with it. Because the magnetic flux is alternating, hence it induces an
emf in the secondary winding according to the principle of electromagnetic
induction.
The frequency of the induced emf in the secondary winding is
the same as that of the flux or that of the AC supply voltage. When an
electrical load is connected to the secondary winding of the transformer. An
electric current flows in the secondary winding due to induced emf.
In this way, the electrical energy is transformed from the
primary winding to the secondary winding by means of electromagnetic induction
without any change in frequency.
Applications of Transformer
In an electrical power system, the transformer is one of the
crucial components of the system. Some common applications of transformers in
electrical power systems are:
- Transformers are used to increase the voltage level from a low value to a high value.
- Transformers are used to decrease the voltage level from high value to low value.
- Transformers are used in generating stations to increase the voltage level for transmission purposes.
- In substations, transformers are used for step-up or step-down voltages.
- In the distribution system, transformers are used for reducing voltage levels to meet the load voltage demand.
- Transformers are also used for isolation purposes, i.e. for isolating two circuits electrically.
- Transformers are also used for the measurement of high voltages and currents, and for protection purposes, such transformers are called instrument transformers.
Hence, this is all about the electrical transformer, its
construction, working principle and working, and applications.
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