BASIC INFORMATION ABOUT TRANSFORMER.

1. TRANSFORMER
PRAYAG RAJ
EL-394-2K17

2. A transformer is a device that transfers electrical
energy from one electrical circuit to another through
mutual (electromagnetic induction) and without
change in frequency. Transformers are an important
part of electrical systems.
Transformers are made in many different sizes, from
a very small coupling transformer inside a
stage microphone to big units that carry hundreds of
MVA used in power grids.
What is a transformer?

3. Structure of transformer

4. Winding - Transformers have two windings, being the
primary winding and the secondary winding. The
primary winding is the coil that draws power from the
source. The secondary winding is the coil that delivers
the energy at the transformed or changed voltage to
the load. Usually, these two coils are subdivided into
several coils in order to reduce the creation of flux.
WINDING CORE

5. Core - The transformer core is used to provide a
controlled path for the magnetic flux generated in
the transformer. The core is generally not a solid bar
of steel, rather a construction of many thin
laminated steel sheets or layers. This construction is
used to help eliminate and reduce heating.
Transformers generally have one of two types of
cores: Core Type and Shell Type. These two types are
distinguished from each other by the manner in
which the primary and secondary coils are place
around the steel core.

6. Significance of transformer
1. Transfers electric power from one circuit to
another
2. It does so without a change of frequency
3. It accomplishes this by electromagnetic
induction
4. Where the two electric circuits are in mutual
inductive influence of each other.

7. How does transformer works?
1. When current in the primary coil
changes being alternating in
nature, a changing magnetic field
is produced
2. This changing magnetic field gets
associated with the secondary
through the soft iron core
3. Hence magnetic flux linked with
the secondary coil changes.
4. Which induces e.m.f. in the
secondary.

8. Transformers and there types
Step up:-As the name states that, the secondary
voltage is step up with a ratio as compared primary
voltage. This can be achieved by increasing the
number of windings in the secondary than the
primary windings .
Step down:- It is use to step down the voltage level
from higher to lower at secondary side .this can be
achieved by decreasing the number of windings in
the secondry than the primary windings .
1) Based on Voltage transfer-

9. 2) Based on core medium-
Air core transformer:- Both the primary and
secondary windings are wound on a non-
magnetic strip where the flux linkage
between primary and secondary windings is
through the air.
Iron core transformer :-Both the primary and
secondary windings are wound on multiple
iron plate bunch which provide a perfect
linkage path to the generated flux.

10. 3) Transformer based on usage
Power transformer :-The power transformers are
big in size. They are suitable for high voltage
(greater than 33KV) power transfer applications.
It used in power generation stations and
Transmission substation. It has high insulation
level.
Distribution transformer :-In order to distribute the
power generated from the power generation
plant to remote locations, these transformers
are used.

11. Transformer Configurations
• Single-phase Power - Single-phase transformers are often
used to supply power for residential lighting, receptacle,
air-conditioning, and heating needs. Single phase
transformers can be made even more versatile by having
both the primary winding and secondary winding made in
two equal parts. The two parts of either winding can then
be reconnected in series or parallel configurations

12. • Three-phase Power - Power may be supplied
through a three-phase circuit containing
transformers in which a set of three single-phase
transformers is used, or on three-phase transformer
is used. When a considerable amount of power is
involved in the transformation of three-phase power,
it is more economical to use a three-phase
transformer. The unique arrangement of the
windings and core saves a lot of iron.

13. • Delta and Wye Defined - There are two connection
configurations for three-phase power: Delta and Wye.
Delta and Wye are Greek letters that represent the way
the conductors on the transformers are configured. In a
delta connection, the three conductors are connected
end to end in a triangle or delta shape. For a wye, all
the conductors radiate from the center, meaning they
are connected at one common point.

14. Losses in transformer
Eddy current loss and hysteresis loss depend upon the
magnetic properties of the material used for the construction
of core. Hence these losses are also known as core
losses or iron losses.
Core Losses Or Iron Losses-

15. Hysteresis loss in transformer:
Hysteresis loss is due to reversal of
magnetization in the transformer core. This loss
depends upon the volume and grade of the iron,
frequency of magnetic reversals and value of flux
density. It can be given by, Steinmetz formula:
Wh= ηBmax
1.6fV (watts)
where, η = Steinmetz hysteresis constant
V = volume of the core in m3

16. Eddy current loss in transformer:
In transformer, AC current is supplied to the primary
winding which sets up alternating magnetizing flux.
When this flux links with secondary winding, it
produces induced e.m.f in it. But some part of this flux
also gets linked with other conducting parts like steel
core or iron body or the transformer, which will result
in induced e.m.f in those parts, causing small
circulating current in them. This current is called as
eddy current. Due to these eddy currents, some
energy will be dissipated in the form of heat.

17. Copper Loss In Transformer-
Copper loss is due to ohmic resistance of the
transformer windings. Copper loss for the primary
winding is I1
2R1 and for secondary winding is I2
2R2.
Where, I1 and I2 are current in primary and secondary
winding respectively, R1 and R2 are the resistances of
primary and secondary winding respectively. It is clear
that Cu loss is proportional to square of the current,
and current depends on the load. Hence copper loss
in transformer varies with the load.

18. Ideal Transformers
Zero leakage flux:
Fluxes produced by the primary and secondary currents are
confined within the core
The windings have no resistance:
Induced voltages equal applied voltages
The core has infinite permeability
Reluctance of the core is zero
Negligible current is required to establish magnetic
flux
Loss-less magnetic core
No hysteresis or eddy currents

19. Transformer Efficiency
Electrical Machines
Transformer efficiency is defined as (applies to motors,
generators and transformers):
%
100


in
out
P
P
 %
100



loss
out
out
P
P
P

Types of losses incurred in a transformer:
Copper losses
Hysteresis losses
Eddy current losses
Therefore, for a transformer, efficiency may be calculated using the
following:
%
100
cos
cos
x
I
V
P
P
I
V
S
S
core
Cu
S
S







20. THANK YOU