Transcript How Electricity enters in our houses

How Electricity enters in our houses
• Electricity supplied to us at our home is 220
volt and A.C.. This main line power and the
wires carrying it are called the mains. The
mains may often bring two different supplies
5A and 15A. The two rating are important
since we use a variety of application such As
Bulbs and Tubes , Heaters, Radios, TV sets,
Refrigerators and so on. Some of these need
5A power while others need 15A power.
Transformer
• A transformer is a static piece of apparatus by
means of which electric power in one circuit is
transformed into electric power of the same
frequency in another circuit. It can raise or
lower the voltage in a circuit but with a
corresponding decrease or increase in current.
The output voltage and current depends upon
the number and turns of wires used in the
primary and secondary winding of the
transformer.
• According to it the voltage may be step up and
step down. If the secondary winding of
transformer has more turns than the primary
winding it is called step up T/R. this is used
whenever it is necessary to increase the
voltage. In step down transformers the
secondary winding has less turns than primary
winding of the transformer.
A transformer is a device that transfers electric
power from one circuit to another.
It does so without a change of frequency.
It accomplishes this by electromagnetic induction
and where the two circuit are in mutual inductive
influence of each
other.
Working principle
• In it's simplest form it consist of, two inductive coils
which are electrically separated but magnetically linked
through a path of low reluctance. If one coil (primary)
is connected to source of alternating voltage, an
alternating flux is set up in the laminated core, most of
which is linked with the other coil in which it produces
mutually-induced e.m.f. (according to Faraday's Laws of
Electromagnetic Induction. If the second coil
(secondary) circuit is closed, a current flows in it and so
electric energy is transferred (entirely magnetically)
from the first coil to the second coil.
Types of transformer
• 1. According to construction:•
a. Core type
•
b. Shell type transformer
•
c. Berry type transformer
• 2. According to the system of winding used in
the transformer:•
a. single phase
•
b. Three phase
•
c. Auto transformer
• 3. According to system of cooling of the
transformer:•
a. Natural air blast cooled
•
b. Oil immersed self cooled
•
c. Oil immersed water cooled
• 4. According to use:•
a. Power transformer:•
i. For low tension transmission lines i.e.
From 2000 to 15000 KVA.
•
ii. For high tension transmission lines i.e.
from 15000 KVA and above
•
•
B. Distribution transformer:i. Small and medium type from 5 to 500
KVA
•
ii. Large type from 500 to 2000 KVA
•
C. Instrument Transformer:- used with
measuring instrument.
•
D. Auto transformer:- used for low voltage
circuits
Advantages of Transformer
• 1.It is one of the economical devices to transmit
the electrical power at high voltage and voltage
can also be reduced at the desired voltage when
required.
• 2. Its efficiency is very high in comparison to
other electrical to other electrical machines.
• 3. since there is no rotating part in it, so it has
very less noise.
• These can be designed for very high as there is
much space to insulate the winding.
• 5. It can be operated very easily with little
attention.
• 6. It is very useful and cheap device for the
distribution and transmission of electrical
energy from place to place.
• 7. Its maintenance cost is less in comparison
to other electrical machineries.
• 8. it can be taken from place to place very
easily and is even used in house and in
industries.