27-04-2011, 10:58 AM
PRESENTED BY:
RAHUL L.KHAIRNAR
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INSULATING MATERIAL
DEFINATION
An insulator, also called a Dielectric, is a material that resists the flow of Electric Current. An insulating material has atoms with tightly bonded Valence Electrons. These materials are used in parts of electrical equipment, also called insulators or insulation, intended to support or separate electrical Conductors without passing current through themselves. The term is also used more specifically to refer to insulating supports that attach Electric Power Transmission wires to Utility poles or Pylons.
Need of Insulating Material
Generally we have seen that we are using a small wire with the insulation basically that is for only safety purpose
Also to avoid the power loss which is taking place in our household wiring.
Therefore in every appliances we have to check that there is proper insulation is provided or not.
Insulation protects the equipment from fire out.
When we touch any wire in our home then we not get shock because that insulation is provided around the conductor
Which protects us & also to any equipment from damaging.
This is done for our house only but on the local poles situated along the street is to be insulated is impossible
Because no one come to touch that conductor.
It is on the proper height from the ground level
But conductor wire is directly connected to the pole then large power loss can be seen while transmission
Of electrical power there fore in over head transmission lines concept of using the INSULATOR is introduced
CHARECTERISTICS
RESISTIVITY
POLARISATION
PERMITTYVITTY
BREAK DOWN POTENTIAL
ELECTRIC STRENGTH
TENSILE STRENGTH
SOLUBILITY
BRITTELNESS
HIGH MELTING POINT
FLEXURAL STRENGTH
HEAT RESISTANCE
MOISTURE CONTENT
HIGH RESISTANCE
POOR CONDUCTOR
EASILY AVILABLE IN NATURE
SOME DIELECTRIC MATERIAL
Classification of Insulator
Mainly classification for any purposes are
Solid
Liquid
Gaseous
Solids:-
All the insulation material Epoxy,porcylne,mica,ceramic all solid insulator
Liquid :-
It contains all the insulators that are inside the electrical equipment like transformer oil
Gaseous :-
it contains used in heavy electrical machines ex. Hydrogen gas
INSULATORS USED INH. V. TRANSMISSION LINES
NEW TRENDS GLASS MATERIAL
New Trends
Today in overhead transmission system we are using the
Epoxy Insulators the material used to creat it is epoxy resins
Which are having the high permittivity & very high resistance
High mechanical strength
It satisfies all the condition for giving the proper insulation
Glass is also used for insulation purpose
One disadvantage is that they are not economical regarding the
safety & line performance it is 100% efficient
CONCLUSION
We have to select that material as insulator
which can satisfy all the characteristics which
are required.
Considering the following points
Long life
Better efficiency
Economical
Withstand with over loading condition