This document discusses dielectrics and their properties. It begins by defining dielectrics as materials that have a permanent electric dipole moment. Common dielectric materials include mica, glass, plastic, and water. Dielectrics can be solid, liquid, or gas. The document then discusses electric polarization, which is the process of inducing electric dipoles with an electric field. It lists several important properties of good dielectric materials, such as high resistivity and dielectric strength. Finally, it examines some common gaseous dielectric materials, including air, sulfur hexafluoride, nitrogen, and inert gases, outlining their composition and uses.

1. DIELECTRICS
PREPARED BY
“THE GREAT”
VINUDHARAN M
(22ECR233)

2. “
”
INTRODUCTION
• Dielectrics arethematerials whichhaving theelectricdipole
moment permanently.
• Adipole isanentityinequalpositive andnegative charges are
separated byasmalldistance…
• Theproductof magnitudeofeither ofthecharges andseparation
distancebetween them iscalledas dipolemoment.
• All dielectricsareelectricalinsulatorsandthey aremainlyused to
store electricalenergy.
• EXAMPLE: Mica,glass,plastic,water, etc.,

3. TYPES OF DIELECTRIC MATERIALS
• Dielectric material can be solid, liquid or gas.
• High vacuum can also be used as a dielectric.
• Solid dielectrics are most commonly used as glass,
rubber, mica, etc.,
• As a liquid dielectric material Transformer oil, cable
oil, vegetable oil can be used.
• Gaseous dielectric materials are used for both as
insulators and cooling agents.
• Example: Air, hydrogen, nitrogen, helium methane,
sulphur dioxide etc.,

4. ELECTRIC POLARIZATION
• The process of producing electric dipoles by an
electric field is called polarization
• The induced dipole moment per unit electric field is
called polarizability
• The induced dipole moment is proportional to the
intensity of the electric field.

5. Properties of a good dielectric material
• It should have high resistivity to reduce the leakage
current.
• It should have high dielectric strength.
• It should have high mechanical strength.
• It should have high fire resistance.
• It should have high thermal conductivity.
• It should have low thermal expansion.
• It should have low dielectric loss.
• It should have low water absorption quality.

6. GASEOUS DIELECTRICS

7. AIR
• Itisnaturally availabledielectricmaterial.
• Dielectriclossispractically zero.
• Thedielectricconstantofairlinearlyincreasewithincrease
inpressure.
• Itisusedasdielectricsinaircondensers.
• Itcanbeusedasaninsulatoronlyinlowvoltageapplications.

8. SULPHUR HEXAFLUORIDE
• It is formed by burning of Sulphur in fluorine
atmosphere.
• It has superior cooling properties than air and
nitrogen.
• It is used in the transformers, electrical switches,
voltage stabilizers, and X–ray.

9. NITROGEN
• Itisimportantgaseousdielectricmaterial.
• Itpreventsoxidation.
• Itisusedincablesandcapacitorsunder pressure.
INERT GASES
• They are used in electronic tubes and discharge tubes as insulators.

10. THANK YOU…!