INDUCTORS

Stores energy in the form of magnetic field and delivers it as and when required.

Whenever current passes through a

conductor, lines of magnetic flux are

generated around it. This magnetic flux

opposes any change in current due to the

induced e.m.f.

This opposition to the current is known as

inductance and the component producing

inductance is known as inductor.

Unit Henry (H).

Induced e.m.f (electromotive force):

L= inductance in Henry

di/dt = rate of change of current.

FACTORS THAT AFFECT INDUCTANCE OF A COIL.

Number of turns in the coil Permeability of the core material. Size of core.

Inductance is given by,

Permeability is the measure of the ability of

a material to support the formation of a

magnetic field within itself.

An inductor consist of copper wire wound around a core made up of a ferromagnetic material.

FERRO MAGNETIC MATERIAL

TYPES

Fixed inductors Air core inductors Iron core inductors Ferrite core inductors

Variable inductors.

FIXED INDUCTORSAIR CORE INDUCTORS

Former made up of ceramic plastic or cardboard.

Air will be there inside former.

It has the least inductance, since in air all magnetic lines produced by changing current do not link with every turn of coil, many of them lost in space.

HIGH FREQUENCY AIR CORE INDUCTORS

IRON – CORE INDUCTOR. Copper wire wound on hallow former Core material passes through the former it

forms closed magnetic path for the magnetic flux.

So, it donot leak outside of coil. Flux line iron + total flux

Former paper or plastic Core silicon steel or ferromagnetic material

in the form of sheets. Laminated Sheets to reduce hysteresis and

eddy current losses.

Iron – core inductors called choke

Useful at low frequencies.

Value few henries.

Applications:Filter circuit in power supplies.Chokes in fluorescent tubes

Eddy current electric currents induced in conductors when exposed to a changing magnetic field.

Disadvantages: enormous increase in hysteresis and eddy

current loss Cannot be used for high frequencies.

FERRITE CORE INDUCTORS For High frequency applications. Core ferrite an insulator having high

permeability.

Ferrite hard, dense ceramics

made of

ferric oxide +metal oxides

Ferrite core solid and not in laminated sheets

Because of their high resistivity.

Value few μH to few mH.

APPLICATIONS R.f chokes for supply decoupling purposes. Switching regulated type d.c power supplies Various types of filters in communication

equipment.

VARIABLE INDUCTORS

THANK Y

OU ALL

…!!!