inductors
Post on 20-Jan-2015
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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
…!!!
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