Magnetization Curve, B-H Curve, Hysteresis Loop, Hysteresis Loss - Alternating Current Video Lecture - Class 12

magnetization curve is a BH curve B is
stands for magnetic flux density and H
is magnetizing force a curve is shown
the region o x is the increase in flux
density is very small from x to y the
flux density increases almost linearly
with the magnetizing force the curve
between y and z again the increase in
flux density is small the region beyond
Z after Z the flux density is almost
constant so this region is known as a
saturation region of the material this
means that if we change excitation
current I a changes but no change in is
there in B
this is a hysteresis loop when a
positive magnetizing current is applied
i ii o ii c is the co o AC is represents
that or the there is a gradual increase
in the current in positive direction
EDD very common word repulsive duration
may this is done by changing the
resistor R value from Maximum to minimum
licking the garam resistance but
Highgate token and come hoga and this is
the curve which is followed C D is the
curve and Jessica say I'm resistant
behind the current will be lesser and
the curve will be followed C D now the
current echo will take a rationale
behind gate though the curve which is we
get is this D e I in this curve will see
the the value of B is decreasing from
here to here the value of B is
decreasing and H is increasing in
negative direction now keep on
decreasing the negative current this
will also reduce the negative flux
density or come oka and the curve which
is we get will be between e to F now we
will brief once again Jessica second
bodega from zero to a fifth AC C bodega
hum conquer a flux Co so yeh see Sadie
khawaja for the negative direction mega
RAM but ra h to DC e further vinaya to e
say fr ziege now start decreasing then
we will get a curve between F and G
now make the current positive gk bath
here ooh stable hum current go past
accordingly the curve which we get is d2
edge and further increase will give us a
curve between H to C this will be the
curve so the hysteresis loop here which
is shown here is drawn from one complete
cycle of magnetization increase in
current and the magnetization decrease
in current so now what is hysteresis
hysteresis is a Greek word meaning lag
or late we find be logs edge hence the
name of loop is hysteresis loop
when the magnetic material and the goes
cyclic magnetization two types of power
losses occurs Pella
is hysteresis loss and the second one is
eddy current loss now we will see now
what is hysteresis loss pH is given by a
wh v into F in what where the edge is
the area of loop under his services in
the BH curve or V is the volume of the
material and F is the frequency eddy
current loss is given here it is PE is
1.645 upon Rho T square F square BM
square Weber per meter cube where BM is
given by maximum flux density F is
frequency of excitation T is the
thickness of the core and Rho is the
resistivity of the core a conductor can
be divided into various shells and each
shell is having induced EMF and u2 in
the induced EMF there will be different
current flowing in the in different
shells so but this current in each
individual cell the current flowing here
is not having a clearly defined path and
this leads to a loss sandwiches no no
eddy current loss
hysteresis loss can be reduced by using
narrow hysteresis loops it can be undone
by using good quality electrical steels
methods to reduce eddy current loss at
low frequencies eddy current loss is
reduced by making the core of a number
of thin sheets called laminations it is
practically and mechanically not
possible to make very thin laminations
and hence granulated or powdered iron
cores are used iron dusters mixed with
the binding eddy current can be further
reduced by using coal material of high
resistivity