Power Study Notes

ELECTRO MAGNER SYSTEM
51
POWER ENGINEERING

NOTES

, MAGNETIC CIRCUIT


.
Concerned with conversion between electric and

mechanical energy
.




°


Induction machines actuators ,
solenoids ,
transformers
,




Magnetic materials used to shape & direct magnetic fields
•


are




{ Magnetic Circuits }




BASICS
Magnetic formed ferromagnetic
°


circuits are
by
materials .




In electric machines the magnetic field
°


most :




or flux is produce by passing an electric current

through coils wound an f- mag .
materials




MAGNETIC °

Also called magnetic flux intensity
Measure of of magnetic field lines
°

FLUX the amount

passing through a surface


of magnetic circuits
"




It's
"

.
like the current




.
Measured in Atm



men

,i H When conductor
current through
-


a passes a a
,



RELATION
magnetic field radiates from it :




* Use right hand rule
µ



*ddd÷
°

The relationship between get and magnetic
field intensity is defined by Ampere 's circuit law



"




integral of the
's
Ampere law The magnetic
°
:
line

field closed path equal
intensity H around a is

to total current linked the contour
"
the by




Jo
H de
=
fi = i it is tis .
. .




-
-6 .




"

- - -
to
"
Cantave
- .
-




Tangle exists
if an
:




JH a dl cos A =

is i

, -


s a basic example consider a circle :




ftt.de Ii
Hf
=




•
Is
Hfde
=
Ii

if H2 tr
= i

H
tier
=




µ




Number of field lines
MAGNETIC FLUX
passing through
0
a given area


DENSITY




Liege
.
B = = T I Tesla ) '
web
.




B -
H °
Magnetic flux intensity H produces a magnetic
RELATIONSHIP flux density B everywhere it exists



UH B hour H
B & =
=



→
I relative
permeability perky permeability
ofthe medium ability
of free space
-
7
= I

.

others = 2am
-
Good




.AE/Cu/insulatars--4TTX1O
.

Relative
permeability large :
a value ur implies
that a small current can
produce a large flux
density