Spring 2014

( )

3. (1)

(Electric Circuit) , (Magnetic Circuit) .

= = (magnetic flux) [Wb]F = (magneto motive force: mmf) [A] = (reluctance) [A/Wb]

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(: magnetic permeability):

(/m) (open circuit).

. .

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r0 = 0 : = 1.257 10/: ( ), .

r

HB = : (flux density): (flux intensity): (permeability)

: 1 . : 1 ( ) : 0 0

:

: , , : , ,

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()

(H ) (B)

(o) (a) . (a) H=0 (b) . .

(a)(b)(c)(d)(e)(f)(a) . ( )

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1885 William Stanley

.

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2

2 (magnetic core) .

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- 0 ( = 0)- (magnetic permeability ) . ,

(reluctance) 0- (leakage flux) . - .

(Amperes law)

(Magnetic field density) .

, Reluctance ,

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===

=-=

==

cc

cc

2211cc

enclosed

0BH

0ININlH

IdlHF

Q,

1

2

2

1

2211

NN

II

ININ

=\

=

(Faradays law)

() N ()

1 2

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( ) ( )dt

tdNtv f=

2

1

2

1

22

11

NN

VV

(t)dtdN(t)v

(t)dtdN(t)v

=

=

=

f

f

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2

1

1

2

2

1

NN

ii

vv ==

12 22

1 2 1 2 11

2 2 21 22

1

L

N VV N N V NZ Z

N N NI IIN

= = = =

** *1 2

1 1 1 2 2 2 2 22 1

N NS V I V I V I SN N

= = = =

:

:

1 2 .

3.1 2

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.

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(Exciting Current) = +

(): (hysteresis) + (eddy current) :

:

(laminated sheet) ():

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(Admittance)

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lHdlHINF

=== [ ]

AB =HB =

: (flux density): (flux intensity): (permeability)

[ ]

dtdN

dtdiLe f==

lINH =

NLI =

( ) ( ) 2Nl

AI

Al

NIN

IAHN

IABN

INL =

====

[ ]

1

2

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5% .

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, , ,

(Core)

0.3~0.6mm

:

, :

, , ,

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: 2 1 1 , 1 1 1 .

. ( ) .

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()

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22.9kV Smartgrid Lab at Kookmin University

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22.9kV/380V

3.2 , , ,

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Q: 200V ?

(Per-unit)( ) = ( )( )

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(Base value)

:

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. . ) 20kW , 100MW

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=newpuZ

. (, , , )

( ) 1 2

. , , 22.9kV

22.9kV ? , 0.0~1.0

. 3 Y, Delta , 3

.

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3.3 2 20kVA, 480/120V, 60Hz . 120V

= 0.052578.13. 2 1 .

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3.4 3 1 30kVA 240V

. (, )

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3.5 2.5 = 4800 Y =

3040 . = 185. = 10 = 480 , a .

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