L12 magnetic circuits

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ELE101 / 102 Dept of E & E Engg, MIT Manipal 1 Series Magnetic Circuit g g 3 3 2 2 1 1 rg 0 g g 3 r 0 3 3 2 r 0 2 2 1 r 0 1 1 g g 3 3 2 2 1 1 l H l H l H l H f Total mm μ μ l B μ μ l B μ μ l B μ μ l B S φ S φ S φ S φ mmf g rg g g r r r g a μ μ l S a μ μ l S a μ μ l S a μ μ l S Where S S S S ce S luc Total 0 3 3 0 3 3 2 2 0 2 2 1 1 0 1 1 3 2 1 tan Re

description

 

Transcript of L12 magnetic circuits

Page 1: L12   magnetic circuits

ELE101 / 102 Dept of E & E Engg, MIT Manipal 1

Series Magnetic Circuit

gg332211

rg0

gg

3r0

33

2r0

22

1r0

11gg332211

lHlHlHl Hf Total mm

μμ

lB

μμ

lB

μμ

lB

μμ

lBSφSφSφSφmmf

grg

gg

r

r

r

g

aμμ

l S

aμμ

l S

aμμ

l S

aμμ

l SWhere

SSSSce SlucTotal

0

330

33

220

22

110

11

321tanRe

Page 2: L12   magnetic circuits

ELE 101 / 102 Dept of E & E Engg, MIT Manipal 2

Exercise

Fig. 1

The iron ring shown in Fig. 1, is made up of a material having a relative

permeability of 1000 and has a flux density of 2 T in the air gap. For the

given dimensions of l1 = 0.15 m, l2 = 0.1 m, l3 = 0.2 m, lag = 1 cm, A1

= A3 = Aag = 2*10-4 m2, A2 = 3*10-4 m2, if the current through the

coil is 1.5 A, compute the number of turns required. Neglect leakage

flux and fringe effect.

11029 turns

Page 3: L12   magnetic circuits

ELE 101 / 102 Dept of E&E MIT Manipal 1

Parallel magnetic circuit without air gap

+-

R AR B R

V

Analogous electrical circuit

21 ;aμμ

lS ;

aμμ

lS ;

aμμ

lS

3r30

1AFEB

2r20

2ADCB

r0AB

1

A

B C

D

E

F

Φ

Φ1

N

Φ2

ADCB2AFEB1

ADCB2AFEB1ABTotal

SSWhere

), S or S(SMMF

mmf)B or ADCB (Path AFEmf Path AB mrequired Total mmf

Page 4: L12   magnetic circuits

ELE 101 / 102 Dept of E&E MIT Manipal 1

Parallel magnetic circuit with air gap

Φ1 Φ2

A

B

C

DE

F

Φ

+- R A

R B V

R a

R bAnalogous electrical circuit

Page 5: L12   magnetic circuits

ELE 101 / 102 Dept of E&E MIT Manipal 1

Exercise

The core shown has a relative permeability of 4000. Find the current

required for the exciting coil to produce a flux of 10 milli Wb in the central

limb. Take total number of turns of the coil as 500 turns.

ANS: 2.387 A