Post on 26-Sep-2015
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B CNG THNG
TRNG I HC CNG NGHIP TPHCM
KHOA CNG NGH IN
----
TIU LUN
IN T C BN
TI : Linh kin th ng
GVHD : L Ngc Tun
Tp.HCM, 2013
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DANH SCH NHM
H & Tn MSSV
Nguyn ng c 12021171 ( Nhm trng)
Trn Tin Thnh 12090931
Nguyn Xun Lanh 12024771
Nguyn Vn Tin 12016151
Nguyn Vn Nhon 12034841
L Trn Hng Duy 12011151
inh Anh Tun 12078721
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MC LC
PHN I: IN TR ............................................................................................................................... 4
PHN II: T IN .............................................................................................................................. 13
PHN 3: CUN CM .......................................................................................................................... 24
TI LIU THAM KHO ..................................................................................................................... 29
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PHN I: IN TR
1. Khi nim
in tr l linh ki c tnh cn tr dng in v lm mt s chc nng khc ty thuc vo v
tr ca in tr trong mch in.
in tr l i lng vt l c trng cho tnh cht cn tr dng in ca mt vt th dn
in. N c nh ngha l t s ca hiu in th gia hai u vt th vi cng dng in
i qua n:
URI
Trong :
U : l hiu in th gia hai u vt dn in, o bng vn
I : l cng dng in i qua vt dn in, o bng ampe (A).
R : l in tr ca vt dn in, o bng Ohm ()
n v : ohm ()
1k =10 1M = 10 = 10 2. in tr ca dy dn
2.1 Khi nim
in tr ca dy dn l i in c trng cho tnh cn tr ca dng in ca dy dn
K hiu l : R, n v l :
Tr s in tr ca dy dn in ln hn hay nh hn ty thuc vo vt liu lm nn dy dn,
chiu di dy dn v tit din ca dy dn.
lRS
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: l in tr sut m L : l chiu di ( m ) S : l tit din ()
R : l in tr ()
2.2 in dn l i lng c trng cho tnh dn in ca dy dn . in dn nghch o ca
in tr.
K hiu : G, n v l : S ( siemens)
1GR
2.3 in tr sut
S o in tr ca ay dn lm bng mt cht no v c chiu di 1m , tit din thng
1 c gi l in tr sut ca cht .
Ty cht khc nhau m c in tr sut khc nhau, in tr sut bin i theo nhit v
s bin i ny c xc nh theo cng thc sau.
= (1 + ) Trong :
: in tr sut o 0 t: nhit ()
: h s nhit
: in tr sut nhit t in tr sut ca mt s cht thng gp:
Cht m Cht m
Bc 0,016.106 Km 0,06.106
ng 0,017.106 Thp 0,1.106
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3. Phn loi
in tr c th phn loi da vo cu to hay da vo mc ch s dng m n c nhiu loi
khc nhau .
3.1 Phn loi theo cu to
a. in tr than
Ngi ta trn than v bt t st theo t l nht nh cho ra nhng tr s khc nhau . Sau
, ngi ta p v cho vo mt ng bng bakelite .Kim loi p st hai u v hai dy ra c
hn vo kim loi , bc kim loi bn ngoi gi cu trc bn trong ng thi chng c xt v m.
Ngoi cng ngi ta sn cc vng mu cho bit tr s cc in tr . Loi in tr ny d ch
to, tin cy kh tt nn n r tin v rt thong dng . in tr than c tr s t vi n vi
M.
b. in tr mng kim loi
in tr mng kim loi c ch to theo quy trnh kt lng mng Ni Cr trn than gm c
x rnh xon , sau ph bi mt lp sn. in tr mng kim loi c tr s n nh, khong in
tr t 10 n 5M .Loi ny thng c dng trong cc mch dao ng v n c chnh
xaac1 cao v tui th cao , t ph thuc vo nhit .
c. in tr oxit kim loi in tr oxit kim loi ch to theo quy trnh kt hp oxit thic trn
thanh Si. Loi ny c n nh cao, chng m tt, cng sut danh nh t 0,25W n 2W.
d. in tr dy qun
in tr dy qun lm bng hp kim Ni Cr qun quanh trn mt li cch in snh s. Bn
ngoi c ph mt nha cng v mt lp sn cch in . gim thiu h s t cm L ca dy
qun, ngi ta qun 1 2 s vng theo chiu thun v 1 2 s vng theo chiu nghch. in tr chnh xc dng dy qun c tr s t 0,1 n 1,2 M , cng sut danh nh thp
t 0,125 W n 0,75 W.
Nhm 0,026.106 Photpho 0,11.106
Vonfram 0,055.106 Ch 0,21.106
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in tr dy qun c cng sut danh nh cao cn c gi l in tr cng sut.
3.2 Mc ch s dng
a. Bin tr (VR :Variable Resistor)
L mt loi in tr c tr s thay i c. Cu to gm mt in tr mng than hay dy
qun c dng hnh cung , c gc xoay l 270 . C mt trc xoay gia ni mt con trt lm
bng than hay bng kim loi cho bin tr than. Con trt s p ln mt din tr to kiu ni tip
xc, lm thay di tr s in tr khi xoay trc.
Bin tr dy qun thng c tr s nh t vi n vi chc . Cng sut kh ln, c th
ti vi chc W.
b. Bin tr than : ngi ta trng mt lp than mng ln hnh vng cung bng bakelit. Hai
u lp than ni vi cc dn in. gia l cc ca bin tr v chnh l con chy bng kim loi
tip xc vi lp than. Trc xoay gn lin vi con chy , khi xoay trc con tr chy di ng trn
lp than lm cho tr s bin tr thay i. Bin tr than cn chia lm 2 loi: bin tr tuyn tnh, bin
tr phi tuyn tnh.
c. Nhit tr (TH Thermistor)
L loi in tr m tr s ca n tthay i theo nhit .
Nhit tr m (NCT): l loi nhit tr c tr s in tr gim xung khi nhn nhit cao hn
v ngc li.
Nhit tr dng (PTC): l loi nhit tr c tr s in tr tng ln khi nhn nhit cao hn
v ngc li.
d. in tr ty p
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L loi in tr c tr s thay i theo in p t vo hai cc. Khi in p gia hai cc
di tr s quy nh th VDR c tr s in tr rt ln ,coi nh h mch. Khi in p gia hai cc
tng cao qu mc quy nh th VDR c tr s gim xung cn rt thp, coi nh ngn mch.
VDR thng c mc song song cc cun dy c h s t cm ln dp tt cc in p
cm ng qu cao khi cun dy b mt dng in qu t ngt trnh lm h cc linh kin khc trong
mch.
e. Quang tr (Photoresistor)
L loi in tr ph thuc vo nh sang (LDR light dependent resistor )
Quang tr thng c ch to t sulfur-cadmiun .Quang tr c tr s in tr ln hay nh
ty thuc vo cng chiu sang vo n . chiu sang cng mnh th in tr c tr s cng
nh v ngc li.
Khi b che ti cc in tr vo khong vi trm k n vi M
Khi dc chiu sang th in tr vo khong vi trm n vi k .
f. in tr cu ch (Fusistor)
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in tr cu ch c tc dng bo v qu ti nh cc cu ch ca h thng in nh nhng n
c dng trong cc mch in t bo bo v cho mch ngun hay cc mch c dng ti ln.
Khi c dng in ln hn dng cho php i qua th in tr s b nng v b t.
in tr cu ch c gi tr rt nh , khong vi
4. Cch mc in tr
4.1 Mc ni tip
td 1 2 3R R R R
Nu mc nhiu in tr ni tip th
= + + + 4.2 Mc song song
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1 2td
1 2
R RRR R
5. cch oc tr s in tr
5.1 c tr s in tr theo quy c vng mu
a. in tr 3 vng mu
L loi in tr c chnh xc thp, sai s cao, gi tr R c tnh theo cng thc sau:
R AB C 20% Trong :
Vng A: l s th 1
Vng B: l s th 2
Vng C: l b s
V d: vng A mu nu, vng B: xanh lc,vng C nu th ta s c gi tr in tr tng ng
l: 115 10 ( ) 20%
R 150 20%
b. in tr 4 vng mu
L loi in tr c chnh xc mc trung bnh, gi tr R c tnh theo cng thc:
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R AB C DD 5%
Trong :
Vng A: l s th 1
Vng B: l s th 2
Vng C: l b s
Vng D: l sai s
c. in tr 5 vng mu
L loi in tr c chnh xc cao, sai s l 1%, c xc nh theo cng thc:
R ABC D E Trong :
Vng A: l s th 1
Vng B: l s th 2
Vng C: l s th 3
Vng D: l bi s
Vng E: l sai s (1%)
5.2 c in tr theo quy c chm mu
Trn thn cc in tr, mt u in tr c mu B khc vi mu than in tr A, gia than
c chm mu C.
Cch c tr s vn nh trn : vng A vng B 10 c s m vng C V d: mt in tr c thn mu xanh l cy, mt u mu , c chm vng
Tr s in tr l 520 k
5.3 in tr c ghi s trn thn
i vi in tr c ghi s trn thn th 2 s u c ngha, s th 3 l s nhn
V d : trn thn ghi 103 th tr s in tr l 10 k
Ngoi ra trn thn in tr c ghi con s v ch th con s ch tr s in tr cn ch ch bi
s : R=1, K= 10, M= 10. Cc gi tr tiu biu : 1.0; 1.2; 1.5; 1.8; 2.2; 2.7; 3.3; 3.9; 4.3; 4.7; 5.1; 5.6; 6.8; 7.5; 8.2; 9.1.
Cc linh kin in tr thng c ch to vi gi tr l cc gi tr tiu chun nhn vi bi s ca
10.
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V d: 10 , 100 , 1,5k
6. Cng sut ca in tr
Cng sut ca in tr l tr s ch cng sut tiu tn ti a ca n.
Cng sut chu ng ny do nh sn xut cho bit di dng ghi sn trn thn hoc kch
thc ca in tr. Kch thc ca in tr ln th cng sut ln. Cng sut ca in tr thay i
theo kch thc.
Cng sut 1/4W, chiu di = 0,7 cm
Cng sut 1/2W, chiu di = 1cm
Cng sut 1W, chiu di =1,2cm
Cng sut 2W, chiu di =1,6cm
Cng sut 4W, chiu di= 2,4 cm
Nn chn cng sut chu ng ln hn hai ln cng sut tnh ton
V c tnh theo cng thc: 2P RI
Trong :
I l cng dng din (A)
R l in tr () 7. ng dng ca in tr
in tr c nhiu ng dng trong lnh vc in v in t .
Ta nhit : bp in , bn i
Thp sng: bng n si t
B cm bin nhit , cm bin quang
Hn dng , chia dng
Gim p , chia p
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PHN II: T IN
1. Khi Nim.
T in l linh kin tch ch nng lng in di dng in trng
2. Cu To K Hiu.
T in c cu to gm hai bn cc bng cht dn in t song song gn nhau nhng
cch bi lp in mi gia.
K hiu ca t in
Bao gm:
T khng phn cc
T phn cc
T c ci sn
T bn i c
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3. S dn in ca t in
Xt nh hnh trn, khi kha K m th n tt.kha K ng ta thy n lo sng ln ri tt .
Nu i ngun VDC bng ngum VAC th khi kha K h n tt, khi kha K ng ta thy n
sng lin tc.
4. in dung
in dung ( capacitance ) l i lng c trng cho kh nng tch in ca t.
K hiu: C, n v : Farad (F)
Thng c dng cc c s ca Farad:
Microfarad: 1 F= 10-6 F
Nanofarad: 1n F= 10-9 F
Picofarad: 1p F=10-12 F
Femptofarad: 1f F = 10-15 F
in dung ph thuc vo cht in mi, t l thun vo tit din ca bn t v t l nghch
vi khong cch gia hai bn t (b dy ca lp in mi).
C = .
C: in dung (F)
S: tit din ca bn t 2m
d: l khong gia hai bn t (m)
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Mt s cht in mi thng c dung lm t nh: khng kh kh, giy tm du, gm,
mica.
Hng s in mi ca mt s cht
Cht in mi Hng s in mi
Khng kh kh 1
Gm 3.6
Giy 5.5
Mica 4-:-5
Paraphin 2
Ebonit 2.7-:-2.9
in dung c th o bng t s in tch ca t trn hiu in th gia hai bn t
=
Nng lng tch tr t in
= 12 Trong :
W: nng lng (J)
C: in dung (F)
U: hiu in th gia hai bn t (V)
Q: in tch (C)
5. in th lm vic
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i vi mi loi t in, ch c th t vo n mt in p ln nht no , ty theo kt cu
ca lp in mi. Nu in p t vo qu ln in mi s b nh thng v ch ln dn in , lm
t in b hng khng dung c na.
in th lm vic chnh l in th ln nht cho php p vo hai u t m t chu ng
c, thng in th ny c ghi trn t.
6. Mch tng ng ca t in
Ngoi in dung, mt t in thc t cn c in tr v in cm nh trong mch tng
ng hnh:
Trong :
Rs : l in tr ni tip do dy dn cc u tip xc v cc in cc.
Rp: in tr shunt do in tr sut ca cht in mi v vt liu lm v, do hao in mi.
L: h s t cm tp do dy dn v cc in cc.
in tr tng ng ni tip ESR ( Equyvalent Series Rcsistance ) l in tr AC ca t
in phn nh c in tr ni tip Rs v in tr song song Rp ti tn s cho hao ca cc
phn t ny c th biu th bng hao ca mt in tr R trong mch tng ng.
Dung khng l i lng c trng cho sc cn in ca t.
K hiu : XC hoc ZC, n v : Ohm ()
Biu thc : X = = XC l dung khng ()
W l tn s gc (rad/s)
C in dung (F)
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F tn s (Hz)
Tng tr ( tr khng ) : khi lm vic tn s cao th phi tnh thm in cm u ra: Z = R + (X + X) Z: tng tr ()
R: in tr ()
XC: dung khng ()
XL: cm khng ()
L: h s t cm (H)
H s cng sut PF ch hao in trong khi t lm vic vi in p AC. t in l tng,
dng s sm pha hn in p gia hai u t in l 900. T thc t, do tn hao cht in mi,
in cc v cc u tip xc nn gc pha nh hn 900 . PF c nh ngha l t s in tr tng
ng ni tip R v tng tr Z . PF c n v : %.
H s tiu tn DF l t s in tr tng ng ni tip R v dung khng XC. DF c n v:
%. DF xp s bng PF khi PF
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in c np vo t theo cng thc:
Q = Q1 = Q2
Q = CU1 = CU2 =>U = ; U = Mt khc ta c:
Q = Ctd U => U =
M : U = U1+U2
=>
=
+
+ +
7.1. Mc song song
Hiu in th gia hai u t : U=U1=U2.
in tch np vo t C1: Q1=C1U.
in tch np vo t C2: Q2=C2U.
in tch np vo t Ctd: Q=CtdU.
in tch np vo t C1,C2 bng in tch np vo t Ctd nn:
Q=Q1+Q2
Ctd.U=C1U+C2U=(C1+C2)U
= > Ctd=C1+C2
Nu c nhiu t mc song song th :
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Ctd=C1+C2++Cn
8. Hin tng np x ca t
Xt mch nh hnh trn, gi s t cha tch in, ta bt kha K sang v tr s 1 th t bt u
np in, lng in tch trn hai bn t tng dn n khi in th gia hai bn t gn bng ngun
VDC (99% VDC) th qu trnh np in ca t chm dt . T c xem nh np y, nu khng
c tc ng khc th hin tng vn khng thay i.
Khi cha tch in th hiu in th gia hai u t bng khng. Trong qu trnh np in th
hiu in th gia hai u t thay i theo dng hm s m: V(t) = V(1 e ) Trong :
e=2,71828
RC
R : in tr ()
C : in dung (F)
: thi gian hng np x ca t
t : thi gian t np in (S)
Trong qu trnh np in , t c dng in np thay i theo dng hm s m:
i(t) = VR e Theo l thuyt, thi gian t np y l v hn (VC(t)=VDC). Trn thc t, sau thi gian
5 t np c 99%VDC, lc ngi ta xem nh t np y.
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Khi t np y, ta bt K qua v tr s 2, t C x in qua R, hiu in th gia hai u t
thay i theo biu thc :
V(t) = Ve Trong :
e=2,71828
C : in dung (F)
RC
: thi gian hng np x ca t (s)
t : thi gian t x (s)
Dng x ca t thay i theo biu thc:
() = 9. Phn loi
9.1. Theo mc ch s dng
T c nh: l t c tr s nh dung c nh. Tr s ny c nh sn xut n nh c sai s
trong phm vi cho php. N dc chia lm hai dng:
T c cc:
T c phn cc tnh m dng.
T khng: phn cc : t c hai cc nh nhau.
T bin i c: l loi t c in dung dc iu chnh theo yu cu s dng.
9.2 Da theo cht in mi
T ha: l loi t c tnh phn cc. t ha c bn cc l nhng l nhm, in mi l lp oxit
nhm rt mng c to bng phng php in phn. in dung ca t kh ln.
Khi dng phi rp ng cc tnh m v dng. in th lm vic thng nh hn 500V.
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T ha tantalum : l t c phn cc tnh, c cu to tng t t ha nhng dng tantalum
thay v dng nhm. T tantalum c kch thc nh nhng in dung ln. in th lm vic ch
vi chc volt.
T giy : l loi t khng c phn cc tnh. T giy c hai bn cc l nhng l nhm hoc
thic, gia c lp cch in l giy tm du v cun li thnh ng.
T mng: l t khng phn cc tnh. T mng c cht in mi l cht mng do nh:
polypropylene, polystyrene, polycarbonate, polyethelene. C hai loi t mng chnh: loi foil v
loi c kim loi ha.
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T gm: l loi t khng phn cc tnh. T gm dc ch ta gm cht in mi l gm,
trng ln b mt n lp bc lm bn cc.
T mica: l loi t khng phn cc tnh. T mica c ch to gm nhiu ming mica
mng, trnags bc, t chng ln nhau hoc ming mica c xp xen k vi cc ming thic. Cc
ming thic l ni vi nhau to thnh mt bn cc. Sau bao ph bi lp chng m bng sp
hoc nha cng .Thng t mica c dng hnh khi ch nht.
10. Cch c tr s in dung
T c ghi s trn thn: .1 c ngha l t c in dung 0.1; .01 ngha l t c in dung
0.01
T c ghi s trn thn: 103K ngha l t c in dung: C 10000 pF 10%
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Hai s u l s th nht v s th 2, s th 3 l s nhn: 10 , ch ch sai s J=5%, K= 10%, 20%
T c ghi hai ch s trn thn, vd: 47/50 th s u l in dung, n v , s th hai l in p lm vic, n v l Volt
10. ng dng
T thng c dng lm t lc trong cc mch lc ngun, lc chn tn s hay cho qua cc
tn s no . T c mt trong mch lc th ng, mch lc tch cc, t lin lc ni gia cc
tng khuch i. T kt hp vi mt s linh kin khc to nhng mch dao ng, ngy nay,
cn c t nano tng cng nng lng b nh nhm p ng nhu cu ngy cng cao ca con
ngi.
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PHN 3: CUN CM
1. Cu to k hiu
Cun cm (cun cm)l nhiu vng dy in t qun lin tip nhau trn mt li.
Li ca cun dy c th l mt ng rng (li khng kh),li st bi ,hay li st l.
Cun dy li st l dng cho cc dng in xoay chiu tn s thp.
Cun dy li st bi dng cho dng in xoay chiu tn s cao .
Cun dy li khng kh cho dng in xoay chiu c tn s rt cao.
H s t thm tng i ca vt liu lm li()l t s gia t trng ca cun dy khi c li
v khi khng c li(li l khng kh)
2. H s t cm
H s t cm l i lng c trng cho kh nng tch tr nng lng t trng ca cun
cm.
K hiu : L
n v o : Henri (H)
Milihenri: 1mH=10-3 H
Mcrohenri : 1 H =10-6 H
H s t cm ph thuc vo s vng dy,tit din ,chiu di v vt liu lm cun cm.
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2 2
o r o r
7o
n dL Sl 4
4 .10 H / m
r : h s t thm tng i ca vt liu lm li i vi chn khng.
n: s vng dy
S: tit din li (m2)
l: chiu di li (m)
d: ng knh li (m)
Nng lng np vo cun cm
Dng in chy qua cun cm v tch tr di dng t trng:
21W Li2
3.Mch tng ng ca cun cm
Ngoi h s t cm L, mt cun cm thc t cn c in tr tn hao (in tr ni tip RS, c
khi k n in dung k sinh C nh mch tng ng hnh di
4. Hin tng t cm
Nu dng in I chy trong mt cun cm thay i theo thi gian, th cun cm s t cm
ng v sinh ra mt sc in ng cm ng
Ie n Lt t
Trong :
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I : vin thin dng in (A)
: bin thin t thng (wb)
t : khong thi gian bin thin (s)
5. H cm
Khi c hai hay nhiu cun cm th s thay i dng in trong mt cun cm s lm t thng
thay di ,cc cun cm cn li phn ng bng cch sinh ra cc sc in ng cm ng khi ngi
ta gi l hin tng h cm.
K hiu : M
n v o : H
6. Cch mc cun cm
a. Mc ni tip
td 1 2L L L
b. Mc song song
5. Hin tng np x ca cun cm
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Xt c tuyn np x ca cun cm:
Gi s cun cm cha tch tr nng lng in bt kha K sang v tr s mt cun cm pht
sinh sc in ng cm ng bng ngun VDC cung cp, do lc u dng in chy qua cun
cm bng bng khng. Sau dng in qua cun cm tng ln theo biu thc sau:
t
DCL
Vi t (1 e )R
LR
l thi gian hng np x ca cun cm
Ngc vi dng in, hiu in th gia hai u cun cm lc u bng ngun VDC nhng
sau gim dn theo biu thc:
t
L DCv t V e
Sau thi gian 5 th cun cm xem nh c np y, nu khng c tc ng khc th hin
tng vn khng thay i.
Khi cun cm np y ta bt kha K sang v tr s 2. Dng in x thay i theo hm s m:
t
DCL
Vi t eR
Trong qu trnh x nng lng in th hiu in th gia hai u cun cm thay i theo
biu thc:
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t
L DCv t V e
Sau thi gian 5 th cun cm s x ht nng lng tch tr trong n.
8. Phn loi
8.1 Cun cm mt lp li khng kh
Cu to :gm mt s vng dy qun vng n st vng kia hoc cch nhau vi ln ng knh
si dy. Dy c th cun trn khung bng vt liu cch in cao tn (gm,thy tinh,nha)
8.2 Cun cm nhiu lp li khng kh
Cu to : tng t nh cun cm mt lp li khng kh nhng c nhiu vng qun hn, v
cun cc vng dy thnh nhiu lp xp chng ln nhau theo kiu t ong.
8.3 Cun cm c li st bi (bt st t)
Cu to :cng tng t nh hai loi trn nhng li dng qun l ferit, thn li c rng
xon c, hai u c kha hai rnh.
8.4 Cun cm c li st ming (st l)
Cu to : cng tng t nh trn nhng li c lm t l thp Si,thp Si ht nh hng.hnh
dng li thng l E,I,U,TMi l thp c cch in bi lp ph rt mng oxit st ,thp Si
hoc vamis.
9. ng dng
Hin nay nh sn xut ch to nhiu loi cun cm c sn di dng linh kin d tr
ta c th dng ngay hoc p ng nhu cu ring ta thit k qun dy, chn li cho cun cm
Cun cm c ng dng lm micro in ng, loa in ng, bin p, cun dy trong u
c aTrong mch in t, cun cm c th mch lc tn s, mch dao ng cng hng,
mch to dng sng, dng xung
Linh kin th ng
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TI LIU THAM KHO
1. PHM TH C L MINH CNG TRNG TRNG TUN M, mch in 1,
NXB HQG TP.HCM, 2013
2. L TH HNG THM, linh kin in t, NXB HCN TP.HCM, 2011
3. TRNG VN TM, linh kin in t, H CN TH
4. Ngun internet