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BotroKienthucLuyenthiDaihocTrenkenhVTV2VatlyPhan2DienxoayChieu p4
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fs«'ifif/,»*/«••«/.'!/«• r.ie
ii i/rim
i''.ff//, t.>i,
iit-n hi-iih
.." •« i m van
Ctr T/VtfHMTVDVVHKhaiig
Bien
Huang dan
I k h o n g t h a y doi => Z k h o n g t h a y doi
Cdch 2: \
2
1
o)iL
/
= R2
+
.
(02L -
1
Vift
N2
• ©10)2
1
=
U
Ur
VR^.(Z,-ZC)^
, Uc p h i ! thuoc 1/Zc
|{R2.Z^)J^--2Z,-;-.1
V i d y 4: M o t mach xoay chieu RLC noi tiep chi c6 tan so f d o n g dien thay doi
d u o c . K h i f = 12,5 H z va f = 50 H z thi cong suat tieu t h u ciia mach nhu
'
B.15.
C.25.
_
^ Zci
ZL
>2
^CO
s C O bao nhieu Ian c u o n g do d o n g dien qua mach bang 0?
A . 50.
1
theo kieu h a m tarn thuc bac 2 nen:
n h a u . Thay d o i f sao cho cong suat toan mach Ion nha't t h i t r o n g t h o i gian 1
r,2
C = ^ ^ ^ ^ = 30(|.iF) ^ Clion B.
D . 75.
V i d u 7: Dat m o t dien ap xoay chieu u = Uocos(1007Tt) V vao doan mach RLC c6
U^R
P = TR =
R2
coL-
+
t::m
COQ = sjo3i(i)2
R = 100\/2
^ , P p h u thuQC CO theo kieu h a m phan thuc nen:
cuon cam thuan c6 do t u cam L < l,5/7t H va tu dien c6 dien
d u n g C thay d o i dugc. K h i dien d u n g t u dien Ian l u g t la Ci = 25/TT (|aF) va
(oC
'-=> i = yjtj^
C2 = 125/(37i) ((.iF) t h i dien ap hieu d u n g tren tu c6 c i i n g gia t r j . De dien ap
-
2 5 ( H z ) . T r o n g 1 chu k i d o n g d i e n = 0 hai Ian, ina
hieu d u n g tren dien t r a R dat cue dai t h i gia trj cua C la
t r o n g 1 s C O 25 chu k i nen so Ian d o n g dien = 0 la 2x25 = 50 Ian = v C h o n A .
A.50/TT(^F).
B. 200/(371) (|.iF).
thay d o i d u g c ) vao hai dau doan mach g o m d i e n t r a t h u a n R, cuon cam
K h i ( 0 = 0)1 hoac co = 002 thi dien ap hieu d u n g giira hai ban tu d i e n c6 cung
COQ =
4^x^2
f
B.
0)g
D.
•
theo kieu h a m tarn thuc bac 2 nen:
1
U r - I . Z r =•
V
thuoc
R2
+
coC
coL -
UK = max o
coC
L2CV-2
I
L
=--,Ucphu
Chuy:
R 2\
C ' 2
theo kieu h a m tarn thuc bac 2 nen: COQ =
.
Zc
....
diing do thi \JQ-
=> Chon B.
T h a y d o i C n g u o i ta thay k h i C = 40 jiF va C = 20 yiF t h i v o n ke chi cung trj
so'. T i m C de v o n ke chi gia trj cue dai.
180
C. 30 ^F.
ZQ2
= ZL
i':
= 100
=> C =
V I':.:.
R2+ZL
'
1
100
CoZr
71
Hu.:.^^^
Z,
2
2
'
_
T^J.'.
,a'J
(|.iF) =:>ChonD.
D . 60 ^iF.
^
(R2+ZM4 -2ZL-^ +1
^
^'Zl:
^Zc
theo ZQ . Dm vao do thi ta se thay:
d u n g C thay d o i . D u n g v o n ke c6 d i ^ n t r a rat Ian mac vao hai dau tu dien-
B. 10).iF.
_ Zci
^) Khi C thay doi dc so sanh cac gid tri Uc c6 the
V i dv 6: M o t mach d i ^ n xoay chieu n o i tiep g o m cuon cam va t u di#n c6 dien
A.20|aF.
ZL = 1 0 0 ( Q )
300
R2 + Z ?
Huang dan
U
1
'Zc
^CO
+ 'A)
«0
U-
"-'zl
= i(co?+coi).
1
•, Uc p h u thuoc 1/Zc
|(R2+ZM-V-2ZL-^-+1
^R2+(ZL-ZC)'
dai. H e thuc lien he g i i i a coi, C02 va coo la
C.
u
UZr
Ur =
m o t gia t r j . K h i o) = coo t h i dien ap hieu d u n g giCra hai ban tu dien dat cue
+C02).
(^F).
Zci = - ^ = 4 0 0 ( Q ) ; Z c 2 = ^ - = 240(Q)
coCi
CoCn
t h u a n C O do t u cam L va tu dien c6 dien d u n g C mac noi tiep, " o i CR^ < 2L.
cOo = i ( c O ]
D . lOO/rt
Huatig dan
V i d u 5: (DH-2011) Dat dien ap xoay chieu u = Uocoscot (Uo k h o n g d o i va ro
A.
C. 20/7T (^F).
*
ZQ canggan ZQQ thi Uc cang Ian, cangxa thi
cang be (Zco =
181
Bo trp kien
thiic V$t li LTDH
tren hcnh
VTV2, t^p 2 - Chu
z +z
UcA = Uc2 = Uc thi
Z'X = —
V.in
BlSn
7-1 + Z ' -1
Zc3e(Zcl;Zc'2)=>Uc3>Uc
—
Zco
=>Uc3 - U c
.125"' =
1) Dc so sank Ua va Ua ta c6 the dung phmrng plidp "gidng day" nhw sau: Tit Uc,
kc duvng song song vai true hodnh neu Ua trcn day thi Ua > Uc, va ne'u duvi dai/
tin Ua
C 2
-
: V^r^': _
Uc Ian nhat trong socdc cong suat dd cho, ta clii ciin so sdnh hai gid tri gan
100"' + Z c ' 2
.Zc2
f
=0,006
^ Z o nam trong (z'e2;Zc;'2) =^ ^(^3 Wn hrfn
Chon C.
(pi); U2 = U V2 cos(l 207rt + 9 2 ) va u i = U ^2 cos(l 107tt + 93) vao hai dau doan
mach g o m d i e n t r o thuan R, cugn cam thuan c6 do t u cam L "a tu dien c6
V i du 8: Dat dien ap xoay chieu vao hai dau doan mach noi tiep g o i n dien tro,
ctien d u n g C mic
c u o n cam thuan va tu dien c6 d u n g khang Z c thay ctoi. Goi Ucm.iv la gia trj
noi tiep thi cuong do d o n g dien t r o n g doan mach c6 bieu
sv? cue dai cua dien ap hieu d u n g tren t u . Dieu chinh Z c Ian i u g t b a n g 50 Q, I S O
thuc t u o n g u n g la: ii = IN/2 cos(1007rt);
ftv Q va TOO Q t h i ctien ap hieu d u n g tren tu Ian l u g t bang U i i, Uc2 va U c i . Ne'u
r V2 cos(n07:t - 2Tt/3). So sanh I va Y, ta c6:
'^t^ U c i = Uc2 = a t h i
= Ucniax.
B. Uc3
> a.
C. Uc3
Huang
Uc, = Uc2 « Zco =
Zc', =50^' =0,02
=150^' =0,0067
< a.
A . I = r.
D . U c - = 0,5Ucn,r,x.
• B.I = rN/2.
..J'^ '
dan
=
- 0,0133 * Zl\ 0,01
i2 = I V 2 cos(120Trt + 27x/3) va h =
C.KI'.
D. I > i ' .
Huoiigdiin
U
Do thi 1 =
U.-a ^ U
theo (0
coL -
1
u.H'>
C O dang n h u h i n h ve. Cang gan vj
• ZQT^ nam trong ^
1* i'fJ 1
tri d i n h d o n g hieu d u n g cang Ion
Z c 2 ; Z a ) =>
> U^.
Chon B.
V i du 9: Dat dien ap xoay chieu 220 V - 50 H z vao hai dau doan mach noi tie])
nen
I' > I
=>ChgnC.
g o m d i e n t r o 50 il, cupn cam thuan c6 cam khang 100 i1 va tu dien c6 d u n g
""^ .
k h a n g Zc thay d o i . Dieu chinh Zc Ian k r g t bang 50 Q, 100 il, 150 Q va 200 Q
Vi du 11: D o a n mach noi tiep g o m dien tro, tu d i e n c6 dien d u n g 0,l/7i mF va
t h i dien ap hieu d u n g tren tu Ian l u g t bang Uci, Uc2, U c 3 va Uc4. T r o n g so
cugn c a m thuan c6 d o t u c a m l/n H . Ne'u dat m o t t r o n g cac uien ap xoay
cac dien ap hieu d u n g noi tren gia t r i Idn nha't la
chieu sau day vao hai dau doan mach tren t h i c u o n g do hieu d u n g trong
A. Uci.
C . UC3.
B. Uc2.
mach Ion nha't l i n g v o i dien ap nao?
D . Uc4.
A . u = U()Cos(105Kt) V.
Humgdan
C . u = U()COs(957it)V.
B. u = Uocos(857it) V
^
.^^
1
V j t r i d i n h : WQ = ^
Zci =50"' =0,02
. c
dan
• = 1007t(rnd/s)
vay, ta chi can so sanh hai gia t r i gan d i n h nhat
=150"' =0,0067
Ta nhan thay, cang gan d i n h Uc cang Ion.
'
Ta nhan tha'y, cang gan vj tri d i n h I cang Ion, v i
=100"' =0,01
Zc'4 =200"' =0,005
• «
D . u = Uocos(707rt) V
Huang
• = 1 2 5 " ' Q « 0,008
va nam
7-' 7-'
dinh
la
(O3 = 957t rad/s
va
true hoanh cat d o t h i tai d i e m t h u hai c6 hoanh
va Z^^^^ gan d i n h h o n nen chi
thj tai d i e m t h u hai CO hpanh do Z't^'j d u g c xac d j n h :
hai ben
tt)4 = 10571 rad/s . Tif I3 ke d u o n g song song v o i
yri
' ' " c a n so sanh U^., va U(^3 . T u Uc2 ke d u o n g song song v o i true hoanh, eat do
182
,
Vi du 10: (DH-2011) Lan l u g t dat cac dien ap xoay chieu ui = U V2 cos(1007i:t +
dinh nhat bang phuvng phdp "gidng day".
A . Uc3
At)
I
do co'3 d u g e xac d i n h n h u sau:
cO(^=ff)3Co'3
OK
=:>(1007t)^ = 957ta)'3 :^co'3 « 1 0 5 , 3 7 t ( r a d / s ) . •
183
CtyTNHHMTVDVVHKhang
Bo trff kicn
Vi
thiic
VTV2. t^p 2 - Chu V0n BiSn
V^t li LTDH tren kenh
W4 e [ c o 3 ; a ) ' 3 ]
V i d u 14: D o a n mach R L C dat d u o i dien ap xoay chieu o n d i n h c6 tan so f thay
n e n I 4 > I 3 => C h o n A .
doi du'oc. K h i tan so la fi va l
Chu y: Mot so hai todn kc't hap) die'u kien cue dqi va do lech pha.
qua mach la -71/6 va 7t/3, con c u o n g d o h i e u d u n g k h o n g thay d o i . T i n h he
V i d u 12: D a t d i e n ap xoay chieu vao hai dau doan mach A B n o l tiep g o m dien
tro R, cuon d a y c a m thuan L va t u dien c6 dien d u n g C thay d o i d i m e . K h j
C = Ci t h i d o n g dien tre pha 7i/4 so v o i d i ^ n ap hai d a u doan mach.
s o c o n g sualt mach k h i f = fi?
C A . 0,5.
B.0,71.
C.0,87.
K h i C = Ci/6,25 t h i dien ap hieu d u n g giua hai t u cue dai. T i n h he so cong
•K
sua't mach A l i k h i do.
,
A . 0,6.
, „,
•.•;.!}:•;;,,;.••
5.0,7.
•
i - . " . ^ .
I i = I2 =^ Z l =
C=
u
= tan —
4
R
^ - Z c 2 =6,25Zci
6,25
Cmax
<=>Zc2 =
R^ + Z
ZQI =
- R
R2 +
V
R = I50V3
2TC/3. C a m k h a n g cua cuon day k h i f = fi la
25R
A. 6 0 0 Q .
12
B. 1 5 0 Q .
I j = I2 => Z j = Z2
* tan so' goc ciia d o n g dien.
C. IOOTI rad/s.
2a =
1
1
LC
(OjC
COi032 = •
D . 107t rad/s.
cpi =
271
^
• a = • —s
—»' ^
3
(P2 =
Humgd^n
*
•
D . 450 a
_
T
_ 7
W2
CO,
D o n g d i e n t r o n g hai t r i r a n g h g p lech pha nhau la
doan mach. K h i C = Ci/2,5 t h i dien ap hieu d u n g giira h a i t u cue d a i . Tinh
B. 50n rad/s.
C. 300 Q.
Huang dan
d u g c . K h i C = C i = 0,l/7i m F t h i d o n g dien tre pha 7t/4 so v o i d i e n ap hai dau
A . 2007t rad/s.
•a =•
d o n g d i e n t r o n g mach c6 gia t r i hieu d u n g n h u nhau n h u n g lech pha nhau
tro R, cuon d a y c a m thuan L = 2/n H va t u d i e n c6 d i e n d u n g C thay do!
'
,
Q va t u dien C. D a t vao hai d a u doan mach hieu d i e n the
V i d u 13: Dat d i e n ap xoay chieu vao hai dau doan mach A B n o l tiep g o m dien
''
9 ] = ~92
..,
u =Uocos27Tft (V) v o i f thay d o i dirge. K h i f = fi = 25 H z h a y f = f2 = 100 H z t h i
=r = 0,8 ^ C h o n C .
3
• coscp^ = cos 92
5
V i d u 15: M a c h xoay chieu n o l tiep g o m cuon day t h u a n cam L , d i e n t r o
R
UR
^
• Chon B.
2
2
2
4R
25R
L ^ 6 , 2 5 ( Z L - R ) =^ ^ i ^ = > Z L =
=^Zc2 =
12
VR'+{ZL-ZC2)'
Hudngddn
D o n g dien t r o n g hai t r u o n g h o p lech pha nhau la 2a = —
3
=6,25(ZL-R)
R
COS(p =
ZL
Z 2 =^ •
D . 0,6.
D . 0,9:
C. 0,8.
Huong dan
C = C i =>tan(p5
C = C i =:>tan(pi = ^ t - ^ 5 £ i = t a n | ^ R = Z L - Z c i
co,Ltancpj = •
C = ^=^Zc2=2,5Za
R
1
cojC
3
3
Z L I - Z Ll
^
CO2
CO1
^R,
_V3=^LI(1L4)^2LI=150(Q)
.\ J. 150V3
=>ChonB.
( Z L - Z C I ) +Z2
U, C m a x 0 Z c 2 =
111Tt
R
7t
R
=
= > C O S ( p i = COS(P2
(p2 = - a
Dong dim trong hai truvng hap lech pha nhau la la.
184
Khi
R
minh aic cong thuc giai nhanh sau day:
thay dot hai gid tri Li vd L2 md co ciing
P
tin
Pmax
khi:
RQ = ^^1^2
•
Khi L thay doi hai gid tri L l vd L l md
= 2 = > CO = IOOTI(rad/s) =5 Chon C.
Chii y: Khi R khong dot va hai gid tri cua L hoac C hoac co ma I, P, UR khong thay dot
„
„
tht Z ] = Z2
:
Chii y: Chung ta co thechmig
*
- 2 ^ ra^LCi = 2
Zcj
'
Vift
*
CO Cling
1, Uc, UR, P tht Lnax, Ucmax, URnmx, Pmax khv. Lg =
CO
3 Cling
UL thi Uiimx
2L
khi:
^
.
>v'i'' ^
'
L
LQ = - — ^ — ^ .
L l + L2
Khi C thay dot hai gid tri Ci vd C2 md
185
B d trp ki£n thiic
CO Cling
CO Cling
V^t It L TBIl
I, UL,
Uc
tren
kSnh
VTV2.
t^p 2 - Chu VSn
UR, P thi Imax, Ulnmx, L/KIHIIA, Pmax khi.
CtyTIVtHMrv
C() =
C1+C2
b ^ 1
2a
co-^
2QC2
CQ =
till Ucm.u khi:
Bicn
C
1
I > VIII
lihang
VIfit
2_
coC
C , + C 2
Khi CO thai/ doi hai gid tri MI va coi nih
CO Cimg I, UK,
Pmax khi:
P th'l hu,ix, Unmax,
2
CO Cling
Uc
thi
Ucmx
khi:
O)Q =
CO Cling
Ul.
thi
Uijiiax
kiii:
li^Q =
*
Ci)(, = ,yo)|Ci)2 .
2
^"^
.1
cothaydoi.
0phjiBHD2:
.
•
...
dcu dien dp liieii
qiian
;,,
~
••
-
doi lien
rt. ft; ihay
L
Z\ ,
•
.
2
4.
• - .
Dat
osi;) ivv;4 O H
= u . ^ = u.-c_
.,.
uSub w o /
i v . ; v i u'l/;!' '.rnit; \ i ' f a ^ ' i • ' i r . . . i M w ' yv]'-.] j ' ^ y j '
RZ',
CM;
f!ufil/.;?r
L
dung.
Bdi todn: M o t doaii mach dien xoay chieu gom dien tro thuan R , cuon day
Thay Zi, = Z^ hay co^ =
......
thuan cam (cam thuan) c6 do tu cam L va tu dien c6 dien d u n g C mac noi
R^
— ' ^ ' ^ o bieu thiVc Uc ta duoc:
........ k ,
...
tiep. Dat vao hai dau docin mach tren mot dien ap xoay chieu ma chi c6 tan
so goc (0 la thay d o i duoc. T i m co de dien ap hieu d u n g tren tu cue dai (Uc)
Ucmax
Dieu kien dien dp hieu dung tren tu, tren cuon cam cue
Dat
=
L
Vc
2) U L
CMl:
("C max
L to")
= max o Zc = Z,. ("L max => C to')
Uc
=
dai.
u
I.Zc = •
R^
+
,
'•}
CMl:
UL =I.ZL
= max
1
coC.
+
Lmax
1
L
R'^
C
2
C'-2
u- C
RZ',
L _ R 2\
C
C
2
2^
C^+l
^'^ ^
L
R
sau do van d u n g hai d i n h ly noi tren. K h i can t i m d i e u kien ciia co ta tinh Z ,
con t u n gia trj
(oL -
-2
L_R 2A
C
ta tinh Z\.
'
i
^1 d u 1: M o t doan mach khong phan nhanh g o m : dien t r o thuan 100 Q/cuon
U
(oC
U L m . n x , Uci.i.>x
2
= = r = max
1 :
+1
2,7
CO
-
day thuan cam co do t u cam 15 m H va tu dien co dien d u n g 1 |.iF. Dat vao
hai dau mach mcit dien ap xoay chieu ma chi tan so thay doi duoc. K h i dien
ap hieu d u n g hai dau cuon cam dat gia trj cue dai thi tan so goc co gia trj la
A. 20000/3 (rad/s).
C. 10000/3 (rad/s).
186
L
u
L
R
De giai n h a n h bai toan loai nay, ta tinh: Z , ^^Q^'Y
U(oL
R2
2
vao bleu tliuc U L ta dugc:
^
=-t> (oL = , — =•
C
- - - - -
( S t 1; i
L_R^
2a
L _ R-^2^
^
£
(i)C
b_
-2
Thay Zc = Z , hay co2_C_2
=
U
(oL
c
RZ'.
,
K
Z L = Z,.
• = U.-
L_R^
Dinh UBHDl:
1) Uc = max «
,.•.sHr•$^,(K-
L_R^
goi la tro to.
2
.
U
-
hoac tren cuon cam cue dai ( U i ) .
*
,.
B. 20000 (rad/s).
'--'^
D . 10000 (rad/s).
' •
187
B6 trp ki&'n thitc
Vpt li L TDH tren hcnh
VTV2. t$p
2 — Chu
V0n
Cty TimnnrvDVVnKhang
Bicn
Huang dan
L
R^
C
2
'l5.10"^
100^
~ V 10-^
2
ULmax « ' C t 6 ' « Z c =Z,
=>ChonD.
•
= 100(Q)
' '
Huang dan
•
„:
1 "
j^hi i = 50 H z , thay doi R:
UZc
"J
,
Ua=IZc =
— = = 100=^(o
100=^(0 =
= ^;-^;;^^^ = 10000(rad/s)
—
coC
100.10"
•^5; V
J) , n
'--^ • '
B m l i /wan: Khi gidi bSng phieang phnp nay thi khoi htgng tinh todn dirge gia,,^
7(R + r ) 2 + ( Z L - Z c ) '
= max:
K h i R = 30 Q, thay d o i f:
xuong mi'rc "cue ticu" va ta se thd'y dirge hicii qua eiia no khi ede hai todn eo so lien
"khong dcp".
Lniax
=
V i du 2: Cho doan mach k h o n g phan nhanh gom dien t r o thuan 80 Q, cuon
- ^ 1 ^ ^ 1 , 5 8 .-^CiionA.
Uc2
•
day C O dien t r o t r o n g 20 Q co do t u cam 0,318H, tu dien c6 dien d u n g 15^9
|aF. D a t vao hai dau mach d i ^ n m o t d o n g dien xoay chieu c6 tan so' f thay
CO
gia t r i la
A . f = 70,45 H z .
B . f = 192,6 H z .
Huong
L
I 0,318
C
Uc„,x
100^
V 15,9.10"''
2
2
C . f = 61,3H2.
D . f = 385,1 H z .
max (^max' I m a x ) » Cong
~122,5(Q)
Ulmax «
= 61,3(Hz)
Chon C,
• = 0,6N/]0U
^/(0 + 1 0 ) ^ + ( 3 0 - 6 0 y
L
1800
^4^5
C
= U.
u.(R + r ) Z \
40.inVi4
VTl
:,1/jju^iJ/iatftig''
1
L
R^
= Z , <=>COcL = ^ | - - - ^
Ucmax
dan
' L t6' < ^ Z L = Z , => 27rfL = 1 2 2 , 5 ^ f = l^f^
U.60
Chu y: Khi co thay doi tJii
d o i dugc. K h i dien ap hieu d u n g giua hai dau t u C dat gia t r i cue d a i t h i taVi
so'f
Vl^t
1
Z c = Z^ <r>
hUdng
o co^ =
L
R^
—- :
—=
COLC
VC
VC
^
^/LC
VLC
VC
2
VLC
V i d u 5: M a c h dien xoay chieu RLC noi tiep co tan so'goc co thay cioi, cuon day
thuan cam. K h i co =
V i du 3: M o t doan mach k h o n g phan nhanh g o m : dien t r o thuan 100 Q, cuon
IOOTI
(rad/s) thi dien ap hieu d u n g tren hai d a u t u dat
day thuan cam c6 do t u cam 12,5 m H va tu dien c6 dien d u n g 1 faF. Dat vao
cue dai, con k h i co =
hai dau mach d i ^ n m o t dien ap xoay chieu co gia t r j hieu d u n g 200 V va c6
cam dat cue dai. K h i tan so goc la bao nhieu t h i dien ap h i ^ u d u n g tren hai
tan so thay d o i dugc. Gia t r i cue dai cua dien ap hieu d u n g tren t u la
dau dien t r o dat gia tri cue dai?
A.300(V).
A . 25071 (rad/s).
B.200(V).
•
•
f
12,5.1010"^
C. lOO(V).
Huang dan
D . 25C (V).
H'
100^
^
'
_
\
%=
^
4OO71
(rad/s) t h i dien ap hieu d u n g tren l . a i dau cuon
B. 2O07t (rad/s).
C. 500n (rad/s).
f) no >
Huang dan
^ ,V%-:\
V^<J^C = 2007r(rad/s) => Chon B.
dy 6: M a c h d i e n RLC n o i tiep dang xay ra cong h u o n g . N e u eh- g i a m tan so'
4
m o t l u g n g raft nho thi
Ucmix = U ,
Cmax
= U ^ t ^ = U - £ - = 200.
j^^'^
Lmax
100.100
C O do t u cam L = 0,3/7i H co dien tro r = 10 Q va 1 bien t r o R. D a t vao dien •iP
xoay chieu co tan so f thay d o i . K h i f = 50 H z , thay d o i R t h i dien ap hiC"^'
d u n g tren tu cue dai la U i . K h i R = 30 Q, thay d o i f t h i dien ap h i ^ u du^i^
tren t u eve dgi la U 2 . T i so U 1 / U 2 bang
•m
B.3,15.
C. 0,79.
D . 6,29.
TJ:U
B. dien ap hieu d u n g tren dien tro thuan khcing d o i .
,r„;T,' r '
v
\yx\
A . dien ap hieu d u n g tu k h o n g d o i .
"'""'^— = 2 5 0 ( V ) ^ Chon D.
V i du 4: D o a n mach noi tiep A B gom tu dien co dien d u n g 1/(6?:) mF, cuon cam
A . 1,58.
D . 300.T: (rad/s).
sS.ti,:;
:i
:
'x^^'mA •<
C. d i e n ap hieu d u n g tren tu tang.
I D . dien ap hieu d u n g tren t u giam.
*•
i
,.::r.
Tu:
f khi
C0(2 < COR < COL
CO = COL
thi
Huang dan
^.-UJA
( k h i co = coc t h i Ucmnx, k h i co =
Utmav)
ta nhan thay, t u v j t r i co =
COR
COR
thi
<d nM> >:/''-'••:
URnwx
(cong huc^ng),
g i a m tan so m o t l u g n g nho
thi CO djch ve phia coc m o t l u g n g nho tiic la Uc se tang
C h o n C.
189
Cty
Bo trg hicn
tluic
V^t li LTBII
tren
h€nh
VTV2.
t^p 2 - Chu VMn
Bigti
V i d u 7: N h a n xet nao sau day la SAl? T r o n g m o t mach d i e n xoay chieu c6
RCL m3c n o i tiep d a n g c6 cgng h u o n g , ne'u ta tang tan so' m a v a n gjf,
TNHllMTVDVv'HKhang
Vift
B. 100 V v a 50 V.
A. 107,2 V v a 88,4 V .
D. 50V2 V v a 5 0 V.
C. 50 V v a 100/3 V.
n g u y e n dien ap hieu d u n g cua n g u o n dien xoay chieu dat vao mach t h i :
Huong dan
A . D i e n ap hieu d u n g U K giam.
UwL
B . D o n g d i e n t r o n g mach t r o nen cham pha h o n dien ap dat vao mach RCL.
C. D i e n ap hieu d u n g tren doan R noi tie'p v o i C se tang.
= ,
coL -
C
1 ^
-
^
^=60(Q)
-5:
2
2
D. C u o n g d o hieu d u n g trong mach se giam.
Huwig
L u c d a u ZQ =
1
(oC
dan
= 0)L = Z L => I = max;
U , „ „ , o Z c = Z , =60Q=>co = : : r ^ = - ^ ^ ~ 1 6 6 , 7 T t ( r a d / s )
Z,-C
3
= max
100.100
co = 1007r=>U, =
Z, - Z r
1
Sau d o tang co t h i ZQ = — < coL = Z L =J> tan(p = —
— > 0 =^ u sSm pha hdn i
R
o)C
UKC=IJR' +
100.200
CO = 20071 => U , =
(0 =
d a u doan mach gc'5m R, L , C mac n o i tiep thoa m a n d i e u k i e n CR^ < 2L. Goi
80V2)'
= 1 0 7 , 2 ( V ) ,. '
l u g t cac von ke chi gia trj cue dai k h i tang dan tan so'la
A. Yi, V 2 , V 3 .
B.V3,V2,Vi.
C. V 3 , V i , V 2 .
D . V i , V3,V2.
-'•••Or:,'..-.../.;r-''v\
••^••'.••^
Hudvgdan
. ,.
+(500/3-60)^
b. Khi (0 thai/ dot qim hai gid tri wt va (02 va cdc dieu kien khdc
lit
• }
K h i 0 ) thay d o i hai gia t r i coi va C02 ma co cung I , U K , P t h i Li>.,x, URmnx, Pmnx k h i
c h o f/c mnx
'o'"
lam
max
COn = JCOICOT = ;
=»03iLI
=
—J
- A7; ^
"
' ^
N/LC
VCO, 0 ) I C V C O 2 M C
ZLI
•3; rif>
COi
CO2
Biet L = C R l D a t vao hai dau doan mach dien ap xoay chieu c^'n dinh, mach
CO him thicn tie coi deii coi tlii
CO Cling he so cong sua't voi hai gia t r j cua tan so goc SOTI rad/s va 200K
de fun ^iii tri Ian nhat nho
rad/s. H e so cong sua't cua doan mach bang
nhat ta so $a)ih gid tri tqi hai
B.1/2.
A . 2/713.
dau giai hqn va gid tri tqi
.'1
dinh.
V i d u 9: Dat d i e n ap xoay chieu u = 100 V2 coscot V v o i co thay d o i tir IOOT: rad/s
•
R 2 + co.L -
cugn cam t h u a n v o i d o t u cam I/TC H va t u d i e n co dien d u n g O/i/rt m F . Dien
ap hieu d u n g giij-a hai dau cuon cam co gia t r i Icjn nhat v a n h o nhat tuonj^
• coiL
cojC \2
^••V''
R
I
o),CJ
\
^
CO]
VC
' '
0.3/^12.
Huang dan
coscpi =coscp2 <=>
0,
'
CAI42.
R
'
= R In
V i d u 1 : C h o mach dien xoay chieu R L C mac noi tiep, cuon day thuan cam.
Chu y: NcU hai todn chi cho
iVng la
CO-
Bay g i o neu cho them dieu kien: ^ = n^R^ t h i
choUi^^ax
den 2007t rad/s v a o hai d a u doan mach noi tiep g o m d i ^ n t r o R = 80 N/2
C02
Za=R
=> Chon C.
'
'/.{-.
Ian l u g t la cac v o n ke'mac vao hai dau R, L , C. K h i tang dan tan so
t u gia t r i 0 t h i thay tren m o i v o n ke deu co m o t gia t n cue dai, t h u t u Ian
190
K106,4(V)
100.500/3
50071
=> C h o n C. '
V i d u 8: Dat m o t dien ap u = Uo cos cot (Uo k h o n g d o i , co thay d o i dugc) vao hni
"
80N/2)" + ( 2 0 0 - 5 0 ) '
Mi '
lam
«88,4(V)
+ (100-100)'
I = — giam dan;U|{ giam dan
Vi , V2,
'
CO,
R 2 + (09L -
1
(OTC
= Z a , | ^ = , / ^ . T h a y i ; = ^ R ' thi:
(02
VC
191
kien thiic
V^t //' LTDII
tren kenh
VTV2. t^p 2-Chu
VSn BiSn
R
• COSCpi = •
VT3
2
R2 +
Rr^-Rp
V«i;
C02
=> Chon A.
V i d u 2: Cho mach dien xoay chieu RLC mac n o i tiep, cuon day t h u a n cam.
=>COS(|)i
(R + r f +
cung he so cong suat 0,35 * 3/N/73 v o i hai gia tri ciia tan so goc (Oi = IOOTI rad/s
va
C02.
Gia t r i C02
A. 507trad/s.
CO
,::
the la
B. IOOTT/S rad/s.
C. lOOn/? rad/s.
D . 1007t/9 rad/s.
Huongddn
COS
R
9 ] = cos 92 <=>
R
1
R 2 + cojL
_
•=>LC = -
R 2 + C02L - -
1
= 0,96
=•
Biet L = CW. Dat vao hai dau doan mach dien ap xoay chieu o n d i n h , mach c6
4 +
(1)2
Chti y: ^hi
huvng
That
cho biet cam khang,
thi
Zc,=-
vqy:
(ofLC -
a)iC
khang
khi co = coi va khi co = ^02 mach
\:
cong
.
Zci
0),
1
1
-LI
IO2
0)2C
V i d u 4: D o a n mach R L C k h o n g phan nhanh mac vao m a n g dien tan so coi thi
cam k h a n g la 20 (Q) va d u n g khang la 60 (Q). N e u mac vao m a n g dien co
1 +
R / ^ - R I ^
0)2
(0,
-\
IOOTC
C02
(02
TOOTT
>/73
tan so 0)2 = 60 (rad/s) t h i c u o n g do d o n g dien cung pha v o i d i e n ap 0 hai
dau doan mach. Gia t r i 0)1 la
A. 20 ^/6 (rad/s).
|
B. 50 (rad/s).
CO2 =90071
Huang
IOOTI =>ChonA.
(02=--—
^^^^^ „
,
j
- ,
•
-
„
i
C. 60 (rad/s).
D . 20 S
hinh dual dang dieu kien vuong
^ - r ; )
pha.
Zci
tiep A M B . D o a n mach A M g o m d i e n t r o R n o i tiep t u dien, d o a n mach M B
chua cuon day c6 d i e n t r o r. Biet dien ap tren doan A M l u o n v u o n g pha v o i
di§n ap tren d o a n M B va r = R . V o i hai gia t r i co = IOOK rad/s va co = 56,25::
B.0,85.
C . 0,91.
Huang
D . 0,82.
dan
L = CR2
U A M J - U M B =>tan(pAM tan (p^B = - 1 => -
^=-l=>
R
r
C =R^
®
=
1
a),C
0)1 = 0)2
V i d u 3: Dat d i e n ap u = 125 N/2 coscot (V), co thay d o i d u g c vao doan mach noi
rad/s t h i mach A B C O cung he so cong suat va gia t r i d o bang
(rad/s).
dan
Z
Chil y: Dieu kien ^ = n^R^ cd thctrd
192
0)1
•.(.(f'J'c:- ( x 5 i ) Q 0 r
Cong hudng o ft)2L :
= •
|R2 +
A . 0,96.
dung
±LL
= 0)2
... 1/
Thay C = L/R2 t h i d u a c : C0]L = R
=> COS
0)2
(O1CO2
1
=R
;l
0),
©2
Chon A .
1
Thay L = CR^ t h i dirge: —
\1
1
=> o)i L C = —
^ . V i u va i cung pha nen 0)2L = —
a)2Cr
-CI
L C = ©2
/
^Ll ^
-CI
(,oj—= 20>/3 (rad/s)
60
Chon D.
Jill
,
still'''
,J
V i d u 5: (DH-2011) Dat dien ap u = U >/2 cos2Ttft ( U k h o n g d o i , tan so f thay doi
dugc) vao hai dau doan mach mac noi tiep gom dien t r o thuan R, cuon cam
thuan CO do t u cam L va tu dien co dien d u n g C. K h i tan so la fi t h i cam khang
va d u n g khang cua doan mach co gia trj Ian l u g t la 6Q va 8Q. K h i tan so la ii
thi he so cong suat cua doan mach bang 1. He thiic lien he giua f i va h la
A . h = 2(^/ 7 3 .5
• B. h = 0,5fi V3 .
./^K*:
CO,
CO,
[Z[7
fi
Huong
C. f2 = 0,75f,.
'
D . ta = 4f,/3.
dan
/6
.
2fi
^,
= . / - = : > t2 = - j = => Chon A .
'
V -CI
193
BS tr^ klSn thtic
Vi
V^t li LTDH
Ircn henh
VTV2. t^p 2 - Chii
Cty TISHH nrv DVVH
l
Huong dan
d v 6: C h o doan mach R L C noi tiep, dat vao hai d a u doan mach d i e n ap
U, = U , . ^ Z L = R
u = Uocos(27Tft) (V) vcVi f thay d o i d u g c . K h i f = 75 H z t h i tha'y c u o n g do
U =7UR+(UL-UC)'
d o n g dien hieu d u n g t r o n g mach cue dai va cam I
=7^36^(136-34)' = 1 7 0 ( V )
U,,
4
so CO gia t i i fii t h i tha'y d u n g khang Zc = 75 Q . Tan so f la
. , A . 50 V2 H z .
B. 75 V2 H z .
C. 75 H z .
D . 100 H z .
f' = 2 f :
1
K h i f = 75 H z t h i mach cong h u o n g : Z^ = 100 = ZQ •= 1507:C
Vi
100
f
75
75
thay vao
Z'r =
dugc 1 7 0 ^ =U'f^ +
1
27Tf C
225U'f^
64
U'K
= 8 0 ( V ) =j.ChonD.
\
R2 +
d u 7: M a c h d i e n xoay chieu K L C mac noi tiep ctien trtr thuan 100 D, cuon
CO2L -
COiC;
ro2C
t h u a n c a m c6 d o t u cam L = 2>/3/TI ( H ) . D a t vao hai d a u doan mach mot
Neu 0)1 > m thi chi c6 thexay
pha Ti/3 so vtVi u . D e i cung pha v o i u thi f c6 gia trj la
27tfL
tancp =
27TfC
R
Cong hitang : f = fo =
C02L
27tVLC
,y„
N e u cho biet L m a k h o n g biet C t h i khir C :
c o j L - ^ = coiRVn^ - 1
7tV3
(2V3 10-^
— =-RVn2-l
"2C
T u he nay c6 the d i theo hai h u a n g :
*
200 S n
tan — = •
100
3
1 •
1
= RVn^ - 1 imt
ra trwang ho'p:
D . 25 V2 H z .
Huong dan
' M ,
1
C. 100 H z .
= nR
c),L -
d i e n ap xoay chieu u =U(.cos2nft, f thay d o i d u g c . K h i f = 50 H z t h i i cham
B.50V2Hz.
=U i +(U'L-U'c)
C\xu y: Khi cho biet hai gia tri coi va 02 ma I i = I2 = Imox/n t h i Z i = Z 2 = nR hay
f = 1 0 0 ( H z ) =>ChonD.
A.40HZ.
„
R
=^ Z r^= —
4
rZ'L=2ZL=2R:=>U'L=2U'R
Huottg dan
K h i f = fo thi d u n g khang: 75 = Z ' c =
KhangVlft
=>\
= 25v/2(Hz)
n-M
7
CO2L
_^\
=^L(o)?-a)^) = R V n 2 - l ( c a i + ( 0 2 ) = > R = - ^
1
I2
= -(02RVn - 1
^ 'fcl)''.;: ...v^ •
N e u cho biet C m a k h o n g biet L t h i k h u L :
=>ChonD.
: ;C/»M2/;'
Khi
i
^
'
,s
thay doi ta)i no ma lien quan den tinh dien np thi ta ap dung
dien dp tong clio liai trwang
=
+ (U, - U^)"
*
Neil f ' = nf tin Z'l. = nZi. = ul
= k-R/n hay U'L = nkiU'n
tniili:
1
RN/U^-I
co^C
CO,
1
RV.7^
1
1
— +—
« 2 C CO?C
C0i0)2Cvr?-l
C02
tinh duoc U vn Zi. = liiR, Zc = foR.
Luc dau:
Vi
cCmg thi'ec tinh
Iigjv
*
' kiU'Rln.
L -
, „„
va U'c =
U " = uf^ + ( U ' L - U ' e ) ^ thi clii
V i d u 9: D a t d i e n ap xoay chieu c6 tan so w thay d o i d u g c vao hai d a u doan
mach R L C n o i tiep. K h i co thay d o i t h i c u o n g d o hieu d u n g t r o n g mach dat
gia t r i cue d a i la L.ux va hai gia t r j un va L02 t h i c u a n g d o hieu d u n g trong
con an duy nhat la U'n.
mach dat gia t r j deu being I„ux/Vs . Cho (cji - i02)/{Cio\co2)
= 60 Q, t i n h R.
d\ 8 : D a t d i e n ap xoay chieu u = UN/2 cos27tft ( V ) vao h a i d a u doan mach
A . R = 30Q. . , .
D . R = 100Q.
B.R = 60Q.
noi tiep g o m d i e n t r a R , cuon cam thuan L va t u d i e n C t h i d i ^ n ap hieu
Huang dan
d u n g tren R , tren L va tren C Ian l u g t la 136 V, 136 V va 34 V . N e u chi tang
tan so ciia n g u o n 2 Ian thi dien ap hieu d u n g tren dien t r o la
A . 25 V .
194 '
B.50V.
C.50V2V.
D . 80 V.
C . R = 120Q.
i " T h a y gia t r j vao cong thuc R =>ChonA.
(cO| - 0)2)
0)10)2 cVi^
_
60
>/5^
= 30(Q)
j
195
Bo tifi hle'n thirc
V^t li LTDI1 tren kenh
VTV2. t^p 2 - CIiu Van
BlSn
f t h i thay d i e n ap h i f u d u n g g i i i a hai dau doan mach g o m cupn day n o i tie'p
V i d u 1 0 : ( D H - 2012) Dat d i e n ap u = Uo coscot (V) (Uo k h o n g d o i , o) thay doi
d u o c ) vao hai d a u doan mach g o m di§n t r o t h u a n R, cuon cam t h u a n c6 do
tu cam 0,8/71 H va t u dien mSc n o i tie'p. K h i co = coo t h i c u o n g d o d o n g dien
hieu d u n g qua d o a n mach dat gia t r i cue dai I m . K h i co = w i hoac co = co2 thi
c u o n g d o d o n g d i e n cue dai qua doan mach bang n h a u va bang I m .
Bie't CO 1 - C02 = 20071 rad/s. Gia trj ciia R bang
A . 150Q,
B. 2 0 0 Q .
,,,
v
C. 160Q.
Huattg
.
D . 50 Q.
dan
Y C L i a bai toan, k h i co = coi hoac co = co2 thi I i = h = Inwv/
.
Sau k h i nghien c u u k i p h u o n g phap noi tren, thay gia t r j vao cong thuc:
0,8
I
A . dat gia t r j cue tieu la 20 V.
B. dat gia t r i cue d a i la 20 V.
C. tang k h i f tang.
D. l u o n luon k h o n g d o i va bang 120 V.
Huang
V(r + R ) 2 + ( Z L - Z c ) '
r +R
= 160(Q) InchonC. ; i
dan
Vr^+(ZL-Zcf
U L r c = I ZL ,r C. r = U
U L r C m i n = U-
.20071
R =
v o i t u di#n C
20
= 2 0 ( V ) = * C h o n A.
V i du 3: ( D H - 2012) T r o n g g i o thuc hanh, m o t hoc sinh mac doan mach A B
U.,c
gom dien t r o t h u a n 40 Q, t y dien co dien d u n g C thay d o i duc7c va cuon day
5. Mot so dau hieu chung k h i L, C va co thay doi.
C O d o t u cam L n o i tie'p nhau theo d i i n g t h u t y tren. G o i M la d i e m n o i giua
a. Dien ap hieu dung tren doan LrC cite lieu
di|n t r o t h u a n va t y dien. D M vao hai d a u doan mach A B mc)t dien ap xoay
,\\
7r^+(ZL-Zcf
LrC
/
= mm
chieu C O gia t r i hieu d u n g 200 V va tan so 50 H z . K h i d i e u c h i n h d i e n d u n g
"
7(r + R f + ( Z L - Z c y
= 0 va U L r C m i n = U
«ZL-Ze
I
cua t u d i e n den gia t r j C m t h i dien ap hi?u d y n g g i u a hai daV. doan mach
I
M B dat gia trj cue tieu bang 75 V. D i e n t r o thuan ciia cuon day la
A.24Q.
r +R
B. 16 a
:;,'.;fi:;;:;f:,'Vr , ^ h ' = r^;- (
D o t h i p h u thuoc Ui.rc theo ( Z L - Zc) co d a n g n h u h i n h ben.
ZL
- Zc = 0
^
U L r C mill
'
u-r + R
LrCmin
t>>,J
:) • " ,1
V i du 4:
Z L - Zc ==oz:>Ui.rCmax = U
r+R
C.30Q.
Huong
dau
• 75 = 200.r + 40
etc) t u cam L thay d o i va m o t tu dien C. K h i L thay d o i gia trj cue tieu cua
d u o c d o t h i lien he giu-a dien ap hai dau
dien ap hieu d u n g hai dau doan mach g 6 m cuon day n o i tie'p v a i tu dien C
p h a n mach chua cuon day va ty d i ^ n n h u
la
h i n h ve. D i e n t r o thuan cua cuon day la
V.
B. 40 V.
C. 40
Huang
U L r C = I Z .L.r cC ^ = U
V i du
2: Dat
72
V.
n)j
= mm =
^(r + R ) 2 - f ( Z L - Z c f
12072 cos27rft
U
7(r
0^
'•f\
\
37145
87/5
C(xIO^/-)
bao nhieu?
D . 60 V.
dan
r'+(ZL-Zcr
m o t d i e n ap u =
87
mach m o t d i ^ n ap xoay chieu co tan
so 50 H z . C h o C thay d o i n g u o i ta t h u
V2
r - 2 4 ( Q ) - Chon A.
C h o mach d i ? n K L C k h o n g phan
doan mach ncYi tie'p g 6 m dien t r o 20 Q, cuon day co d i e n t r o t h u a n 10 Q, chi
, A . 60
-
dan
nhanh, cuon day co d i e n t r o r. Dat vao hai
V i du 1 : Dat m o t dien ap u = 120 V2 cosl007tt (V), (t d o bSng giay) vao hai dau
D . 40 Q.
'iiJ
fii;'.
-=40(V)
+ R)^+02
(V), (t d o bang giay) vao hai dau
doan mach noi tie'p g o m dien t r o 80 Q, cuc}n day co d i e n t r o t h u a n 16 Q co
A.50Q.
B.
C.90Q.
D.56Q.
^
' ^
180a
Huang dan
C = 0=^Zc = o o = > U j L c = U = 87{V)
U , L C = I . ZrM
LCr = U .
r^+(ZL-Zc)^
!(R + r ) 2 + ( Z L - Z c ) '
,
'1
= min o
Zi
=Zr
=•
- = 100(Ci)
2niC
d o t u cam 0,2/7i H va m o t tu dien co dien d u n g C = 1/K m F . K h i chi thay d o '
196
197
u
r L C mill
= u.R+r
5
R+r
C = o o ^ Z c = 0 = > UrLC = U
> 3VT45 = 8 7
|25r^ +100^
{R +
'Vi
•R + r = 5r
if+Zl
Huang dan
•r = 50(Q) =>ChonA.
Nhu c h i i n g ta da biet, " v a n ba't dac d i " m o i phai d u n g den dao h a m de t i m
cue t r i ! D o i v a i hai bai toan nay chi con each d u y nhat la di^mg dao ham
( k h o n g con each nao khac!).
R'+ZL
*
R' + ( Z L - Z c f
C. 960 V.
D.57V.
,
^ 1 = ^
=
= 3 6 0 ( V ) . C h , „ B. .
^ £ | L =
-^0_+V80^+4.302
-Zc + yZc+4R2
lA.r::,. iii'
V i du 3: M o t mach dien mac noi tiep theo d u n g t h u t u g o m cuon thuan cam c6
do t u cam L = l,5/7i ( H ) , dien t r a thuan R va tu dien c6 dien d u n g C bien
thien. D a t vao hai dau doan mach m o t dien ap xoay chieu c6 bieu thuc u =
U V 2 coslOOTit (V). Thay doi C = Co thay dien ap tren doan mach RC cue dai
va gia t r j cue d a i d o bang 2U. Co bang
Z^+R2
URC-I.ZRC=U.
V
^'^ Z2 - 2 Z L Z C + (R'
+ (ZL - Zc)'
A. 100/71 (HF).
+
2
Z^-2ZLZC+(R2+Z[)"
B.50/7t()iF).
C. 75/71 (^F)
D . 25/7i (^iF). •
Huong dan
Zl)
-2Z,(z^-Z,Zc-R^)
Z , . V i ^ : 4R^
—
^
—
—5- = U => Zc =
—
^
Z^^W4Rl^^200Q^C = - ^
2
(oZc
7t
^ ^
Vi du 4: Dat dien ap u = U ^y2 cosl007rt (V) vao hai dau doan mach mac n o i tiep
theo d i i n g t h u t u g o m cuon cam thuan c6 cam khang 120 Q, d i f n t r a thuan
UR
+
R va t u dien c6 dien d u n g C thay d o i . K h i C = Co t h i di^n ap h i ^ u d u n g tren
4R^
doan mach chua RC dat cue dai va gia trj cue dai d o bang 2 U . D u n g khang
2
CliM y ; Dede nha ta viel chung dot xung L, C nhu sau:
K h i L thay d o i : URLmax =
UR
-Zc + Vz^
-»Z,
+ 4R^
cua tu liic nay la
Zc + ^/zJ~+ 4R^
-
K h i C thay d o i : Upcmax =
UR
- Z L + 7ZL+4R
2
A. 160Q.
=-C:>Zr =
ZL+VZ^+4R2
B. lOOQ.
C. 1 5 0 Q .
D . 20C Q.
Huong dan
URCmax =
2
198
^^^^^ ^ ^^^^ ^_
Huong dan
ZL = -
-Zc+Vz^+4R^
-ZL+
B. 360 V.
U,,„„.
UR
RCmax ~
2
A B no'i tiep g o m cuon cam thuan c6 d o ttf cam L thay d o i , d i e n t r a thuan R
•^Z^-2ZLZC+(R'+Z2)
K h i C thay d o i :
U
"
Y i du 2: Dat dien ap xoay chieu o n d j n h 120 V - 50 H z vao hai d a n doan mach
A. 224 V .
• = U.
-2Zc(z^Z,Zc-R^)
^
—
-— - 0
Z ^ - 2 Z-,L ^ZCr ++{(l R ^ + Z L
u RLmax
= o ^ . ^ o . ^ . . . . .
2
doan mach chua R L dat cue dai. Gia t r i cue dai d o la
URL=I.ZR
, =U.
•RL
Tim.'.,,,..
= - C - y - ^ - -
= 30 Q va t u dien c6 d u n g khang 80 Q. Thay d o i L de d i e n ap hieu d u n g tren
K h i L thay d o i :
'
Z c + 7z^ +4R^ _ 80 + VSO^ + 4.30^
UKL.ax «
b. Tim L/K/.HMA khi L thay doi va tim Unomx khi C thay den
*
1 : D a t dien ap xoay chicii o n d j n h vac iiai dau doon mach A B n o i tiep
g o m cuon cam thuan c6 do tu cam L thay d o i , dien t r a tJiuan R = 30 Q va t u
(Jien CO d u n g k h a n g 80 Q. 1 hay doi L de dien ap hieu d u n g tren doan mach
chua RL dat cue dai. Cam khang ciia cuon cam thuan li'ic nay la
p,,50Q.
B. 180Q.
C. 9 0 Q .
D. 56 Q.
71—T
- Z L + V Z L + 4R^
^
2U =
^^r=T
^ =
-120 + V120^+4R^
T
ZLWz[^^,,0(Q)^ChonA.
r
199
BS
trpkien
thtic
V$t If LTDH
t r e n kenh
VTV2.
t^p 2-Chu
CtyjmtH
Van Bl6n
•:f^iV
M A Y DiEN„.„. ;
,
.... ,
o
,
•
Vl^t
Huang dan
27p
10
Chu d e 2 .
'"^••"-t::
MTV i>VVHKhang
V i p la so n g u y e n nen p = 2 => f = n , p i = 27.2 = 54(Hz) => Chon D.
'^x: ^
Chi'i y : Khi may phat c6 so'cap cue thay dot Ap va so vong quay thay doi An (nen
BAITOAN LIEN QUAN DEN MAY PHAT DifN XOAY CHIEU 1 PHA
dot don vi la vdng/giay)
thi tin/ thuoc triiv'ng hop delira chon dau '+' hay dau '-'
An{vdng/s)
Ne'u may phat c6 p cap cue n a m cham va roto quay v o i toe d o n v6ng/s thi
,,
J,
tan so d o n g d i e n do may phat ra: f = np .
^
trong cdc cong thuc sau :
^ ^
Hi
=•
Pi
f2 = n2P2 - ( n i ± A n ) ( p i ± Ap) =^ Pi = ?
Ne'u may phat c6 p cap cue nam cham va roto quay v o i toe d o n vong/phut
V i d u 3: M o t m a y phat dien xoay chieu m o t pha phat ra d o n g dien c6 tan so'60
t h i tan so d o n g d i e n do may phat ra: f = ^ .
Hz. Ne'u thay roto ciia no bang mot roto khac co nhieu hon m o t cap cue,
Ne'u liie dau p h a p t u y e n eua k h u n g day h h o p v o i cam u n g tir B m o t goc
m u o n tan so v a n la 60 H z t h i so v o n g quay cua roto t r o n g m o t g i o thay doi
a t h i bleu thue tir t h o n g g u i qua mot v o n g day O i = BSeos(cot + a).
7200 v o n g . T i n h so cap cue cua roto c i i .
Ne'u cuon day c6 N v o n g g i o n g nhau, t h i suat dien d o n g xoay chieu trong
A. 10.
cuon day la: e = - N ^ ^
= ojNBSsin(rj)t + a ) .
7200(o6n^)
Ttr t h o n g cue dai g u i qua 1 v o n g day: cI>o = BS.
Bien d o cua sualt dien d o n g la: E(, = coNBS.
Sua't dien d o n g hieu d u n g : E =
EQ
mNBS
^ri =
:: j .,r}
.^>c-,,'.u,
^.j, ^...j-jni, >^. v
=
D . 5.
Huang dan
,
= 2{vongls)
,,
,, .
..
^ . u . . . . , b rfnn . •
ynouv rr5 iv (r> on :
V I:-
lob
^^'vfiT'
f] = n ] p i = 6 0 ( H z ) = > n | = —
Pi
W'^ Mi('h:c':>'£'v
, ^.I/^M
'
Ne'u liic dan n nguvc huvng voi B thi a= K (mat khung vuong goc voi B j .
i i vuong goc voi B thia = ±7r/2 (mat khung song song voi B j .
H
K h i p2 = p i + 1 ma f2 = f i nen toe d p quay phai g i a m tuc la n2 = n i - 2:
h = "2P2 = ("1 ~ 2 ) ( p i +1)
Ne'u luc dau n ciing huvng voi B ih'i a=0 (mat khung vuong goc vai B ) .
Nculucdau
7200(uon^)
C. 15.
Uftn 0£ / ii;GI rs
•'•6 •
Chuy:
B. 4.
> ' "- ^
• • '
,H>,' i.i£K
Thay h = 60 H z va n j = — ta duoc: 60 =
Pi
60
-2
(PJ + 1 )
P ] = 5 => Chon D.
Pi
V i d u 4: M o t k h u n g day det h i n h v u o n g cgnh 20 cm co 200 v o n g day quay deu
V i d u 1 : (CD-2010) M o t may phat dien xoay chieu mot pha c6 p h a n cam la rotd
trong t u t r u o n g k h o n g d o i , co cam u n g 0,05 (T) v o i toe d p 50 vong/s, x u n g
n
quay v o i toe d o 375 vong/phut. Tan so cua sua't dien d o n g cam u n g ma ma\
quanh m o t true nam t r o n g mat phc^ng k h u n g d a y va v u o n g goc v o i t u
tr
phat tao ra la 50 H z . So cap cue ciia roto b3ng
t r u o n g . Tai t h o i d i e m ban dau phap tuyen cua k h u n g day ngug-c h u o n g v o i
A. 12.
>(i ,
B. 4.
,
'
, ,
C. 16.
Hudtig
dan
T u cong thuc f =
=> 50 = ^
=^ p = 8
^
60
60
^
D . 8.
« fiso• :l v* sw
'
' '
t u t r u o n g . T u t h o n g qua k h u n g 6 t h o i d i e m t co bieu thuc
A. (j) = 0,4sinl007tt ( W b ) .
B.^ = 0,4cosl00Ttt (Wb).
C.
D . (j) = 0,04cosl00Tct(Wb).
Huang dan
=>ChonD.
V i d u 2: H a i may phat dien xoay chieu m o t pha phat ra d o n g dien xoay chicni
200
o) = 271.50^1007t(rad/&);
l^f.q ,i^m iMi^in-'^'-yr
C O cung tan so f. M a y t h u nha't c6 p cap cue, roto quay v o i to'c d o 27 vong/^
O = NBScos{1007tt + n) = 200.0,05.0,2^ cos (lOOjtt + 7t)
M a y t h i i hai c6 4 cap cue quay v o i toe do n v6ng/s ( v o i 10 < n < 20). T i n h f.
O = 0,4cos(1007tt + 7t)(Wb)
A . 50 H z .
n^ChonC.
B. 100 H z .
C. 6 0 H z .
> V
D. 54 H z .
'
201
V i du 5: ( D H - 2 0 n ) Mot khung day dan phang quay deu voi toc do
goc
quanh mot true co djnh nam trong mat phang khung day, trong mot t i i
truong deu c6 vecto cam ung tu vuong goc voi true quay cua khung. Sua't
dien dong cam ling trong khung c6 bieu thiic e = Eocos(cot + nil).
Tai thoj
diem t = 0, vecto phap tuyen cua mat ph^ng khung day hop voi vecto cam
. ^Ju 8: Mot khung day dan det hinh tron ban kinh 1 cm gom c6 1000 vong,
uay voi toe do 1500 (vong/phiit) quanh mot true nam trong mat phang cua
khung day, trong mot tCr truong deu eo cam ung tu 0,2 T c6 huang vuong
rrdc voi true quay. Tinh sua't dien dong hieu dung trong khung day.
A.8(V). '
B.5(V).
C.7(V).
D . 6 (V).
Huongdan
ung tir mot goc bang
A. 45".
B. 180".
C. 90".
D. 150".
O = NBScos(Mt + a)
= 25(Hz)
..I^
^60
Huang dan
N.27tf.BS _ N.27rf.B7tr^ _ 1000.271.25.0,2.71.10"^ ~ 7 (v) =i> Chon C
V2 "
sl2
~
^/2
«^ ( ) =^ on .
{V- ' '
e = - O ' = o)NBSsin((ot + a) = EQ COS a)t + a - 7 t / 2
71
•a
2
=> Chen B.
71
= — : • a = 71
Vi dy 9: Phan cam ciia mot may phat dien xoay chieu mot pha c6 hai cap cue.
Cae cuon day cua phan ung mac noi tiep vao eo so vong tong eong la
2
240 vong. Tir thong cue dai qua moi vong day va c6 toe do quay cua roto
V i du 6: Mot khung day det hinh chu nhat c6 200 vong, dien tich moi vong
phai CO gia tri the'nao de sua't dien dong c6 gia trj hieu dung la 220 V va tan
300 cm2, dugc dat trong mot t u truong deu, cam ung tir 0,015 T. Khung day
so la 50 Hz?
CO the quay quanh mot true doi xung ciia no, vuong goc vol t u truong. Khi
A. 5 (mWb); 30 (v6ng/s).
B. 4 (mWb); 30 (v6ng/s).
toe do quay bang M thi suat dien dong cue dai xuat hien trong khung day la
C. 5 (mWb); 80 (v6ng/s).
D . 4 (mWb); 25 (v6ng/s).
7,1 V. Tinh do Ion sua't dien dong trong cuon day 6 thoi diem 0,01 s ke tu
liic no CO vj tri vuong goc voi tu truong.
A.4V.
B. 4,5 V.
C.5V.
Huang dan
f = np => n = — = 25(v6ng/s)
D. 0,1 V.
p
Huong dan
E^^N27^^
Eo = NcoBS =^ 0) = - •«79(rad/s)
NBS
^
• '
nr
Liig dau khung day vuong goe voi tu truong nen a = 0 hoac a = TI.
Ta chon a = 0 thi e = E,, sin at
"'
Vi du 7: (CD-2010) Mot khung day dan ph5ng det hinh chii nhat c6 500 vong
day, dien tich moi vong la 220cm2. Khung quay deu voi toe do 50 vong/giay
quanh mot true doi xung nam trong mat phcing ciia khung day, trong mot
t u truong deu c6 vec to cam ung tu vuong goc voi true quay va c6 do Ion
A.110N/2V.
I
.
B.220V2V.
•
C.llOV.
Huongdan
Mot t u truong deu nen p = 1 va f = np = 50(Hz).
=^ Eo = N.2nf.BS = 500.27t.50.^^^.220.10~^ - 220>/2 (V)
71
Chon B.
202
D.220V.
"
N27rf
rh'V:--r:^5c
240.271.50
^
,
F^S;-.".-:'
hieu dung, cong suat toa nliiet va nhiet luvng toa ra Ian luot la:
=> Chon C.
0,2 V2 /TI (T). Suat dien dong cue dai trong khung day bang
! »
^
220.72 , , , o ^ 3 ( ^ , )
V2
=>Ch0nD.
,;
:„ • -
Chu y: Nen mach dime noi kin va tong dien tro thuan cm niach la R thi cumig do
->e = 7,1.sin 79.0,01 « 5 ( V )
Luu y: NeU may tinh dechedo D thi se triing voi dap sosai la 0,1 V!
^/2
>
,
E .
V2
= i;P
= I 2 R ; Q = Pt = I^Rt
•
R
, j,^^
'> ' ^ 'V: '
'
Vi du 10: Phan ung eiia mot may phat dien xoay chieu mot pha c6 2 0 0 vong
day. T u thong qua moi vong day c6 gia tri cue dai la 2 mWb va bien thien
dieu hoa voi tan so 5 0 Hz. Hai dau khung day noi voi di|n tro R = 1000 Q.
Tinh nhi#t lugng toa ra tren R trong thoi gian 1 phiit.
A . 4 1 7 J.
B.474J.
'
(0 = 27:f = 1007r(rad/s)
O
T^Rt
Ept
2R
, =>ChonB.
C.465J.
Huongdan
^' 'vP-^^-^/^C^^^^^^^^^^^^
(NcoBS)^ t _ (200.10071.0,002)^ .60 ^
2R
D.47CJ.
'
y:
2.1000
.
, •;. . f '
203
Cty
TISHH MTV
D VVH
Khang
Vipt
V i du 1 1 : Mot vong day c6 dien tich S = 0,01m2 va dien tro R = 0,45Q, quay dgq
du 13: Neu toe do quay cua roto tang them 1 v6ng/s thi tan so cua dong
vai toe do goc co = T O O rad/s trong mot tu truong deu c6 cam ling tu B = 0,1^
dien do may phat ra tang tu 60 H z den 70 H z va suat dien dong hieu dung
' xung quanh mot true nam trong mat phang vong day va vuong goc vol ca^
do may phat ra thay doi 40 V so voi ban dau. Hoi neu tiep tuc tang toe do
duong sue tu. Nhiet lugng toa ra trong vong day khi no quay dugc
IOOQ
vong la
bao nhieu?
A. 1,39 J.
'
B. 0,35 J.
'
Huong
C . 2,19 J.
=^Q = m
1
= -I^Rt = -
D . 0,7 J.
A. 320 V.
• - 7 7 "
-'-miii-iLlA
D . 400 V .
Huang dan
1
Jn = 6
. .:-
80
_
tu B = 5.10"2 T. Hai cue eiia may phat dugc no'i voi dien tro thuan R, nhung
vao trong 1 kg nuac. Nhiet dg cua nuoc sau moi phut tang them 1,9". Tong
tro cua phan ung cua may dao di^n dugc bo qua. Nhiet dung rieng cua
nuoc la 4186 J/kg.dg.TinhR.
70-60
40
E2-E1
v^:,
J'
n : ir-i ' i u : , iisH r o M .T,0£',,() Vi
El
E l =240(V)
70
E l + 40
n = 6(v/s)
n
El
6
_240
^
_
_
n +2
E'
6+2
E'
. E ' = 320(V)
each 2:
n
n +1
CM y: To'ng sovdng
day cua phan leng N =
n <~ qn
C . R = 45,3Q.
D. R = 35,0Q.
^' •. Neu phan ung gom k cuon day
(0<t>()
giong nhau mac nCn ticp thi sovdng day trong moi cuon: N i = — .
Hu&itg dan
K
f = np = 25.2 = 5 0 ( H z ) => w = 2n( = 1007:{rad/s)
Eo
V2~
100.100n.5.10"^.6.10~^
V2
72,
Vi du 14: (DH-2011) Mot may phat dien xoay chieu mgt pha c6 phan ung gom
bon cuon day giong nhau mac noi tiep. Suat dien dong xoay chieu do may
*66,64(V)
phat sinh ra eo tan so 50 H z va gia tri hieu dung 100 72
66,64\60
Q/r]a=-;rt = Q i i , u = c m A t " = ^ R = -
R
crnAt"
4186.1.1,9
« 3 3 , 5 ( Q ) =^ChonB.
Chii y: Khi toe d(i quay cm roto thay doi thi tan so':
,
^
En
27tfNO(,
= —-j=—
E21.
E3 =
f3
E2-E1
204
h-h
2.ifiNOo
cua phan ung la
A. 71 vong. •"' " /
,
72
27:f3N
72
B. 200 vong.
C . 100 vong.
Huong dan
.
P = 27tf = l 6 0 K ( r a d / s )
N-
E72
100.7272
D . 400 vong.
h'lB'A .J inn gro/' • •
= 400 : . N i = — = 100
cup g n u b u':iiH oh
I O O K ^ I O " ^
V2
27if2NOo
V . T u thong cue dai
qua moi vong cua phan ung la 5/n mWb. So'vong day trong moi cuon day
= (n + An')p = ?
E,=
...
p =?
f2 = (n + A n ) p
f3
^
=7
I
fi = np
Suat dt^n dong hicu dung tuang leng: E =
',,
,b ;
= ^ £ 3 = 3 2 0 ( V ) =^Ch9nA.
60
la phan ung gom 100 vong day dan dien tich mot vong 6.10-2 j^i^ ^am ung
NwBS
•
f3=(n + 2)p = 80(Hz)
-3
B.R = 33,5a
'' '
f2 = ( n + l ) p = 70(Hz)J ^ | p = 10
f = np:
Cachl:
V i d\ 12: Mot may dao dien eo roto 4 cue quay deu vol toe dg 25 v6ng/s. Stato
A . R = 35,3Q.
C . 280 V.
f i = n p = 60(Hz)
iP.i7.r:.v.
.0,45.2071« 0,7(J) => Chon D.I
{9
B. 240 V.
;,. ; n
dan
t = nT = n — = 1 0 0 0 . — = 207t(s) - .;S.(X!Ot
(0
100
_NcaBS _ 1.100.0,1.0,01 2
.
OK
ciia roto them 1 v6ng/s nOa thi suat dien dong hieu dung do may phat ra la
71
-i: :
ChonC.
-
'
7'"'':
Chu y:
Khi may phat dien xoay chieu 1 pha mac
'"in.
L
R
C
v&i mack RLC thi cudng do hieu dung:
1=
E
„
<(E,fy>
205
B S trp k l ^ n thiic
V^t If LTDii
tr£n k€nh
VTV2.
Cty
t^p 2 - Chu VSn BiSn
f:'r:;'\Ha'V::.r
0
x/2
Khin' = knthi E'= kE;Z'i = kZL;Z'c = —
jj f ^
kE
Huong dan
R2 + kZ,
V i d u 15: Roto cua may phat dien xoay chieu mot pha c6 100 vong day, dien
cam ling t u 0,20 T. Noi hai cue ciia may vao hai dau doan mach gom: dien
tro thuan R = 10 Q, cuon cam thuan c6 he so tu cam L = 0,2/n H va tu dien
CO dien dung C = 0,3/n mF. Khi roto cua may quay deu voi toe do n = 1500
vong/phut thi cuong do hieu dung qua R la
,,„ui:„:«,,r.,: y
B. 0,7997 A.
f = ^ - 25(Hz)
60
C. 0,2316 A.
m = 27rf = 50n =^Z^=aL
D. 1,5994 A.
A
.;,
= 10(Q);ZL = — = — ( Q )
^^NcgSj00.50..0,360.10-^^^3 33^^^
v/2
'+(kZLf
Khi toe do quay tang 2 Ian thi cam khang cung tang 2 Ian: Z ' L = 2 Z L =
•. .
doan mach AB gom dien tro thuan R mac no'i tiep voi tu dien. Bo qua dien
tro cac cuon day cua may phat. Khi roto ciia may quay deu »'6i toe do n
vong/phiit thi cuong do dong dien hieu dung trong doan mach la 1 A. Khi
roto ciia may quay deu voi toe do 3n vong/phiit thi cuong do dong dien
A. 2 R V 3 .
C.RVS.
B. 3R.
D . 1,5RV7.
Huong dan
doan mach mac noi tiep AB gom dien tro thuan R, cuon cam thuan L va tu
Ap dung:
7S
I
deu voi toe do n vong/phut thi dung khang cua C bang R va bang bon ian
cam khang cua L. Neu roto cua may quay deu voi toe do 2n vong/phiit tlVi
B. giam 2 Ian.
C. tang 2,5 Ian.
D. giam 2,5 Ian.
Huang dan
372 = 3.
VR^+Z
I
Zr =
3R
77
Khi toe do quay tang 2 Ian thi dung khang giam 2 Ian: ,
Z'c=-
cuong do hieu dung qua mach AB se
2
R2 +
dien C. Bo qua dien tro cac cuon day cua may phat. Khi roto cua may quay
= R, Z L =
V3
do 2n vong/phiit thi dung khang cua doan mach AB la
V i d u 16: N o i hai cue cua mot may phat dien xoay chieu mot pha vao hai dau
Luc dau:
2R
=> Chon B.
> 2 ^ ( Z L - Z C )
A. tang 2 Ian.
,J (
hieu dung trong doan mach la 3\/2 (A). Neu roto ciia may quay deu voi toe
V2
= s:0,2316(A) =>ChonC,
"^^^
JR_
= 3.-
Vi du 18: Noi hai cue cua mot may phat dien xoay chieu mot pha vao hai dau
Huong dan
.iimi^^u
.(•.. ,
V 3 _
A p d u n g : 7 = 1<
tro khong dang ke, dien tich moi vong 60 c m l Stato tao ra t u tr'jong deu co
A. 0,3276 A.
Vifl
yji du 17: (DH-2010) Noi hai cue ciia mot may phat dien xoay chieu mot pha
vao hai dau doan mach AB gom dien tro thuan R mac noi tiep voi cuon cam
thuan. Bo qua dien tro cac cuon day cua may phat. Khi roto cua may quay
deu voi toe do n vong/phut thi cuong do dong dien hieu dung trong doan
mach la 1 A. Khi roto cua may quay deu voi toe do 3n vong/phut thi cuong
do dong dien hieu dung trong doan mach la >/3 (A). Neu roto cua may
quay deu voi toe do 2n vong/phut thi cam khang cua doan mach AB la
A.2RV3.
B.2R/V3.
C.RVS.
D.R/-/3.
f = np => CO = 27tf => Z L = coL;Z(;; =
E=
TNHH nrv O VVn Khang
1,5R
2
77
I
Chon D.
Vi du 19: Mot may phat dien xoay chieu mot pha c6 dien tro trong khong dang
ke. Noi hai cue may phat voi cuon day c6 dien tro thuan R, he so tu cam L.
R
Khi roto quay voi toe do n v6ng/s thi dong dien hieu dung qu?. cuon day la
-J
1 A . Khi roto quay voi toe do 2n v6ng/s thi cuong do hieu duag qua cuon
day la 2 7 M (A). Neu roto quay voi toe do 3n v6ng/s thi cuong do hieu
I
'
R2 + k Z L -
V
= 2,5=>ChonC.
dung qua cuon day la
A. 0,6 7 2 (A).
B. 0,6 7 5 (A).
.-: - .
C. 0,6 7 3 (A).
D. 0,4 7 3 (A).
B o t r g hien
thiic
V^t liLTDtl
t r c n kdnh
VTV2,
t a p 2j-Chu
V^n
Cty
BiSn
2E,
• = l;l2 =
+4Z^i
Ll
l3 =
3E,
3RN/2
VR^ +9Z^i
V R ^ - 9R^
dung khi do la
A.2V2 (A).
ZLI=R
• = 0,4V2 :
El =RN/2
= 3 7 0 2 (A) => Chon B. . , ; v .
/
V i du 20: Mach RLC mac vao may phat dien xoay chieu. Khi toe do quay cua
roto la n (vong/phut) thi cong suat laP, he so cong suat 0,5 N/3 . Khi toe dp
quay cua roto la 2n (vong/phut) thi cong suat la 4P. Khi toe do quay cua
roto la n ^/2 (vong/phut) thi cong suat bang bao nhieu?
B. P>/3.
C. 9P.
D.24P/13.
Htfoiig dan
vera
-!)
t6\
coscp ==
^
. ( Z L - z c r = — (1)
JR^ + ( Z L - Z c r
F
/ji\
=k
p
2
T.->2
R2+(ZL-Zcr
R2 +
R
^
kZL -
4 = 4.R2 +
R
^
k'Z,
-
k'
R2 +
V2
R2 +
• = 2-
kZ,-^
Vift
R-^
R
R
V3
V2V3
:
R2 + (RS/3)'
2Z,
= 8 = > I ' = 8(A)
Zc
2
- »
Chon B.
Chu y: Khi dieu chinh toe do quay cua wto deniqch cong huv'ng thi rwinig do hieu
dung chwa chac cue dai va khi cuvng do hieu dung cue dai thi mach chua elide eong
huong.'
• • '^^ ^"1! •
•• ' ' '
« ^ T'' •
Vi du 22: Doan mach noi tiep AB gom dien tro R = 100 Q, cuon day thuan cam
CO L = 2/71 H noi tiep va tu dien eo dien dung C = 0,1/7T mF. Noi AB voi may
phat dien xoay chieu mot pha gom 10 cap cue (dien tro trong khong dang
ke). Khi roto cua may phat dien quay voi toe do 2,5 v6ng/s thi cuong do
dong di^n hieu dung trong mach la %/2 A. Thay doi toe do quay cua roto
cho den khi trong mach c6 eong huong. Toe do quay cua roto va cuang do
dong dien hieu dung khi do la
»a
< hf tn
hi i^ll^j
'; B. 25 >/2 v6ng/s va 2 A.
D. 2,5 72 v6ng/s va 2V2 A.
16
7
'ixw
OP ..f
St' .8
*d£
Hudnvddn
4'\
16.
=^P" = —P =>Chon A.
Ir,
7
V i du 21: Noi hai cue cua may phat dien xoay chieu mot pha vao hai dau doan
mach AB gom dien tro thuan R, cuon cam thuan va tu dien mac noi tiep. Bo
qua dien tro cae cuon day cua may phat. Khi roto cua may quay deu voi toe
do n vong/phut thi cuong do hieu dung trong mach la 1 A va dong dien tiic
thai trong mach cham pha 7i/3 so voi ctien ap tuc thai giua hai dau doan
mach. Khi roto cua may quay deu voi toe do 2n vong/phut thi dong dien
208
^R2+(ZL-ZC)'
2R
^
P"
R2 +
Khang
D. 2(A).
• tan —: Zi - Z c =RN/3
3
C. 25 V2 v6ng/s va 72 A.
R^
I
r =k
R
C.4(A).
Huxmg dan
A. 2,5 V2 v6ng/s va 2 A.
2Z,
(2).Tu(l),(2)suyra: Z L =
B. 8(A).
ZL-ZC
tan(p = '
C/i« y: Ncu bai toan lien qiian den do lech pha hone he so cong sud't thi ta scrut ra
Z, - Z c
tan (p =
R
dime he thirc ci'ia Zi, Zc theo R:
R
cos(p =
/R-+(Z,,-Zcf
A. 16P/7.
MTVDVVtl
trong mach ciang pha vol dien ap tuc thai giCta hai dau AB. Cuong do hieu
Huang dan
I , =•
TIMIII
,rxV:f
•• '
f = np = 25(Hz) => CO = 2ni = 507t(rad/s); Z L = loL = lOO(Q); Zc = — - 200(Q)
coC
=>E = I 7 R ^ + ( Z , . - Z C ) ' =200(V)
, •
Khi eong huang: 27if'L = - ^ -=>•f' = 2572(II/) = f72
27if'C
=>n' = n72 =2,572(i;6n^/s)
^^^^
qn.^
^:
E' = E72 = 20072 (V) =^ I ' = 1^ = 272(A) => Chon D.
'«u 23: Doan mach noi tiep AB gom dien tro R = 100 Q, cuon day thuan
Ccim
'^o L = 2/71 H noi tiep va tu dien c6 di^n dung C = 0,l/7t mF. No'i AB voi may
?hat dien xoay chieu mot pha gom 10 cap cue (dien tra trong khong dang
P). Khi roto ciia may phat dien quay voi toe dp 2,5 v6ng/s thi euang do
long dien hieu dung trong mach la 72 A. Thay doi toe do quay cua roto
.
m..
B S trgklin
thitc
V^t li L T D H tren
V T V 2 . t^p 2-Chu
kenh
V^n Bien
CtyTimnnrvown
cho den k h i c u o n g do d o n g d i e n hieu d u n g t r o n g m a c h dat cue dai. To'c (j.
v i dv 25: M p t m a y phat d i e n xoay chieu m o t pha c6 d i e n t r o t r o n g k h o n g dang
quay cua roto va c u o n g dp d o n g dien hieu d u n g k h i do la
ke, mac vao d o a n m a c h no'i tiep RLC. K h i to'c d p quay ciia roto b a n g n i hoac
A . 2,5 N/2 v6ng/s va 2 A .
B. 10/^/6 v6ng/s va 8/V7 A .
r\2 t h i c u c n g d p hieu d u n g t r o n g mach c6 c i i n g gia t r i . K h i to'c d p quay ciia
D . 2,5 V 2 v6ng/s va 2 V 2 A .
roto la no t h i c u o n g dp hieu d u n g t r o n g mach cue d a i . C h p n he t h i i c d i i n g .
:
C. 25 N/2 v6ng/s va V 2 A .
Huang
dan
f = n p = 25Hz=>co = 27if = 5071
^
Z L = coL = 1 0 0 ( Q ) ; Z c = ^
coC = 200(Q) ^
i:>Ei=200(V)
R2 + x Z i -
V
X /
8V7
3
7
0
'
B. no^ = 0,5(ni2 + n22).
C. no-2 = 0,5(nr2 + nr^).
D . no = 0,5(ni + n2).
Huang
^R^+{z[-Zcf
E=
/ 2^^
1 + X —
V
A . no = (nm2)0'S.
Xy
A ; n = xni =
•3-^ + 1
x
V
5^6,
.(v/s)
3
dan
Htiti
f = n p => CO = 2ni = 2npn
2x
2V6
= - = > X = •
X
=
xE
D a t n = xtt] => I = -
Vi
Khang V/pt
1 =
EQ _ N O Q
72
7 2
-co
72
1
1
Vc 2
24: N o i hai cue cua may phat dien xoay chieu m o t pha v o i m p t doan
R2 +
1
NcDn
•Chon B .
(0
72
-2
,
1
c o L - coCJ
D a y la h a m kieu tarn i h i i c do'i v o i
L_R^
C
+1
2
CO
1
bien so'l/co^ =>
CO?
m a c h A B g o m R, cuon cam thuan L va C mac no'i tiep. K h i l o t o ciia may
'
1
4 J
CO2
• C h o n C.
quay deu v o i to'c d o Ian l u g t ni vong/phut va m vong/phiit t h i c u o n g do
Hi t,f" 1
d o n g dien hieu d u n g va tong t r d ciia mach t r o n g doan m a c h A B Ian lupt la
I i , Z i va h , Zi. Bie't I2 = 4Ii va Z2 = Z i . De tong t r o ciia doan mach A B c6 gia trj
n h o nha't t h i roto cua may phai quay deu v o i to'c d p bang 480 vong/phut,
Gia t r i ciia ni va 1x2 Ian l u a t la
BAI
'.
. ^
., jD. 240 vong/phiit va 960 vong/phiit.
• ry
dan
*
Nguon mac sao - T a i mac sao
T
U
U
P = Pl+P2+P3=I?Ri+liR2+l3R3
V2
A = Pt
(02 = 4cO] => n2 = 4 n i
1
(B2C
cojC
-(OiL=>cof = 0 , 2 5
LC
=> n^ = 0,5no = 240 ( v o n g / p h i i t ) ;
=> C h o n D .
U ,
(If.
N27ifOo
1
CHIEU
3
PHA
ngoai.
D i e n ap d j n h m i i c tren m o i tai U .
•U = U p
60
C02L-
D i f N XOAY
D i e n ap day Ud la d i e n ap g i i i a hai dau day n o n g ciia m a y phat d u a ra
v.
C. 360 v o n g / p h i i t va 640 vong/phiit.
l2=4Ii
PHAT
D i e n ap pha U P la dien ap g i i i a hai d a u m p t cuon ciia may phat.
B. 120 vong/phut va 1920 vong/phiit.
E=
LIEN QUAN D E N MAY
Phuang phdp gidi
A .,300 vong/phut va 768 vong/phiit.
Huang
TOAN
Nguon mac sao - T a i mic tam giac
LC
:> COj = 0,5(0o
n 2 = 4 n i = 960 (vong/phiit)
U = Ud =Up73
I1
u
Zj
Z2
^3
P = Pl+P2+P3=I?Ri+l2R2+l3R3
A = Pt
'
> i'
•
B6 trjf Men
thiic
V^t li LTBII
t h u a n lOO Q mac noi tiep v o l t u dien c6 di#n d u n g 0,l/7i (mF). T i n h c u a n g
VTV2. t^p 2 - Chu Vin Bl£n
tren henli
Nguon mac tarn giac - T a i mac tarn giac
do d o n g dien d i qua m o i tai.
U = Ud=Ui.
I
- ^
I
-
A. 4,4 A .
^
I
-
U
S3
\\:*ifKVi
o:»
B. 3 V2 A .
%
C. 2 >/3 A .
Huang dan
Z C = ~
P = Pi + P2 + P3 = i f R i + I^R2 + I3R3
^
Nguon mac tam giac - T a i mac sao
'f^^* Vfeo^
_ U _ UI,N/3 ^ 200^y2^/3 _ 2j3(A)
Z
Z
100vy2
^ ^
^
D . 1,8 A .
• ••„ gti<:ff'': s' j ' • ' V , * , '
= 100(Q);Z = 7R^+ZC =100V2(Q)
A = Pt
,
rr;.if> V ,
^^i'bm'j^m''
r^ChonC.
U =
Ii =
V i d u 4: M o t may phat dien xoay chieu 3 pha mac h i n h sao c6 d i e n ap pha la
V3
V3
u
I
_
u
220 V, tan so 60 H z . M o t co so san xuat d u n g n g u o n dien nay m o i ngay 8
u
gio cho 3 tai tieu thu g i o n g nhau m3c h i n h tam giac, m o i tai la cupn day R =
300 Q, L = 0,6187 H . Gia dien cua nha nuoc d o i v o i k h u v u c san xuat la 850
P = Pi + P2 + P3 = I i R i + I 2 R 2 + I3R3
d o n g cho m o i K W h tieu t h u . C h i p h i dien nang ma co so nay phai thanh
A = Pt
V i d u 1 : M o t may phat dien ba pha mac h i n h sao c6 d i e n ap pha 127 V . Tai mac
h i n h sao m o i tai la m o t bong den c6 dien t r o 44 Q. D o n g dien hieu d u n g
t r o n g m o i day pha va d o n g dien t r o n g day t r u n g hoa n h a n gia t r j d i i n g nao
t r o n g cac gia t r j sau day?
A. Iph= 1,5 A ; I.h = 0,2 A .
'
B. Iph = 2,9 A ; I.h = 0 A .
C. Iph = 5,5 A ; I.h = 0 A .
Huang
=>ChonB.
'4
A. 183.600 d o n g . B. 61.200 d o n g .
C. 20.400 d o n g .
D . 22.)50 d o n g .
>1
Z L =coL~233,24(Q);Z = J R 2 + Z ^ «380(Q)
= I2 = I3 = - =
^ 1(A)
P = 3I?R = 9 0 0 ( W ) = 0 , 9 ( k W )
.f:
A = Pt = 0,9.8.30 = 2 1 6 ( k W h )
dan
V i tai d o i x u n g nen d o n g d i e n qua day t r u n g hoa bang 0. i , j
R
"^
D. Iph= 2,9 A ; I.i, =0,25 A
toan hang thang (30 ngay) la
ii/sq ^f,
jj^w
= > T i e n d i e n = 2 1 6 ( k W h ) x 8 5 0 = 183600(VND) '
'
T'
=> Chon A.
^•'=2,9(A)
R
V i du 5: M o t may phat dien xoay chieu 3 pha k h i boat d o n g , n g u o i ta d i i n g
M'l..'v- '''V
^
,
,
von ke nhiet de do dien ap hai dau m o t cupn day t h i so chi ciia no la 127 V.
V i d u 2: M o t may phat d i e n ba pha mac h i n h sao c6 d i e n ap hieu d u n g pha
N g u o i ta d u a d o n g 3 pha do may phat ra vao 3 b o n g den g i o n g het nhau
127(V) va tan so 50 ( H z ) . N g u o i ta dua d o n g d i e n xoay chieu ba pha vao ba
boat d o n g v o i d i e n ap hieu d u n g 220 V t h i cac den deu sang K m h t h u d n g .
tai n h u nhau mac h i n h tam giac, m o i tai c6 dien t r a t h u a n 12Q va d o t u cam
Chon p h u o n g an d u n g .
51 ( m H ) . Xac d j n h tong cong suat ca ba tai tieu t h u .
A. M a y mac h i n h sao, tai mac h i n h sao.
• A . 991 W .
B. 3233 W .
t
Z L - ( 0 L = 16(fi):
^
^
=>ChonC.
Z
C. 4356 W .
Huang dan
'
Z - 7 R 2 + Z [ =20(Q)
Z
D.1452W.
'
P = 3I?R = 4356(W)
•
V i d u 3: M p t m a y phat dien ba pha mac h i n h sao phat d o n g xoay chieu c6 tan
,
•/
•
/v„-,,fi')
-
^
B. M a y mac h i n h sao, tai mac h i n h tam giac.
C. M a v mac h i n h tam eiac, tai mac h i n h sao.
•'
,
,
.,
D. M a y mac h i n h tam giac, tai mac h i n h tam giac.
Huong dan
nil
_
i-.hi
,
N e u U = U P t h i de tai boat d o n g b i n h t h u o n g nguon mac sao - tai mac sao
hoac n g u o n tam giac - tai mac tam giac.
N e u U = V3 U P t h i de tai boat d o n g b i n h t h u o n g nguon mac sao - tai mac
, so 50 H z , suat dien d g n g hieu d u n g m o i pha la 200N/2 V . Tai tieu t h u g o m
ba doan mach g i o n g n h a u mac tam giac, m o i doan m a c h g o m d i ^ n tra
213
Neu U = U P /
Huang dan
t h i de tai hoat d p n g b i n h t h u o n g n g u o n mac tarn giac - ta
22072Z^
mac sao.
=i. Chon B.
Ith
V i du 6: (CD-2011) T r o n g m a y phat d i ^ n xoay chieu ba pha d a n g hoat dong
suat d i e n d o n g tiic t h o i t r o n g m o i cuon day con lai c6 do Ion bang nhau va
bang
;>,t
A . 0,5Eo V3 .
B. 2Eo/3.
liiln niri^iiift'MiCtfixt lif-irl -jtfi.:
ej =
62
EQ
= EQ
6)
1-2=0
cos cot
^
= E g COS
^
63
cot +
= E() COS
'
2n
n
U
' 3 ,
2n
K
22072
2
R
1-
2
•^1
U T , .
^ +^
(cong3
V i du 7: M a y phat dien xoay chieu ba pha mac h i n h sao d u a van ba tai cung
R'
38
h = 2cos(1007rt - 27i/3) ( A ) , b = 2.cos(1007tt + 27i/3) ( A ) . D o n g dien chay qua
, ;,
,
/
, |
D.ith = 2 c o s l 0 0 t ( A ) .
Huang dan
i,l^=ii
'3 , ' 7 1
38
+ i 2 + i 3 = 3 + 2 Z - | ^+ 2 Z ^ = l
iti, - c o s l 0 0 7 i t ( A )
V i du 8: M a y phat d i e n xoay chieu ba pha mac h i n h sao d u a vao ba tai cQng
mac h i n h sao. Bie't suat dien d o n g trong cuon 1, cuon 2 va cuon 3 ciia may
phat Ian l u g t la: e i = 220>/2 coslOOTtt ( A ) , e2 = 220 V2 cos(1007t: + 2K/3) (A),
63 = 220 V2 cos(1007tt - 2K/3) (A) va d u a vao ba tai theo d i i n g t i i u t u tren la
, d i f n t r o thuan R = 10/ N/3 Q , cuon cam thuan c6 cam khang Z L = 20 Q va tu
Cong suat tieu t h u dien: P =
P.
:iu'h
HUV*I « K 1 ' I \.
ciia day n o i va ciia day t r u n g hoa. D o n g dien chay qua day t r u i . g hoa c6 gia
214
A . 77 ( A ) .
?
B. 33 76 ( A ) .
,^
QU<'/l\viil\' isk''
= UIcoscp
,(11'
Sau t h o i gian t, dien nang tieu thu va nang l u g n g co c6 ich: ,
p.
A = Pt = - i - t = tUIcos(p
H
Ai =Pit
•
Doi d o n v j : l ( k W h ) = 10^ W.3600s = 36.10''' (J);1(J) =
C. 33 73 ( A ) .
D . 99 ( A ) .
. 'H
,
^ ,
l(kWh)
36.10-"^
du 1 : Mo*- d o n g co dien xoay chieu san ra m o t cong suat co hoc 8,5 k W va co
hieu suat 85%. D i e n nang tieu thu va cong co hoc cua dcing co t r o n g 1 gio
hoat d o n g Ian l u g t la
' A. 2,61.107 (J) va 3,06.10^ (J).
" C . 3,06.10^ (J) va 2,61.10^ (J).
B. 3,06.10^ (J) va 3,6.10^ (J).
D . 3,6.10^ (J) va 3,06.10^ (J).
Huattgdan
d i e n CO d u n g k h a n g Zc = 20. Bo qua dien t r o cac cuon day ciia may phat,
trj hieu d u n g la
2n
2,757Z-
J
=> Chon A.
•
3• =
24
V,,
Hieu suat ciia d o n g co: ^ = ^
day t r u n g hoa c6 bieu thuc
,
22072^_2Tt
H
B. i.h = 2cos(100t + 7c) ( A ) .
\ii vi.
R
mac h i n h sao t h i d o n g dien chay trong ba tai Ian l u g t la: i i = 3cosl007it (A),
C ith = cos(100t + 7:) ( A ) .
22072^271
Phuangphdpgidi
^2
^ A . ith = coslOOTct(A).
'^.-f
D . 2,76 A . .;
BAITOAN LIEN QUAN DEN DQNG CGf Dif N
\- ..,il>i ^
sophuc)
''v-
4 . . . ; i „
9 7S7
I,h = ^ 72
^ = - « 1/95(A) => Chon B . '
3
Chu y: Neu nguon va tai deu mac hinh sao thi dong dien ti'tc thai qua day trung
Uj
ith = i i + i 2 + i 3 = - = ^ + -
R
u-'-^'",
C. 3,38 A .
, . 1 ^ I " 3 _ ""73'" , " 7 3 '
.
E0V3
^{"'••{••^
Huang dan
E(,73
"
> Chon A.
hoa:
•••vn.fi'i. ' K - ^
B. 1,95 A . i . ,,,
A. 0 A .
•;<'•, I V T ' S O ' V I :
.,1
9=
"^^y P^^*
^
^'"'^ '^^ '^^^^
^^^^ '^^^Z day
220V, cac tai mac theo h i n h sao, 6 pha 1 va 2 c i m g mac m o t b o n g d e n c6
dien t r a 38Q, pha t h u 3 mac den 24Q, d o n g dien hieu d y n g t r o n g day t r u n g
hoa nhan gia t r j :
D . a S E o V2 .
•'"'^•^'b
'
.
cos cot
= EO COS
63
C. 0,5Eo.
Huang dan
3 _33g
-20i r^f^'^
^ i(h = 3376 cosl007rt(A) => Chon C.
suat dien d o n g xoay chieu xuat hien t r o n g m o i cuon day ciia stato c6 gia tri
cue dai la Eo. K h i suat di?n d o n g tuc t h o i t r o n g m p t cuon day bang 0 thi
22072Z--2;?
. • • 22072 — — 3
='i"'^"'^=W7^"
20i '
A = Pt = . ^ t = ^ ^ ^ ^ . 3 6 0 0 = 3,6.10^(J) •
=> Chon D.
215
v i d u 2: M o t d o n g ca dien xoay cliieii san ra mot cong stui't co hoc 10 k W va
hicLi
theo h i n h sao.
sua't 80% d i i o c mac vao mach xoay chieu. Xac d i n h dien ap hieu dui-,^
6 hai dau d o n g co bie'l d o n g dien co gia t r i hieu d u n g 100 ( A ) va tre pha
voi dien ap hai dau d o n g co la 7i/3.
A. 3 3 1 V .
B. 250 V.
D. 3 cuon day ciia m a y phat mac theo h i n h sao, 3 cuon day ciia d o n g co mac
theo h i n h t a m giac.
''
t v:
dan
'/fx/'f:; ' 'i:: '/f.b n\
..rt u . u •
y'^'^'-' D . 5 6 5 V .
C. 500 V .
Huong
./ Huong dan
^A
,;, ^•
Theo so lieu U = 220 V, U P = 127 V tuc la U = Ui>
. M u o n d o n g co hoat
d o n g b i n h t h i r o n g t h i n g u o n mac sao - tai mac tam giac => C h o n D .
p = ^ = U I c o s ( p ^ U = — ^ • = 2 5 0 ( V ) ==>ChonB. ,
H
H I cos (p
V i du 5:
V i d u 3: M o t d o n g co dien xoay chieu san ra mot cong sua't co hoc 8,5 k W va c6
(CD-2010) M o t d o n g co k h o n g d o n g bo ba pha mac theo kieu h i n h
sao d u g c noi vao mach dien ba pha co dien ap pha Ui'i^ = 220 '^L Cong sua't
hieu sua't 88%. Xac d j n h dien ap hieu d u n g 6 hai dau d o n g co bie't dong
dien ciia d o n g co la 6,6N/3
dien CO gia t r i hieu d u n g 50 (A) va tre pha so v o i dien ap hai dau d o n g co
C u o n g d o d o n g d i e n hieu d u n g qua m o i cuon day ciia d o n g co bang
7r/12.
A. 20 A .
HtiOfig
p = I i = Ulcos(p:
H
=:>ChonB.
•
dan
= 200(V)
'
•
•
Chu y: Khi miic dong ca 3 pha co dien ap dinh mux trcn moi tdi la U oao may pUdl
dien xoay chieu 3 pha c6 dien dp pha Id UP tin Hiy vao do Ian cua U jd Ui' md yen
can miic lunh sao liny mac hinli tarn gidc.
Neil U = Ih' vd dong ca hoat dg)ig hinh thwang th'i nguon mac sao - tdi mac sao
,
hoiic }iguon mac tam gidc - tdi miic tarn gidc.
*
Neil LI = Ui'yfs
,
tarn
P
3 U cos (p
dan
6,6^3.10^
3.220.
I = 2 0 ( A ) z:>ClionA. ,|,
V3
V i du 6: M o t d o n g co k h o n g d o n g bo ba pha mac h i n h sao vao m a n g dien xoay
chieu ba pha mac h i n h sao, co dien ap day 380 V. D o n g co co cong sua't 10
KW.
H e so cong sua't 0,8. C u o n g do d o n g dien hieu d u n g d i qua m o i cuon
thirang tin nguon mac sao - tdi nm
, , ,
»Jj
. •••
•: .
A. 57,0 A .
B. 18,99 A .
i:\:0'.'-:'.>- ^
c
mac sao.
Cong sua't tieu tliu ciia doug ca 3 pha: P = 3UIcos(p (I la ctrang do Ideu dung (/'"'
=^ChonB.
vd dong ca hoat doug hinh thwang th) nguon mac tarn gidc - tin
C. 45,36 A .
Huongdan
^''^
D. 10,96 A .
N g u o n mac sao - tai mac sao nen U = U P = U^l/^/3 :
P = 3UIcos(p=^I =
'
3Ucosq,
V''
Neil U = Ui'/yf}
D . 35 A.
v,
day CO gia trj bao nhieu?
*
vd dgiig ca hogt dong Imh
Huong
P = 3UIcos(p=>I-
0,88.50 cos
' ^
C. 105 A .
N g u o n mac sao - tai mac sao nen U = UP:
8,5.i0'^
H I COS (p
k W ; he so cong sua't cua d o n g co la 0,5^3 .
B. 6 0 A .
D.565 V.
C.231 V.
B. 200 V.
A . 3 3 1 V.
*
C. 3 c u o r day m a y phat mac theo h i n h sao, 3 cuon day cua d o n g co mac
lO.lO,3
3 380
—
V3
0,8
a 8,99
(A)
V i du 7: M o t d o n g co k h o n g d o n g bo ba pha dau theo h i n h tam giac vao mang
moi tdi vd cos
d i e n ba pha mac h i n h sao c6 dien ap hieu d u n g pha 220 V. D o n g co c6 he so
d i e n the hieu d u n g giira 2 dau m o i cuon day la 220 V. T r o n g k h i do chi co '
cong sua't 0,85 va tieu t h u cong sua't 5 k W . C u o n g d o d o n g d i e n qua m o i
m a n g dien xoay chieu 3 pha do 1 may phat dien tao ra, sua't d i e n d o n g hieL'
cuon day cua d o n g co la:
d u n g 6 m o i pha la 127 V. De d o n g co m^c b i n h t h i r a n g t h i ta phai mac thei'
A.15,4A
B.27A.
A. 3 cuon day mac theo h i n h tarn giac, 3 cuon day cua d o n g co mac the"
h i n h sao.
B. 3 cuon day ciia may phat mac theo h i n h tam giac, 3 cuon day cua dgnj?
216
C. 5,15
Huong
each nao sau day:
CO mac theo h i n h tam giac.
, (i
•
A . ( ^ f K !•
dan
N g u o n mac sao - tai mac tam giac nen U = Ui' V 3 :
P = 3Ulcos(pz^I =
D. 9 A.
P
5.10-'
3Ucos(p
3.220/3.0,85
•
•''''''
: 5 , 2 ( A ) =>ChonC.
'
217
?o' trf> kien thitc V^t If LTPH tren Ttenh^PTV2. t^p 2 - Chu van
BieiT
/ i d u 8: M o t d o n g ca k h o n g d o n g bo ba pha co dien ap d i n h m i i c m o i pha la
Vao t h o i d i e m u = 3^2 A va dang tang nen co the chon cot = - - ( n a m 6 nua
4
380 V va he so cong suat bang 0,85. D i e n nang tieu thu ciia d o n g co t r o n g
mot
ducji V T L G ) . Thay gia trj nay vao bieu thcic 12 va is:
ngay hoat d o n g la 232,56 k W h . C u o n g d o d o n g d i e n h i e u d u n g qua
moi cuon day ciia d o n g
A . 30 A .
la
CO
^:
B. 5 0 A .
, •:m^_i^<•r^ {ki^KtS
C. I O A .
,--it
= 6 cos
D. 6 A.
13
„
A
232,56.10^Wh
= 9690(W).
Co ng suat tieu t h u cua d o n g co: P = — =
P
9690
271
__ + _
K
27C^
"4
. ,
a , 55 ( A )
• Chon C.
-5,80 ( A )
Chii y: Cong suat tieu thu cua dong ca goni hai phan: cong sua't ca hoc va cong suat
haophi do toa nhiet.
^
*
Dong ca 1 pha: UI cos (p=-
+ I'r
*
Dong ca 3 pha: 3UI cos (p~P
Theo bai ra U = 380 V nen P = 3UI coscp
=>! = 3Ucos(p
= 6cos
7t
.=10(A)
Vi
fi,'••'••;•-'/(•:•
\
it (
3.380.0,85
=>ChonC.
+ 3rr
Vi du 11: M o t d o n g co dien xoay chieu co dien t r a day cuo'n la 32 .Q, mach dien
Vi du 9: M o t d o n g co k h o n g d o n g bo ba pha mac theo kieu h i n h sao vao mach
CO d i e n ap hieu d u n g 200 V t h i san ra cong sua't co hoc 43 W. Biet he so'cong
dien ba pha mac h i n h sao co dien ap pha la 220 V. D o n g co co cong suat co
sua't cua d g n g co la 0,9 va cong sua't hao p h i nho h o n cong sua't co hoc.
hoc la 4 k W , hieu suat 80% va he so cong suat ciia d o n g co la 0,85. T i n h
c u o n g do d o n g d i e n chay qua m o i cuon day cua d o n g CO.
A. 21,4 A .
Huong
P
Pj _ 4.10'
H
•
C. 0,225 A .
Huang
D . 17,3 A .
dan
UIcoscp = Pi-fI^R=> 200.1.0,9 = 4 3 + 1^32. P h u o n g t r i n h nay co 2 nghiem:
Ii = 5,375 A va I2 = 0,25 A , ta chgn n g h i e m I2 = 0,25 A v i v o i n g h i e m t h u nha't
= 5000(W)
cong sua't hao p h i Ion h o n cong sua't co ich!
5000
P = 3UIcos(p
3.220.0,85
I = 5,375(A)=^P,,p = I 2 R = 5 , 3 7 5 ^ 3 2 - 9 2 4 , 5 W > 4 3 ( W ) => Chon A.
'
Vi du 12: (DH-2010) M o t d g n g co dien xoay chieu k h i hoat d g n g b i n h t h u o n g
=>ChopD.''
'
Chu
i^id tri tire thai ii, i tron;^ moi pha tn viet hieu thi'tc u, i roi can cu
'
vao quanhe. de tinh.
•
M
.
Vi du 10: D o n g ca k h o n g d o n g bo 3 pha mac h i n h sao, k h i d o n g co hoat d o n g
b i n h t h u o n g a d i e n ap 200 V t h i cong sua't tieu t h u ciia d o n g co bang
1620 V2W
B. 5,375 A .
*
dan
0,8
y: Detinh
C u o n g d o d o n g hieu d u n g chay qua d g n g co la
A . 0,25 A .
D . 8,9 A .
C. 26,7 A .
B. 7,1 A .
'
voi d i ^ n ap hieu d u n g 220 V t h i sinh ra cong sua't co hgc la 170 W . Biet d g n g
CO CO he so'cong sua't 0,85 va cong sua't toa nhiet tren day qua'n d g n g co la 17
W. Bo qua cac hao p h i khac, c u o n g do d o n g d i e n cue dai qua d g n g co la
A.
72 A .
C.2A.
Huang
va he so cong sua't la 0,9 cho m o i pha. Pha ban dau ciia d o n g
dien (dang h a m cos) 6 cac cuon day 1, 2 va 3 Ian l u g t la 0, 27t/3 va -27r/3. Vao
B. l A .
Ulcos(p = Pi
+%
D.
73 A .
dan
=> 220.1.0,85 = 170 +17 =i> I = l A = > I o
t h o i d i e m d o n g d i e n a 1 cuon co gia trj bang i i = 3V2 A va d a n g tang t h i
=>Chon A.
d o n g dien o cuon 2 va 3 t u o n g l i n g bSng
du 13: M o t d g n g co dien xoay chieu k h i hoat d g n g b i n h t h u o n g c u o n g do
A . 1,55 A va 3 A .
;v
C. 1,55 A va -5,80 A .
.
A,
%: ufi
n.^t)
B.-5,80 A va 1,55 A .
•
D . 3 A va - 6 A .
'
Huang
i i = 6 c o s ( c o t ) ( A ) ; i 2 = 6 c o s cot + •
d o n g d i e n hieu d u n g qua d g n g co la 10 A va cong sua't tieu t h u d i e n la 10
/ :
kVV. D g n g co c u n g cap nang l u g n g co cho ben ngoai t r o n g 2 s la 18 k j . T i n h
tong d i e n t r o t h u a n cua cuon day trong d g n g co.
,', • ^
162072 = 3.2001.0,9 =>
, "•
A. 1 0 0 Q .
B.IOQ.
C. 90 Q.
Huong
I = 3V2 ( A )
( A ) ; i 3 = 6cos cot--
11, • ,•
i
dan
T u cong thuc:
P = 3UIcos(p
p.
=l72 = 72(A)
2n
(A)
P = Pj + l 2 r = > P = 5. + l2rr:>10'* = l ^ ^
D.9C.
dan
+ 1 0 2 r = > r = 10(Q)
^ChpnB.
219
Bdtrgkic'n
Ihitc
Vfit
ULTOlllrcn
kcnh
VI VJ, t ^ p ^ e - f ^ n u
vanm e n
Chii y: Ncii doan mqch xony cliicu AB gain inach
RLC run tiSp vai dorv^ ca dien 1 pha thi bleu thiic
dien dp iren RLC, tren dgng ca Ian linrt la:
i = IN/2
cos Wt :
•-R
' LC = U K L C ^ C O s ( a ) t
L
+ (pRLc)
"-'dong,..) = U ^ / 2 c O s ( 0 ) t + (p)
cty
R
trong do:
C
tan(|).
P = UIcos(p = ^
Dien dp hai dau doqn mqch Id ton;^ hap ci'ia hal dao dang dleu Iwa:
UAB = "RLC + "dong_<,d
UAB = U R I C
= UAB^cos(ojt +
(PAB)'
V;- -../>(,,
+2UKI.CUCOS(CP-
Uj^i c
sin (PRI
c + U
UKi(;COS(pK,t-
U«384(V)
+ Ucostp
xoay
chieu. Biet dien ap hai dau dong co co gia trj hieu dung 331 (V) va som p h a
so vol dong dien la n/6. Dien ap hai dau cuon day co gia tu hieu dung
125(V) va som pha so voi dong dien la n/3. Xac dinh dien ap hieu dung cua
mang dien.
A . 331V.
B. 344,9 V.
,
V:
= U|L +
C . 230,9 V.
i ; D. 44^ V.
Huong dchl
+ 2UKLU cos (cp - cp^L)
/I ..(p^ODf I
• P- r,..f / <. A
=
UiB=331^+1252+2.331.125.cos-^UAB«444(V)=>ChonD.
V i du 15: Mot dong co dien xoay chieu san ra mot cong suat co hoc 8,5 kW va
CO hieu suat 85%. Mac dong co voi cuon day roi mac chung vao mach xoay
cos((p2
,
, nr-2
-cpi)\2= 270,6^
+125^ + 2.270,6.125.cos30''
'•:;.^o:. . r J . K t ;rU
•
hai dau dong ca la n/6. Dien ap hai dau cuon day co gia trj hieu dung 125
''i - ,.;;iJ<--. ..U',. : i - .
Uisincp,+U2sin(pT
tan (p = —•
21!
i
U j coscpj + U 2 C0SCP2
=^ChonC.
•—I
Chu y: Ne'u doqn mqch xoay chieu AB gam mqch R not tie'p vai
dong ca dien 1 pha thi bleu thuc dien dp tren R, tren dong
ca Ian heat la:
UR
i = lV2coscot:
=URr^COSQ)t
I-
"d<)nK_c« = UV2
cos (cot + (p)
k
A
'''>^. 0> j ,
* »
U':'":!',
>,»i;,',J^
trong do: P = UI cos cp = - i -
vj;,
H
Dien dp giua hai dm doqn mqch la tong hap cua hal dao dong dim hdx.
"AB = UR + Lidong_ccJ = UABN/2cos(cot + 9AB)' trong do:
IT2
TT2 ^Tr2 ,
TT
UAB = UR+U +2URUCOS(P;
,
<^h^,
UR sinO + Usincp
tancpAB = —
i
^[
;:U
—
UR COSO + Ucostp
chieu. Biet dong dien co gia trj hieu dung 50 ( A ) va tre pha so voi dien np
"
9375 7 r « 2 7 0 , 6 ( V )
p = - B l = 9375(W) = U,Icos(pi => U i =
sin
V i du 14: Mac noi tie'p dong co voi cuon day roi mac chiing vao mach
'
pha voi I'M mot goc 30". Hieu dien the'a hai dau cuon cam la 125 V va som
pha so voi dong dien la 60". Hi^u dien the hieu dung ciia mang di^n va do
lech pha cua no so voi dong dien Ian lugt la •;, „.:>;H n l
o> <-'ir'A. 384 V va 40". B. 834 V va 45".
C. 384 V va 39".
D. 18-1 V va 39".
Huang dan
i r IT
UT2 _TT2
= Uf +, TT2 +, 2o U
1U2
trong do:
vt^t
TimnnrvpyvnKbang
t.
<'J
rni
V i du 17: (DH-2010) Trong gia hoc thuc hanh, hoc sinh mac noi tie'p mot quat
(V) va som pha so voi dong dien la n/3. Xac dinh dien ap hieu dung cua
dien xoay chieu vai dien tro R roi mac hai dau doan mach nay vao dien ap
mang dien.
A . 331V.
xoay chieu co gia tri hieu dung 380 V. Biet quat nay co cac gia trj djnh muc:
B.345V.
C. 231 V.
Huong dan
p:UIcos,4^U.50cos^ = l
D. 565 V.
^ = • 0^231 (V)
U^B = U|L + U ' +2UKLUCOS((P-CP,„J
UIB = 231^ +125^+ 2.231.125.COS- => U^B ^ 345(V)
=> Chon B.
6
V i du 16: Mot dong co dien xoay chieu san ra cong suat co hoc 7,5 kW va co
hieu suat 80%. Mac dong co noi tie'p voi mot cuon cam roi mac chung vho
mang dien xoay chieu. Gia tri hieu dien the hieu dung o hai dau dong co 1'^
U M biet rang dong dien qua dong co co cuong do hieu dung I - 4 0 A va trf
220
220 V - 88 W va khi hoat dong diing cong suat djnh muc thi do l^ch pha
giij-a dien ap a hai dau quat va cuong do dong dien qua no la
A.
180 Q.
B. 354 Q.
C.
361 Q.
Huang dan
P = U I cos(p => 88 = 220.1.0,8 =^ I = 0 , 5 ( A )
,V U D. 267 fi.
in t^-d iui^i-ih
Cdch 1: U^B = U | + U ^ + 2URUcoscp
/v
Cdch 2:
UAB = UR + U
U^B = U | + U ^ + 2URUcosq)
Un
• 380^ - U ^ + 220^ + 2UR220.0,8 UR = 180,337 =^ R = ^
= 361(n)
•Chon C.
221
VTV2. l.ip-J - Chu V^n
Bd trfi klen thiic V$t li LTBll tren kenh
Bl&n
V i d u 18: T r o n g g i a hoc thuc hanh, hoc sinh mac no'i tiep m o t q u a t d i e n xoay
chieu v o i d i e n t r o R = 352 Q roi mac hai d a u doan mach nay vao d i e n ap
P ' = UIcos(p:
80
100
.100 = U.0,5cos(p =0 U c o s 9 = 1 6 0 ( V )
xoay chieu c6 gia t r j hieu d u n g 380 V. Biet quat d i e n nay hoat d o n g 6 che'dg
D i e n ap hieu d u n g tren R : U R = I R = 5 0 ( V )
d i n h m u c v o i d i e n ap d i n h m u c dat vao quat la 220 V v a k h i ay t h i d o lech
T u p h u o n g t r i n h vec to:
pha g i i i a d i e n ap a hai d a u quat v a c u o n g d o d o n g d i ^ n qua n o la cf), v o l
U A B = U R + U chieu len true hoanh
coscj) = 0,8. H a y xac d i n h cong suat d j n h m u c cua quat d i e n .
A. 90W.
B. 2 6 6 W .
t
'<',•••':!,;-,(;.,
C. 80 W .
Huang dan
UAB =U+ U R ^ U^B =
va true t u n g ta duge:
D . 16CW.
;
t
l
j
j
j
u
.
UABCOSCPAB = U R
-
+ U | + 2 U U R coscp
+Ucos(p
UABsincpAB = 0 + Usin(p
r220cos(PAB = 5 0 + 160
=^ 380^ = U | + 220^ + 2UR.220.0,8 =i> U R = 1 8 0 , 3 4 ( V ) => I =
0,512(A)
P = UIcos(p = 220.0,512.0,8 = 9 0 , 1 7 ( W ) = ^ C h o n A .
,
>
V i d u 19: Cho mach d i e n xoay chieu g o m b o n g den day toe mac n o i tiep v o l
d g n g ca xoay chieu 1 pha. Biet cac gia t r i d i n h m i i c cua den la 120V - 24UW,
'
: A
(-
L A B =17,34"
M
N
,1) • a , c r ; ! : ,0 ^ ^
|220sin(pAB = 0 + U s i n ( p ^ [ U s i n ( p = 65,574
• "
Ket h o p Usincp = 65,574 v d i Ucos(p = 160, suy ra: cp = 22,286^, U = 172,9 V .
K h i d o n g ca hoat d o n g b i n h t h u o n g :
P = U I cos cp
100 = 11 O.I. cos 22,286 r=> I = 0,9825 ( A )
d i e n ap d i n h m i i c cua d o n g ca la 220 V . K h i dat vao 2 d a u d o a n mach dien
T u p h u o n g t r i n h vec to: CFAB = U R + U chieu len true hoanh v a true t u n g ta
ap xoay chieu c6 gia t r j h i e u d u n g 331 V t h i ca den v a d o n g ca deu hoat
duge:
+Ucos(p
d o n g d u n g cong suat d j n h m u c . Cong suat d i n h m u c cua d o n g ca la
UABCOSCPAB = U R
A . 389,675 W .
UABsincpAB = 0 +Usincp
/
B. 305,025 W .
•;•'>•'•• ••••V',-j:\'::i.
120
C. 543,445 W .
D . 485,888 W .
Uuongdan
•.>:
^ '
U AB = U + U R = > U i s ==
f220cos(pAB = U R +110.eos22,286
[220sin9AB = 0 + 110.sin22,286
(PAB = 10,93° = > U R = 1 1 4 , 2 3 = > R = ^ » 1 1 6 ( Q )
' . I V;?;,.
De quat hoat d o n g b i n h t h u a n g t h i R tang 116 - 100 = 16Q.
V i d u 21: T r o n g m o t g i o thuc h a n h m o t hoe sinh m u o n m o t quat d i e n loai 180
+ U R + 2 U U R cos (p
V - 220 W hoat d o n g b i n h t h u o n g d u o i m o t dien ap xoay chieu c6 gia t r i
,
9
,
1417
33r - 220^ +120^ + 2.220.120.cos(p ^ c o s ( p = ^ ^
h i e u d u n g 220 V, nen mac no'i tiep v o i quat m o t bien t r o . Ban d a u hgc sinh
d o de bien t r o c6 gia t r i 70 Q t h i do thay c u a n g do h i e u d u n g t r o n g mach la
=^ P = UIcos(p = 2 2 0 . 2 . — = 389,675(W) => C h o n A .
0,75 A v a cong suat cua quat d i e n dat 92,8%. M u o n quat hoat d o n g b i n h
V i d u 20: T r o n g m o t g i a thuc h a n h m o t hoc sinh m u o n m o t quat d i e n loai
t h u a n g t h i p h a i d i e u c h i n h bien t r a n h u the nao?
110 V - 100 W hoat d o n g b i n h t h u a n g d u o i m o t d i ^ n ap xoay chieu c6 gia
A . G i a m d i 20 Q.
B. Tang them 12 Q.
t r i hieu d u n g 220 V , nen mac n o i tiep v o i quat m o t bien t r o . Ban d a u hoc
C. G i a m d i 12 Q.
D . Tang them 20 Q.
Huang
sinh d o de bien t r o c6 gia t r j 100 Q t h i d o thay c u a n g d p h i e u d u n g trong
^
»__p5l.»_^Bq^
^
dan
m a c h la 0,5 A va cong suat ciia quat dien dat 80%.
L u c d a u , d o n g co hoat d o n g d u o i d j n h muc, cong suat tieu thia cua no:
T i n h h§ so cong suat toan mach, he so cong suat cua
P ' = UIC0S(p:
quat v a d i e n ap h i e u d u n g tren quat liic nay. M u o n
quat hoat d o n g b i n h t h u o n g t h i phai dieu c h i n h bien
^•
A
92,8
100
-.120 = U.0,75eos(p
=t>Ueos(p = 1 4 8 , 4 8 ( V )
t r o n h u the nao? Biet d i e n ap g i i i a hai dau doan mach
T u p h u o n g t r i n h v e c t o : U^g = Up, + U
s o m pha h o n d o n g dien t r o n g mach.
chieu len true h o a n h v atrue tung ta
Humg
dan
L i i c d a u , d p n g c a hoat d o n g d u a l d i n h muc, cong sua't tieu t h u cua no:
999
^
UABCOSCPAB = U R
+Ueos(p
U A B s i n (PAB = 0 + U s i n (p
duge:
f220eos9AB
^'
=70.0,75 + 148,48
1220 s i n CPAB = 0 + U s i n cp
223
So' tr(> kicn
lltuc
V^t li^LTDtlJrcn
kcnh
VTV2. t^p 2-
CQ^ T/vmMTVDvvnKhang
=:>Usin 9 = 89,482 ket h o p v o i U cosip = 148,48 , suy ra: (p
' V •
cosq) = 0,8565.
*
'
'^JKii
K h i d o n g co hoat d o n g b i n h t h i r o n g :
P = UIcoscp
120 = 180.1.0,8565
0,5424 rad hay
Huang
•
D
irjin
„o».;
H =
:
I = 0,7784(A)
0
Pco
Ulcoscp-Php
P
UIcoscp
dan
11
= 1
VIft
220.0,5.0,8
= 0,875 = 87,5%
=>ChonD.
d u 24: M o t d o n g co k h o n g d o n g bo ba pha tieu t h u cong sua't la 3,6 k W ,
Tir p h u o n g t r i n h vec to: U A B = U R + U chieu len true hoanh va true t u n g ta
dien t r o t r o n g ciia m o i cuon la 2 Q va he so cong sua't la 0,8. D o n g co mac
duoc:
h i n h sao mSc vao m a n g dien mac h i n h sao v o i d i e n ap hieu d u n g 200 V t h i
U A B COS(PAB =
220coscpAB = U K
+ Ucos(p
220sin(pAB = 0 + 180.sin0,5424
U A B sincpAB = 0 + Usin(p
^
+180.cos0,5424
U , , = 45,25 => R = H i i - 58(n)
1
is:,,,,;
dong CO hoat d o n g b i n h t h u o n g . Coi nang l u o n g v 6 ich chi do toa nhiet
trong cac cuon day ciia stato. H i e u sua't d o n g co la
A. 92,5%.
U,
,'
j,B.7,5%.
Huang
Oiu y: Neu bie't dien tra tron^ cua dong ar thi c6 thetinh duvc hieu suat cua dong ca
nhu'sau:
Dong ca 1 pha:
ucos(p
axW)
Mpmnr
Dong ca 3 pha:
3Ucos(p
,.
,
O r . A.
t r o n g 7,568 Q va he so cong suat la 0,86. M ^ c no vao m a n g d i e n xoay chieu
CO d i e n ap hieu d u n g 220 V t h i d o n g co hoat d o n g b i n h t h u o n g . H i e u suat
d o n g CO la
B.90%.
C.87%.
D . 77%.
Huang dan ^"^^^''^'^
P-I^r
P
473
=
220.0,86
l_^:^LZi^
"
473
A. ra cuon 2.
B. ra cuon 3.
^11 t
Huang
dan
Gia s u tai t h o i d i e m t = 0, t u t r u o n g tong h o p tai O
CO h u o n g ra k h o i cuon 1 t h i B i = Bo.
Tai t h o i d i e m t = T/3 thi
cos
T
3
3
= Bo, t u c la t i r t r u o n g
(jj
tong h o p h u o n g ra k h o i cuon 3 => Chon B.
''hvcmgphdpgidi
= 0,9 = 90% = > C h o n B.
H i e u suat cua d p n g ca (ti so giua cong sua't hi>u ich va cong sua't tieu thy
224
C. vao cuon 3.
BAI TOAN L I E N QUAN D E N MAY B I E N A P
suat cua d o n g co la 0,8. Bie't rang cong suat hao p h i cua d o n g c o la I I W .
f
Suat d i e n d o n g hieu d u n g : E =
C 92,5%.
Cong thuc m a y bien ap:
= ^ ^ ^ ^
v2
V2
=
U2
; H =
N2
=
if.ll !;'>'j'
}hh£2^
P,
1
, n
Ujli
'6ng thuc m a y bien ap l i t u a n g ( H = 100%) va mach t h u cap co he so cong
4""'
B. 9 0 % .
11
P-3l2r
^ 3.7,55^2
— =1
= 90,625% = ^ C h o n D .
P
"
3600
diC'n ap hieu d u n g 2 2 0 V , c u o n g do d o n g dien hieu d u n g 0 , 5 A va he so cong
A. 8 0 % .
<•
= 2,5(A)
Vi dy 23: ( D H - 2 0 1 2 ) M o t d o n g co d i e n xoay chieu hoat d o n g b i n h t h u o n g v o i
toan phan) la
it,
cuon 1 t h i sau 1/3 chu k i no se co h u o n g
D3 = BQ
Ucoscp
^1
271/3) (T). Vao t h o i d i e m nao do tir t r u o n g tong hg-p tai O co hi r a n g ra k h o i
I'Hl
P
P
Vi du 22: M o t d o n g co dien xoay chieu co cong suat tieu t h u la 473 W , d i ? n t r o
P
„
Pi
ri = —
P
3.200.0,8
diem O Ian l u o t la: Bi = Bocoscot (T), B2 = Bflcos(cot + 27i/3) (T), B i = Bocos((ot -
P = 3UIcos(p=>I =
P
3Ucos(p
ba true cuon day ciia stato. Gia s u t u t r u o n g t r o n g ba cuon day gay ra 6
p
P = UIcos(p=>I =
dan
Vi du 25: T r o n g d o n g co k h o n g d o n g bo ba pha, goi O la d i e m d o n g q u y cua
P-I^r
A . 86%.
D . 90,625%.
'Q . . ( . . . A j a i r O S S -
G i a m d i 70 - 58 = 12 Q =^ Chon C.
P = UIcos(p=:> I =
C. 99,7%.
^ yA
D . 8 7 , 5 %.
suatcos(p2: - 1 = _2.cos(p2 = — ^
.
,
B d trp hidn
th-ic
V^t IILTDH
tr&n k&nh
VTV2.
t4p 2 - Chu Van Bien
Chti y: Nc'u nigt cuon day nao do (VD cuon sa cap) c6 n vong day quart nguvc thi tie
Cong thuc m a y bieh ap h' t u o n g ( H = 100%) va t h u cap noi v o i R:
truvng ciia n vong nay ngirgc vai tir truvng ci'ia phan con Iqi nSn no c6 tac duni^
khic bat tir truv'ng ciui n vong day con Iqi, lux la cuon day nay bi mat di 2n vong.
U2
I,
N2
Or (-.-(.r n ' l i h i O - v a f e j s o i r M d m ; Jvv". fOf'?
Uj^^Nj—2n
" :•• ,.• .
V i d u 1: C u o n t h u cap cua mot may bieh ap c6 800 v o n g . TiJ" t h o n g trong
bieh the bieh thien v o i tan so 50 H z va gia t r i t u t h o n g cue dai qua i-ngj
v o n g day bang 2,4 m W b . Ti'nh sua't dien d o n g hieu d u n g cuon t h u cap.
A . 220 V .
E =
.,
B. 456,8 V
.
,
C. 426,5 V .
V2
t h u cap g o m 150 v o n g day. Mac hai dau cuon so cap vao m a n g dien xoay
chieu CO dien ap hieu d u n g 5 V. Neu 6 cuon so cap c6 10 v o n g day bj quah
n g u g c t h i dien ap hieu d u n g 0 hai dau cuon t h u cap k h i de h o la
Humgdan
Ec, ^ 2nfNOo ^ 27t.50.8002,4.10-^ ^ 4 2 6 , 5 ( V )
V2
D . 140 V .
V i d u 5: M o t may bieh ap l i t u o n g c6 cuon so cap g o m 100 v o n g day va cuon
C h o n C.
A . 7,500 V.
B. 9,375 V .
V2
V i d u 2: (DH-2008) M o t may bieh ap c6 cuon so cap 1000 v o n g day d u o c mac
'•
C. 8,333 V .
•
D . 7,780 V .
, ^ i-,:,,;' .';!S:,?1.
Huang dan
C u o n so cap xem n h u mat d i 20 vong:
j,,
......1..
(ilMi!
:
f*i'-.
vao m a n g dien xoay chieu co dien ap hieu d u n g 220 V . K h i do dien ap hiei,
d u n g 6 hai dau cuon t h u cap de ho la 484 V . Bo qua m o i hao p h i cua may
B. 1100.
D. 22ro.
C. 2000. ,,, .
N,
220
1000
U2
N2
484
N2
^T^
N2
= —7z
U2
.
\
, ' .
.
(W»
V i d u 6: M o t may bieh ap cuon so cap g o m 1100 v o n g mic vao m a n g dien xoay
nhieu?
•
A . 75.
B. 60.
''''
,.
^
CO 15 v o n g day bj quah ngugc t h i tong so v o n g day cua cuon t h u cap la bao
> N2 = 2200 => Chon D .
Chu y: NcU tliay do] vai trd ciiu ak cuon day thi:
=>U2 = 9 , 3 7 5 ( V ) =:>ChonB.
150
chieu 220 (V) va cuon t h i i cap de lay ra dien ap 15 (V). N e u a r u g n t h u cap
Huattg dan
U,
= —T;
U2
bieh ap. So v o n g day cua cuon t h u cap la
A . 2500.
7^
U2
N2
U',
_N2
=>
U,U',
-1
U,U',
' ' C'm.
'
D . 105.
''P^:'
Humgdan
r i :
Ui
N]
220
1100
77^ = r ^ — — - = > - ~ ^
=i>N2 =105
U2
N2-2n
15
N2-3O
^
^,
^
Chon D .
•
V i d u 3: D a t m o t dien ap xoay chieu u = 200coscot (V) vao hai dau cupn day so
V i d u 7: M o t m a y bieh ap v o i cuon so cap g o m 1000 v o n g d u g c mac vao mang
cap cua m o t m a y bieh the l i t u o n g t h i dien ap hieu d u n g do d u g c a hai dau
dien xoay chieu. C u o n t h u cap g o m 50 vong. Bo qua m g i hao p h i 6 may
cuon t h u cap la 10 V2 V . N e u dien ap xoay chieu u = 30cosail (V) vao h^n
bieh ap. C u o n t h u cap noi v o i dien t r a thuan t h i d o n g dien chay qua cuon
dau cuon day t h u cap t h i dien ap do d u g c 6 hai dau cuon day so cap bang
A.300V.
B.2OOV2V.
C.3OOV2V.
D.I50V2V.
Huaitg dan
UiU',
IOO72.I5V2
=1
U2U'2
'
'
=1
t h u cap la 1 ( A ) . H a y xac d i n h d o n g dien chay qua cuon so cap.
A . 0,05 A .
B. 0,06 A .
C. 0,07 A .
Huangdau
'
D . 0,08 A .
;
''T
'
V i may bieh ap l i t u o n g va cuon thii cap noi v o i R nen ta ap d u n g cong
U'2 = I50V2 ( V ) => C h o n D«
10^/2U'2
V i d u 4: M a c cuon t h u nhat cua m o t may bieh ap l i t u o n g vao mg^ nguoV. diC'^
xoay chieu t h i suat d i e n d g n g hieu d u n g trong cuon t h u hai la 20 V,
=> Chon A.
'
v-v
Chu y: Nc'u cuon thu cap cm may bieh ap not vai RLC:
"
V
ioK
cuon t h i i hai vao n g u o n dien xoay chieu do t h i suat dien d g n g h i ^ u d^-f'
t r o n g c u o n t h u nhat la 7,2 V . T i n h d i e n ap hieu d u n g cua n g u o n dien.
A . 144 V .
B.5,2V.
C. 13,6 V .
U2 = : ^ -12
=
U2
N2
D.12V.
,
^R2+(Zi_-Zcf
•
W
'•'
M r.: M >
j'' n
Huang dan
UiU'i
U,U',
.
=1
E.E
P,
U,I,
= 1 ^ E = 12(V) ^ C h o n D .
20.7,2
227
Ir^t
hit^n
I hut
V^t l i Lmil
l i c n hcnl,
VTV2.
2 - Chu
t4ip
Van
c i y innn nrv own
Blin
Huang dan
d\ 8: Cho m o t m a y bien ap c6 hieu suat 80%. C u o n so cap c6 100 vong,
cuon t h u cap c6 200 v o n g . M a c h so cap l i t u o n g , dat vao hai d a u cuon so
cap d i e n ap xoay chieu c6 gia t r j hieu d u n g 100 V va tan so 50 H z . H a i dau
cuon t h i i cap n o i v o i m o t cupn day c6 dien t r o 50 Q, d p t u ce,m 0,5/7t ( H ) .
C u o n g d p d o n g dien hieu d u n g mach so cap nhan gia t r i :
100
•0,8 =
Uili
P,,=P„^UiIi=U2l2+U3l3=:>Ii = 0 , 0 5 5 ( A ) = > C h o n C .
d a u v o i m o t d i e n t r o R' = 10 Q. Coi d o n g d i e n va d i e n ap l u o n c u n g pha.
= 2^^(A)
C u o n g d p d o n g d i e n h i ^ u d u n g chay t r o n g cupn so cap la
8.50
Chon A.
•Ii=5(A)
100.1
A . 0,150 A .
B. 0,450 A .
la 2. C u p n t h u cap n o i v o i tai tieu t h u c6 dien t r o 200 Q, c u p n S T cap n o i v o i
U2
cupn SO cap la
C. 0,5 A .
D . 0,8 A .
s-i •
U,
I,
.1,
Ni
N,
I1 =
N2
N,
= 0,5(A)
Chon A.
dau ra) va cdc dau ra noi voi R tin ap dung cong thuc:
Psc=P.c=>UiIi=U2l2+U3l3i
Kl-
•
,
^
„ -
U2
I,
N2
Neu ap dung cong thuc —^
U i = -iI2 = —^
Ni
U2=40(V)=>l3
=
R
40
U3
40
R',
10
= 0,5 ( A )
= 4(A)
• 400.Ii = 20.0,5 + 40.4 => I i = 0 , 4 2 5 ( A )
N2 „
,
U 2 = — ^ . U i => I2 =
hu y: Dot voi may him ap ly twang ma cuon thw cap c6 nhieu dau ra (chang hqn c6 2
I, =
Ni
100
sau: <,
Ni
R'
^
P2-I^R;H =-
^
+ (ZL
Pi=?
V i du 12: M o t m a y bien ap l y t u o n g c6 t i so' v o n g day c u p n so cap va t h u ca'p la
2:3. C u p n so cap n o i v o i d i e n ap xoay chieu c6 gia t r j h i e u d u n g 120 V.
CO d i e n t r o t h u a n 60 Q, cam khang 60^3
R
U3
Ni
C u p n t h u cap n o i v a i tai tieu t h u la mach d i e n RLC k h o n g p h a n n h a n h g o m
U2_
N3_
^
nhu
U2
---
IT
.I2=0,25(A)
\J2_N2
U3
^
Chu y: Khi cho biei Ui, N1/N2, H va mach thu cap noi RLC, detinh Pi, Pz ta lam
i
U , = ^ . U i = lOO(V) => I2 = ^
U 2 _ I , _ N2
1000
D . 0,015 A .
C h o n C.
V i m a y bien ap l i t u o n g va cupn t h u cap n o i v o i R nen ta ap d u n g cong
'
400
UiIi=U2l2+U3l3
;
Huong dan
thii'c:
50
M3
U,,, a,,, .
B. 0,6 A .
U2
N2
d i ^ n ap xoay chieu c6 gia t r j hieu d u n g 200 V. D o n g d i e n hieu d u n g qua
,
C. 0,425 A .
Huang dan
i du 9: M o t may bien ap h' t u o n g c6 t i so v o n g day cua cupn so cap va t h u cap
A . 0,25 A .
200.il =10.0,5 + 200 ^ ^ . 1 , 2
1000
'
Na = 100 v o n g . GiCra 2 dau N2 dau v o i m o t d i e n t r o R = 40 Q, giua 2 d a u N 3
U2 =200(V)=^l2 =
200
N3
dien ap hieu d u n g k h o n g d o i U i = 400 V . T h u cap g o m 2 c u p n N2 = 50 vong,
Huang dan
100
U3=Ui
V i d v 11: M o t m a y b i e n ap l y t u o n g , cupn so cap Ni = 1000 v o n g d u p e n o i vao
D . 2,5 A .
C. 2 A .
B. 10 A .
A. 5 A.
nitang vipr
Q va d u n g k h a n g 120 ^/3 Q. Cong
suat toa nhiet tren tai tieu t h u la
A . 180 W .
B. 90 W .
Huang dan
yini
U
II
N;
1 ^ _L = i ! l t h i se dan den ket qua sai!
Ui
I3
N.
i du 10: M o t m a y bien ap ly t u o n g , cupn so cap c6 Ni = 1000 v o n g d u p e n o i
vao d i e n ap hi?u d u n g k h o n g d o i U i = 200 V. T h u cap g o m 2 d a u ra v o i so
C. 135 W .
120
U2
N2
=>ChonC. „ •
D . 26,7 W . „
/
2
= - rr> U 2 = 1 8 0 ( V ) : ^ P2 = I 2 R =
U2R
y = 135(W)
R2+(ZL-ZC>'
•
v o n g day Ian l u p t la N2 v o n g va Ns = 25 vong, d u p e n o i k i n t h i c u o n g d p
V i du 13: Cho m o t m a y bien ap c6 hieu suat 90%. C u p n so cap c6 200 vong,
hi?u d u n g Ian l u p t la 0,5 A va 1,2 A . D i e n ap hieu d u n g hai d a u cupn N2 la
cupn t h u cap c6 400 v o n g . C u p n so cap no'i v o i d i ^ n ap xoay chieu c6 gia t r i
10 V. C o i d o n g d i e n va dien ap l u o n cung pha. C u o n g d p d o n g d i e n hieu
d u n g chay t r o n g cupn so cap la
A . 0,100 A .
B. 0,045 A .
C. 0,055 A .
D . 0,150 A .
hieu d u n g 150 V . H a i d a u cupn t h i i cap no'i v o i m o t cupn day c6 d i ^ n t r o
hoat d o n g 90 Q va cam khang la 120 Q . Cong suat mach so cap la
A . 150 W .
B.360W.
C.250W.
^
D. 400 W .
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