VI du 2: Di^n nang dupe tai tu tram tang ap toi tram ha ap b5ng duong
Phdn tich vd htcang ddn gid
)i?n ap giCia hai d a u d p n g co s o m pha m p t goc j = — so v o i c u o n g d p d o n g d i ^ n , nen d p n g ca
6m d i ^ n t r o R v a c u p n day t h u a n L .
'Jhu vay theo bai ra ta co g i a n do vecto r u p t n h u sau:
p 953 )i?n t r o ciia d p n g co la: R = - y = — 0
Nen U R = 2 3 8 . 2 5 V .
160
A
Suy ra = tancpi-Up = 137.6V E>i^n ap g i u a hai d a u cupn day
chay qua n o nen ta co: = Ujcoscpj = 60V.
E>i?n ap giCra h a i d a u cupn day s o m p h a m p t goc cpj = - s o v o i d o n g d i ? n 3
Va = tan ^ i ^ r = 60N/3V.
D i e n ap hieu d u n g g i u a hai dau d o a n mach la: U = ^ ( U „ + U , ) + ( U L , + U L ^ = 3 8 4 V .
Chpn dap an C
V i d u 6 : M o t d g n g co d i e n xoay chieu san ra cong suat co hoc 7,5kW va c6 hieu suat 8 0 % . Mac d o n g co noi tiep v o i m o t cuon cam roi mSc c h i i n g van m a n g dien xoay chieu. Gia tri hieu dien t h e h i ^ u d u n g 6 hai dau d o n g co
la U M biet rcing d o n g diC^n qua d o n g co co c u o n g do h i e u d u n g I = 4 0 A va
tre pha v o i uvi m o t goc n/6 . H i e u dien the 6 hai dau cugn cam Ui. = 125V
va som pha so v o i d o n g dien qua cuon cam la n/3. T i n h h i e u d i e n the hieu d u n g cua m a n g d i e n va do lech pha cua no so v o i d o n g dien.
A . 3 8 4 V ; 4 0 " B. 8 3 4 V ; 4 5 " C . 3 8 4 V ; 3 9 " D . 1 8 4 V ; 39"
'Phdn tick vd hitang ddn gidi
P„ = I 1 . Z 5 H 0. 9 3 7 5 ( W ) H 0 , 8 Mi) P M = U M . l.Cosc}) U A(p U M = • M 9 3 7 3 l.COSip, 4 0 A p d u n g d j n h ly h a m cosin
Cho tam giac A N B ta co: ^ ^ 6 .
i • U = VU'M+U^^+2UM.UJ.COSA(P U = VU'M+U^^+2UM.UJ.COSA(P 1 ' 270,6^+125^ 2.270,6.125.Cos cosa = n 13 -.0 = 384(V) 2 . U . U a = 9"=>(t) = a + 3 0 " = 3 9 ^ M Chpn dap an C CO B A I T A P V A N D U N G :
C a u 1: M o t d g n g co d i ? n xoay chieu k h i boat d g n g b i n h t h u o n g v o i dien hieu d u n g 220 V t h i sinh ra cong suat co hgc la 170 W . Biet d g n g co co he cong suat 0,85 va cong suat toa nhiet tren day quan d g n g co la 17 W . Bo q^" hao p h i khac, c u o n g d o d o n g d i e n cue dai la bao nhieu?
A.4,4A B.1,8A C. N/2 A D . 4 A
Cty TNHH MTV DWH Khang Viet
^hdn tick vd hitang ddn gidi
C o n g suat tieu t h u toan phan: P = Va + \\-,
Hay: P = U.I.coscp = R, + Php ^ • 2 2 0 . - ^ . 0 , 8 5 = 170+17
C u o n g d g d o n g d i e n cue dai I„ = -Jl A.Chpn dap an C
» U 2 : M o t quat d i e n ma tren do ghi 200V-100W. de quat boat d g n g b i n h t h u o n g d u o i d i e n ap 220V n g u o i ta mac noi tiep v o i no 1 d i e n t r o thuan R. Biet rang he so cong suat cua quat la 0,88. Xac d j n h c u o n g d o d o n g d i ^ n t r o n g mach va d i ^ n t r o R.
A . 39Q B. 35n C. 93Q D . 5 3 n (adsbygoogle = window.adsbygoogle || []).push({});
^hdn tick vd himng ddn gidi
p = UI cos(p => I = P 100 25 U.cos(p 200.0,88 44 U 200 I 25 .44 = 352Q Va cos (p = — - = 0,88 => r = 0 , 8 8 . Z . , = 31OQ V o l d g n g CO r, L ) Z^,^. = + Z L « 3 5 2 = ^ 3 1 0 ^ +zf Z^ = 1 6 7 Q Do R mac noi tiep v o i d g n g co (r, L), nen de d g n g co boat d g n g b i n h t h u o n g thi I qua R phai b5ng 2 5 / 4 4 ( A ) .
U . 220
.44 = 387i^ Ta CO tong t r o cua ca doan mach Z =
• 1 25
R mic n o i tiep v o i d g n g co (r, L) ta co Z = ^^(R + r)^ + Thay so: 387 = 7(^ + 310)^ +167^ R = 3 9 0 .
Chpn dap an A
a u 3 : C h o mach dien g o m 1 bong den day toe mSc ncYi tiep v o i 1 d g n g co
xoay chieu 1 pha. Biet cac gia t r i d j n h m i i c cua den la 120V - 330W, d\qn ap
d j n h m i i c cua d g n g co la 220V. K h i dat vao 2 dau d o a n mach 1 d i e n ap xoay chieu CO gia trj hieu d u n g 332V thi ca den va d g n g co deu boat d g n g d u n g cong suat d j n h m i i c . Cong suat d i n h m i i c ciia d g n g co la:
A . 5 8 3 W B . 6 0 5 W C. 543,4W D . 485,8W
^hdn tick m huang ddn gidi
Do boat d g n g 6 cac gia trj d j n h m i i c N e n:I = i ^ = ^ = 2,75(A)
U dm 120
Bt quye't on luyeii llii tint hoc dat diem toi da Viit If, tap 1 - Le Van Vitih^
(Rpnt R D C ntL)
Ta CO gian do vecto trup-t
A p dung dinh ly ham cosin cho tarn giac A M B
= + U^jc - 2 . U D . U D C C O S ( 1 8 0 ' ' - ( P D C )
o 3 3 2 ^ = 1 2 0 2 + 2 2 0 ^ - 2 . 1 2 0 . 2 2 0 . c o s ( 1 8 0 ° -(p^c) =>COS(PDC = 0 - 8 9 8 1 8
V i vay: Cong suat dpng co la
P = U D C - I D C - ™ S C P D C
= 2 2 0 . 2 , 7 5 . 0 , 8 9 8 1 8 = 5 4 3 , 4 ( W )
C h p n d a p a n C
C a u 5 : (Trich de thi thtr S u pham Ha Npi Ian 1 nam 2013) Phat bieu nao sau day ve dong co khong dong bp ba pha la sai?