Bổ trợ kiến thức luyện thi đại học môn vật lý phần dòng điện xoay chiều p2

B trp hien thitc V^t I I L T D H tren Mnh VTV2 t^p - Chu V^n Bicn , , Huong dan 7625-x^ A M N E :N E = V M N ^ - M E ^ = / < ,.,;iV;l,„ / ^ ^ A A E B : A B ^ = A E ^ + EB^ L * N ' / ! l:o^/3 30" - 60N/3 ^ Z L = ^ 1681 = (25 + x)^ + (29 - ^ ^ ) " =^r = - ^ = 37,5(n) V- U L = 120v/3 sin yl625-x^ • f^f'H =»MAN = a A A M N can tai M vda^ = 29 - / X = 15 A A N B can tai A md M A I = NAB EB 120 M / 25V / UL X •4 t = 15V6i r, L Ur S.41V —'B Cau 29: Dat dien ap xoay chieu 120 V - 50 Hz vao doan mach noi tiep AB gom dien tro thuan R, tu dien va cuon cam Khi noi hai dau cuon cam voi m o t ampe l Z L = R = ^ U ' L = 3U'K UL=120(V) Uc = 40(V) ^ U = > / U ? < + ( U L - U C ) ' = V + ( - f = 4075 (V) V, +K}ii thay ddi C thi U van Id 40V5 (V) yd U ' L = 3U'R >u2=ui+(UL-ucr > 8000 = U ' K + (3U'K - f > U ' K =45,64(V) i Mill :] A.50Q 300 ' ^ B 15Q r- ! ,J ,s) Cau 32: Dat dien ap xoay chieu tan so 300 V - 50 Hz vao hai dau doan mach AB Cau : Dat dien ap xoay chieu u = 41V2 coscot (V) vao hai dau doan mach noi tiep gom dien tro R, cuon cam c6 tu cam L, c6 dien tro thuan r va tu die'^ C thi cuong hieu dung dong qua mach la 0,4 A Biet dien ap hieu dung tren dien tro, tren cuon cam va tren ty di^n Ian lugt la 25V, 25V va 29V Gi^i trjrbSng lOU'K - 360U'K - 4400 = ^ C.37,5n ^-.f^^^:,: ' r^' D.30a gom hai doan mach A M va MB mSc noi tiep Doan A M gom d''en tro thuan mac noi tiep voi cuon cam thuan, doan MB chi c6 tu dien Biet dien ap hieu dung giua hai dau doan mach MB la 140 V va dong dien mach tre pha hon dien ap giua hai dau doan mach AB la cp cho coscp = 0,8 Dien ap hieu dung giija hai dau doan mach A M la A 300 V B.200V C 500 V D 40C V 301 B S Ira hicti Vdl !i I r o l l llnic t r e n kenh VTV2, Huong 30o7l - / j ^ / ' OVVII Khang Vi^t + (p,) va f2= Iocos(cot + 92) C O cung gia t r j tuc thai 0,5 ^3 1,,, n h u n g m o t d o n g ^/IK: dien dang tang c o n m o t d o n g dien dang g i a m H a i d o n g dien lay lech pha cos^^ = 180 => E M = EB + B M = 320 A.71/3 ^240^ + 320^ = 400(V) A M = VAE^ + EM^ TnHHMTV Cau 34: Vao cung m o t t h o i d i e m nao d o hai d o n g dien xoay chieu n = Iocos(cot dan A E = 300cosip = 240(V) BE = SOOsin^p = Cty t^p - Chu VSn B i e n = ^ B 271/3 C TC Huang i^ = l C O s ( c D t + ( p , ) = =!() cos(K)t + •(cot + cp,) = - " cp2)= , n i'2 =-coIoSin(cot + {p2) Acp = (cot + 92 ) - (ct)t ,,,, dan i ' l =-coIosin((ot + ( p i ) > 12 D 7I/2 + 11' ) = 1; ^ Cau 35: Dat dien ap xoay chieu on d j n h vao hai dau doan mach g o m cuon day noi tiep v o i t u dien c6 dien d u n g C i K h i d o dong dien t r o n g mach la i i va 'R cong suat tieu t h u ciia mach la Pi Lay mot t u dien khac C = C i mac song E Cau 33: M o t mach d i e n xoay chieu noi tiep g o m t u d i e n c6 dien d u n g C, dien t r a thuan R va cuon day c6 t u cam L c6 dien t r o thuan r D u n g v o n keco dien t r o ra't i o n Ian l u o t d o hai dau dien tro, h a i dau cuon d a y va h a i dau doan mach thi so chi Ian k i g t la 50 V, 30 V2 V va 80 V Biet dien ap tuc thoi tren cuon day som pha h o n d o n g dien la Tt/4 D i e n ap hieu d u n g tren t u la A 30 V B.30V2V C 60 V E^NE V Id tarn gidc vuong can tai = EB = 30V^ME Tii gldc AMNB dien ap hai dau doan mach v o i ii va i2 A 91 = n/6 va 92 = -n/3 = MN + NE = 80V = AB J j» :^ ,U , r , , C 91 = 7i/4 va 92 = -7t/4 j B 91 = -71/6 va 92 = 7t/3 j D 91 = -7r/4 va 92 = 7r/4 ; Huong dan D 20 V Huong dan AAMB song v o i t u dien Ci thi d o n g dien mach la i2 va cong suat tieu t h u la P2 Biet Pi = 3P2 va i i v u o n g pha v o i i2 Xac d j n h goc lech pha 91 va 92 giua P = UIcos9 = — c o s ^ = > = ^ R P2 C2 = C i + C' = 5Ci =>Zc2 = Id hinh ch a nhat =^ Uc = A M = EB = ( V ) Zci cos 9] - => C O S 92 COS 92 cos9i -i^y'-' 73 7t •92 , = - (P2 = i + M R w L, r 92 -sm9| 73'" cos9[ cos 9] cos 7C •91= Cau 36: Tren doan mach xoay chieu k h o n g phan nhanh c6 bon d i e m theo d i i n g t h u t u A , M , N va B Giua hai diem A va M chi c6 cuon day, ffua hai d i e m M va N chi c6 d i e n t r o thuan, giiia diem N va B chi c6 t u dien D i e n ap hieu d u n g g i i i a hai d i e m A va N la 60 (V) va dien ap hieu d u n g giija hai d i e m M va B la 40 N/3 (V) D i e n ap tuc thoi tren doan A N va tren doan M B P lech pha 90", dien ap tuc thoi tren doan M B va tren doan N B lech pha 302 303 Ctyrmin 30" va cuang hieu dung mnch la N/3 (A) Dien t.6 thuan cua cuon day la A 40 Q B 10 Q ''" • C 50 Q Huong dan A O U K U M B : U K = 40x/3.sin 30" = 20^3 ( V ) ZA.OUK+,.UAN : U K „ ^tj^ D 20 Q |U'R=80(V) fi ' n -CO truong hop bang A 75 W B 160 W Dap an C C 90 W ' D 180 W ' ' 307 Bo trp kien thiic V$t IS LTOtl tren henh VTV2 t^p - Chu VSn Bien' "au 47: Doan mach A B no'i tie'p g o m hai doan mach A M va M B Doan mach Cau 44: Dat m o t n g u o n dien xoay cliieu c6 hieu dien the'hieu d u n g U va tan so A M la m o t cuon day c6 dien t r a thuan R = 40 Vs n va d g t u cam L = 0,4/n f vao hai d a u d o a n mach g o m R, L, C mac noi tie'p, t r o n g d o cuon day If H , doan mach M B la m o t tu dien c6 dien d u n g C thay d o i dugc, C c6 gia t r i t u o n g N o i hai dau t i i dien v o i ampe ke thi thay no chi l A , d o n g thoi h u u han va khac k h o n g Dat vao hai dau doan mach A B m o t d i e n ap: d o n g dien tuc t h a i chay qua ampe ke'cham pha m o t goc — so v o i hieu dien UAii = 240cosl00t (V) Dieu c h i n h C de tong dien ap hieu d u n g (UAM + U.MB) dat gia t r i cue dai T i m gia trj cue dai cua tong so'nay the tuc t h a i g i i i a hai d a u doan mach N e u thay ampe k e b a n g m o t von ke A.240V B.240^/2V , Huong t h i thay no chi 167,3V d o n g thai hieu dien the tuc thai giiJa hai dau v o n ke c h a m pha m o t goc ^ so v o i hieu dien the tuc t h o i giiJa h a i d a u doan mach SM" dung Biet rang ampe ke va v o n ke deu l i t u o n g H i e u d i e n the hi6u d u n g cua 120N/2 _ A M _ M B n g u o n dien xoay chieu la sin 60'.0 A 100V V > • B 125V < >L, u C 150V C 120V ^ sin a ' , A ' i ' , ' ' , s i n a + sinp => D a p an C ^ ^ sinP AM + MB D 175V D ^ V i , dan dinh li ham so sin cho A A N B : '= nii-j ,.:> :'• ' -''' o Cau 45 ( D H 2010): Dat dien ap xoay chieu c6 gia t r i hieu d u n g k h o n g d o i , tan so' 50Hz vao hai d a u doan mach mac no'i tie'p g o m dien t r a t h u a n R, cuon 2sin"tPcos"^P '^,^8"^''^' cam t h u a n c6 t u cam L va t u dien c6 dien d u n g C thay d o ' dugc Dieu chinh dien d u n g C den gia t r i t = —VLC ——F 471 hoac ——F In t h i cong sua't (UAM+UMB)-240V2COS^ tieu t h u tren d o a n mach deu c6 gia trj bang Gia trj ciia L bang A — H B - H C — H /li,^, = max-240V2(V) tn' - r : D - H => D a p an D C a u 48: D a t m o t n g u o n dien xoay chieu tan so 50 H z vao hai d a u d o a n mach Cau 46: M o t d o a n mach xoay chieu noi tie'p A B g o m d i e n t r o t h u a n R, cuon R L C mac n o i tie'p, t r o n g dien d u n g C bien d o i K h i tu d i e n c6 dien d u n g cam t h u a n L va t u dien c6 dien d u n g C D i e n ap giua hai dau doan A B la , Ci = l/(37r) m F t h i c u o n g hieu d u n g cua d o n g dien t r o n g mach c6 gia trj u = Udcoscot (V) t h i dien ap tren L la UL = Uocos((ot + 7i/3) (V) M u o n mach cue d a i K h i t u d i e n c6 dien d u n g C2 = 3/(257t) m F t h i hieu dien t h e ' h i e u xay cgng h u o n g t h i dien d u n g ciia t u bang A.CV3 d u n g a hni dau tu dien c6 gia t r i cue dai Dien t r o R c6 gia t r i la C 0,5C B C D 2C A.30Q , Zi - Z r 7t (PL = — m a (pi - = — =>(p = — => tan (p = —i= ^ = tan — R =>R = (ZL - Z c ) V >0 ,j, , 71 , 7t 71 UAB=UL^ZAB=X/R'+(ZL-ZC)' =ZL coC cong hi/dng thi Z'c = 2-^=>c'=o,5c mC : = coC D.60Q HumgdUn Z c i = - ^ = 30Q coCj =^2(ZL-ZC) = ZL=^ZL=2ZC Muohxdy • • • ZC2 C.50Q B.4OQ 250 /mnxZL=Zci=30Q R'+Z2 Ucmax Zc2 = - 250 R^+30^ "T~ 30 R = 40Q Cau 49: Dat d i e n ap xoay chieu c6 gia trj hieu d u n g U va tan so k h o n g d o i vao =Zi =>Z'c=2Zc , hai d a u A va B cua doan mach mac noi tie'p theo t h u t u g o m bie'n t r o R, • , cuon cam t h u a n c6 t u cam L va t u dien c6 dien d u n g C thay d o i Cac gia trj R, L, C hfru han va khac k h o n g V o i L = L i t h i dien ap hieu d u n g giira hai d a u bien tro R c6 gia t r i k h o n g doi va khac k h o n g k h i thay d o i gia trj R cua 309 j bien tra V a i L = L i thi dien ap hieu dung tren doan mach chi chiia R C bang 100 V G i a trj U bang A.200V ' \ I O O V V D.20GV2V ClOOV Hu&ngddn U R = IR = R U I cuon cam t h u a n v o i d p t u cam 1/n H va tu dien c6 dien d u n g 0,l/7t m F D i e n l i n g la •gR=>ZLi =Z, A 59,6 V va 33,3 V C 50 V v a 100/3 V L = 2LI:^ZL2=2ZLI=2ZC = U den 2007t rad/s vao hai dau doan mach n o i tiep g o m d i e n t r o R = 300 Q, ap hieu d u n g giira hai dau cuon cam c6 gia t r i Ion nhat va n h o nhat t u o n g R2+(ZL-Zcr ^ U R C = I Z R C Cau : Dat d i e n ap xoay chieu u = 100 ^y2 coscot V v a i 00 thay d o i l u IOOTI rad/s R^2 + Z^ V R ' + ( Z L - Z C ) ' =u " R^ = U = lOOV V R ' + ( Z C - Z C ) ' ' 300^ 1/71 VIO~VTC Cau : M o t doan mach A B g o m doan A M va M B mac n o i tiep D o a n A M g o m ^ tren A M va tren M B l u o n h i o n lech pha TC/2 K h i mach cong h u o n g thi khong ton tai (0 : = 0 = ^ U L = dien ap tren A M c6 gia t r i hieu d u n g U i va tre pha so v o i d i ^ n ap tren AB va 50 V UcoL A B m o t dien ap xoay chieu chi c6 tan so thay d o i d u g c t h i dien ap tuc thai ap tuc thai tren A M lai tre pha hon dien ap tren A B m o t goc V2 V lOO.lCO 100 ^300^ + ( 0 - 0 f "3 100.200 80VS ^300^+(200-50)^ CO = IOOTI = > U L = dien tro R n o i tiep v o i t u d i e n C, doan M B chi c6 cuon cam L Dat vao i m o t goc a i D i e u chinh tan so de dien ap hieu d u n g tren A M la U2 t h i dien B.lOOVvaSOV > D 50 Huang dan :33,3V » 59,6 V Cau 52: D a t dien ap xoay chieu u = Uocoscot (Uo k h o n g d o i va co thay d o i dugc) vao hai dau doan mach g o m dien t r a thuan R, cuon cam t h u a n c6 d o t u cam Biet a i + a2 = n/2 va U2 = 0,75Ui T i n h he so cong suat cua mach A M k h i xay L va tu d i e n c6 dien d u n g C mac noi tiep, v o i CR^ < 2L K h i co = 90 rad/s cong h u o n g hoac CO = 120 rad/s t h i dien ap hieu d u n g g i i i a hai d a u cuon cam co cung A 0,6 B.0,8 C.l D.0,75 Huong dan m o t gia t j D i e n ap hieu d u n g giCra hai dau cuon cam dat cue d a i k h i A 105 rad/s ' B 72 V2 rad/s Huong U, COStti ^ =—- U U2 costto = — ^ = S i n a i ^ U ^ + ^u J = 1- U2=0,75U] - i l l = 0,8 u co, COo C0|C02 V2 C 150 rad/s D 75 V2 rad/s dan = 72 V271 (rad/s) ^/cof+cof ^2 J Cau 53: Dat dien ap xoay chieu u = UocoslOOTit (V) vao hai dau doan mach mac ncVi tiep g o m dien t r o thuan R, tu dien co dien d u n g 0,4/7r (mF) v'a cuon cam t h u a n CO cam k h a n g Z i thay d o i Dieu chinh Z L Ian l u g t bang 15Q, 20Q, 29Q va 50 Q t h i c u o n g dc) hieu d u n g qua mach Ian l u g t bang I i , I2,13 va I4 T r o n g so'cac c u o n g d o hieu d u n g tren gia t r j Icrn nhat la C h B I2 A I i Huang Zr=- coC * D k dan = 25(Q) Vi t r i dinh ZLO = Zc =25(Q) Gang g a n d i n h I cang I d n = > Z L va Z L g^n h d n Z L O = 25Q hcfn n e n chi can so s a n h I2 va I3 Zu, = ^ ' ' ^ :=> 25 ^ ^ Z'L2 = > Z L ^ I2 < I3 311 Cau 54: Cho m o t donn mach xoay chieu g o m dien t r o thuan R thay d o i duoc, Mach cgng hudng => Z L = cupn day thuan cam L va tii d i e n C theo thiV t u mac noi tiep v o i Dat vao hai dau donn mach mot liK/n ap xoay chieu co gia trj hieu d u n g 0 V va tan so f thay doi dugc K h i f = H z t h i c u o n g d o d o n g d i c n hieu d i u i g Uc =100(V) = Ui = R thay d o i Dien d u n g nho nha't cua tu dien la A 25/TC(HF) .V , B 50/Tt (HF) C 0,1/7r (|.iF) D 0,2/:: (nF) Huong dan U R L = I.ZK,., = U I c^zf R^ + zf ""'^ = — = lOOQ ^ V =>C> ? ^ hai dau mach dien mgt dien ap xoay chieu co gia t r i hieu d u n g 0 V va co tan so thay ctoi dugc Gia tri cue dai cua dien ap hieu d u n g tren cugn cam la A.300(V) V „ • ,J .r R^ Z\ n y J thuan cam c6 d o tir cam H , tu d i c n c6 dien d u n g 10'' (F) Dat vao hai dau m a c h dien dien ap xoay chieu chi co tan so goc o) thay d o i K h i dien ap hieu d u n g hai dau tu C dat gia tri cue dai t h i co co gia trj la B 707 (rad/s) ,^ C 2,5.10"^(rad/s) D 500 (ra'd/s) Huong dan -„ C , B 0 ( V ) (l000^/2f VlO-^' I ^ = 1000(Q) ^ ' U c max Z L = Z , =>(oL = 1000 =>(o = 500 (rad / s) C 0 ( V ) Huong dan '12,5.10-"^ 10 100' ,-6 u C max D ( V ) J- vj.v = 100Q Hi rnfi;j ngtjo ,/J 12,5.10,-3 L C a u 55: C h o doan mach k h o n g phan nhanh dien t r o 1000V2t), cugn day A 400 (rad/s) ,73 ii day thuan cam co t u cam , m H va t u dien co dien d u n g pF Dat vao gR Z[ < lOOQ => Z c = Z L < 200Q = ^.10-^F lOOn.200 >R = 0 ( Q ) Cau : M g t doan mach khong phan nhanh g o m : dien t r o thuan 0 iX cugn = ( Z , - Z c ) ^ =>Zc = Z L Z = sJR^+Zl U ' - U ? , + ( U L - U C ) ' v ' A R U K =100V3(V) 73 +Mdc von ke : t r o n g mach la A va dien ap hieu d u n g giCra hai dau R L k h o n g thay d o i = L-6 = u , _ = u ^ = u C • = 200.- 10 R Z \, " 100.100 •J - = 250(V) iA\) Cau 58: Cho doan mach M N theo thi'r t u gom dien tro R mac noi tiep v thuan cam L ncYi tiep vcVi tu dien co dien d u n g C thay d o i dugc la diem noi L v o i C Dat vao dau doan mach dien ap xoa i UMN = 100 V2 cos(1007it + (p) V Thay d o i C de dien ap hieu d u n g tren doan 0' thay d o i C de dien ap hiei-i d u n g tren t u cue dai t h i lap bieu thuc dien ap p,\l,a :?.S • A M cue dai thi bieu thuc dien ap tren d o la UMA = 0 ^ c o s l 0 i t V N e u tren doan M A la Cau 56: M o t doan mach xoay chieu noi tiep A B g o m dien t r o thuan R, cugn A UMA = 100V6cos(1007it + 7T/6) V B UMA = 200 76 cos(1007:t + 7r/6) V cam thuan L va t u dien C K h i noi hai cue cua tu dien v o i m g t ampe ke'co C UMA = 10076 cos(1007rt + 7t/3) V D UMA = 200 76 cos(1007:t + 7t/3) V ' dien t r o ra't nho thi so chi ciia no la 0,5 A va d o n g dicn qua ampe ke tre pha Hwwi^ dan so vcVi dien ap giua hai dau doan A B la 7i/6 Ne'u thay ampe ke bang von ke = IZviA = + = ^ « Cong hUdng , f I J,.,j.„ ,, T nmQ mAh U U | L iMA s d m p h a h d n u M N la vS 313 " M A = 0 C O S lOOTCt V • ; A + - (V) (R + r) C O S ( p i = C S ( P • 2) l(R+rr + ^ 200 / 0, cojC L=CR L-^^ =>LC = Or A' '-—^ (R + r)^ \ M C02L - 0J2C =R ^-^•Wfi^ * C02 (R + r) • cos (pj = • n (R4-r)2 + cojC C0|L = R 100 (R + r) R./'^i -R^2 CO2 Y ™i ( 1—- "1- = 0,96 \ CO2 \ •'•)'r''Xifiyi'iV lV«2 Cau 61: Cho mach dien noi tiep gom cupn day thuan cam co tu cam L ! thay doi dugc, tu dien C va dien tro R Dien ap dat vao hai dau doan mach N u = 100 V6 coslOOnt (V) Khi dien ap hieu dung tren cuon day dat gia trj cue Cau 59: Dat dien ap xoay chieu vao hai dau doan mach noi tiep pom dien tio dai ULMnx thi dien ap hieu dung tren doan mach chua RC la 100 (V) Gia trj R, cuon cam thuan L va tu dien c6 dien dung C thay doi dirge Khi C thay ULM.IX la doi thi dien ap hieu dung cue dai tren R, L va C Ian lugt la x, y va z Ne'u A 100 (V) B 150 (V) z/y= V'S thi z/x bang i C 300 (V) D 200 (V) ] B 0,75 V2 ,,; A 0,5 N/5 yy.) ryAii; ' m.^imii C 0,75 Huong dan u , ( U R m a x va U L ^ , , cong huang I ^ , , = - ' :, , _ w D >/2 > ^i , { Huong dan 'y U Cmax iy-iiQ / l > ioifrJ |UJ-URC u, => ; U L = 7100^+3.100^ = 200( V ) Z = U I R U, z = R = , V U ^ - = 0,5N/5 Cau 62: Cho mach dien xoay chieu RLC vol R la bien tro va cuon day co dien X Cau 60: Dat dien ap u = 125 -Jl coscot (V), co thay doi dugc vao doan mach noi I t r a thuan r = 10 Q Khi R = 15 Q hoac R = 39 Q cong suat cua toan mach la tiep AMB Doan mach A M gom dien tro R noi tiep tu dien, doan mach MB I nhu De cong suat toan mach cue dai thi R bang chiia cuon day c6 dien tra r Biet dien ap tren doan A M luon vuong pha v6i | A 27Q B 25Q rad/s thi mach AB co cung he so cong suat va gia trj bang B.0,85 : C.0,91 (R + r ) ^ + ( Z L - Z c ) Huong dan -Zn Zr U A M -L U M B =^ tancpAM t a n ^ M B = -1 => ~ — — = -1 => L = CR^ c-\ > t)K MI D 36 Q - => (R^+r) + (R2 + r) = (R,+r)(R2+r) = ( Z L - Z c r ^-^U 2ZL-ZC R^ 314 u2(R + r) D 0,82 C 32 Q j Hwang dan dien ap tren doan MB va r = R Voi hai gia trj co = lOOn rad/s va co = 56,257T A 0,96 ft; RQ + r = |ZL - Z C ' i 315 CtyTmiii Pirv t> VVH Khang-yi^T— (Ro + r f = ( R , + r ) ( R + r ) = ^ R n +10 = ^ ( + 10)(39 + ) = ^ Ro = Q B 1/ ::' f R r, L = R>/5 Ucmax Z r = =R«0,499 — JR2+(ZL-Zcf ' ^_ u, \ / \" —> M M u' t Cau 63: H a i doan macli n o i tiep R L C khac niiau: mach T va mach 2, cona h u o n g v o i d o n g dien xoay chieu c6 tan s o g c k Ian l u g t la (oo va 2(oi) Biet tu cam ciia mach gap ba t u cam ciia mach N e u mac noi tiep hai doan mach d o v o i m o t mach t h i no se cong h u o n g v o i d o n g di(R = L(coj-ci)2) = 100Q =>y' = u = > R = 80(P.) VI202 ^ 4j,2 _ » Zco = —^""^-V^ = A > Z c „ = 75(Q) ^ Zc3 ^ Uc3 ^ Ucnnax (OjL VIft ^ ( Z L - Z c ) ' + r + r = 2lZL-Zc Rrmax = 2Pn 2ZL-ZC R2=ZL-ZC R2 + = 76^ r = 2R2-76 =^R2 =60,8Q Cty TNHHMIV Cau 71: Dat dien ap xoay chiou 220 V - 50 H z vao hai dau doan mach n o i tiep Huang g o m dien tro 50 f2, cuon cam thuan c6 cam khang 100 Q va tu dien c6 d u n g khang Zc thay d o i Dieu chinh Zc ian i u g t bang 50 Q, 100 Q, 180 Q va 200 Q thi dien ap hieu d u n g tren t u Ian l u g t bang U c i , Ucz, U c i va Uc4 T r o n g so cac dien ap hieu d u n g noi tren gia t i i ion nha't la A Uci (,,,:; n B Uc2 C.Va P= u2(R Zro = , ,5b::;ipvfi^'>-, , , = " k : ) ^ 0,008R2+Zf Zcl, = ' ' =0,0056 •" ^'«> A:-; muh Zc4 = 0 ' ' =0,005 Gang gan di'nh 1,;,' (R + r ) ^ + ( Z L - Z c ) «Ro =?> ( R „ + r ) +r= ZL-ZC = ( R i + r)(R2 + r) R„ + = 7(15 + ) ( + ) ; -f' \ u- Ro = Q "'"'^ 7 ^ = 1,58 x/T4 U C = L J L „ , , , = U (R „ + r ) Z \4 =u 4,5 ^ ~ r^- CI : ^au 73: Cho mach dien xoay chieu RLC v o l R la bien t r o v a cuon day c6 dien t r a t h u a n r = 10 Q K h i R = 15 Q hoac R = 39 Q cong sua't ciia toan mach la n h u D e c o n g sua't toan mach cue dai thi R bang 20 B.25Q C 32 Q R = 100V5 = ^ = 2,5Zc2 = , ( Z L - R ) = ^ Z L = R ZL Ur 1800 I /-M II I U^R^ + Z^ Zci " = 10VT4Q L L C A.27Q -——^-2,5Zc2 u Cmax J(R + r ) + ( Z L - Z c f i.t.ii^D Zci ' UZc " U c i = IZQ = ^'^' D 36 Q U C , = H S 0 R ^ VR^ 4R' R = 0 = > U = 100^/5(V) u 75: M o t doan mach R-L-C mac noi tiep Dat vao hai dau doan mach m o t dien ap xoay chieu c6 gia t r i hieu d u n g U , tan so'thay doi duac Tai tan so 80 H z dien ap hai dau cuon day thuan cam cue dai, tai tan so 50 H z dien ap hai ban tu cue dai De cong sua't mach cue dai ta can dieu c h i n h tan so' den gia trj A.loVSHz B.20VTOHZ C.loViOHz D.lOHz 321 B6 tr^hicn thJrc V^t liLTDH tren kenh VTV2 tpp - Cliu V^n Blen Huang L R2 ULmax CO1CO2 = L va tu dien cc) d i i ' n d u n g C mac ncVi tiep, vc'>i CR^ < 2L K h i (o = coi hoar co = = ^ = C02= 2OVTO t r o R, cuon day cam thuan L = 2/7i H va tii dien c6 dien d u n g C thay doj 2coi t h i dien ap hieu d u n g giua hai ban tu dien co ciang m o t gia tri K h i CO = 50 rad/s thi dien ap hieu d u n g giua hai ban tu dien dat cue dai T i n h co: A 25 V2 rad/s B 10/lO rad/s doan mach K h i C = Ci/2,5 thi dien ap hieu d u n g gifia hai tu cue dai Tinh tan so goc cua d o n g dien A 2OO7: rad/s B rad/s SOTT •'•f^ C IOOT: rad/s i •• Huang dan +C = C, =^ tan(p, = ^ ^' = D lOjtrad/s \""r" ' ' \ ^ K =Z L -Zci ;y C 100/3 rad/s «o = ^ ( « i + « ) ^ ' - S ' ^ ' =2,5(of =>o), =:10x/iO( rad/s) cuon cam thuan ccS dc) t u cam 1/n H Ne'u dat mc)t t r o n g cac dien ap xoay chieu sau day vao hai dau doan mach trC'n thi c u o n g dc) hieu d u n g r^,;.j mach kVn nha't iVng vcM dien ap nao? C u = U«cos(957rt) V ^' + Uc = max Z(22 = — ; ^ n 71 ^»^' | D u = Uocos(707tt) V , " • ; ' => — = 2 1(1^"' • (o^LC, = ^ co^ ^ B u = Ui)Cos(857tt) V Huang dan ^/->Z(2i = '''''' Cau 79: Doan mach ncVi tiep g o m dien tro, tii dien co dien d u n g 0,l/7i mV va A u = U()Cos(1057it)V 2,5 D 12,5^/lO rad/s Hmhtg dciu dupe K h i C = C: = OAlu mF thi d o n g dien tre pha K/4 S O v o i d i e n ap hai dau " vao hai dau doan mach g o m dien tro thuan R, cuon cam thuan co tu cam Cau 76: Dat dien ap xoay cliieu vao hai dau doan mach A B no'i tiep g o m dien ' =0,14 Cau 78: Dat dien ap xoay cliieu u = Uocostot (Uo k h o n g doi va co thay d o i duc)c) C0,|, = VC0,C02 => f,|, ^ ^ LC U c m a x ^ Z L =(02L = Z , TT =-, = rr> CO = 1007c(rad/s) Gang gan v i t r i cong h i f d n g I cang Ic'in chi can so s a n h CO3 = 95:1 rad/s va CO4 = 10571 rad/s ^" '^^ :,,„:, •, rg- Cau 77: Dat dien ap xoay chieu vao hai dau doan mach A B n o i tiep g o m dien tra R, cuon day cam thuan L va tu dien co dien d u n g C thay d o i d u g c Khi ' C = Ci t h i d o n g dien som pha n/4 so v o i dien ap giica hai dau doan machK h i C = Ci/6,25 t h i dien ap hieu d u n g giua hai tu cue dai T i n t i he so cong sua't mach A B k h i A 0,14 :? , •! ••;•••;/• B.0,71 C.0,8 D 0,9 | HuOltg dmi ';'' +C = Ci =^tan(pi = ^ i - ^ ^ = t a n y =:>Zc, = Z L + R ' , ^ ^ COQ = C ) ' r=> (IOOTT)^ = ( ' ^ { ' * 105,371 > CO4 = > I3 < I4 ' -i r'ii' Cau 80: M o t doan mach A B g o m doan A M va M B mac noi tiep D o a n A M g o m tu dien C noi tiep vcVi dien t r o R, doan M B chi co cuon cam L Dat vao A B m o t dien ap xoay ciiieu chi co tan so'goc (o thay d o i d u g c thi dien ap tuc t h o i tren A M va tren M B l u o n l u o n lech pha 7r/2 K h i mach cong h u o n g t h i dien ap tren A M va M B co cung gia trj hieu d u n g K h i o) = coi thi dien ap tren A M ccS gia trj hieu d u n g U i va tre pha so vc>i dien ap tren A B m o t goc a i K h i co = (02 thi dien ap hieu d u n g tren A M la U2 va dien ap tiic thai tren A M lai tre pha h o n dien ap tren A B m o t goc a2 Bie't a i + a2 = TC/2 va +C = - - r - = > Z c = , Z c i - , ( Z L + R ) 6, 2n U i = 0,75U2 T i n h he so cong sua't cua mach l i n g v o i coi va C02 , ,-,7 *\'tr., fi-V A 0,75 va C 0,75 va 0,75 0,45 B 0,45 va 0,75 , • D 0,96 va 0,96 Huang divi ;; 322 + U c = max , ( Z L + R) = ^ Z^ ^ Khi cong hMng U ^ M = U ^ B = > U R = U, ' 323 la 92,0% Biet dien tro suat ciia dong nho hon dien tro suat ciia nhom 1,47 TraSng hap Mt k i : Ur cogR = — {•MY>r rr,(p = ^ a -9^0 u " =? => cos(p = ssin2a inza , AM Ian Neu dung day dan bang dong cung kich thuoc voi day d i n bang nhom noi tren de thay day nhom truyen tai dien thi h i | u suat truyen tai di^n se la MB T H I : cos iii; Cau 82: Hieu suat ciia qua trinh truyen tai dien nang tren day dan b3ng nhom U sinp = iii- ; • r_ A 92,5% n')ih !:n cos(p2 = 0,96 ; • • ^/ ^ /; - ' \'' ' PR, I-H1 = PR: 1-H, = l-Hi_Ri 1-0,92 1-H, 1-H, R, = 1,47 =:>H2 =^0,946 U^cos^cp Cau 83: Mot may bien ap c6 loi do'i xung gom n nhanh nhung chi c6 hai nhanh dugc qua'n hai cuon day Khi mac mot cupn day vao dien ap xoay chieu thi cac duong sue t u no sinh khong bi thoat ngoai va dugc chia deu cho hai nhanh lai Khi mac cuon vao dien ap hieu dung U thi a cuon de ho c6 dien ap hieu dung U2 Khi muc cuon vai dien ap hieu dung U2 thi dien ap hieu dung a cuon dg ho la A U(n + l)-2 B U ( n - l ) - D U ( n - l ) C Un-2 Huang dan 02 = Cau 81: Mot mach xoay chieu RLC noi tiep chi c6 tan so f dong dien thay doi dirge Khi f = 12,5 Hz va f = 50 Hz thi cong sua't tieu thu cua mach nhu Thay doi f cho cong suat toan mach Ion nhat th' thai gian s c6 bao nhieu Ian cuong dp dong dien qua mach bang 0? A 50 B 15 C 25 Pi = P2 ^ I , = I2 ^ R2 + co,L =>f = 7W = 25(Hz) (24 'ft a A f C O TT L M »2Cj = max =>(o = — =^0) =(0,0)2 M ^ n % J J o ( ( i wC (n-1) (n-l)Ni El (n-1) U2U'2 _ N2 N,02 N2O', (n-1)' (n-l)N2 U2.U'2 U.U2 (n-1)" u U ' , =• ' (n-1)" n,,f,v,v , AB gom R, cuon cani thuan L va C mac noi tiep Khi roto cua may quay deu voi toe Ian lugt ni vong/phiit va n2 vong/phiit thi cuong dong dien ^ R2 + coL - U2 _ N2O2 _ Cau 84: No'i hai cue ciia may phat dien xoay chieu mot pha voi mot doan mach D 75 Huong dan O2 = O, hieu dung va tong tro cua mach doan m^ich AB Jan luct la Ii, Zi va I2, Z2 Biet I2 = 411 va Z2 = Zi De tong tro ciia doan mach AB c6 gia t n nho nhat thi roto ciia may phai quay deu voi toe bang 480 vong/phiit Gia tn ciia ni va n2 Ian lugt la A 300 vong/phiit va 768 vong/phiit V B 120 vong/phiit va 1920 vong/phut => Tron^^ chu k i dong dien = hai Idn C 360 vong/ phiit va 640 y^ng/phut.#^ => Trong s dong dien = Ola 25.2 = 50 idn D 240 vong/phiit va 960 vong/phut 325 Bo trp kien thiic V$t li LTBH tren henh VTV2 t^p - Chu van Huang f= E = Bien Q^U 87: D i e n ap h i ^ u d u n g giua hai cue cua mot t r a m phat di§n can tang len dan = o ) | => n2 = n i CO = 27lf 60 N2TrfO, l2=4Ii a)2L- V2^ cojC •cof =0,25 (0, = 0,5cO() => n j = 0,5n() = 240 =i> n2 = n , = 960 Z| = (oL = 1OOQ; Z c = bao nhieu Ian de g i a m cong suat hao p h i tren d u o n g day tai dien 100 Ian, n = xnj „^,,,, ^ , , ,;, ^ XZL-^C 276 ^ i 2x j ,; xE h • = max ( 877 2^ x , A ; n = xn] = x 576, x , (v/s) • N = 2000 327 Cau 89: M o t may phat dien xoay chieu mot pha c6 d i e n t r o t r o n g k h o n g dang Huang ke, mac vao doan mach n o i tiep RLC K h i toe d o quay ciia roto bang n i hoac n2 t h i c u a n g d o hieu d u n g t r o n g mach c6 cCing gia t r i K h i toe d o quay cug roto la n(i t h i c u o n g hieu d u n g t r o n g mach cue d a i C h o n he t h i i c d u n g A n() = (nin2)"-\• • ' - B no^ = a5(ni2 + n22) • C nir2 = 0,5(nr2 + n2-2) „^ Huong ' " E = NOn ^/2^V2 + n2j A D i e m C each d a u A m o t doan A 25 k m ; CO " B 50 k m C 75 k m Huong sib; ^ B.220 C 250 Huang P- Pcos^ D 85 k m dan D e h d d a u B : x - f R = — = 75Q=:>R = - x I D o a n m a c h dKu B : 2x AC = N e u dat ae m a y tai nha may dien thi cung cap d u d i e n nang cho cp P- , , D 200 •2x + dm P^R 16U^ cos^ cp P^R 64U^ cos^ (p 100 R.(200-2x) U 500 R + (200-2x) Q A B = 25km (75-2x)(200-2x) 500 275 - 4x X = 25Q 100-x •— = 192P, B P = 200Po 100- = 198R X C a u 93: M o t m a y bien ap eo loi d o i x u n g g o m ba n h a n h n h u n g chi c6 hai " : D i e n nang d u g c t r u y e n t u may tang ap dat tai A toi m a y ap dat tai n h a n h duoe qua'n hai cuon day K h i mac m o t cuon day vao d i e n ap xoay B bang day d o n g tie't dien t r o n d u o n g k i n h cm v o l t o n g chieu dai 200 k m chieu t h i cac d u o n g sue t u d o no sinh k h o n g bj thoat ngoai va dugc C u o n g d o d o n g dien tren day tai la 50 A , cae eong suat hao p h i tren d i r o n g chia deu cho hai n h a n h l a i K h i mac cuon vao dien ap hieu d u n g 60 V day tai bang 5% cong suat tieu t h u B Bo qua m o i hao p h i t r o n g cac may thi cuon k h i cte h o eo dien ap hieu d u n g U2 K h i mac cuon v o i dien ap bien ap, coi he so cong suat cua cac mach so cap va thtr cap deu bang 1, hieu d u n g U2 t h i dien ap hieu d u n g cuon k h i de h a la dien t r o suat cua d o n g la 1,6.10 « Q m Dien ap hieu d u n g may t h u cap cua may tang-ap c? A la A 43 k V 528 = 41000(V) n g u o n la 0,168 A K h i dau B h o t h i c u o n g d o n g d i e n qua n g u o n la 0,16 , d u d i e n nang Ian l u o t cho 192 may hoat d o n g va 198 m a y hoat dong P,t = P - A P = 0,05 k h o n g d a n g ke K h i l a m dc:)an mach dau B t h i c u o n g d o d c n g dien qua J Ian lu'ot m a y tang ap c6 ti scY v o n g day N2/N1 = va N2/N1 = t h i ncxi tieu A 280 0,05 t o n g cong cua d u o n g day la 200 Q D o day each dien k h o n g tot nen tgi m o t Cau 90: D i e n nang t r u y e n tai t u nha may phat dien den n o i tieu t h u N e u d i i n g thu 50.41 d i e m C, n g u o i ta d u n g n g u o n dien eo suat dien d o n g 12 V, d i e n t r o t r o n g V \ I,R d i e m C nao d o tren d u o n g day c6 hien t u o n g ro d i e n De phat hien v i t r i C f A P = i f R = 0,05PB = , U , I | ^ U j = U = U j + I j R = 41.10-^50.41 = ( V ) * ( k V ) V2 Z ^ rL 71(0,5.0,01) 7r(0,5df dan CO l l S 200.Kr ~ ( Q ) -8 Cau 92: M o t d u o n g day tai dien g i i i a hai d i e m A, B each 100 k m D i e n tro -co NOn V2 = 1,6.10 Dien dp diXa ten diCdng day d A : .,ll,!r,i1 = D nu = 0,5(ni + n2) f = n p =>(o = 2ni = 2npn En R = p— = p diin , , P !2 JvV .V: { C 40 kV A 15 V B 60 V Huong x D 20 k V C 30 V HD: -1 ^ ^ 2 D 40 V ' ' ' ' dan U'2 =15V 329 •xiry'rrwnTivrv-a-rrTr-Tanmg-r,^ l a u 94: M o t thiet bj dien diroc dat d u o i dien ap xoay ciiieu u = 200':oslOOnt (V), t t i n h bang giay (s) Thiet bj ciii boat d o n g i 2.10 = ^ • • 13 = 6cos cot f = - ^ = 12,5=>(o = 27:f = 257t 60 E > '.li'r; i i = 6cos((i)t) = 372 va dang tang A C = — ^ 257T.80 2.V2VR2+(10-Zcf ^ ^ 5^ ^ = r ^ R = 30Q Day c h i u dupe c u o n g dp d o n g dien hieu d u n g toi da la A Bie't nhiet ^ l u p n g to.i mdi t r u o n g x u n g quanh t i le thuan v o i d i e n tieh mat ngoai eua =-.lO^^F 7C day Ne'u day eo d u o n g k i n h m m t h i day m o i ehju dupe c u o n g d p d o n g dien hieu d u n g toi da la ^ A 32 A R Zau 96: D o n g co k h o n g d o n g bp pha mac h i n h sao, k h i d o n g eo hoat d o n g B A , - ^ d i e n cac cuon day 1, va Ian l u p t la 0, 27r/3 va -27r/3 Vao t h o i d i e m Tidj Q = k7ld2i = 24 A D A Huong dan Q = k7rd,URiI?t = p ^ I ? t b i n h t h u o n g a d i e n ap 200 V thi eong sua't tieu thu cua d o n g co bang 1620 72 VV va he so eong sua't la 0,9 eho m o i pha Pha ban dciu eua d o n g , R2l2t = p A - l t nd2 ill 41? , , ,; I9=ll d2 Ui; 1,5 1,5 = = 24A 10,5; 331 Cty Tisnii nirv nx'vii Cau 99: Neu toe d o quay cua roto tang them v6ng/s thi tan so ciia d o n g dien d o II = 0 ( , ) ^ + 400(0,1)2 : ! = , V may phat tang t u 60 H z den 70 H z va suat dien dong hieu d u n g d o may phat thay d o i 40 V so voi ban dau H o i neu tiep tuc tang toe cua roto Cau 102: M o t may bien ap l i t u o n g luc m o i san xuat c6 ! i so d i e n ap hieu d u n g them v6ng/s nua thi suat dien dong hieu d u n g may phat la bao nhieu? giOa cuon so cap va t h u cap bang Sau m o t t h o i gian s u d u n g d o l o p each A 320 V d i e n kern nen c6 x v o n g day cuon t h u cap bj noi tat, v i vay t i so d i e n ap hieu B 240 V C 280 V Hu&iig f, = n p = 60Hz f = np: D.400 V dan d u n g giua cuon so cap va t h u cap b3ng 2,5 De xac d j n h x n g u o i ta quan them vao cuon t h u cap 135 v o n g day t h i thay t i so d i e n ap hieu d u n g cuon fn = f2 = ( n + l ) p = H z J ' ^ | p = 10 so cap va t h u cap bang 1,6 So v o n g day bj noi tat la f3 = ( n + ) p = 80Hz A X = 50 v o n g N2nf Dap an C A \ u., , , M j y rv^UK "I I = , ( A ) => P(„ = I R = 5,375^32 = 1584,2W > 178W 334 42) le t h u a n v o i chieu dai cua day) Do su co, d u o n g da / bi ro d i e n tai d i e m Q cong sua't cua d o n g co la 0,9 va cong sua't hao p h i nho h o n cong sua't co hpc I = 1(A) y day CO d i e n t r o tong cong Q (coi day tai dien la d o n g cha't, r o dien tro ti •>< C a u 106: M o t d o n g co dien xoay chieu co dien t r a day cuon la 20 Q, mach dien A 72Z, + j =4 Zc dien nang d u g c truyen tai den noi tieu thu N , each M k m Biet d i r o n g IOOI2 A 0,25 R + ( Z , - Z C ) ' xac d j n h v j t r i Q , trirdc tien n g u o i ta ngat d u o n g day k h o i may phat va tai CO dien r.p hieu d u n g 220 !>•• ^ -= R2 I rioo72f UV2 J =^ZC=2R;ZL=R D 300 V ^ luV2 1 IURLV2, + I - Cau 108 ( D H 2012): T i r m o t t r a m phat dien xoay chieu m o t pha dat tai v j t r i M , u KL C max < ^ U R L 2Z, + = R2 ' i'K ' >•) 'I ' , ' 1, ' * ' I » 'AM ( ( jiiy !4>i (J,)^;' / \ I * ', iifi < (1 - / I 1 , ' ' ill , , ^ , I, ^ , t A ! • , 331 [...]... cupn day vao dien ap xoay chieu thi cac duong sue t u do no sinh ra khong bi thoat ra ngoai va dugc chia deu cho hai nhanh con lai Khi mac cuon 1 vao dien ap hieu dung U thi a cuon 2 khi de ho c6 dien ap hieu dung U2 Khi muc cuon 2 vai dien ap hieu dung U2 thi dien ap hieu dung a cuon 1 khi dg ho la A U(n + l)-2 B U ( n - l ) - 2 D U ( n - l ) C Un-2 Huang dan 02 = Cau 81: Mot mach xoay chieu RLC noi... Dat vao A B m o t dien ap xoay ciiieu chi co tan so'goc (o thay d o i d u g c thi dien ap tuc t h o i tren A M va tren M B l u o n l u o n lech pha nhau 7r/2 K h i mach cong h u o n g t h i dien ap tren A M va M B co cung gia trj hieu d u n g K h i o) = coi thi dien ap tren A M ccS gia trj hieu d u n g U i va tre pha so vc>i dien ap tren A B m o t goc a i K h i co = (02 thi dien ap hieu d u n g tren... -1 ^ ^ 2 2 D 40 V ' ' ' ' dan U'2 =15V 329 •xiry'rrwnTivrv-a-rrTr-Tanmg-r,^ l a u 94: M o t thiet bj dien diroc dat d u o i dien ap xoay ciiieu u = 200':oslOOnt (V), t t i n h bang giay (s) Thiet bj ciii boat d o n g i