h, = - H , ^ = PR ^1-H, 1-H2 - H ; _ ~ VU2 1-0,35 t r o n g cac mach l u o n ciang pha v o i dien ap L a n l u o t dien ap d u a len la U i H , =0,974 {5J U2 COS^ (J) va U t h i h i ^ u suat t r u y e n tai t u o n g l i n g la H i va H T i m t i so U2/U1 hai tru'ong h o p : a) cong sua't d u a len d u o n g day khong doi; Chon B ' ' b) cong sua't n h ^ n d u o c cuoi d u a n g day k h o n g d o i V i d u 16: Can t r u y e n tai cong sua't dien va dien ap nhat d i n h t u i.ha may ^1^'; noi tieu thu bang day dan c6 d u o n g k i n h day la d Thay the'day truyen t'^' Huong dm A p dyng cong thuc: h = - H — ' ;• ; d i e n ' b a n g m o t day khac c u n g chat lieu n h u n g co d u o n g k i n h 2d t h i hi'^^' sua't tai d i e n la % H o i k h i thay the'day t r u y e n tai bang loai day cijng cli'''| lieu n h u n g co d u o n g k i n h 3d t h i hieu sua't t r u y e n tai d i e n k h i la b'^' - H = PR U^'os^cp nhieu? A.96% I) h = l B.94% C.92% " P 95% I-H2 PR •2::; _ U | c o s2:> 1-H 1-H2 Ujcos cp 24^ Bd trg kiSn thtic V$t It LTOtI tr6n kgnh VTV2 t^p b) Thay P = P'/H vao cong thuc h = - H = >(1-H)H = P'R U^cos^cp - Chu Vdn Blgn PR P'R ^ ta du"oc: - H = HU^cos^ U cos cp ( - H ) H _ U^cos^(p _ P'R "(l-Hi)H, " 'l' H i e u suat t r u y e n tai dien sau (P' g i u nguyen AP' = H, = P'+AP' P'+ P' 1900 1901 Ap d u n g : U2 _ (l-H,)Hj _ (1-0,95)0,95 U]Cos (p 1900"i 1900 Lai khuyen: Den day ta nen nha hai ket qua quan de giai tiCv cdc hai todn phicc tap hon: Khi P khong doi thi ^ 1901J1901 bao nhieu Ian de g i a m cong suat hao p h i tren d u o n g day tai dien n Ian, v o i {l-Hi)Hi dieu kien cong suat truyen den tai tieu thu k h o n g doi? Biet rang k h i chua (1-H2)H2 tang dien ap d o g i a m dien the tren d u o n g day tai dien bang x U ( v o i U la d i e n n o i tieu t h u k h o n g d o i , bSng mot d u o n g day nhat d j n h N e u dien ap dien ap hieu d u n g giira hai cue cua tram phat dien) Coi c u o n g d p d o n g dien t r o n g mach l u o n cung pha v o i d i e n ap dat len d u o n g day Huang dan dua len d u o n g day la k V thi hieu suat tai dien la 75% De hieu suat tai B.5,96kV CSVskV D 15 k V Hwang dan Ap d u n g : ^ (l-Hi)Hi V(1-H2)H2 U2 hi=l 1(1-0,75)0,75 ^(1-0,95)0,95 Chii y: Neu cho biel giam the tren duang day ta tinh dugc hieu suat truyen tai: UIcoscp U I P' = H i P = ( l - x ) P = > P = ^ „ AU (1-x) -H = = x ' U AP = h j P = -P' 1-x cos(p P' H , =• P'+ AP' I f , 111 ' ' J'(;.(!' 11 H i e u suat t r u y e n tai dien sau (P' giir nguyen AP' = U2 « , ( V ) =^Chon B P ^ ^ H i e u suat t r u y e n tai dien t r u o n g hop d a u : dien 95% t h i dien ap dira len la A.3kV Chon D V i du 21: D i e n ap hieu d u n g giua hai cue cua m o t tram phat dien can tang len V i du 19: Can t r u y e n tai dien t u nha may den nai tieu t h u cho cong suat ' = 9,505 ^ U2 = 9,505Ui Chii y: Dethn cong thicc dep ta giai bdi todn tong qiidt han 1-Hi Khi P khong doi thi U2 1900 1900 P' P' P' AP 100 AP n n(l-x) P'): n(l-x) n(l-x) + x n(l-x) V i dy 20: D i e n ap hieu d u n g giiia hai cue ctia mot tram phat dien can tang len 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, v o i dieu kien cong suat truyen den tai tieu thu k h o n g doi? Biet rang Ap d u n g : Hi- Ui "\((1-H2)H2 1_ 7^ n(l-x) n ( l - x ) + x^ n ( l - x ) + x chua tang dien ap g i a m d i ^ n the tren d u o n g day tai dien bSng 5% dien ap h i f u d u n g giiia hai cue ciia tram phat dien Coi cuong d o d o n g dien n(l-x) + x x(l-x) 0-Hi)Hi V i du 22: D i e n ap hieu d u n g giua hai cue ciia m o t tram phat d i e n can tang len t r o n g mach l u o n cung pha v o i d i ^ n ap dat len d u o n g day bao nhieu Ian de giam cong sua't hao p h i tren d u o n g day tai d i e n n Ian, v o i A 8,515 Ian dieu kien cong suat truyen den tai tieu thu k h o n g doi? Biet rang k h i chua B 9,01 Ian C I O Ian D 9,505 Ian tang dien ap g i a m dien the tren d u o n g day tai dien bang x U ' ( v o i U ' la Huang dan dien ap hieu d u n g n o i tai tieu thu) Coi cuong dg d o n g dien t r o n g mach H i f u suat t r u y e n tai d i ^ n t r u a n g h o p dau: y u = H i P = C,95P=>P= H i = , = > H i =0,95< A P - h i P = 0,05P = ^ ^ 0,95 l u o n cung pha v a i dien ap dat len d u o n g day Huang dan H i e u sualt t r u y e n tai dien t r u o n g h a p d a u : , , : ' >• M; '.; a', • 245 tid itp klStt ihat: 11 tttJti h, = - H i = AU U i.ip tr€n k&nh VTVJ AU X U'+AU x +1 '/ s lui van P' = H i P = AP BISti H i e u sua't t r u y e n tai sau (P' giCr nguyen AP' = x +1 AP = h i P = xP' _ U2_ (l-Hi)H, V(1-H2)H2 Ui 1~ + X 1+ n n + X n + X n n + (1 Ap Gia sir he so cong suat n o i tieu thu bang De hao p h i t r u y e n tai giam di 100 Ian so v o i t r u o n g hop dau thi dien ap dua len d u o n g day la A p d u n g : ^2 _ ] n+X ( l + x)>/n • => C h g n B a- U, kn kn + x kn X [T (k + x ) V n J kn + X tai tieu thu k h o n g doi? Biet r§ng chua tang dien ap g i a m dien the tren d u o n g day tai dien bang 10% dien ap hieu d u n g tren tai tieu t h u Coi c u o n g d o n g dien t r o n g mach luon cung pha v o i dien ap dat len d u o n g day B 9,5 Ian ^ • ^ Ui + 0,1 , may the If f u o n g c6 ti so v o n g day N1/N2 = k va cuon t h u cap noi v o i tai tieu t h u D i e n ap hieu d u n g giua hai cue ciia m o t trcim phat dien can tang CO tieu tliu -^-n^-^r: , • • • 1 (CT) cong to thi sochi cm cong ta nang ma dong • ? VlOO Chu y: Klii dong ca dim mac sau chinh la dim D 9,3 Ian Huangddn'' (k + x ) V n =>ChonB nsii.4 C 8,7 Ian - ]^.^J-J-^^^ni.9,5 Apdung: 9:;, nS'(iJ'J* k +x k + x ^_ y(l-H2)H2 hao p h i tren d u o n g day tai dien 100 Ian, vai d i r u kien cong sua't t r u y e n den ' Jivyu^j^ u i ^ t.i '>t: i;i.,r,5, = 10.10^.40 = 4.10^' ( V ) ' D 192 V : , '.jSil/ ly'l V/:,; ; • ; ]!!:, : • /iX;';: '"•fim^'M A U = a%Ucos(p ^ A U = 0,05.4000.0,96 = ( V ) =>ChonD = lO.lO^.gO'X - 9.10^' ( V ) , , ' V i du : D i e n n a n g d u g c t r u y e n tai t u A den B bang hai day d o n g c6 d i f n t r o tong cong la Q C u o n g hieu d u n g tren d u o n g day tai dien la 100 A , V i du 28: M o t t r a m phat d i e n t r u y e n d i cong suat 1000 k W bang day dan c6 d i e n t r o t o n g cong la Q, d i e n ap hai cue cua may la 1000 V H a i cue cua m a y d u g c n o i v o i hai dau cuon so ca'p cua may tang ap l i t u o n g ma so'vong cong suat tieu hao tren day tai dien bang 2,5% cong suat tieu Hiu B T i m cong suat tieu t h u B A.20kW day cua cuon t h u cap gap 10 Ian so v o n g day cuon so cap Bie't he so cong suat cua d u o n g day la H i e u suat qua t r i n h t r u y e n tai la : A 80% I -;i,.aOir[;Mn ^ D 20,35 k W AP = ^ R = » , ( k W ) = > C h o n C P = PMP'H I Theo bai ra: AP = a % U I cos m b a n g Xac d j n h cong suat hao p h i tren d u o n g day A 20,05 k W 'I' C M V B 87% C.92% Huang D 95% ;•: B.200kW •A', s i v : , j i , C M W Huang dan I^R = 0,05PB => lOOls = 0,05.Pu => Pg = 2.10" ( W ) D 2000 W , AJO I A - ::^#« MfciU-;vW*;»,::{6,t>,.- ; ; • = > C h o n C X' dan Chu y: Neii noi tieu thu diing may dp vd cong suat hao phi tren duang day bang if/o U-U = 1000.10 = ' ' ( V ) PR H =l - h = l 10^8 = 92% 10*^ P = P„pH = 10''(W) cong sud't tieu thu tren tai thi: I?R = a%U2l2Cos(p2 r^ChonC Chuy: I, ' " lj| 1) Neil cho biel cong siiat hao phi tren duong day bang a% cong suat am len duong day thi AP = a%P I^R = a%UIcos(p o IR = a%Ucos(p o A U = a%Ucos(p 2) Nell cho Met cong siid't hao phi tren diivng day b^ng «% cong suat suat nhan dugc cuo'i dudng day thi AP = 248 a%P' R l2COS(p2 Dien dp dua len duang day: U = U , + A U = U , + I , R V'! V i du 32: N g u o i ta t r u y e n tai dien nang t u A den B b i n g he t h o n g day dan t u CO d i e n t r o Q t h i c u o n g d o n g dien hieu d u n g tren day la 60 A Tai B d u n g m a y t h e ' l i t u o n g Cong suat hao p h i tren day bang 5% cong suat 249 Wi l,a hicn V^t n LIVII Ih'it lien HBlin VMVJ, IJI/J tieu thu a B va dien ap a cupn t h u cap cua may t h e c o gia trj hieu d u n g d u : D i e n nang d u g c t r u y e n t u may tang ap dat tai A t o i may ap dat tai la 300 V l u o n ciJng pha v o i d o n g dien qua cuon t h u cap T i so so v o n g day B bang day d o n g tie't dien tron d u d n g k i n h cm v o i tong chieu dai 200 k m ciia cuon t h u cap va so cap cua may the la C u o n g d o d o n g dien tren day tai la 100 A , cac cong sua't hao p h i tren d u o n g A 0,01 B 0,004 C 0,005 - ' Huong dan • D 0,05 day tai bang 5% cong sua't tieu thu B Bo qua m o i hao p h i t r o n g cac may ' * '• bien ap, coi he so cong suii't cua cac mach so cap va t h u cap deu b3ng 1, dien fro sua't 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 Theo bai ra: i f R = a % U l cos(()2 N2 11 U2 = — ^ = N, U1 A 43 60 N2 ! tang ap A la l = 0,05.300.12-1 => I2 = 0 ( A ) r=>—i- = I2 cos(p2 N, =^ChonD = 0,05 J 1200.1 ^f,il'\H-M'4hA ' -Hhibi nwirii ' ir\f(\T •5 kV B 42 kV C 40 k V ; " ^i''"' D 86 kV ••• ; *^f • -muh :;mm\Kn(.lM tai dien m o t pha c6 dien tro R = 30 Q Biet dien ap hieu d u n g a hai dau cuon K(o,5d)2 s ' / i d u 3 : Dien nang d u g c tai tu tram tang ap toi t r a m ap bang d u o n g day A P = 5%PB ^ K(o,5.o,oi)2 I ? R = 0,05U,I, ^ ' ^ ,, ,:., '" ' so cap V a t h u cap cua may ap Ian l u g t la 2200 V va 220 V, c u o n g dong dien chay t r o n g cuon t h u cap cua may ap la 100 A Bo qua ton hao nang l u g n g cac may bien ap Coi he so cong sua't bang Dien ap hieu d u n g o hai dau cuon t h u cap cua may tang ap la Dien ap hieu d u n g may t h u cap cua may tang ap d A : , U = U , + I , R = 82.10^ +100.41 = ( V ) * ( k V ) ^^-H^^^^ =^ChonD A 2200 V Ui B 2500 V 2200 I2 U2 _ I i 220 _ 100 I, C 4400 V D 2420 V •r:>I, =10(A) Vi d u : ( D H - 2012) T u mot t r a m phat dien xoay chieu m o t pha dat tai v i t r i ,Via;t£«i , (jfiodD- U = U , + A U = U , + I i R = 2200+ 10.30 = 2500(V) j^rifo gaoi A, : =>ChonB M , dien nang d u g c t r u y e n tai den n o i tieu thu N , each M 18O k m Biet d u d n g day c6 dien tro tong cong 80 Q (coi day tai dien la d o n g cha't, c6 dien tro ti le thuan v o i chieu dai cua day) D o su co, d u o n g day bj ro d i e n tai die'm Q (hai day tai dien bj noi tat boi m o t vat c6 dien t r o c6 gia trj xac d i n h Vi d y 34: C u o n so cap cua may tang the A dugc noi v o i nguon va B la may R ) De xac d i n h v i t r i Q, truoc tien n g u o i ta ngat d u o n g day k h o i may phat the CO cuon so cap noi voi dau cua may tang the A Dien tro tong cong cua va tai tieu t h u , sau d u n g nguon dien k h o n g d o i 12V, dien t r o t r o n g day noi tir A den B la 100 Q M a y B c6 so v o n g day cua cuon so cap gap 10 so k h o n g dang ke, noi vao hai dau cua hai day tai dien tai M K h i hai dau day v o n g day cua cuon t h u cap Mach t h u cap cua may B tieu thu cong sua't tai N de h o t h i c u o n g d o n g dien qua n g u o n la 0,40 A , k h i hai dau lOOkW va c u o n g hieu d u n g mach t h u ca'p la 100 A Gia su ton hao cua day tai N d u g c noi tat boi m o t doan day c6 d i e n t r o k h o n g d a n g ke thi cac may bien the A va B la khong dang ke He so cong sua't tren cac mach c u o n g d o d o n g dien qua n g u o n la 0,42 A Khoang each M Q la deu bang Dien ap hieu d u n g hai dau mach t h u ca'p cua may A la A 135 k m A.llOOOV B 10000 V ;;„X < ".c-,;i«il!o C 9000 V Hu'migddn ^ = l l ^ l , = l ^ = 0 - = 10(A) N, I2—i^.^ N, 10 Pi = P2 =^ U i l i = P2 ^ U i l O = 100.10^ >ifi i clJ ft)j«{ j i f i >.f 250 I idq triu?, vjinwuJ ti ,: t • m/fif^M) (;d gntib -tfii R = — = 30(Q) I =i'R=30-2x U i = 10* ( V ) ,.^, \Bm D 90 k m K h i dau N de ho, d i e n t r o cua mc^ch: 2x + U = U i + A U = U i + I i R = 10^+10.100 = 11000(V) fl , => Chon B C 45 k m Hitdiigdan „^r'^ , _ MdyB: B 167 k m D 12000 V ^ ' ' " X * K h i dau N noi tat, dien tro cua mach: ^ 2x+ • ^-(-"-^-^ =M.^(Q) R + (80-2x) I ^ ' 40-x * ^ * R N 40-x 251 Cty TNHtt nrv D vvn Hhang Vtft no-4x => MQ =-J^MN = 45(km) B A I T A P D|NH TINH Chon c V i du 37: Mot duong day tai dien gii>a hai diem A, B each 100 km Dien tro tong cong cua dirong day la 120 Q Do day each dien khorg tot nen tai mot diem C nao tren duong day c6 hien tugng ro dien De phat hien vi tri diem C ngudi ta dung nguon dien c6 sua't dien dong 41 V, dien tro IQ Khi lam doan mach dau B thi cuong dong dien qua nguon la 1,025A Khi dau B ho thi cuong dong dien qua nguon la A Diem C each dau A mot doan A 50 km B 30 km C 75 km "> D 60 km Humg dan De hd dau B : 2x + R + r = y = 41Q => R = 40 - 2x Doan mach d^u B : 2x + R + (120-2x) + >2x + (40-2x)(100-2x) 160-4x => AC = 60 Ck\i 1= Cac gia tri hieu dung eiia dong dien xoay ehieu '' A duoe xay dung dua treH tac dung nhiet evia dong dien B chi duoc bang cac arqpe ke xoay chieu C bang gia trj trung binh chia cho ^ ' "1 "Jry) '••x = 15Q hieu dien the hieu dung hai dau cuon day va cuon day Dc U = Ui + U2 AB = 30(km) can CO dieu kien nao sau day? P A L i n = L2r2 60-x R ' i t t v «)[!iiirh ifi \) B 60-x B Lir2 = L2ri C L1L2 = r i r i D Li + L2 = n + r2 •, o!:) • ^ Cau 4: Cho mach dien gom dien tra thuan R, cuon cam thuan L, tu dien c6 dien dung C Chon cau diing: ;,j;, A Dien ap tiie thoi giiJa hai dau L va cuong dp dong dien tuc thai mach luon dat cue dai ciing mot liic B Dien ap tiie thoi giQ-a hai dau C va cuong dong dien tuc thai mach luon dat cue dai cung mot luc '1, • C Dien ap tuc thai giija hai dau mach va cuong dong dien tuc thai mach luon dat cue dai cung mot luc • t'k r D Dien ap tuc thoi giCra hai dau R va cuong dp dong dien tuc thoi mach iuon dat cue dai cung mot luc Cau 5: Cho mach dien gom cuon day c6 t u cam L noi tiep vol hpp kin X Phuong trinh cuong dong dien qua mach va hieu dien the hai dau doan mach la • i = IQCOS (Ot + — 252 ( A ) ; U A B = UoCos cot — ( V ) 3J 6J X chua nhCrng phan t u nao? A R, L va C B R va C C R va L 253 Bo trp hien thiic V^t li r mil licit h.cnh VTV2, t^p - Chu Vdn Bi^n Cty TNirn MTV o vvii Khang Cau ( D H 2008): Cho doan nicich gorn dien t r o thuan R noi tiep v o i t u dien co doan mach k h i doan mgch t r o cua doan mach la A CO L va C mSc n o i tiep B chi co tu C C CO R va C mac noi tiep D co R va L mac noi tiep R2 + •not fi)'vj,^;/sdft; coC C ^ R + ( O ) C ) ^ " B A cung tan so v o i hieu dien the o hai dau doan m a c h va co pha ban dau D 7R^-(COC)^ m o t dien ap xoay chieu o n d i n h D o thi ciia dien ap tuc t h o i gii>a hai dau ^, doan mach t h e o c u d n g d o n g dien tuc t h o i mach c6 dang 1^ A hinhsjn B doan thang C di^ong t r o n c a m k h a n g v a d u n g khang tuan theo bieu t h i k R = Z L = 3Zc Ket luan nao ,,;,;f,;Sau day la d u n g k h i noi ve c u a n g d o d o n g dien hieu d u n g chay qua cac j p h a n t u t r o n g mach? ^m^mm^am * • C a u 9: C h o n cau d u n g k h i noi ve d o n g dien xoay chieu? XKA ••-•'ai.l •• C D i e n l u g n g chuyen qua tiet dien thang cua day dan c6 d o n g dien xoay chieu chay qua t r o n g m o t khoang thoi g i a n b a t k i deu bang p Cong suat toa nhict t r u n g binh cua dong dien xoay chieu bien thien dieu hoa B H e so cong suat cang Ian thi cong suat hao p h i cua mach cang Ion C D e tang hieu qua su' d u n g dien nang, ta phai t i m each nang cao he so ^ C a u 11: C u o n g d o d o n g dien l u o n l u o n som pha h o n hieu dien t h e o hai dau doan mach k h i C doan mach co R va C va L mac noi tiep D doan m a c h co L va C mac noi tiep " «*"'^ / ^ ~ •) A Zi < Zc n v r i f q B Zi, = Zc ' pnif, C Zi = R D Zi > Zc D e dien ap hieu d u n g giira hai (Jau doan niach A N k h o n g p h u thuoc R t h i tan so goc co bang A - i ^ 2V2 B.(0iV2 C ,t> gnr> ' ' ' D.2(oi N/2 ^ K C a u 16 ( C D 2012): D a t dien ap u = U(icos(cot + ) vao hai dau doan mach g o m dien t r o thuan R va cuon cam thuan co d o t u cam L mac n o i tiep H e so B.-, C A D C a u 17 ( D H 2012): Dat dien ap u = Uocoscot vao hai d a u doan m a c h g o m dien tro t h u a n R, cuon cam thuan co t u cam L va tu dien co dien d u n g C mac noi tiep G o i i la c u o n g d o n g dien tuc thoi doan mach; u i , U2 va us D Cong suat cua cac thiet bj dien t h u o n g phai c6 coscp > 0,85 B doan mach co R va C mac noi tiep mach dien l u o n CO A ^ A H e so'cong suat cang Ion thi cong suat tieu t h u cua mach cang I o n ; chieu u = Uocoswt t h i d o n g dien t r o n g mach la i = Iocos(tL)t + TT/6) Doan cong suat cua doan mach la C a u 10: Chon cau tra l o i sai k h i noi ve y nghia cua he s o c o n g suat coscp? A doan mach co R va L mac noi tiep C S u 14: Dat vao hai dau doan mach RLC k h o n g phan nhanh m o t dien ap xoay d u n g C D a t (Oj = — ^ = p Gia t r j t r u n g b i n h cua c u o n g d o d o n g dien t r o n g m o t chu k i bang cong suat C l u o n lech pha nil so v o i hieu dien t h e o hai dau doan mach tiep v o i cupn cam t h u a n co d o t u cam L , doan N B chi co t y i e n v o i dien fi.),;>( A Co the d i i n g d o n g dien xoay chieu de ma dien = U iuv d = i i r i ^ ,'I j^ntv-'.! o ; ' hai doan mach A N va N B mac noi tiep Doan A N g o m bien t'-o R mhc noi •••• D l K = l L = I rc- -il )n\f« ;jri6:* Cau 15 ( D H 2010): Dat dien ap u = U%/2 coscot vao hai dau doan mach A B g o m BB 3 Il KK = l L = I c , , , , « r f , ; , : e , c k.k-k luonb^ngO B cung tan so va c i m g pha v o i hieu dien the hai dau doan mc.ch D CO gia trj hieu d u n g t i le thuan v o i dien t r o cua mach D eHp C a u 8: Cho doan mach xoay chieu R, L, C mac n o i tiep Gia t r j cua dien tro, A-IR=2IL=3IC j C a u 13 ( C D 2007): D o n g dien xoay chieu doan mach chi co dien t r o thuan C a u 7: Cho mach dien xoay chieu chi c6 tu dien Dat vao hai dau doan mach 254 Cau 12: C t f o n g d p d o n g dien l u o n l u o n tre pha hon hieu d i ? n tiie a hai dau d i e n d u n g C K h i d o n g dien xoay chieu c6 tan so goc bi chay qua thi to'ng A Vjft Ian l u g t la dien ap tuc thoi g i t i a hai dau dien tro, g i i i a hai dau cuon cam va g i u a hai dau tu dien; Z la tong tro cua doan mach H e thuc d i i n g la A i = uscoCfi ' B i = ^ C i = ^-.^.b D i = ^ i C a u 18 ( C D 2012): Dat dien ap u = U Q cos(a)t + ^) vao hai dau doan mach g o m dien t r o thuan R mac noi tiep v o i cupn cam thuan co d p t y cam L, c u o n g d p B o t r g kien thiic V^t U LTDH tren kenh VTV2 tap - Chu Viln Blcn cty T/mriflft f/ Khang Vi^t B D i e n ap giua hai dau dien tro thuan sam pha 71/4 so v o i dien ap g i i i a hai d o n g d i e n t r o n g mach la i = IQ sin(cot + • ^ ) Biet Uo, lo va co k h o n g d o i He dau doan mach thuc d i i n g la ;)•• ,:AJ'r'.t V; vi'sTi: C C u o n g d o d o n g dien qua mach som pha 7T:/4 SO v o i d i e n ap giira hai dau A R = 3coL B a)L = 3R C.R=>/3coL D coL=^/3R doan mach Cau 19 ( C D 2012): Dat dien ap u = U%/2 cos27tft (trong U khor-g d o i , f thay D Dien ap giua hai dau dien t r o thuan tre pha 7t/4 so v o i d i ^ n ap giira hai doi du-oc) vao hai dau d i e n t r a thuan K h i f = fi t h i cong suat tieu t h u tren d i e n t r o bang P K h i f = ii v o i h = f i t h i cong suat tieu t h u tren d i e n t r o bang A V P B - CP dau doan mach Cau 24: Dat m o t dien ap xoay chieu vao hai dau doan mach g o m d i e n tro thuan R, cuon cam thuan c6 cam khang Zi va t u d i e n c6 d u n g k h a n g Zc D.2P ll mac nol tiep theo t h u t u tren N e u R2 == Z i Z c t h i Cau 20 ( C D 2012): Dat dien ap xoay chieu vao hai dau d o a n mach X mac no! K A cong suat cua mach se giam neu thay d o i d u n g k h a n g Zc tiep chiia hai t r o n g ba phan t u : dien t r o thuan, cuon cam t h u a n va tu dien H B dien ap giira hai dau doan mach ciang pha v o i d o n g d i e n t r o n g mach Biet r^ng d i e n ap giira hai dau doan mach X l u o n s o m pha so v o i c u o n g d o n g d i e n t r o n g mach m o t goc nho h o n ^ D o a n m a c h X chua A cuon cam t h u a n va tu d i e n v o i cam k h a n g Ion h o n d u n g k h a n g B d i e n t r a t h u a n va tu dien C cuon cam t h u a n va t u dien v o i cam khang nho h o n d u n g k h a n g D d i e n t r o t h u a n va cuon cam t h u a n ' C d i e n ap tren doan mach RL som pha h o n dien ap tren d o a n mach RC la 71 • D dien ap tren doan mach RL cham pha hon dien ap tren doan mach RC la _^ 4' : ice uftft'OBn -ysidj ettl Vfmm HKO'O ^ n o i i iv.)\Xf •^•non oh fyitiu-j Cau 25: D i e n ap g i u a hai dau m o t doan mach RLC noi tiep s o m pha 7T/4 SO v o i Cau 21 ( C D 2009): Dat dien ap u = UQ cos(cot + J ) vao hai dau doan mach chi c u o n g d o n g d i e n Phat bieu nao sau day la diing d o i v i d o a n mach CO tu d i e n t h i c u o n g d o d o n g d i e n t r o n g mach la i = I(icos(ft)t + cpi) Gia t r i ciia nay? (pi b a n g A H i e u so'giua cam khang va d u n g khang bang dien t r o t h u a n cua doan A.-^ B C ^ D ^ Cau 22 ( D H 2011): D a t d i e n ap u = U V coscot vao hai dau m o t t u di?n t h i c u o n g d o n g d i e n qua no c6 gia t r i hieu d u n g la I Tai t h o i d i e m t, d i e n ap hai dau t u dien la u va c u o n g d o d o n g dien qua no la i H e thuc lien he g i i i a cac dai l u o n g la , u^ i^ U2 j2 M u " i p ^ ,, B T o n g t r o cua doan mach bang hai Ian dien tro thuan cua mach .^jf-, C Tan so' d o n g d i e n t r o n g doan mach nho h o n gia t r i can de xay cong hudng D D i e n ap gi&a hai dau dien t r o thuan som pha TC/4 so v o i d i e n ap giija hai ban tu dien ^ u^ ^2 i^ j2 0,444 Cau 23: D a t d i e n ap u = Uocoscot vao hai dau doan mach g o m d i e n t r o t h u a n R va t u dien C mac no'i tiep Biet dien ap giCra hai dau d i e n t r o t h u a n va dien ap giira hai ban t u dien c6 gia trj h i ^ u d u n g bang n h a u Phat bieu nao sau day la sai ? A C u o n g d o d o n g d i e n qua mach tre pha n/4 so v o i d i e n ap g i i i a hai dau d o a n mach mach v Cau 26: Dat d i e n ap xoay chieu u = Uucos27Tft (Uo k h o n g d o i , f thay d o i duoc) vao hai dau doan mach chi c6 tu dien Phat bieu nao sau day diing? A C u o n g d o n g d i e n hieu d u n g doan mach cang Idn k h i tan so f cang Ion ; > B D i e n ap giua hai dau doan mach som pha n/2 so v o i c u o n g d o n g dien doan mach C C u o n g d o n g dien hieu d u n g doan mach k h o n g d o i k h i tan so f thay d o i D D u n g khang cua tu dien cang Ion k h i tan so f cang I o n 257 Cty Timnnrvown Bo tiy hicn thiic V^t li L TDll tren kenh VTV2 t^p - Chu VSn Bien Khang Vipt Cau 27: D a t vao hai d a u doan mach chi c6 m o t phan tir m o t hieu d i e n the xoay Cau 32: D o a n mach xoay chieu A B chi chua m o t t r o n g cac phan t u : D i e n t r a chieu CO bieu thuc; U = UN/2COS m t - • ( V ) t h i d o n g d i e n chay qua phan 4^ V thuan, cuon d a y hoac t u dien K h i dat m o t dien ap u = Uocos(cot + n/6) V vao hai d a u A B t h i d o n g dien t r o n g mach co bieu thuc i = Iocos(cot - n/3) A tir d o CO bieu thuc i = lV2 sin c o t - - ( A ) Phan t u d o la m o t c D o a n mach A B chua A dien t r a thuan B t u dien C cuon day t h u a n cam •.i,,,::^:.,:,, D cuon day c6 d i e n t r a C a u 28 ( D H 2010): D a t dien ap u = Uocoswt vao hai d a u cuon cam thuan c6 t u cam L t h i c u o n g dt) d o n g dien qua cuon cam la ' A i = H o cos(o)t + - ) o)L ^ B i = - H ) ^ C i = HiIcos(c,t-^) (oL ^ , • I ' ' B D i ^ n t r o t h u a n " C C u o n d a y co d i e n t r a t h u a n D C u o n d a y t h u a n cam " C a u 33: D i e n ap giira hai d a u m o t doan mach R L C no'i tie'p s a m p h a ^ so vc>i c u o n g d o d o n g dien Ket luan nao sau day la dung? A T o n g i r o ciia mach bang Ian dien t r o R cua mach cos((ot + - ) (0LV2 r A T u dien B H i e u so g i u a cam k h a n g va d u n g khang bang ' C C a m k h a n g bang V2 Ian d u n g khang D.i=-4^cos(cot-^) coLV2 "f''-'' > 1f " ' < D T o n g t r o cua mach bang V2 Ian dien t r o R cua mach.' C a u 29 ( C D 2010): D a t dien ap xoay chieu u=U()Coso)t vao h a i d a u doan mach C a u 34: D a t m o t d i e n ap xoay chieu co gia t r j hieu d u n g U va tan so goc ro chi CO dien t r o t h u a n Goi U la dien ap hieu d u n g g i i i a h a i d a u doan mach; k h o n g d o i vao hai d a u m o t doan mach co R, L, C mac no'i tie'p, i r o n g d o R la H i , lo va I Ian l u o t la gia t r i tuc t h o i , gia t r i cue dai va gia t r i hi?u d u n g ciia m o t bien t r o , Zc ^ Zi K h i thay d o i R de cong sua't cua doan mach cue dai : c u o n g d o d o n g d i e n t r o n g doan mach H e thuc nao sau day sai? thi A — - -1- = Uo lo A cong sua't cue d a i d o bang B Uo + ^ = N/2 C ^ - T = I„ U I D ~ + ^ = Uo C a u 30 ( C D 2010): D a t dien ap u = Uocoswt co (o thay d o i d u o c vao h a i dau doan mach g o m cuon cam thuan c6 t u cam L , dien t r o t h u a n R va tu dien CO d i e n d u n g C mac n o ! tie'p K h i co < J— t h i VLC ,,, '" ' A dien ap hieu d u n g g i u a hai d a u dien t r a thuan R bang d i e n ap hieu d u n g g i u a hai d a u doan mach d u n g g i u a h a i d a u doan mach doan mach D c u o n g d o d o n g dien t r o n g doan mach cung pha v o i d i ^ n ap g i i i a h a i dau ^ C a u 31(CD 2008): D a t m o t hieu dien t h e x o a y chieu co gia t r i hieu d u n g k h o n g d o i vao hai d a u doan mach R L C k h o n g phan nhanh H i e u d i e n the g i i i a hai dau : A doan mach l u o n cung pha v a i d o n g dien mach B cuon day l u o n ngugc pha v o l hieu dien the'giua hai d a u t u dien C cuon d a y l u o n v u o n g pha v a i hieu dien the'giua hai d a u t u dien D t u d i e n l u o n c u n g p h a v o i d o n g dien t r o n g mach 258 - *• C t o n g t r a ciia doan mach la | Z L - Z c | ' < D he so'cong sua't ciia doan mach la coscp = — C a u 35 ( C D 2007): D o a n mach dien xoay chieu g o m dien trtV thuan R, cuon day l i n g la h i ^ u d i e n the tuc t h o i hai dau cac p h a n t u R, L va C Q u a n he ve pha ciia cac hieu dien the'nay la C c u o n g d o d o n g dien t r o n g doan mach tre pha so v a i d i e n ap giua hai dau doan mach B gia t r j bien t r o la ( Z L + Z , ; ) thuan cam (cam thuan) L va tu dien C mac no'i tie'p K i hieu UK, UI., UC t u o n g B dien ap hieu d u n g gii>a hai d a u dien t r o t h u a n R n h o h a n d i e n ap hieu i A UR tre pha 7T/2 so vcS-i uc C UL s o m pha TI/2 SO v a i uc ' ,< B uc tre p h a TT so v a i UL ' D Uu s o m p h a n/2 so v o i ui, C a u 36 ( C D 2007): D a t vao hai d a u doan mach R L C k h o n g p h a n n h a n h m o t hieu d i e n t h e x o a y chieu u=Uo sincot K i hieu U u , U L , Uc t u a n g u n g la hieu dien the hieu d u n g h a i d a u dien t r a thuan R, cuon day t h u a n cam (cam thuan) L va t u dien C Ne'u U R = Ui./2 = Uc t h i d o n g d i e n qua d o a n mach A tre p h a n/2 so v o i hieu dien the'a hai d a u doan mach * ' ' B tre p h a n/i so v a i hieu dien the h a i dau doan mach '* C s o m pha n/4 so v a i hi§u dien the'a hai dau doan mach D s a m pha Tr/2 so v o i hieu dien the'6 hai dau doan mach 259 Bo trf) hicn thitc V^t li LTDtl tren k&nh V T V t^p < Ini VSn ' Cty Blen Train MTV DVVH Khang Vi^t C t r o n g mach CO cong h u o n g dien D Thay d o i R thay k h i R = R i hoac R = R2 t h i mach tieu t h u cong suat ban D dien ap giua hai d a u cuon cam lech pha 7T/6 SO v o i dien ap j i u a hai d a u n h a u M a c h tieu t h u cong suat cue dai k h i R = •j(R^ + R2 ) doan mach Cau 88: D o n g dien (xoay chieu) tuc thoi t r o n g mot doan mach R L C mac n^^j Cau 93 ( D H 2007): Dat hieu dien the'u = Uosincot (Uo k h o n g doi) vao hai dau tiep d a n g som pha h a n so v o i dien ap tuc thoi giua hai dau dean mach Ta doan mach RLC k h o n g phan n h a n h Bie't dien tro t h u a n ciia mach k h o n g l a m thay d o i t r o n g cac thong so ciia doan mach bang each neu sau day doi K h i CO hien t u o n g cong h u o n g dien t r o n g doan mach, phat bieu nao M u o n xay hien t u o n g cong h u o n g dien t r o n g mach, ta phai sau day sai? A tang tan so d o n g dien xoay chieu B g i a m dien d u n g cua tu dien * D tang dien t r o cua mach > tiic t h a i o hai dau dien tro R ! C Cam k h a n g va d u n g khang cua doan mach bang D H i e u dien the hieu d u n g hai dau dien t r o R nho h o n hieu dien t h e h i e u pha so v o i dien ap hai dau doan mach M u o n xay hien t u o n g cong h u o n g dien t r o n g mach phai d u n g hai d a u doan mach d o i d u g c Bie't d u n g k h a n g ciia t i i dien bang R Vs D i e u c h i n h L de dien ap C g i a m dien t r a cua mach hieu d u n g giua hai dau cuon cam dat cue dai, k h i do: D g i a m tan so d o n g dien xoay chieu A dien ap giua hai d a u t u dien lech pha n/6 so v a i dien ap giCra hai dau Cau 90: D u n g k h a n g cua m o t mach RLC mSc noi tiep d a n g c6 gla t r i n h o hon cam khang M u o n xay hien t u o n g cong h u o n g dien t r o n g mach ta phai ,7 C Z L Z C = R +Zc B dien ap giua hai dau cuon cam lech pha n/6 so v o i dien ap giua hai dau d o a n mach doan mach Cau 95 ( D H 2012): Dat dien ap u = Uocos2/rft vao hai d a u doan mach g o m dien t r o thuan R, cuon cam thuan c6 t u cam L va tu dien c6 dien d u n g C L dat cue dai Bieu thiic sai la v s ; \m :K ' ' • D dien ap giua hai dau dien tro lech pha n/6 so v o i dien ap giua hai dau T r o n g U , m , R va C k h o n g d o i Dieu chinh L de dien ap hieu d u n g tren + • \ t r o n g mach c6 cong h u o n g dien Cau : Dat dien ap u = uV2coscat vao hai dau doan mach R L C n o i tiep = U| + I f A f^S'i) ' T r ' ; D g i a m tan so d o n g dien xoay chieu A doan mach ! A tang dien d u n g ciia t u dien : :; tiep g o m dien t r o t h u a n R, tu dien va cuon cam thuan c6 t u cam L thay B tang he s o ' t u cam ciia cuon day C g i a m dien t r o cua mach Cau 94 ( D H 2009): Dat dien ap u = UoCOscot vao hai d a u doan rr.ach mac noi A tang dien d u n g cua t u dien B tang he so t y cam cua cuon day VfCi^i B H i e u dien t h e t i i c t h a i hai dau doan mach ciing pha v o i hieu dien the » Cau 89: D o n g dien xoay chieu t r o n g m o t mach RLC mac n o i tie'p d a n g cham ii h-'44rd i ' A C u o n g hieu d i m g cua d o n g dien t r o n g mach dat gia trj I a n nha't ' ,1 M L I C g i a m he so t u cam cua cuon day , -fi, ^ j B U [ - U C U L D U^^ = ^ ^ = ^^l^ — mac n o i tiep Goi UK, U I , UC Ian l u g t la dien ap hieu d u n g giua hai dau dien tro, giua hai dau cuon cam va giCia hai dau tu dim T r u o n g h g p nao sau day, dien ap tiic t h a i giua hai dau doan mach cung pha v o i dien ap tuc thoi giua hai dau dien tro? Cau 92: Dat dien ap u = Uocoscot vao hai dau doan mach mac n o i tiep g o m dien t r o thuan R, t u dien va cuon cam thuan c6 tir cam L thay d o i dugc Bict d u n g k h a n g cua tu dien bang R^/3 Dieu chinh L de dien ap h i ^ u dung ' giira hai d a u cuon cam dat cue dai, k h i A dien ap gii>a hai dau dien tro lech pha n/6 so v a i dien ap giua hai dau doan mach B Thay d o i R deUcnwx C Thay d o i L de D Thay doi f de Ucnux Ui.nvix Cau 96 ( C D 2012): Dat dien ap u = U(icos((ot + (p) (voi Uu va (o k h o n g doi) vao hai dau doan mach g o m bie'n tro niclc noi tiep v o i cuon cam thuan Dieu chinh bien t r a de cong sua't toa nhiet tren bien tro dat cue dai K h i A dien ap hieu d u n g giua hai dau bien t r o bang dien ap hieu d u n g giCJa hai ' B dien ap giua hai dau t u dien l^ch pha n/6 so v a i dien ap giij'a hai dau doan mach • :;;,;,>::::270 A Thay d o i C deUKni.vv •••• , dau cuon cam thuan 271 Bo tr^ klen thitc V^t I I L T D t l tren hinh VTV2, Cty t^ip - Chu Van Bl6n B dien ap hieu d u n g giua hai dau bien t r o bang hai Ian dien ap hieu d u n g giiia hai d a u cuon cam thuan > ' '» • ' C he so cong suat cua doan mach bang n) Cau 97 ( C D 2012): Dat dien ap u = U(icos(cot + cp) (Uo va (p k h o n g doi) vao hai dau doan mach mac noi tiep g o m dien t r a thuan, tu dien va cucn cam thuan CO t u cam L thay doi duoc K h i L = Li hoac L = L2 thi c u o n g d o d o n g dien hieu d u n g t r o n g doan mach bang De c u o n g d o n g d i e n hieu d u n g doan mach dat gia t r i cue dai thi gia t r i cua L bang A.i(L,+L2) B - ^ C - ^ , D.2(L,+L2) Cau 98: Dat dien ap u = U()COs((iit + (\>) vao hai dau doan mcach c6 F,L,C mac noi tiep Bie't co^LC = Dieu nao sau day k h o n g dung? iJcb tf iS: A C u o n g d o n g dien hieu d u n g mach Ion nhat mach Ion nhat ij; D Dien ap tuc t h o i giCfa hai dau doan mach bang d i ^ n ap tuc : h i g i i i a hai ' ' Cau 99 ( C D 2009): Dat dien ap xoay chieu u = Uocos27:ft, c6 Uo k h o n g d o i va f thay d o i d u o c vao hai dau doan mach c6 R, L, C mac noi tiep K h i f = to thi doan mach c6 cong h u o n g dien Gia tri cua fo la - A -3=^ VLC • B.-S= N/LC • ' C.-i= ' VLC ' D' 271^V L C • d u o c ) vao hai dau doan mach g o m dien tro thuan, cuon cam thuan va tu dien mac noi tie'p Dieu chinh co = coi thi cam khang cua cuoxi cam thuan bang Ian d u n g khang cua tu dien K h i co = 0)2 t h i mach xay hien t u o n g cong h u o n g dien He thuc d u n g la B a)2 = 2coi C ci)i=4co2 au 102 ( D H 2009): Dat m o t dien ap xoay chieu co gia t r i hieu d u n g U vao hai va tu dien co dien d u n g C mac no'i tie'p theo t h u t u tren Goi Ui,, U R va Uc Ian i u g t la cac dien ap hieu d u n g giiia hai dau m o i p h a n t u Bie't d i e n ap giua hai dau doan mach A B lech pha ^ so v o i dien ap giira hai dau doan mach N B (doan mach N B g o m R va C ) He thuc nao d u o i day la dung? A D co2 = 4coi u = UN/2 cos(27rft) ( V ) , v o i U k h o n g doi f thay d o i duoc H i e n t u o n g ifij,,;.- ; A thay d o i t u cam L de dien ap hieu d u n g giua hai dau cuon cam (thuan) dat cue dai B thay d o i dien d u n g C de dien ap hieu d u n g giCra hai ban tu dien dat cue dai C thay d o i R de cong suat tieu t h u tren doan mach dat cue dai 272 + B C U ^ = U f ^ + U ^ + U ^ = U|+ + D U | = U ^ + U^+U2 Cau 103 ( D H 2008): Doan mach dien xoay chieu khong phan nhanh g o m cupn chay qua doan mach t h i he so'cong suat ciia doan ,1, a v i i j * mach A p h u thuoc dien t r a thuan ciia doan mach B bang C p h u thuoc tong t r o cua doan mach D bang Cau 104: Doan mach xoay chieu g o m m o t cuon day mac noi tie'p v a i m o t t u dien D i e n ap hieu d u n g giira hai dau cuon day g i i i a hai ban t u hai dau doan mach Ian l u o t la Ucd, Uc, U Bie't U d = \Jcs[2 va U = Uc I-Jhari xet nao '"^'j^'i-^ " A C u o n day co dien tro thuan k h o n g dang ke va d o n g dien t r o n g mach cung pha v o i dien ap giua hai dau doan mach B C u o n day co d i e n t r o thuan dang ke va d o n g dien t r o n g mach v u o n g pha vox dien ap giua hai dau doan mach C C u o n day co dien t r o thuan dang ke va d o n g d i ^ n t r o n g m^ch c i i n g pha v o i dien ap giiJa hai d a u doan mach ''^ S>"'7'5 ^'•*> vfix iff.>II D D o U L > Uc nen Z L > Zc va mach k h o n g the thuc hi&n d u g c cong huong Cau 101: Dat vao hai dau doan mach R L C mac n o i tie'p m o t dien ap xoay chieu cong h u o n g dien xay k h i = U| + sau day la d u n g v o i doan mach nay? Cau 100: ( C D 2012): Dat dien ap u = Uocos((ot + cp) (Uo k h o n g d o i , co thay doi A coi=2co2 dai dien CO tan s o g o c C D o lech pha giua c u o n g dong dien va dien ap gii>a hai dau doan dau dien t r o R D thay d o i tan so' f de dien ap hieu d u n g giCra hai dau dien t r a R dat cue day CO t u cam L, dien t r o thuan R va tu dien co d i e n d u n g C K h i d o n g PCM):* rlCii* '{! B Cong suat tieu thu cua doan mach la UoV 2R q Vi^t dau doan mach A B g o m cuon cam thuan co t u cam L , dien t r o thuan R D he so cong suat cua doan mach bang 0,5 '" TNHH MTV D VVH Khang ' ' ^au 105: H e so cong suat ciia doan mach xoay chieu R, L, C k h o n g phan nhanh CO gia t r i cue dai k h i A tan so cua n g u o n xoay chieu bang tan so'rieng ciia mach B lech pha g i i i a c u o n g dp d o n g d i ^ n mach va d i ^ n ap g i i i a hai dau mach bang 90" ' ^ C chi k h i h i ^ u d i ^ n the giua hai ban t u dien co tr} so bang di?n ap ciia nguon ,, ' 273 Cty TIMll! D lech pha giua cuong dong dong dien mach va dien ap hg, A U o dau dien tro R bang 90" C a u 106: K h i dien ap giua hai dau doan mach R L C mac noi tiep som pha 7t/4 so ^ ' ^ ^ VT^t D 4UoV2 Cau 110: Mot dien tro thuan R mac vao mach dien xoay chieu tan so' 50 H z voi dong di^n mach thi Muon dong dien mach som pha hon di?n ap giira hai dau doan mach A tan so ciia dong dien mach nho hon gia trj can xay hien tuorig mot goc 7t/2, nguoi ta phai cong huong "'V"* A mac them vao mach mot tu dien noi tiep voi dien tro B tong tro ciia mach bang hai Ian phan dien tro thuan R ciia mach D dien ap giiia hai dau dien tro som pha '''' ' •' 's B mac them vao mach mot cugn cam thuan noi tiep voi dien trc C hieu so giij-a cam khang va dung khang bang dien tro thuan cua mach (lien B 3Uo MTV D VV/f Khahg C thay dien tro noi tren bang mot tu dien D thay dien tro noi tren bang mot cugn cam thuan so voi dien ap giua hai d a u tu ' ' ' * Cau 111: Mach xoay chieu R L C c6 dien ap hieu dung a hai dau doan mach 'f*' " khong doi Hi^n tugng cong huong dien xay A thay doi R de dien ap hieu dung tren dien tro R cue dai C a u 107: K h i c6 cpng huong dien doan mach di|n xoay chiei; R L C thi ' ' B thay doi tan so' f de dien ap hieu dung tren tu dat cue dai A dDien ap tuc thoi giua hai dau dien tro thuan ciing pha voi dien ap tuc • ' ' C thay doi dien dung C de dien ap hieu dung tren tu dat cue dai thai dat vao hai dau doan mach D thay doi tu cam L de dien ap hieu dung tren dien tro R drt cue dai B di?n ap tuc thai giiia hai dau di^n tro thuan cung pha voi di?n ap tuc thoi giiJa hai dau cuon cam Cau 112: Mach dien xoay chieu khong phan nhanh theo dung thu tu gom dien JJ tro R, tu dien C va cugn cam thuan c6 tu cam L thay doi Dieu chinh L de C dien ap tuc thai giiia hai dau dien tro thuan cung pha voi di$n ap tuc thoi giiia hai ban tu dien dien ap hieu dung tren cugn cam dat gia tri cue dai thi di^n ap giua hai dau ^ D cong suat tieu thu tren mach dat gia trj nho nhat Cau 108: Mgt mach di^n xoay chieu khong phan nhanh gom mpt cupn d a y mach W' u = Uocoscot (voi Uo va co khong doi) Ket luan nao sau day la sai ve hien tugng thu dugc thay doi C? A Den gia tri ma hieu dien the hieu dung tren tu dien dat gia Iri cue dai thi mach dien c6 tinh dung khang B Gia trj cue dai ciia hieu dien the hieu dung tren tu C dat dugc nho H o n hoac bang gia tri hieu dung cua hieu dien the tren hai dau mach dien C K h i xay cong huong thi hieu dien the tren tu di^n se vuong pha so v o i hieu dien the tren hai dau mach dien D Voi gia trj cua C lam cho cong suat tieu thu tren cugn day d j t cue dai th' dong dien mach se cung pha so voi hi^u dien the tren hai da>^' mach dien C a u 109: Mot cugn day mac noi tiep voi tu dien c6 dien dung thay doi dugc l O ' mac vao nguon dien xoay chieu c6 bieu thuc u = UoCos(X)t(V) Thay d^' 4; K B lech pha 71/2 voi dien ap tren L CO he so tu cam L , dien tro thuan R va mot tu dien C c6 dien dung thay doi dugc Dat vao hai dau mach mpt hieu di^n the xoay chieu xac d i n h A lech pha 71/2 voi dien ap tren doan L C C lech pha 7i/2 voi dien ap tren C ||, D lech pha Tt/2 voi dien ap tren doan R C ' ^ C a u 113: Mach dien xoay chieu R L C noi tiep c6 dung khang Ian hon cam khang De c6 cong huong dien, ta c6 the A giam dien dung cua tu dien B giam he so'tu cam ciia cugn day • *J51 I H C tang dien tra thuan cua doan mach D tang tan so'dong dien Cau 114: Mach dien xoay chieu khong phan nhanh theo diing thu tu gom tu di^n C , dien tra R va cugn cam thuan L Dieu chinh C de di?n ap hi^u dung tren tu dat gia tri cue dai thi dien ap gii>a hai dau mach A vuong pha voi di^n ap tren doan R L o'; ' B vuong pha voi dien ap tren L : *)£,' C vuong pha vdi dien ap tren C - n D vuong pha voi dien ap tren doan R C dien dung cua tu dien de cong suat toa nhi^t tren cugn day dat cue dai th' jCau 115: Trong doan mach R L C noi tiep dang xay cong huong Tang dan dien ap hieu dung tren hai ban tu la 2Uo Di^n ap hieu c'ung giua h'^' tan so'dong dien, giCr nguyen di^n ap hieu dung giua hai dau doan mach va dau cugn day liic la giu nguyen cac thong so'cua mach, ket luan nao sau day khong diing? ' •! n • •••no-ii^n 275 B S trp MSn thiSrc V$t H LTDH tren hgnh : VTV2 t^p - Chu VSn Bign C a u 121: C h o n phat bieu dung? M o t t r o n g n h u n g u u d i e m cua may bie'n the A H e so'cong suat ciia doan mach giam t r o n g sir d u n g la B C u o n g hieu d u n g cvia d o n g dien g i a m A k h o n g birc xa song dien tir t C D i e n ap hieu d u n g g i i i a hai ban tu dien tang 4^5, jv^j /; , , " '"Mg B k h o n g tieu t h u d i e n nang ., D D i e n ap hieu d u n g giiia hai dau dien t r o g i a m sul /» v h "-''^f''' •-^'^^^ C Co the tao cac hieu dien the'theo yeu cau sir d u n g C a u 116: T r o n g m o t doan mach d i e n xoay chieu RLC mac noi tiep, k h i xay cong h u o n g t h i phat bieu nao sai? A D i e n ap tuc t h o i tren doan mach bang dien ap tuc t h o i tren d i ^ n t r o B T o n g d i e n ap tuc t h a i tren tu dien va tren cuon cam bang ,.||| , D K h o n g C O s u hao p h i nhiet d o n g dien Phuco f»'ht " ' ' ' • '' • * C a u 122: C h o n phat bieu d u n g ? ' ^'^^ A C h i CO d o n g dien ba pha m o i tao tir t r u o n g quay ' ' 8'"'^' • "' B Roto ciia d o n g eo k h o n g d o n g bo quay v o i to'c d p g o t cua tir t r u o n g C T o n g d i e n ap h i ^ u d u n g tren tu dien va tren cuon cam bang 3, ,j D D i e n ap hieu d u n g gii>a hai dau doan mach bang d i f n ap h i f u d u n g tren SO C a u 117: T r o n g mach dien xoay chieu RLC n o i tiep d a n g c6 cong h u o n g dien t h i ket l u a n nao sau day SAI? d a u t u d i e n ,f-, ^ ( \ rtq unoM B C u o n g d o hieu d u n g t r o n g mach cue d a i imiti veox ft^ib r{:'f,M :Sri C D i e n ap hieu d u n g hai dau doan mach I o n h o n d i e n ap hieu d u n g hai dau d i e n t r o R C a u 118: T r o n g m o t d o a n mach dien xoay chieu RLC mac noi tiep, k h i xay cong h u o n g t h i phat bieu nao sau day sai? i \ n Ian ma k h o n g thay d o i cong suat truyen d i , ta can ap d u n g bien phap nao neu sau day? ' D T r o n g mach chi eo dien t r o thuan hoae c6 xay cong h u o n g d i e n / ap? A D u n g l o i sat C O d i ^ n t r o suat nho Cau 123: C h o n cau sai k h i noi ve d o n g co k h o n g d o n g bo pha C a u 125: De g i a m cong suat hao p h i tren m o t d u o n g day tai d i e n x u o n g bon C a u 120 : Bi§n phap nao sau day khong gop p h a n tang hieu suat ciia may bie'n n? D Toe d o goe ciia d o n g co k h o n g d o n g bp p h u thuoe vao to'c d o quay ciia t r u o n g quay D D i e n ap hai d a u mach c i i n g pha v o i dien ap hai dau d i e n t r o K •ri • tir t r u o n g va vao m o m e n can A D i e n ap hieu d u n g a hai dau cuon cam bang dien ap h i ^ u d u n g gii>a hai , C Vecto cam i r n g tir ciia tir t r u o n g quay l u o n thay d o i ve ca h u o n g Ian trj A' dien t r o ' '• ' A Tang dien ap giua hai dau day tai t r a m phat dien len b o n Ian ( I B Tang dien ap giua hai dau day tai t r a m phat d i e n len hai Ian C G i a m d u o n g k i n h tiet dien day d i bon Ian *• B D i m g day c6 d i e n t r o suat nho l a m day quan bie'n ap C D i m g l o i sat g o m nhieu la sat m o n g ghep each d i e n v o i n h a u D Dat cac la sat cua l o i sat song song v o i mat phang ehua cae d u o n g sue tii^ ' D G i a m dien t r o d u o n g day d i hai Ian C a u 126: De g i a m bat hao p h i d o toa nhiet tren d u o n g day k h i can tai dien d i xa T r o n g thuc te^ eo the d i i n g bien phap • 4^sl''iifidH s-cl • 277 Bo' tr^ k i c n thUc V^l li L mil t r c n kenh VTV2 t^p - Chu V^n BiSn Cty A g i a m hieu d i e n the may phat dien n Ian de g i a m cirang d o n g dien C cong con} suat tieu thu dien h u u ich tang dien tren d u o n g day n Ian MTV nvyil KhungVl^ B ccuoi u o n g d o d o n g dien hieu d u n g tang tren day n Ian, g i a m cong suat toa nhiet x u o n g n^ Ian B tang hieu d i e n the n o i san xuat dien len n Ian de g i a m c u a n g dong ' , , j D cong suat tieu t h u P giam CaU 132: Goi N i la so v o n g day ciia cuon so cap, N2 la so v o n g day cua cugn C D i i n g day d a n bang vat lieu sieu dan d u o n g k i n h Ion t h u cap cua m o t may bien ap Bie't N i > N2, may bien ap co tac d u n g D Xay d y n g nha m a y gan n o i tieu t h u dien de g i a m chieu da: d u o n g day A tang cuong dong dien, giam dien ap t r u y e n tai dien ,.,,,,,,^,1,,,,^.,,:,,„ B giam cuong dong dien, tang dien ap Cau 127: D i e u khang d j n h nao sau day la d u n g k h i n o i ve may bien ap? A M a y bien ap c6 the lam thay d o i dien ap cua d o n g dien m o t d i i e u *''' , D giam cuong dong dien, giam dien ap Cau 133: Goi fi, ii, C N e u so v o n g day cuon so cap Ion h o n s o v o n g day cuon t h u cap t h i goi la may ap ' ^-' ' C tang cuong dong dien, tang dien ap B M a y bien ap c6 tac d u n g lam thay doi tan so cua d o n g dien xoay chieu , Ian l u g t la tan so d o n g dien xoay chieu ba pha, tan so'ciia t u t r u o n g , tan so ciia roto dong co k h o n g d o n g bo ba pha Ke't luan nao sau day la d u n g k h i noi ve mo'i quan he giua cac tan so' D N e u so v o n g day cuon so cap Ion h o n so'vong day cuon t h u cap thi goi la A.fl = f2 = f3 C fl = f < f may tang ap B.f, = f2>f3 ,v'-'^^#*-*'>^ D f l > f = f3 V'tJ Cau 134: K h i d o n g co k h o n g d o n g bo ba pha hoat d o n g o n d j n h v o i toe Cau 128: D i e u nao sau day la sal k h i noi ve d o n g ca k h o n g d o n g bo ba pha? A Co hai bo phan chinh la Stato va Roto quay cua t u t r u o n g k h o n g d o i thi to'c quay ciia roto B Bien d o i dien nang nang l u o n g khac A Ion h o n toe quay cua t u t r u o n g C T u t r u o n g quay d o n g co la ke't qua cua viee sir d u n g d o n g dien B l u o n bang toe quay cua t u t r u o n g • C nho h o n toe quay cua t u t r u o n g xoay chieu m o t pha D H o a t d o n g d u a tren co so hien t u g n g cam u n g d i e n t u va s u d u n g t u t r u o n g quay , ' D CO the Ion h o n hoac bang toe quay cua t u t r u o n g , t u y thuoc tai Cau 135: K h i cho d o n g dien k h o n g d o i qua cuon so cap cua m a y bien ap t h i : ,,|,v,,>,., „;;:',,,„ mach k i n cua cuon t h u cap Cau 129: D i e u nao sau day la sai k h i noi ve ttong co k h o n g d o n g bo ba pha? A Toe goc da on dinh cua khung day luon nho hon toe goc cua t u truong quay B K h o n g the thay d o i chieu quay cua d o n g co chi bang viee dao v i t r i ba pha d u a vao ba cuon day tren Stato A CO d o n g dien xoay chieu chay qua ' B CO d o n g dien m o t chieu chay qua ' C CO d o n g dien k h o n g d o i chay qua ' '" " D Vi^c d u a d o n g t h a i ba pha cua d o n g dien xoay chieu ba pha vao ba cuon ' t r u o n g quay t r o n g d o n g co co tan so ' ' ^ A bang tan so'ciia d o n g dien chay t r o n g cac cuon day ciia stato cua d o n g dien xoay chieu d u a vao B Ion h o n tan so'ciia d o n g dien chay t r o n g cac cuon day ciia stato ,, Cau 130: D o n g dien pha mclc h i n h co tai do'i x u n g g o m cac b o n g den N e u d u t day t r u n g hoa thi cac den co sang B k h o n g d o i , T Cau 136 ( C D 2009): K h i d o n g co khong d o n g bo ba pha hoat d o n g o n d j n h , t u day tren Stato la de tao t u t r u o n g quay v o i tan so quay bang tan so' A tang ,' D k h o n g CO d o n g dien chay qua C D o n g CO hoat d o n g d u a tren nguyen tac cua hien t u g n g cam u n g d i e n t u isn TlStin ' C CO the Ion h o n hay nho h o n tan so'ciia d o n g dien chay t r o n g cac cuon day ciia stato, t u y vao tai C giam ' D k h o n g sang D nho h o n tan so'ciia d o n g dien chay cac cuon d i y ciia stato co Cau 137: K h i truyen tai m o t cong suat dien P t i l noi san xua't den noi tieu thu, de d i e n v o i cong suat d j n h m u c P va dien ap d j n h m u c U , neu nang cao h$ so giam hao p h i tren d u o n g day toa nhiet thuc te'nguoi ta tie'n hanh lam n l i u cong suat thi lam cho the nao? Cau 131: D o i v o i cac d u n g cu tieu thu dien n h u quat, tu lanh, d o n g A cong suat toa nhiet tang MV,,;, ;^ r - ? A Dat o d a u ciia nha may dien may tang the'va a noi tieu thu may the 279 f/y Men thetc V^t It Ltvil uau KKIUI VIVJ I^/J J " t^Miu-nrrr B D a t dau ciia nha may dien may the va dat n o i tieu t h u may t h e h o a c tang the'tuy vao n h u cau t u n g dja p h u a n g C a u 143: Phat bieu nao sau day d u n g v o i may phat d i e n xoay chieu? A D o n g dien cam u n g chi xua't hien a cuon day cua p h a n u n g , k h o n g the C C h i can dat dau cua nha may dien may tang the, dieri tren d u o n u day d u g c s u d u n g true tie'p ma k h o n g can m a y bien the xua't hien cuon day cua phan cam B Tan so ciia sua't d i e n d p n g t i le v o i so v o n g day ciia p h a n u n g D Dat dau cua nha m a y dien may tang t h e v a dat n o i tieu t h u may the hoac tang the'tuy vao n h u cau t u n g dja p h i r o n g C Bien d o ciia sua't d i e n d o n g cam u n g t i le v o i so v o n g day ciia phan l i n g D Co nang c u n g cap cho m a y d u y c bie'n d o i hoan toan t h a n h diijn nang C a u 138 ( C D 2012): M o t m a y phat dien xoay chieu m o t pha c6 phan cam jg C a u 144: Phat bieu nao sau day la d i i n g k l i i noi ve may phat dien xoay chieu ba roto va so'cap cue la p K h i roto quay deu v o i toe n (v6ng/s) t h i t u thong pha qua m o i cuon day cvia stato bie'n thien tuan hoan v o i tan so ( t ' n h theo don A M a y phat dien xoay chieu ba pha bien dien nang co nang va ngugc , viHz)la A lai B M a y phat d i ^ n xoay chieu ba pha hoat dong nho hien t u g n g cam u n g dien 60 ,, B — 60p C.60pn ^ D.pn ^ , ^ C a u 139: M o t may tang ap c6 cuon t h i i cap mac v o i dien t r a t h u a n , cuon so cap do, c u n g tan so'va cung pha mac vao n g u o n d i e n xoay chieu Tan so'dong dien t r o n g cuon thi'r ca'p A l u o n Ion h o n tan so d o n g dien cuon so cap ^, C bang tan so d o n g d i e n t r o n g cuon so cap C a u 145 ( D H 2008): Phat bieu nao sau day la d i i n g k h i noi ve d o n g d i ^ n xoay ' chieu ba pha ? D CO the n h o h o n hoac Ion h o n tan so d o n g dien t r o n g cuon so r a p C a u 140: M o t m a y bie'n the'co t i so'so v o n g day ciia cuon so cap va t h i i cap la >i m o t pha, lech pha goc — D g i a m hieu dien the'lO Ian va tang c u o n g d o n g dien 10 Ian C a u 141: N h a n xet nao sau day ve may bien the la k h o n g diing? ^ , A M a y bien the'co the tang hieu dien the xoay chieu j^ B M a y bien the'co the g i a m hieu dien the xoay chieu , , , A Sua't d i e n d o n g ciia may phat dien xoay chieu ti le v o i toe d o quay cua C a u 146: Phat bieu nao sau day la diing? B N g u o i ta CO the tao tir t r u o n g quay bang each cho d o n g dien xoay chieu chay qua n a m cham dien C N g u o i ta CO the tao tir t r u o n g quay bang each cho d o n g dien xoay roto B D o n g dien xoay chieu m o t pha chi c6 the may phat d i e n xoay chieu m o t pha tao chieu m o t pha chay qua ba cuon day cua stato ciia d o n g co k h o n g dong bg ba pha C D o n g d i e n d o may phat dien xoay chieu tao l u o n c6 tan so bang so D N g u o i ta CO the tao tir t r u o n g quay bang each cho d o n g d i e n xoay chieu ba pha chay qua ba cuon day cua stato cua d o n g co k h o n g d o n g bo v o n g quay t r o n g m o t giay cua roto 280 t r o n g hai pha lai cue tieu chieu chay qua n a m chain dien D M a y bie'n the'co tac d u n g bie'n d o i c u o n g d o d o n g dien xoay chieu D C h i CO d o n g xoay chieu ba pha m o i tao d u g c tir t r u o n g quay D K h i c u o n g d g d o n g dien t r o n g mot pha cue dai t h i c u o n g cig d o n g dien A N g u o i ta CO the tao tit t r u o n g quay bang each cho d o n g dien mot C M a y bie'n the'co the thay d o i tan so d o n g dicMi xoay chieu Cau 142: Phat bieu nao sau day dung? , , C D o n g dien xoay chieu ba pha la he thong g o m ba d o n g dien xoay chieu fh '|h C tang hieu d i e n the'lO Ian va giam c u o n g d o n g d i e n 10 Ian , , ,,,,, -^ B C h i CO d o n g dien xoay chieu ba pha m o i tao dugc t u t r u o n g quay - ,-r B g i a m hieu dien t h e v a d o n g d i e n 10 Ian A K h i c u o n g d o d o n g dien t r o n g m o t pha bang k h o n g t h i c u o n g d o n g dien t r o n g hai pha lai k h a c k h o n g :10 Bo qua hao p h i m a y bien the D u n g m a y bie'n the c6 the A tang hieu d i e n t h e v a d o n g dien len 10 Ian D M a y phat dien xoay chieu ba pha hoat d o n g n h o viec su d u n g t u t r u o n g quay B l u o n nho h o n tan so d o n g dien cuon so cap , C M a y phat d i e n xoay chieu ba pha tao ba d o n g d i e n m o t pha c u n g bien j: ^, bapha , •n:nv^.y^, J L ^ •„ , • ,,: 281 BS tty klSn thitc V^t II LTOn tren kSnh VTV2, t^p - Chu Van Cty Blen Cau 147: Phat bieu nao sau day d u n g do'i v a i may phat d i e n xoay chieu m o t TNIIII MTV nvvil ltiiangVl£t D de g i a m to'c quay ciia ro to n g u o i ta g i a m so'cuon d a y va g i a m so cap cue t u plia? A Bien cvia suat dien d o n g p i i u thuoc vao so cap cue ciia n a m chiam Qli\x 152: T r o n g he t h o n g t r u y e n tai d o n g ba pha d i xa theo each mac h i n h B Tan so ciia sua't dien d o n g p h u thuoc vao so v o n g day ciia phan u n g thi: C D o n g dien cam u n g chi xuat hien cac cuon day ciia phan l i n g A C u o n g hieu d u n g ciia d o n g dien t r o n g day t r u n g hoa b^ng t o n g cac D N e l l phan cam la n a m cham dien thi n a m cham d u g c n u o i b o i d o n g d i ^ n xoay chieu " ''' -.J^ • Cau 148: Phat bieu nao sau day la sai? T r o n g qua t r i n h t r u y e n tai dien nang d i c u o n g hieu d u n g ciia cac d o n g dien ba day pha B D o n g dien t r o n g m o i day pha deu lech pha 2A,/3 so v a i dien ap g i i i a day pha d o va day t r u n g hoa xa, cong sua't hao p h i tren d u o n g day tai dien ti 1| C C u o n g d o n g dien day t r u n g hoa l u o n bang A v o i t h o i gian t r u y e n dien D D i e n ap hieu d u n g g i i i a hai day pha Ian h o n dien ap hieu d u n g giira m o t B v o l chieu dai du'ong day tai dien ? " , C v o i b i n h p h u o n g cong sua't truyen d i D nghjch v o i b i n h p h u a n g dien ap giCra hai dau day t r a m phat dien Cau 149: Phat bieu nao sau day ve d o n g co k h o n g d o n g bo ba pha la sai? A Roto cua d o n g co quay v o i toe goc nho h a n toe goc cua tir t r u o n g quay C N g u y e n tac hoat d o n g cua d o n g co dua tren hien t i r g n g cam u n g dien tu va su' d u n g t u t r u o n g quay D Vecto cam u n g t u cua tCf t r u a n g quay t r o n g d o n g ca l u o n thay d o i ve ca h u o n g va t r i so ' 'j' v '' d o n g bo ba pha CO Ion k h o n g d o i d o n g bo ba pha co p h u o n g k h o n g d o i C C a m u n g t u ca ba cuon day gay tai tam stato cua d o n g co k h o n g d o n g bo ba pha co h u o n g quay deu i \.J,J>C = coC lOOco 50 1 1 1 1 • + 0,5.• = 0=>co = 100(rad/s) Huang dan 0) 100(0 100© loi^ 0 CO 10000 ^ Ui Dong chieu : Ij = Dong xoay chieu : I2 = U A M I U MB tan 9AM tancpMB = - : (R coscpi =C0S(P2 L = CR^ -Zc R + r) # + r)^ (OiL (R + r)2 + •=R cojC =^LC = 100^y2 U _ ^ R + Z^L C02C C02_ L - rRC ^ - : - l = > U AM J- " M B = Z T Z C = rR C r "MB AM R 30 = + u 0MB / + UoAM-50(V) 2 U o A M +Uo^ 3=100^ ' ).„.:.!*••• lOOV cOjL = R UQMB; — CO2CO2 40V3^ ,UOAM u^jyl tre pha hcjn U^B 1^ — => " A M - 50cos A 0)1 - = 1A Vl 00^+100^ ' 0AM; (02L- (OiC = 2A VlOO^ + ,L Huang dan O A M (R 200 Cau 4: Dat dien ap u = 100cos(cot + 7c/12) (V) vao hai dau doan mach AB gom hai doan AM va MB mac noi tiep Doan AM gom tu di^n co di?n dung C no'i tiep voi dien tro R va doan MB chi co cuon cam co dien tro thuan r va co ty cam L Biet L = rRC Vao thoi diem to, dien ap giu-a hai dau cuon cam bang 40 >/3 V thi dien ap giiia hai dau mach AM la 30 V Bieu thuc cua dien ap giiia hai dau doan mach MB C O the la « i A U A M = 50cos(cot-57t/12)(V) ' B U A M = 50cos(cot - 7t/4) (V) C U A M = 200cos(cot - 7i/4) (V) D U A M = 200cos(cot - 57t/12) (V) y R^ (R + r) _ : ^ i = i i + I =V5(A) = -1: r U_ Z2 ' Cau 2: Dat dien ap u = 125 \/2 coscot (V), co thay doi dugc vao doan mach noi tiep AMB Doan mach AM gom dien tro R noi tiep tu dien, doan mach MB chua cuon day co dien tro r Biet dien ap tren doan AM luon vuong pha vol dien ap tren doan MB va r = R Voi hai gia tri co = IOOTT rad/s va co = 56,257: rad/s thi mach AB co ciing he so'cong suat va gia tri bang A 0,96 B 0,85 C.0,91 D 0,82 Huong dan , u = 400cos^ (507tt)= 200 + 2Q0cos(1007ct) •• 10000 vift n Uo:4B=50V3(V) 7tV 12 (V) I C02 • cos (pj = • (R + r) (R + r)^ + R COi CO, -0,96 -R C02 COi 4+ -A2 CO1 (02_ C02 (Oj Uc UiL 50V ,1 M 286 287 Botr^klcn thiJrc V^t l i LTDH t r c n k€nh VTV2 t^p - Chu VMn Bicn Cau 5: Dong dien xoay chieu qua mot doan mach c6 bieu thuc i = Iocos(1007tt 7r/3) ( A ) (t bang giay) Thoi diem thu 2010 gia trj tuyet doi ciia cuong dong dien tiVc thoi bang cuong dong dien hieu dung la A t = 12043/12000(5) B t = 9649/1200 (s) C t = 2411/240 (s) D t = l/48(s) Humigdait *(0) = IOOTT.O ^ ^H)5, ^ Chuyen theo chieu dUcfng au 7: Dat mot dien ap u = 50 %/2 coslOOTtt (V), (t bSng giay) vao hai dau doan mach noi tiep gom dien tro R = 30 Q, tu dien va cuon day Biet dien ap hieu dung tren tu la 80 V tren cuon day la 10V26 V va tren dien tro R la 30 V Cong sua't tieu thu dien cua doan mach la A 20 W B 30 W •i C 50 W D 40 W Huong dan - U,d = = V2 >/uf+uF = V U L = * ^ :* •: • : 50^ = h.% ::^.\c ^'^ "^Jb r =^ I J^G P = Ldn ; t4 = 13T T T _ 19T 24 ^ ^ ~ 24 Ldn 2010 = 502 + 4: tjoio = 502T + 1^02 I = Hii R = lA^'"'^"' 10 r ( r + R) = 40(W) A A F B : A B ^ = A F ^ + FB^ 7T 12055T 2411, , : 502T + — = = (s) 24 24 240 EB = EF - EB = - 0 = ( + x)^ + [ - V O O \^600^ - x= 10 P = l2(r + R) = I ( I r + IR) = ^ ( U r + U R ) - — ( + 30) = 40(W) R MAU \^2) A 0,51„ = + 30^ + 60.Ur + 80^ - 160.Ui^ A N E B ; BE = V N B ^ - N E ^ = 0 ^ 11=502 + lil oi; u,=io , U2=(UK+U,f+(UL-Ucf 'V - Uc = 80 V ; imA :.< * ' : Ldn i • t T 24 T T T 7T Lan J : ty = — + — + — = — 24 8 24 7T T T 13T Ld?i 3:U = 24 ^ ^ •' ' C M Lr \ ijja \i TM \ \ ( ) \ ^d)„„ = - 7t/3 Cau 6: Dat dien ap xoay chieu c6 gia tri hieu dung 120V tan so 69Hz vao hai Cau 8: Dat dien ap xoay chieu on dinh vao hai dau doan mach gom cuon day dau mot bong den huynh quang Biet den chi sang len dien ap dat vao noi tiep voi tu dien co dien dung C thay doi Khi C = C i dong dien den khong nho han 60V2V Thoi gian den sang moi giay la: mach la i i va cong sua't tieu thu cua mach la P i Khi C = C2 < C i thi dong A.l/2(s) dien mach la i2 va cong sua't tieu thu la P2 Biet P2 = (7 - ^/3 ) P i va i i B l/3(s) C.2/3(s) D 0,8 (s) vuong pha voi i2 Xac djnh goc lech pha (pi va (p2 giua di^n ap hai dau doan Huang dan 288 Thdi gian hoat dong mot giay chu hi la: \ b 6072 2, , t = t.4.—arccos = 60.4 arccos ^ = -(s) CO Uo 1207t 120V2 3^ ^ ^ mach vol i i va i2 A (pi = 71/12 va (p2 = -57r/12 B (pi = -71/6 va 92 = n/3 C (pi =-7t/3 va(p2 = 7i/6 D (pi = - n / r va (p2 = 7i/4 -89 Bo tro kicn thiic VJt 11LTDII licn kcnli VTV2, t^ip - Chu Bicn Viin Ctyjmin liicong dan P = — C O S (p => - V = Huang 92 = 'Pi - Pi cos^cpi C2 < C , =i>Zc2 > Z c i =>(Pi - = - Khang Vipt ^ =R/n^=6R co^C CO, 2R2 L=nCR2 AM«2 ="0 = ; ^ y ^ coscpi O VVll dan - = nrv nR' coscpi miL = R^ n - ^ = l , R C02 71 • i = •— Cau 9: Cho mach d i e n xoay chieu g o m m o t cuon day k h o n g t h u a n cam mac noi tiep v o i m o t t u dien D i e n ap xoay chieu dat vao hai dau doan mach c6 gia t r i hieu d u n g 100 V he so cong suat tren toan mach la 0,6 va he so cong Z = JR^ + c o i L - - = 0,5RV85 C0|C Cau 1 : D o a n mach xoay chieu A B noi tiep g o m dien t r o t h u a n R, t u dien C va sua't tren cuon day la 0,8 D i e n ap giua hai dau t u dien c6 gia t^-j hieu d u n g cuon cam t h u a n L Goi U L , UC, UR Ian l u a t la d i e n ap tuc t h o i tren L, C va R la Tai thoi diem ti cac gia t r i tiic thoi UL(ti) = -20 ^ V, uc(ti) = 10 V, UR(ti) = OV A.125V.;, B.45V C.75V D 90 V ' L UR(t2) = \/2 V T i n h bien d p dien ap dat vao hai d a u mach A B ? ,1,1 Huang dan A.50V ' U , = A E = ABcoscp = 100.0,6 = ( V ) AAEB: Tai t h o i d i e m t2 cac gia trj tuc thoi ui.(t2) = - I V V, uc(f-2) = V V, B 20 V ••••;.•:;•.•::.) EB = ABsincp = AB^/l -cos^cp = 100.0,8 = ( V ) Uj^ = U Q R AAEM M E = A E tan = AE coscp,,^ t = ti 0,8 COS(p,d = 45(V) if : Huongdun V: 1; ; C::D.20^/2V ' ' ,v •ii:;.-'; cos cot; U L = U Q L cos cot + — ; u c = U o c C o s ^ c o t - ^ ^ 2y UR =0 UoL = V ( V ) " L = -UoL = - V ( V ) ; u c = Uyc = 1072 ( V ) ^ j u y c = 10V2 ( V ) U l = 20V2cos cot +• U c = M E + EB = ( V ) C.30N/2V = - V ( V ) C A p n cot2 t = t /3 = UQR cos cot , = V = ^ U o R Y = ^5^/2=>UoK = T N / ( V ) cd Uo=VU(^R+(UoL-Uo2f =20V2(V) B A •X I (t/'li / I Tai t h a i d i e m t i cac gia trj tuc t h o i ui.(ti) = - l O V S V , uc(ti) = 30V3 V, lOOV UR(ti) = V Tai t h a i d i e m t2 cac gia t r j tuc t h a i ui.(t2) = V, uc(t2) = - V, UR(t2) = OV T i n h bien dien ap dat vao hai d a u mach AB? A V '•i'f V^t li LTDlt tren henh TTj> Tram nrv vvvn nnang r/px VTV2 tnp - Cliu VMn Bl&n ui = c o s cot, + — = -10>/3 ( V ) - > Chqn coti = R UoK.^ = = > U „ R = ( V ) = UQR C O S C O t ] = : Uo = M < + ( U o L - U o ) ' = 50(V) M A -mm >' • i C a u 13: C h o d o n g dien xoay chieu i = 7rsin(1007it) ( A ) (t d o bang giay) chay qua b i n h dien phan chua d u n g dich H2SO4 v o i cac dien cue tra T i n h the tich k h i d i e u k i e n tieu chuan thoat thai gian 16 p h u t giay m o i dien cue •' , A 0,168 h't I ( B 0,224 l i t C 0,112 l i t (v Huong dan Qi/2=2l^ =2 CO IOOK ! D 0,056 l i t = 0,02(C) • • 'rijI ' I \ V02 V = 965 mach A M g o m dien t r o R n o i tiep v o i t u dien c6 d i e n d u n g C, doan mach \ V H , = ; ^ ^ n , = | ^ : ^ l l , = 0,1121 T 96500 0,02 96500 t Qi/2 C a u 15: Doan m a c h xoay chieu A B g o m hai doan mach A M n o i tiep M B Doan f M B C O cuon cam c6 dO t u cam L va dien t r a r Biet R^ = 0,02 hieu d u n g giua hai d a u M B I o n gap VS di§n ap h a i d a u A M H e so cong 5,6 = 0,0561 = -5,6^ T 96500 0,02 96500 VH2 +V02 =0,1681 r.:.,: = L / C va dien ap suat cua A B la , B 0,755 A 0,887 C a u 14: Tren doan m a c h xoay chieu k h o n g phan n h a n h c6 b o n d i e m theo d u n g thii' t u A , M , N va B Giira hai d i e m A va M chi c6 dien t r o R, gii>a h a i d i e m Huong tan cpAM t a " D 0,975 C 0,866 dan ^ ^u?, => A A M B vuong tai M M va N c h i eo cuon cam ma d i ^ n t r o thuan r = 0,5R va d o t u cam L = I/TT H , giua d i e m N va B chi c6 tu dien c6 dien d u n g C = 50/TI [i¥ D i e n ap tren AM doan A N c6 hieu d u n g la 200 V D i e n ap tren doan M N lech pha v a i dien ap tren A B la n/2 Bieu thuc dien ap tren A B la UAB = Uucos(1007Tt + 7T/12) V Bieu t h u c d o n g d i e n t r o n g mach la '' A i = 2COS(1 OOnt - TX/3) A ^.^^^ B i = 72 cos(100Tct - n/4) A C i = 2cos(100Ttt + 7X/3) A ^ i b r l v , D i = >/2 cos(1007Tt + n/4) A n o u , 'J f%:fW: ^ f.fV>it 292 Zi V?:\'ftr i Huong dan j j j f,,,, ] rj; , AM cos[i = MB , „ „ A A N B diu: Uc N B = 0 = > I = - ^ = 1A Zc cp = — i = V2cos i sdm pha /icfii U A R Id — ,^ 1007lt + — + - 12 6J vf.i ' - u t i t JB/' AM MB t,h it tanP = - ^ : U i l = V3 ^ A>i-xV P = 60" = a + P - 90° = 30° =^ coscp = 0,866 ,j ,Y«iti! i o f l i ' i f , - ; = coL = 1OOQ; Z c = — = 200Q = Z L => A M Id trung tuyen cua A A N B MC V] M viia Id tdm vi^a Id trt/c tdm i / "\Ja • •1: i / \ • \ c M / 'B A'/ ei 293 Cau 16: M a c h d i e n xoay chieu noi tiep A B theo d i i n g t h i i tir g o m cam t h u a n L, d i e n t r a t h u a n R va t u d i e n C Cho biet d i e n ap hieu d u n g URC = 0,75URL va R2 = L/C T i n h he so cong suat ciia doan mach A B A 0,8 B 0,864 " = ZLZC=>U?, = U , L = rRC — = Z L Z C = rR •• ZL -ZC dan = -1 R Q 0,5 Hwang R ' = ^ Huang " A M dan lu " A M UoAM MB U, "MB + U ^ A M + U 0MB • A v u o n g t a i O : tan a = 0,75 Jcosa = 0,8 [sina = 0,6 =1 UQMB = Uo \ 36 64 u GAM u 0MB =1 U O A M = ( V ) ^ U A M = V ( V ) UoMB=80(V) ULM+U,^MB=1002 C R Cau 19: Doan mcich dien xoay chieu c6 R, cuon thuan cam L va tu C k h o n g d o i mac noi tiep vao nguon dien xoay chieu c6 dien ap hieu d u n g k h o n g d o i n h u n g tan so thay d o i K h i f = fi hay f = f2 = fi - 50 (Hz) t h i mach tieu t h u Cling U R = 0,75a cos a = 0,6a A 100 H z = a cos a = 0,8a R => cos = — = Z Vu|+(UL-Ucf 0,864 HD : cuon day D i e n ap hieu d u n g d hai dau cuon day la 120 V D o n g dien t r o n g mach lech pha TI/6 so v o i d i e n ap giCra hai dau doan mach va lech pha %/3 so v o i dien ap giira hai dau cuon day Tong t r a cua mach bang B 30 (Q) C 90 (Q) Huong dan ^ B 0 V H z C 120 H z D 90 H z D 60 V2 (Q) ( f i - 40) = f(? = 60^ =^ f i = 90Hz Cau : M o t mach dien xoay chieu g o m m o t t u dien C n o i tiep v o i m o t cuon day D a t vao hai dau doan mach m o t dien ap u = U V2 coscot (V) t h i d i e n ap giua hai dau h i d i e n C la uc = U V2 cos(cot - TC/3) (V) T y so g i i i a d u n g khang va cam k h a n g bang A 1/3 B.1/2 .r • A A M B can tai A f => C/R = M B - 120(V) => I = ' C.l , Huang dan / luon ludn sdm pha hcfn Ucla-md = 4(A) tre pha /lo^ / Zd - =i>(p = - 6 A M E B : U L = M B sin 60° = 60V3(V) AAEB: U = AB = • sin 30 k h i f = fo = 60 H z t h i dien ap giua hai dau mach d o n g Huattgddn Cau : D o a n mach d i e n xoay chieu g o m dien t r a thuan 30 (Q) mac n o i tiep v o i A 30 V3 (Q) pha v o i c u o n g d o d o n g dien t r o n g mach Gia t r i f i bang: U c = 0,75a sin a = 0,45a UL cong suat, = 120V3(V) UAB = U C ^ U = > Z = y = 30V3(Q) ZAB = + (ZL D.2 theo hai U sdm pha hcfn llQld-mnU tan cp = - ZC ) M , R = tan-?^ => R = ( Z c - Z L ) V3 > = Z C =^ ( Z C - Z L ) = Z C => Z C = 2ZL Cau : D a t d i e n ap xoay chieu 120 V - 50 H z vao doan m a c h n o i tiep A B g o m d i e n t r o t h u a n R , t u dien va cuon cam K h i noi hai dau cuon cam m o t ampe Cau 18: Dat d i e n ap u = 100cos(cot + 7i/12) (V) vao hai d a u d o a n mach A B g o m ke CO dien t r a rat nho t h i so chi cua no la N/3 A N e u thay ampe k e b a n g v o n hai doan A M va M B mac noi tiep Doan A M g o m t u d i e n c6 d i e n d u n g C ke CO d i e n t r o rat I a n t h i no chi 60 V, d o n g t h o i d i e n ap tiic t h o i giua hai dau noi tiep v o i dien t r a R va doan M B chi c6 cuon cam c6 d i e n t r o t h u a n r va c6 v o n ke lech pha 7t/3 so v o i d i e n ap g i i i a hai dau doan m a c h A B T o n g t r o t u cam L Biet L = rRC Vao t h o i d i e m to, dien ap tren M B bang 64 V t h i cua cuon cam la d i e n ap tren A M la 36 V D i e n ap hieu d u n g tren doan A M la A.40Q A.50V B.50V3V C.40V2V D.30V2V B 40 73 a C.20V3Q D 60 Q Cty TNIIH MTV DVVH Khang Vlft Httoitg dan + Mac dmpe - ke thi Lr hi noi tat: Z[^(; = y- = 40N/3 + Mac von - ke, ve gidn vcctd: ;/,/,'- UKC = _ Vl20^ Z,L _ +60^ _ -2.120.60.cos60" = 60>/3 ''' ',\ 60 = 40Q I y U, C R •"• • J i I •:; i 60 —>j ^—^ •if:.,mlh iiii \H 02 = *Pi2 - i l = ^ => = -92 = ^ => C O S C p i = C O S ( p = cos^ « 0,71 C a u 24: Lan luot dat dien ap xoay chieu 220 V - 50 Hz vao cac dung cu P va Q P thi dong som pha hon so vol dien ap la n/3 doi voi Q thi dong ' cung pha voi di^n ap Biet cac dung cu P va Q chi chiVa cac dien tro thuan, cuon cam va tu dien Khi mac dien ap tren vao mach chua P va Q sin V"AN = 7^"~ cos^ip^N = 0/6 ^^^±^ -^^ I = 90(n) mSc noi tiep thi dong dien mcich co gia trj hieu dyng la „ j j ^IA A 0,125 V A va tre pha 7r/4 so voi dien ap gii>a hai dau doan mach B 0,125 y/l Ava som pha n/4 so voi di?n ap giua hai dau doan mach => ABF = A N M = tpAN {soc co canh tiCOng ling vuong gdc) A B s i n ^ A N = 90(V) ~92 j^y D 90 Q A A N B Id tarn gidc uuong tai A vi: NB^ = A N ^ + AB^ ^ AF • C O S C p j = C O S ( p =>a hai d i e m A va N la 120 (V) va dien ap hieu d u n g giiia hai d i e m M va B la 80 73 (V) Dien ap tuc thoi tren doan A N va tren doan M B lech pha 90", dien ap tuc t h o i tren doan M B va tren doan N B C a u 25: Dat vao liai dau doan mach chi c6 cuon cam thuan m o t dien ap xoay chieu u = UocoslOOTit (V) Biet gia t r i dien ap va c u o n g d o n g dien tai thai lech pha 30° Dien t r o thuan cua cuon day la A.40Q B 60Q A 50 V A M N B : M N - U K B lOOV C 50 73 V ' r 2.2500 _ ^ Uo = lOO(V) 2500 Uc^ = R isii dien ap tuc t h o i hai dau doan mach la 100 72 V t h i d i e n ap tiic t h o i giua hai dau dien t r o va cuon cam deu la -100 76 V T i n h gia trj hieu d u n g ciia d i e n ap hai dau doan mach A B 298 ,r C 300 V \ U^= E N- M N ^ ' 2073 ^^==Ur-^-30Q UR 2 t h u t u A , M , N va B Giira hai d i e m A va M chi c6 cuon day, giiia hai d i e m cam thuan) K h i dien ap hieu d u n g hai dau dien t r o R la 200 V K h i B.615V '\ Cau 28: Tren doan mach xoay chieu k h o n g phan nhanh c6 b o n d i e m theo d u n g Io = 2(A) C a u 26: Cho mach dien xoay chieu R, L, C mac noi tie'p theo t h i i t u (cuon A 500 V D 20 Q = M B s i n " = 4073(V) A A E N => E N = A N c o s 30" = 6073(V) Hu'&itg dan ili Huong dan d i e m ti la u i = 50 V2 (V), i i = V2 (A) va tai thoi d i e m t2 la U2 = 50 (V), i2 = -73 , ( A ) Gia t r i Uo la: C 30 Q D.200V M va N chi c6 dien t r o thuan R, giOa d i e m N va B chi c6 t u dien Dien ap i;hieu d u n g tren A B , A N va M N thoa m a n he thuc UAB = U A N = U M N = 12073 (V) D o n g hieu d u n g mach la ( A ) D i e n ap rue t h o i tren A N va tren doan A B lech pha m o t goc d u n g bang goc lech pha giCJa ' d i e n ap tiic t h o i tren A M va d o n g dien T i n h cam khang cua cuon day A 60 73 Q B 15 76 Q C Q D.30 72Q