oE rnt xY rnuAr slEtt 2 - K99 ( 06.2002)
Thoi gian lAm biti : 120 phit. SV dUqc phep s(I dung tAi liQu. 7 )Au 1 : DOng cd m6t chi6u kich tr] doc lAp , c6 cdc th6ng sd dinh mfc sau :
- di6n ip cung cap cho phdn r-tng U = 250 V - dong phdn rlng lr: = 50 A
- dong kich ttj i t<t = 1,5 A
- di6n trd phdn Lrng Ru = 0,3 Q.
Khi lAm thf nghi|m kh6ng tAi ( mAy lAm viQc 6 chd dQ mdy phat ):
Uo ='308 V, i11= 1,5 A vd tdc dQ n = 1200 vdng/phtlt
Khi ldrm thi nghilm kh)ng t1i ( may ldm viQc 6 chd d0 deng co ): c6ng sudt ti6u thg ndi pndn dng po = 1200 W, U = 250 V.
Trong sudt bai to6n, lufln gifr di6n dp U = 250 V, ikt = 1,5 A. BO qua diQn ap rdi tr|n chdi than, phAn Ung phAn fing.
a/ tinn dong kh6ng tai lo, t6c d0 dOng cd lric kh6ng tii ns. Chltng minh rbng khi mdy ldm vi6c kh6ng tAi, c6 thd b6
qua tdn hao Joute so vdi cdc tdn hao kh6c. Suy ra moment kh6ng tAi (ma sdt, quat gi6, do tdn hao sit) ms. Sau
dAy, mo ddQc xem kh6ng phu thuQc viro tdc d0 (1didm)'
b/ Tinh cdc gid tri srlc di6n d6ng cAm ung, tdc dO, moment di6n tr-t, moment tr6n truc m6y trong didu ki6n tai dinh
mfc (1didm).
c/ Chf ng minh rdng moment di6n ttt ti le thuan voi ddng phdn rlng lu (1didm).
CAu2: M6y ph6t ddng bO 3 pha r6to cgc tit dn, dAy qudn stato n6i Y,5000 V,50 Hz, tdc dd dinh mrrc n66 = 250 vong/ph6t, dong phdn dng dinh mrJc ly = 200 A, cosrp6sl = 0,87 tr6. DiCn trd dAy qudn stato (pha) Ru = 0,02 Cl .
Tdng tdn hao cOng sudt co hqc lir 220 Rw (kh6ng ddi).
Khi thi c6 drjoc SAU :
irt [A] 0 10 20 30 40 50 60 70 BO 90 100
Eo [V] 0 1 050 21 00 31 50 4200 5200 5950 6550 7000 7300 7500
vdi i11 : dong kich ttJ, Eq : stlc didn d6ng (gi6 tri di6n 6p dAy) khOng t6i '
Khi fhi nghiQm ngdn m4ch. vdi dong kich tr-t itt = 40 A, dong phdn Ung ngSn mqch lgnm = 2500 A. Tinh :
a/ sd cuc tr; (1 didm).
b/ dien'khdng ddng bO XoO, drroc giA sfi kh6ng thay dcji trong cdc cAu sau (1 didm).
c/ sr-rc di6n ddng (dAy) kh6ng tai Eo , khi tU th6ng cqc dai dudi 1 c{c tLI la 0,025 Wb, s6 vdng dAy/pha ldr Wpna = 810 vong (1 didm).
d/ srtc diqn dQng khdng tai Eo khi mdy lim vi6c trong didu ki6n t6i Oinh mfc. Dong kich ttJ hlc bay gid ?(1 didm) Ciu3: D6ngcokhOngddngb63pha,statondiY,3S0V,50Hz.Di6ntrddAyqudnstatoRl=0,40o/pha.
Thi nghi1m kh6ng t|i':di6n,ap U = 380 V, tdc dd d6ng co - 15OO vong/phrlt, c6ng sudt ti6u thU Po = 1150 W,
dong di6n (dAy) to = 11,2 A. Thf nghiQm vdi tAi dinh mtJc;di6n 6p cung cdp 3BO V, 50 Hz, vdi c6c sd lirOu do drJqc :
- d0 trudt s = 4"/"
- c6ng sudt di6n ti6u thu = 18,1 kW
- dong dien (dAy) ti6u thu = 32 A. Tinh :
al cAi tdn hao Joute trong dAy qudn stato khi khOng tAi. Tdn hao Joule trong rdto khi lAm thi nghiOm kh6ng tAi ?.
(0,5 didm ).
b/tdn hao sdt, bidt rdng tdn hao cd hqc li 510 W (0,5 didm ).
ci hO sd cOng sudt dinh mrlc vdr tdc d6 dinh mtrc (0,5 didm )'
d/ tdn sd ddng di6n trong rdto 6 d0 truqt s = 4"/o. Tdn hao sit trong r6to ? (0,5 didm )'
e/ rdn hao Joute trong dAy qudn stato vi r6to trong didu ki6n tAi dinh mltc (0,5 didm ).
f/ cdng sudt tr6n trtlc m6y, hiQu sudt, moment khi tai lir dinh mdc (0,5 didm ).