1. D6ng co kh6ng ddng bQ r6to ldng s6c 3 pha c6 c6ng sudt Olnfr mtlc Pdm = 28 kW, di6n 6p
dinh m0c Udm = 380 V, tdn s6 50 Hz, ddu Y, 6 crlc, hO sd c6ng sudt dinh mlrc cosgdm = 0,88, tdc dO dinh muc ndm = 980 v/ph. (Tdn hao ddng + tdn hao sdt statol ld2,2kw, tdn hao
cd (do ma sdt, quat gi6...) la 1,1 kW, khi d6ng cd lam vi6c 6 tai dinh mfc. Tinh, luc ta-i dinh
mfc:
a/ hd s6 truqt sdm (0,5 d)
b/ tdn hao ddng r6to pCu2dm (0,5 d)
c/ hi6u sudt qdm (0,5 d)
d/ ddng di6n stato lldm (0,5 d)
e/ tdn sd dong di6n r6to f2 (1d)
2. Miry phdt di6n ddng bd cung cdp di6n cho hd ti6u thu m6t c6ng sudt S = 2500+j3000 kVA, 6 di6n 6p 6,3 kV.
a/ Tinh tdng tdn hao trdn drJdng dAy vA trong m6y ph6t, biet rdng di6n tr6 c0a duong dAy /
phaldrrd=0,15C),di6ntrddAyqudnphdnfng/phac0amdyphdtldrrl=0,045 O(1d).b/ Ndu ddt th6m mQt dQng cd di6n ddng bO ldm vi6c trong chd dd qud kich tit, phdt ra cOng b/ Ndu ddt th6m mQt dQng cd di6n ddng bO ldm vi6c trong chd dd qud kich tit, phdt ra cOng
sudt pnAn khdng, vdi S = 30- j3000 kVA, thi tdng tdn hao tr6n s6 ld bao nhi6u ? (2d)
3. Mdy bidn 6p 1 pha c6 c6c sd ti,Ou sau :c6ng sudt dinh muc Sdm = 100 kVA, tdn sd 60
Hz, di6n dp dinh mrlc U1/U2 =7200/480 V, co cdc th6ng sd tfnn bing ohms: R,cao dp = 3,06 X,cao 6p = 6,05 XM, cao eip = 17 809
R,h4 dp = 0,014 X,ha Ap = 0,027 RM, cao 6p = 71 400
Mdy biSn dp cung cdp diQn cho tAi ti6u thtl dong dinh mr.tc, d di6n 6p dinh mtrc 480 V, tai c6 cosrp =0,75 tr5. VE so dd mach tudng dudng c0a mdy biSn dp vd tinh :
'al di6n trd vA di6n khdng tuong dudng c0a mdy bidn dp nhin trl phia cao 6p (1
d) b/ tdng trd nhin vdo mdy bidn dp trr phia cao 6p (k€i cA tdng trd c0a tAi) (1 d)
c/ di6n dp phia cao dp c0a mdy bidn dp khi do (1 d)
d/tdng tr6 nhinvdo mdy bidn dp ttl phia cao dp khi kh6ng tai (1 d)
4. D6ng cd diQn 1 chidu kfch trt song song, c6ng suSt dinh mfc Pdm = 95 kw, di6n 6p dinh mUc Udm'- 220V, dong ti6u thU dinh mrlc ldrn = 470 A, ddng kich trj dinh mfc iktdm = 4,25 A, ndm = 500 v/ph. Di6n trd dAy qudn phdn ttng rU = 0,0125 O. Tinh :
a/ hi6u sudt 10,s o;
b/ tdn hao ddng trong m6y, tdn hao khi khdng tAi vd dong kh6ng tai (0,5 d)
c/ moment cr3a d6ng cd (1 d)
d/ di6n tr6 didu chinh Rdc cdn thidt mdc ndi tidp tr6n phdn rrng dd O6ng cd quay vdi n = ndm, lU = ludm vd trl th6ng giAm di40 % (1 d).