THC MC V CCH TNH TON "DY IN DN DNG"
1. Bn c phi dn hc in khng vy m hng dn tnh ton tng cng sut nh vy,
ti hng dn bn mt cht nh : v d vi mch cm cp in cho cc thit b in di
ng, c theo quy chun mi dy cm c 7 cm,h thng cm ny s cp in cho cc
thit b nh ni cm in, m un nc, my git, t lnh, bn i, l vi sng nhng
nhng thit b ny khng bao gi hot ng ng thi nn bn phi tnh cng sut da
vo c th s dng in ca cc thit b ch.
- Tuy nhin, hu nh khng c thi im no m tt c cc thit b in trong nh
hat ng ng thi cng mt lc, cho nn ngi ta c th gim cng sut tnh tan
xung cn khang 80% cng sut tnh tan ri mi chn la dy dn theo cng sut c
gim. Khi gim xung 80% nh vy ngi ta c cch gi khc l chn h s ng thi
(kt) = 0,8.- Vi nh 1 lu nh trn, chn HST = 0,8 l cng c ri, bn chn
thp qu, l gp ba tic tng, tang gia, cng sut s dng thc t ti mt thi im
tng vt th ng dy bn chn chu sao cho ni?- Bn c th cho v d, vi cm 7 l
(c th cm 7 phch cm), mi l c mt mc ti c th th bn s chn dy in cho cm
ny nh th no? v d 7 l, cng sut thit k cc thanh ng l 12A/l th cng sut
ca ng dy chnh phi chn l bao nhiu A? chn dy bao nhim mm2?- Tui cng
ng vi ci h s ng thi. Cho tui ni thm rng, thnh ph th nh 5-7 tng c th
c h s ng thi tng i thp, nhng thn qu th khng u, nhng lc gi chp ci hi
th overload l ci chc nu mnh ko h s ng thi xung. V tui cho rng khong
70% dn s VN l nng thn nn khng dm rt ci HSDT ny xung. Ci hng dn ny
cng tit kim lm ri , theo tui bit c rt nhiu trng hp ngi ta cn tng ln
khong 30% cng sut d phng tng thm thit b sau ny na .- Ci chn dy cho
cm nhiu l cng hay , tui mi va xem qua cun tiu chun TCVN 6188-1:
1996/ IEC 884-1: 1994 nhng vn cha thy cp ti vn ny, tm ci HST cho b
cm nhiu l l mt cng hay hay, t hm na ranh rnh tui tm hiu th th
no.
2. Cc anh em cho mnh hi l, cch ly ngun t li in nh nc theo cng
thc no, v d nh thit k cho mt h thng nh. vi tng cng sut cc ph ti P=
100.000kw th li in cn ly l bao nhiu? c phi l ly in h th vi kv sau
qua my bin p ca ta nh ri phn b in i phi khng?Cu hi ca bn cch ly
ngun t li in nh nc theo cng thc no c l l trong Quy phm trang b in
ca nh nc c cu tr li, ti cha c k nn cha th ni chnh xc l cng sut h
tiu th bao nhiu th buc phi dng trm h th m khng c dng li h th sn c
cho bn c. Theo ti thng thy, cng sut chng 500kVA ngi ta dng trm h th
ring ri, cng sut bn hi ln ti hn 100.000kVA th c l l phi dng trm h
th ring ri. Cp h th cui cng thng thng VN l 22kV hoc 15kV (mng c)
xung 0,4kV (220V/380V) ch khng phi vi kV bn .3. Ti c vic nh anh ch
gip nh. Ti ang cp in cho mt dy chuyn may nh (50 my), mi my 250W-1
pha. Ngun in vo xng 3 pha. Nay ti nh chia u 3 pha mi pha chu 17, 18
my. Vy ti nn dng dy in c tit din nh th no cho ng tng v cc ng nhnh (
ti nh dng dy nhm 1 li cng v y rt r v d kim.)Cm n anh v cc anh em ch
gip.V kh nng dn th dy nhm bc PVC 6mm2 c th lm dy chnh (4 dy, 380V).
Dy cho 3 nhnh cng chng 6mm2 (2 dy, 220V). Nhng y mi l kh nng dn dng
thi, cha bit chiu di dy nn cha bit st p bao nhiu, bn cn tnh st p ri
nng tit din dy ln cho (cho php st p c 5% thi)4. em cung vua ra
truong nhung khong biet nhieu ve thiet ke dien lam.em muon hoi cac
anh la can cu vao cai ji de tinh khoi luong day dan?vi khi lap dat
theo ban ve tuc la co the tinh tung doan day 1 roi cong laij nhung
he so cho fep la bao nhieu vi co khi day fai di vong hay gap cho
noi chang han
Hin nay, hu nh cha thy nh sn xut no in dng nh mc trn dy dn bn .
iu ny ch c th xut hin trn cc on dy ngun cho cc thit b gn sn cc u cm
(bn M thng gi on dy ny l Cord, s d c vy l v chiu di dy c xc nh.+ V
khi lng dyth cc nh sn xut cho bit khi lng gn ng ca mi loi dy ri
(kg/km). H s nhn thm vo bn c th xem trong cc sch hng dn v lp t, mi
cch lp t (ko trn tr, t trong ng, trong mng) c th c cc h s khc
nhau.+ V schth bn c th tham kho nhiu sch c lin quan, chng hn: Cung
cp in, T/g Nguyn Xun Ph, Nguyn Cng Hin; Hng dn thit k lp t mng in
trung tm thng miTheo cng dng in th a s cc nh sn xut cung cp bng dng
in cho php (Ampacity), tuy nhin n mi ch l c s ban u bit kh nng ca
dy (ch yu v nhit) ch khng phi chn dy l ch cn c vo Ampacity m c, v
khi chn dy cn phi quan tm ti cht lng in nng, kh nng bo v mch hng dn
trn ch hng ti nh v cng c lm gn cc bc trung gian (ch cn cng sut ti,
tit din v chiu di dy thi) cho mi ngi khng chuyn d hnh dung, d thc
hin m.i vi cch in PVC th dy > 300mm2 n c khc cht t so vi cc c dy
300mm2 c nhit khi ngn mch trong 5giy l 140C, trong khi dy ci ny do
sp yu cu), em tnh i dy chnh l 4 dy li Cu CV 60 cho 3 dy pha + trung
ha c c khng? Cn cng sut 200 KVA th xin vui lng anh tnh gim em nn i
dy c bao nhiu?V xin anh cho bit Cty anh c sx my bin tng in t t 50Hz
=> 60Hz khng? Nu c th gi khon bao nhiu cho my 20 Kw Ch Cty em
hin ang s dng qua Dinamo chy n khng chu ni, ci ny hi trc vi thng na
mi t. (*_*)
Mnh thy bn chn CV 60 cho 100KVA l cng c ri (h s ng thi khong
70%), nhng cp CV 60 hi kh mua (t thng dng) nn chn CV 70 cho d. Tng
t, vi 200KVA chn cp CV 120l c ri. C 2 trng hp u p ng in p ri ko w
5%.
