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BI TIU LUN TRANG B INTNG QUAN V CC THIT B DNG TRONG MCH IN
1.1.
Cc kh c in : 1.1.1. Nt nhn : Cn gi l nt iu khin , l mt loi kh c in dng ng ngt t xa cc thit b in t khc nhau ; cc dng c dng bo hiu v cng chuyn i cc mch iu khin , tn hiu lin ng bo v , o chiu quay ng c in ... C 2 dng nt nhn : nt nhn ON(START) v OFF ( STOP)
1.1.2.
Cng tc t (Contactor ) :
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Cc thnh phn contactor bao gm : Nam chm in : gm 3 thnh phn : cun dy dng to ra lc ht nam chm , li st , l xo phn lc Thanh dn ( dng ni tt kn mch in khi cung cp in cho cun cy ca contactor
H thng cc tip im , c 2 loi : tip im thng ng v tip im thng m .
1.1.3.
R-le thi gian ( Timer Relay) :-
Khi lp rp v thit k h thng mch iu khin truyn ng , ta thng s dng hai dng r-le thi gian sau : R-le thi gian tc ng tr ( On Delay TimingPage 1
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BI TIU LUN TRANG B INRelay ) .R-le thi gian ngt tr ( Off Delay Timing Relay ) .R-le thng c 8 chn v thng c lp trn chn . Dng iu khin thi gian ng ngt ca cc thit b trong mch iu khin . 1.1.4. Aptomat ( CB) :
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L mt thit b dng ng ct mch in (1 pha hoc 3 pha ) ng lc c dng n trong cng nghip . Ngoi ra Aptomat cn c tc dng bo v qu ti , bo v ngn mch , bo v thp p ...
1.1.5.
R-le trung gian: R-le trung gian l mt kh c in dng trong lnh vc iu khin t ng .Trong r-le c cc tip im thng ng v tip im thng m
1.1.6.
Van kha in t
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Van kha hay van chn int l van ng m trc tip hoc gin tip kt hp :
Van in t tc ng trc tip : thng c nng sut lu lng nh dng cho c cht kh v cht lng .ng knh van thng < 10 mm . Trn van c b tr ca van vo v ra cho mi chtGVHD : Thy TRN VIT HNG Page 2
BI TIU LUN TRANG B INVan in t tc ng gin tip : thng l loi van c ng knh trung bnh v ln ( n 200 mm ) .Thn van c 1 thng lm bng kim loi c nhng cng c th bng kt cu hn hoc tin c b tr van lin thn van .
1.1.7.
R-le p sut cao : R-le p sut cao l r-le hot ng p sut ngng t ca mi cht lnh v ngt mch in khi p sut vt qu mc cho php bo v my nn .
1.1.8.
R-le hiu p du :
Thut ng : Differential range : phm vi hiu pGVHD : Thy TRN VIT HNG Page 3
BI TIU LUN TRANG B IN Scale reading : s c trn thang o Operating range : phm vi hot ng Contact differential : vi sai tip im Realease time : thi gian tr
Hot ng :-
Nu khng c p sut du khi khi ng hoc khi p sut du gim xung di gi
tr t khi vn hnh th my nn s c ngt dng sau khi thi gian tr tri qua . Mch in c chia lm trong hai mch r , mt mch an ton v mt mch vn hnh .R-le thi gian trong mch an ton s hot ng ng mch khi hiu p sut du tt xung di gi tr t v s ngt mch khi hiu p du li tng tr li gi tr t .
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BI TIU LUN TRANG B IN
TNH TON CHN CC THIT B IN TRONG MCH IN
- Da vo cc s liu tnh ton c trong n thit k my ng , nhm a ra bng cng sut cho cc thit b nh sau :
STT1 2 3 4 5
TN GICng sut my nn Cng sut dao ct Cng sut bm nc lnh tun hon Cng sut bm nc gii nhit Cng sut qut thp gii nhit
TR S (kW)5,25 0,1875 0,6 0,6 0,2
- T nhng cng sut thu c nh trn , nhm s tnh ton cc gi tr : tr s dng in , hiu in th tng ng vi tng thit b tnh ton cc gi tr ph hp
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BI TIU LUN TRANG B IN
2.2. -
c im cc thit b trong mch in
Cc thit b in trong mch in iu khin : 1 aptomat tng , 1 CB cho mch iu khin 4 contactor cho my nn ( MC ) , bm + qut thp gii nhit ( MF ) , ng c bm
nc lnh tun hon + cp dch ( MW ) , ng c dao ct ( MD ) . 2 timer , 7 r-le trung gian , 2 van in t , 1 thermostat , 1 chung bo , cc n
bo , nt nhn v nt xoay ... 2.3. Nhim v ca cc thit b trong mch in
o Nt nhn ON : dng khi ng cho mch o Nt nhn OFF : dng ngt in ngng hot ng ca mch o Nt nhn BZ STOP : tt chung khi s c xy ra o Nt nhn RESET : phc hi mch khi khc phc s c o Cng tc xoay : dng chn ch cp dch v x ch AUTO hay MANUAL o Contator MC : dng khi ng my nn o Contactor MF : dng khi ng bm + qut thp gii nhit o Contactor MW : dng khi ng bm nc lnh + cp dch o Contactor MD : dng khi ng dao ct o Timer T1 : dng to thi gian tr khi khi ng my nn . o Timer T2 : dng chnh thi gian x GVHD : Thy TRN VIT HNG Page 6
BI TIU LUN TRANG B INo R-le trung gian AX1 : bo s c qu ti bm + qut thp gii nhit o R-le trung gian AX2 : bo s c qu ti my nn o R-le trung gian AX3 : bo s c p sut cao o R-le trung gian AX4 : in khin x o R-le trung gian AX5 : ngt my nn khi c s c xy ra bt k o R-le trung gian BZX : iu khin chung bo o R-le trung gian RSX : iu khin phc hi li mch khi khc phc s c
o Van in t SV1 : cp dch cho thit b bay hi ( ci ) o Van in t SV2 : cp gas nng dng x 2.4. Tnh v chn cc thit b in :
H thng s dng ngun in 3 pha 380 V .Ta c
P = 3U.I.cos I= P 3U.cos Chn cos = 0,8 Cng sut my nn P1 = 5,25 kW , I1 = 10 A Cng sut dao ct P2 = 0,1875 kW , I2 = 0,35 A Cng sut bm nc lnh tun hon P3 = 0,6 kW , I3 = 1,14 A Cng sut bm nc gii nhit P4 = 0,6 kW , I4 = 1,14 A Cng sut qut thp gii nhit P5 = 0,2 kW , I5 = 0,38 APage 7
o o o o o o
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BI TIU LUN TRANG B INo Vy cng dng in ca ci :o
It = I1 + I2 + I3 + I4 + I5 = 13,01 A 2.3.1. Chn Aptomat tng :
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Vic la chn Aptomat ch yu da vo dng in tnh ton trong mch , dng
in qu ti , tnh thao tc c chn lc , c tnh lm vic ca ph ti : IAptomat > Itt Vi : IAptomat : dng in nh mc ca Aptomat Itt : dng in tnh ton trong mch Ty theo c tnh v iu kin lm vic ca ph ti , ngi ta hng dn chn
dng nh mc ca mc bo v bng 125 % , 150 % hay ln hn na so vi dng tnh ton trong mch .-
Ta chn : IAptomat = 2,5 Itt = 2,5 .13,01 = 32,525 A Vy ta chn Aptomat c dng nh mc bng 40 A 2.3.2. Chn contactor
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Khi la chn contactor theo ch lm vic ta nn ch n k hiu trn
Contactor , ngha v phm vi s dng ca Contactor c trnh by nh sau : K hiu AC1 : quy nh gi tr dng in qua cc tip im chnh ca Contactor
khi Contactor c la chn ng ngot cc ph ti xoay chiu c cos > 0,95 K hiu AC2 : Contactor khi c la chn theo ch ny dng khi ng nhanh nhp nh , hm ngc cho ng c khng ng b roto dy qun . Khi khi ng : Ik I mcGVHD : Thy TRN VIT HNG Page 8
BI TIU LUN TRANG B INVi : I k : ng khi ng i qua cc tip im ca Contactor. I mc : dng in nh mc ca ng c . K hiu AC3 : Contactor c la chn theo ch ny dng iu khin ng
c khng ng b roto lng sc . Khi khi ng : Ik = ( 5 7 ). Imc Chn theo dng in nh mc ca ng c :
Im I mc Um = ( 380 400 ) V-
Chn in p nh mc cho cun dy Contactor (Ucd )
Ucd = ( 85 110 ) %.Um Nu Ucd = ( 60 70 ) %.Um th cun dy nhp nh v tip im b ngt . 2.3.3. Chn Contactor my nn Imn = I mc = 10 A-
Contactor my nn dng khi ng lm vic theo ch AC2
Im 2,5 .I mc = 25 A-
Chn contactor c : Im = 30 A v Um = 380 V 2.3.4. Chn contactor bm + qut thp gii nhit
Ibq I mc = 1,52 A Contactor bm qut lm vic theo ch AC2
Im 2,5 .I mc = 3,8 A
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BI TIU LUN TRANG B IN-
Chn contactor c : Im = 4 A v Um = 380 V 2.3.5. Chn contactor dao ct :
Imn I mc = 0,35 A Contactor dao ct lm vic theo ch AC2 .
Im 2,5.I mc = 0,875 A-
Chn contactor c : Im = 1 A v Um = 380 V 2.3.6. Chn contactor bm nc tun hon
Imn = I mc = 1,14 A Contactor bm qut lm vic theo ch AC2 .
Im 2,5.I mc = 2,85 A-
Chn contactor c : Im = 3 A v Um = 380 V 2.3.7. Chn r-le nhit
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c tnh c bn ca r-le nhit l quan h gia thi gian tc ng v dng in
ph ti chy qua ( cn gi l ng c tnh thi gian dng in A s ) .Mt khc cc i ng cn bo v cng c c tnh thi gian dng in . V vy ta chn r-le nhit sao cho c tnh A s ca r-le thp hn v gn st vi c tnh A s ca i tng bo v-
Trong thc t thng chn It = ( 1,2 1,3 ). Im
Vi : It dng tc ng ca r-le nhit .-
Thi gian tc ng ca r-le nhit : tt = 20 pht Vi ng c cng sut nh v trung bnh , c iu kin khi ng nng , bi s
khi ng ln , thi gian khi ng tng i di . Ta chn h s ti Ki = I ti /I m = 8 c tt = ( 1 5 ) s .GVHD : Thy TRN VIT HNG Page 10
BI TIU LUN TRANG B IN-
Vi mch ng lc c bi s dng khng cao , thi gian khi ng ngn , thng
chn Ki = 2,5 v tt = ( 3 20 ) s .-
Dng ti ng ca r-le nhit c th thay i trong phm vi nh bng nt iu
chnh .Thng r-le nhit c hai phn t t nng i vi 2 pha mng in hoc c 3 pha-
Khi dng ti ca ng c qu ln (Ic > 100 A ) th ta dng bin dng kt hp vi
r-le nhit 2.3.8. Chn r-le nhit my nn It = 1,3. I mmn = 1,3.10 = 13 A 2.3.9. Chn r-le nhit bm qut thp gii nhit It = 1,3. I mbq = 1,3.1,52 = 1,976 A 2.3.10.Chn r-le nhit dao ct It = 1,3. I mc = 1,3. 0,35 = 0,455 A 2.3.11.Chn r-le nhit bm nc tun hon It = 1,3. I mb = 1,3.1,14 = 1,842 A 2.3.12.Chn CB mch iu khin Um = 380 V v : Im = 20 A 2.3.13.Chn r-le thi gian Um = 220 V v Im = ( 1 5 ) A Chn thi gian iu chnh ty trng hp 2.3.14.Chn nt nhn Um = 380 V v Im = ( 1 5 ) AGVHD : Thy TRN VIT HNG Page 11
BI TIU LUN TRANG B IN2.3.15.Chn dy i mch iu khin Loi dy 1,5 ca CADIVI 2.3.16.Chn dy cho mch ng lc S dng cp CADIVI
MCH IN H THNG MY Nguyn l hot ng ca mch in ( cng tc xoay ch AUTO ) 3.1. Khi ng
Khi bt CB : AX5 c in , tip im thng ng ca AX5 m ra v tip im
thng m ca n ng li . Nhn nt ON : Contactor MF c in iu khin bm qut thp gii nhit hot
ng ( tip im thng m ca MF ng li duy tr cho mch khi ng ) . ng thi timer T1 c in bt u m thi gian .
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BI TIU LUN TRANG B INSau 5s 10s tip im thng m ca timer T1 ng li cp in cho contactor
MC iu khin cho my nn hot ng v n L1 sng .ng thi tip im thng m ca MC ng li cp in cho contactor MW iu khin bm nc l hot ng .Tip im thng m ca MW cng ng li cp in cho SV1 cp dch cho ci v n L2 sng. H thng khi ng hon chnh . 3.2.-
X :
Khi h thng lm xong , u d nhit nc ca thermostat ( TH ) gn pha
trn ci tc ng iu khin tip im thng m ca n ng li cp in cho AX4 .Tip im thng ng ca AX4 m ra ngt in ca contactor MW ngng cp dch vo ci , ng thi tip im thng m ca AX4 ng li cp in cho van in t SV2 a gas nng vo ci , contactor MD dao ct hot ng , timer T2 bt u tnh thi gian x v n L3 bt sng . Khi thi gian x kt thc , tip im thng ng m chm ca timer T2 m ra
ngt in ca AX4 , tip im thng m ca AX4 m ra ngt in ca SV2 , L2, contactor MD v tip im thng ng ca n ng li cp in cho contactor MW cp dch cho ci bt u mt m mi .
3.3. -
Bo v
Bo v qu ti bm + qut thp gii nhit : khi xy ra s c qu ti bm + qut
thp gii nhit , tip im thng m ca r le nhit OL1 ng li cp in cho AX1 , tip im thng ng ca AX1 m ra ngt in ca contactor MF v AX5 ngng bm qut thp gii nhit , tip im thng m ca AX1 ng li cp in cho chung BZ ku bo s c ng thi duy tr cho AX1 (v khi contactor MF mt in th tip im OL1 m ra ) .Nu mun chung ngng ku th ta nhn nt BZSTOP , lc ny BZSTOP c cp in v tip im thn ng ca n m ra ngt chung , tip im thng mGVHD : Thy TRN VIT HNG Page 13
BI TIU LUN TRANG B INca n ng li duy tr cho BZX khi nhn nt BZSTOP h ra .Khi khc phc s c xong phi phc hi li mch in v trng thi ban u bng cch nhn nt RESET , khi RSX c in v tip im thng ng ca n m ra ngt in ca AX1 , tip im duy tr ca n m ra v ngt in cp vo chung bo Hot ng ca mch bo v my nn v bo v p sut cao cng tng t nh hot
ng ca mch bo v qu ti bm + qut thp gii nhit .
3.4. -
Dng my
Nhn nt OFF , contactor MF v timer T1 mt in ko theo ton b mch b mt
in , h thng dng ton b .Tt CB ngt mch iu khin . Mch in ng lc
3.5.
Cc mch in :
TI LIU THAM KHO
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