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GVC.Ths. Phm Xun H

TRNG I HC S PHM K THUT TP. HCMKHOA IN IN T

Bo co Kh c bo vnhm 7

Ni Dung :

01Khi nim v cng dng02Phn loi cu ch03Nguyn l lm vic04Cu to cu ch05Thng s k thut06La chn cu ch07Tra cu cu ch 1 s hng sn sut

1.Khi nim:Fuse mt loi kh c dng bo v thit b in v li in trnh khi dng qu ti v ngn mch(cho xem video)

Mt s cu ch

Cng dng: thng c dng bo v ng dy in, MBA, C, cc loi thit b in khc, M,MCS.

K hiu trn hnh v mch in:

Tiu chun quc tTiu chun chu u

Institute of Electrical and Electronics Engineers Vin k ngh in v in tInternational Electrotechnical Commission y ban k thut in quc t

oBo v cho cp v ng dy: L oBo v ng c:M oBo v linh kin bn dn: R oBo v my bin p:ToBo v gia dng :FoBo v c bit dy ngm: BK t u tin trn cu chCu ch bo v qu ti:IECCu ch d phng :K t th hai trn cu chg aPhn loi

Theo hnh thc s dngCu ch bo v qu ti Cu ch d phng

Theo phm vi s dngCu ch gia dngCu ch dng trong cng nghip

Theo kt cu (Cu ch h, cu ch vn, cu ch hp, cu ch kn khng cht nhi, cu ch kn c cht nhi )Theo thi gian ct mchCu ch chy nhanh Cu ch chy cc nhanh Cu ch chy chm

2. Phn loi:

Cu ch gia dng, loi gFCu ch dng trong cng nghipaR: cu ch chy cc nhanh, dng bo v bn dn, c khnng ct b phn (ch bo v ngn mch).gR: cu ch bo v bn dn, c kh nng ct ton phn (bov qu ti v bo v ngn mch).gL/gG: cu ch s dng tng hp, c kh nng ct tonphn (bo v qu ti v bo v ngn mch).aM: cu ch bo v ng c in, c kh nng ct b phn(ch bo v ngn mch).gM: cu ch bo v ng c in, c kh nng ct ton phn (bo v qu ti v bo v ngn mch).gF/gTF: cu ch bo v my bin p lc/dy cp in ngm.gB: cu ch bo vdy cp in ngm, dy dn hm m.+ in p nh mc+ Dng in nh mc+ Kh nng ct dng in s c Khc nhau v: dng in nh mc.in p th ging nhau, cu ch khng tiu th in nng nn khng c cng sut.Ch

3.NGUYN L LM VIC.Trong mch in cu ch c mc ni tip bo v thit b cn c bo v.Khi c qu ti hay ngn mch, nhit lng sinh ra ti dy chy lm tan chy dy hoc dy chy b un cng lm ngn mch, v vy bo v c li in, loi c s c trn li in.

CU CH BO V N TRONG MCH N CU THANG

Qa trnh ct dng inGiai on trc h quang Thi gian ny l ts ,Thi gian ny khng ph thuc vo in p ngun2. Giai on h quang pht sinh v b dp tt Thi gian ny l Tl. Thi gian ny ph thuc vo in p ngun , nhng nu Tl >40 ms, th c th b qua Tl. Khi ta = ts + tl = ta

Cu ch h p GND ca CNC

CU CH H P H.R.C CA HNG CNC

Cu ch h p kiu loi 5SG5, NEOZED, ba cc do Siemens ch to

Cu ch h p4. Cu to

5.Np tin hiu1.Thn cu chi4.Cht nhi3.u ni cu chi2.Dy chay6.Vo cu chi

Cu ch h p

Thn cu chB phn chnh bn vng lin kt cc b phn khc.Lm bng vt liu cch in nh gm s, thy tinh, thy tinh si hay php.Hnh dng ca thn c th l hnh tr ng hay hnh hp.C bn c hc tt, chu c nhit sinh ra khi cu ch b chy, bn cch in tt.

Cu ch h pDy chyVt liu: km, ng, ch, nhm, bc, hp kim ca bc

Hnh dng khc nhau: dy trn si nh hoc dtc ct vt hnh ch V hay U hay c l

Cu ch h pCht nhi

Cu ch h pCht nhiCt thch anh hay chn khng.Ngn cn qu trnh oxy ha dy chy.Lm mt dy chy trong qu trnh dn in.

Lm ngui v dp tt h quang sinh ra khi cu ch b t.

Cu ch h pV cu chL b phn lp cu ch ,thng c v np.

Cu ch h pNp tn hiuMt s cu ch c np tn hiu u ca thn cu ch, khi np b bung ln ngha l cu ch b t.

5.THNG S K THUT

Dng in nh mc(A) InThi gian quy c (gi)Dng quy c khng nng chyInfDng quy c nng chyIf 411,5In2,1In4 - 1611,5In1,9In16 - 6311,25In1,6In63 - 16021,25In1,6In160 - 40031,25In1,6In>40041,25In1,6In

DNG IN NH MC(c ghi trn nhn cu ch)

29

Kh nng ct nh mcI: gi tr hiu dng ca dng in qua cu cht: thi gian tc ng ca cu ch= t/g nng chy + t/g h quang

I2t tng = I2t nng chy + I2t h quangL nhit lng pht ra trong mch trong qu trnh cu ch tc ng

1. Trng hp c dng in xung chy qua cuch. cu ch khng b t :I2t nng chy ca cu ch I2t xung*Fp(Fp: h s xung)

H s xung FpCu ch ccu to knCu ch c dychy tip xcvi khng khS xungH s FpS xungH s Fp1 100.0001,251002,11.0002,610.0003,4100.0004,6

Cu ch APHA NGUN

PHA PH TI

Cu ch B1

Ngn mch

c tnh giyampe

Quan h gia dng in v thi gian tc ng ca cu ch c xc nh bng o lng m bo tnh ng nht v chun xcvi hng lot l cu ch c sn xut.Quan h ny c th hin bng th bn

100A

100A1000A

0,2sc tnh ampe giy cu ch gG 500V AC 16250A

3000A

3.10-3 s

ng c tnh ampe giy dng phi hp vi thit b c cu ch bo vt

i tngbo vCu chThi gian10010

10,1Dng inc tnh cu ch

c tnh cu ch

tI

ImIgh

Cu ch khng bo v

Cu ch bo vIgh/ Im= (1,62) viCughmI/ I= (1,251,4) vi PbIgh/ Im= 1,15 vi (Pb+Sn)

ng dc tnh TB cn bo v .ng c tnh bo v l tng.ng thc t bo v ca cu chng c tnh K v qu ti TB.1234

Cu chCng tc t

Mng c

c tnh cu ch

Thi gian12 345 6 7 Dng ina. c tnh thp nht ca cng tc t.b. c tnh tc ng ca cng tc tc tnh qu ti ca ng cc tnh ampe giy ca cu chc tnh cu ch b tc tnh tc ng ca cu chABCThi gian khi ng ng cab cde f

c tnh cu ch

Phi hp cc cu ch mc ni tip vi nhau

My bin pCu ch chnh F3Cu chnhnh F2Cu ch nhnh F1Cu ch pha ngun

Cu ch pha ngunCu ch pha ph ti

S c ngn mch

Ct mch

Cu ch pha ngun= 1,6 : 1,0Cu ch pha ph ti

i vi cu ch gG200ACu ch pha ph ti315A500A

c tnh ct dng in (t tnh hn ch dng in)

Cu ch ct dng in s c trc khi n tng n gi trnh nn ta ni cu ch c kh nng hn ch dng inKh nng ny c th hin bng th

c tnh ct dng cu ch 690V AC - gG,hng Siemens

c tnh ct dng cu ch 690V AC- gG, hng Siemens

240A

2600A

5000A2000A

6. LA CHN CU CHDng in lm vic nh mc.in p lm vic.Nhit mi trng.Qu dng v thi gian m cu ch phi ct.Dng in s c ln nht c th c.Dng xung, dng st, dng tng t bin, dng khi ng, nhng hin tng qu ca mchGii hn v kch thc nh chiu di, ng knhhoc b dy.Tiu chun p dng.Nhng yu cu v lp t.Nhng yu cu i vi lp cu ch.Nhng th nghim kim tra v chng ch cht lng trc khi sn xut.

iu kin la chn thng thng:

UmCC UmL

ImCC Itt

Itttng ng vi cng sut tnhton ca thit b tiu th in

a. i vi ph ti khng c hin tng qu ti

ImCC= (1,1 1,2)IptmaxImCC l dng nh mc ca cu chIptmax l dng ph ti ln nhtVd. Chn cu ch bo v cho 10 bng hunh quang,mi bng c P = 60W, in p 220V,cos = 0,8.

I = P/(U*Cos) = 60/(220*0,8) = 0,34AIptmax = 0,34*10 = 3,4A ImCC = 1,1*3,4 = 3,75A 4A

b. Chn cu ch trong nh Cng sut (Watt)Cu ch cchn7003 A1.0005 A> 1.00013 A

d dng trong vic chn cu ch trong nh , c s hng dn chn theo cng sut ca tt c cc thit b c lp t trong nh c in p 220V nh sau:

c. Chn cu ch bo v dy cp inBo v qu tiBo v chng ngn mch

Cu ch gGBo v qu tiCcthng s lin quan n vic chn cu chbo v qu ti dy cp in:Dng in lm vic ca dy cp IBDng in ln nhtm dy cp c th tic IZDng in nh mc ca cu ch ImCCDng in quy c nng chy ca cu ch If

IB ImCC IZ

If 1,45 IZ

Dng in nh mc ca cu ch ImCC (A)Tit din ca cp ng hay thanh dn (mm2)Thi gian quy c (gi)IZ (A)1211152007032134002403461

c. Chn cu ch bo v dy cp in

Dng innh mc ca cu ch (A)Tit din cacp ng hoc thanh dn (mm2)Thi gianquy c(h)IZ (A)121115161,5119,520&252,512632413540614650&631016380162851002521121253521381605021682007032132501203299

Bo v ngn mchI2tcc < I2tcpVi I2tcp= K2S2K115Cp bng ng bc PVC135Cp bng ng bc cao su74Cp bng nhm bc PVC87Cp bng nhm bc cao su

d. Chn cu ch bo v ng c in

C th chn cu ch loi gG hoc aM, nhng u tin chn loi aM.

Khi c cu ch aM 1 pha no b t th nn thay c 2 pha kia.

c tnh dng in khi ng ca ng c

c tnhampe giy car-le bo v qu ti

c tnh ampe giy ca cu ch

c tnh ampe giy gii hn chu nhit ca r-le bo v qu ti

Kh nng ct ca cng tc t Dngin Iz giao im 2 ng c tnh ampe giy

Dng in IThigian t

d. Chn cu ch bo v ng c in

Chn cu ch bo v ng c ini vi nhm mt ng c in

dmCCI Imm Kmm Idm

dmPdmDC3.U..cosIdmDC Kmm : H s m my Kmm = 5, 6, 7. = 2,5 i vi ng c m my nh, khng ti. = 1,6 i vi ng c m my nng, c ti(cn trc, my nng, cn cu).

1mm maxdmCCtidmimmdm maxdmCCIK.IKIKti .IdmiIIn11n1i vi nhm nhiu ng c inChn cu ch bo v ng c inImi : Dng in nh mc ca ng c th iImmmax : Dng in m my ca ng c c dng nh mc ln nht.Kti: H s ti thc s ca ng c th IThng Kti = 1

ng c ba pha 400vng c 3 pha 500vCuchkWM lcIn (A)kWMlcIn (A)Incc (A)7,51015,5111518.4201115221520232515203018,52528,54018,52537253439,54022304430404563253451405460633040604560658037507251707510045608563109891005575105801101121257510013811015015616090125170132180187200110150205160220220250132180245220300310315160218300315

* Cn ch ti cc yu t:- Dng in tng vt khi ng t in-Nhng dng in sng hi-Qu trnh qu in p trn u cc cu ch saukhi ct dng s c.-ImCC 2IC IC(dng nh mc ca t in)e. Chn cu ch bo v t in cng sutS t in(KVAR)510203040506075100125150Imcc gG(A)20326380125160200200250400400

f. S dng cu ch trong mch dng in 1 chiuThi gian h quang dng 1 chiu ln hn nhiu so vi dng xoay chiu.in p phi gim, gim bt nhit lng, tng ng vi nhit lng khi ct dng xoay chiu.

Ch : cu ch aM khng th dng trong mchdng in 1 chiu

g. Phi hp c chn lc

My bin pCu ch chnh F3

Cu chnhnh F2

Cu ch nhnh F1 kim tra s phi hp c chn lc, cn c c tnh ampe giy v gi tr ca ng sut nhit ca cu ch.

400A100A

im c ngn mch,dng ngn mch 1000A

Phng php nh gi s phi hp c chn lc i hi nhiu vic lm cng phu.I2ttng,cu ch pha ph tiI2tnng chy,cu ch pha ngun