Kĩ Năng Thao Tác Đường Dây

7/31/2019 K Nng Thao Tc ng Dy

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TAI LIEU CO BAN-TBA

TI LIUBI DNG NGH CNG NHN QLVH TRM BIN P

CP 1 V 2A

I. N TP CHUNG KIN THC C BN TRONG QLVH:

1. Cc dng ngn mch thng gp l:Ngn mch 3 pha.Ngn mch 2 pha.Ngn mch 1 pha chm t.Chm t 2 pha ti 2 im khc nhau.

2. Cc qui nh v vic nh s thit b trong h thng in.

9.1. Ch s c trng cho cp in p c quy nh nh sau:

Cp in p (KV) K hiu ch s500 5220 2110 166 735 322 415 810 96 6

9.2. Tn thanh ci c qui nh gm cc k t:K t th nht l ch C.K t th hai ch cp in p.K t th ba ch s th t thanh ci, s 9 k hiu thanh ci ng vng.V d: C11 c th gii thch l thanh ci 110kV s 1.

9.3. Tn ca my ct in c quy nh gm cc k t:K t th nht c trng cho cp in p. i vi my ct t k hiu

th nht l ch T, khng in k t th nht l ch K cn k t th hai lch cp in p.

K t th hai (ba i vi my ct khng v t) c trng cho thit b

c bo v ca my ct, c quy nh nh sau:- My ct MBA: ly s 3- My ct ca ng dy: ly s 7- My ct MBA t dng: ly s 4- My ct u cc MF: ly s 0- My ct ca my b quay: ly s 0- My ct ca t: ly s 0


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- My ct khng in: ly s 0K t th ba (i vi my ct khng v t) th hin s th t: 1,2,3i vi my ct ca thanh ci vng hai k t tip theo k t th nht l:

00i vi my ct lin lc gia hai thanh ci, hai k t tip theo k t th

nht l s th t ca cc thanh ci.V d: 271 l my ct ca Z 220kV s 1.

9.4. Tn ca my bin p c quy nh gm cc k t :Mt hoc hai k t u c k hiu nh sau: i vi MBA lc k

hiu l ch T (Transformer), i vi MBA t ngu k hiu l ch AT(Auto Transformer), i vi MBA t dng k hiu l TD.

K t tip theo l s th t ca MBA.9.5. Tn ca khng in c quy nh gm cc k t :

Hai k t u l ch KH, khng trung tnh k hiu l KTK t th ba c trng cho cp in p

K t th t l s 0K t th nm l s th t ca mch mc khng in9.6. Tn ca T in c quy nh gm cc k t :

Ba k t u i vi t b dc l ch TBD, t b ngang k hiu l TBNK t th t c trng cho cp in pK t th nm l s 0K t th su l s th t ca mch mc t in

9.7. Tn ca my bin in p c quy nh gm cc k t :Hai k t u l TUCc k t tip theo ly tn thit b m my bin in p u vo, i

vi cc thit b m tn ca thit b khng th hin r cp in p th sauhai k t u s l k t c trng cho cp in p, tip theo l tn thit b.9.8. Tn ca my bin dng in c quy nh gm cc k t :

Hai k t u l TICc k t tip theo ly tn thit b m my bin dng in u vo, i

vi cc thit b m tn ca thit b khng th hin r cp in p th sauhai k t u s l k t c trng cho cp in p, tip theo l tn thit b.

9.9. Tn ca chng st c quy nh gm cc k t :Hai k t u l CSK t th ba l du phn cch (-)Tip theo ly tn thit b c bo v, i vi cc thit b m tn ca

thit b khng th hin r cp in p th sau ba k t u s l k t ctrng cho cp in p, tip theo l tn thit b. i vi chng st van nivo trung tnh MBA thm hai k t phn bit l du phn cch (-) v s0

9.10. Dao cch ly lin quan ca my ct, khng, t v TU c quy nhgm cc k t :

Cc k t u l l tn ca my ct ni trc tip vi DCL (i vi


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DCL ca TU, cc k t u tin l tn ca TU, tip theo l tn thit b nitrc tip vi DCL), tip theo l du phn cch (-)

K t tip theo c k hiu nh sau: DCL v thanh ci ly s th t ca thanh ci ni viDCL DCL v ng dy ly s 7 DCL v MBA v khng in ly s 3 DCL v thanh ci vng ly s 9 DCL v ni tt mt thit b(my ct,khng, t) lys 0

DCL ni ti phn on no (pha phn on no) th ly s phnon thanh ci (hoc thanh ci) .

9.11. Tn ca DCL ni t trung tnh MBA c quy nh gm cc k t :K t th nht c trng cho cp in pK t th hai l s 3K t th ba ly theo th t ca MBA(v d MBA T1 ly s 1)K t th t l du phn cch (-)K t th nm l s 0

9.12. Tn ca DCL trung tnh MBA ni vi cun dp h quang hoc intr ni t trung tnh MBA, cu dao khng in trung tnh c quy nhgm cc k t :

Cc k t u ly tn ca my ct khng trung tnh hoc cun dp hquang (trong thc t c th khng c my ct nhng khi nh s vn coi lc my ct) hoc tn ca in tr ni t trung tnh MBA, tip theo l duphn cch (-)

K t tip theo l s 39.13. Dao tip a c quy nh gm cc k t :

K t u tin l tn cu dao (hoc thit b c lin quan trc tip)clin quan trc tip

K t tip theo c trng cho tip a, dc quy nh nh sau: Tip a ng dy v t in ly s 6 Tip a MBA, khng in v TU ly s 8 Tip a my ct ly s 5 Tip a thanh ci ly s 4

9.14. Tn cc in tr trung tnh MBA c quy nh gm cc k t:K t th nht l ch R biu th cho in tr (Resistance).K t th hai c trng cho cp in p.Tip theo l tn ca MBA m R c u vo.

9.15. Cc thit b ng ct cc nhnh r, cc phn on gia ng dy khiu nh sau:

i vi my ct: Cc k t u nh s my ct theo quy nh nh snh trn.


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i vi cu dao on ng dy hoc cu dao nhnh r: cc k t uly s ct ti im t cu dao, tip theo l du ( - ) sau l k t ctrng cho cp in p. i vi cu dao phn on ng dy t ti trmin khng c my ct, vic nh s dao thc hin coi nh c my ct.

Cc k t cui cng l tn a danh ch phn on hoc nhnh r.

9.16. Trong qa trnh thc hin nh s thit b, c mt s trm c nhiu cpin p hoc c nhng kt dy c bit, th nhng phn kt dy chnh catrm phi da trn quy nh trn nh s, phn cn li phi ly nhng sthch hp d nh v trnh trng vi nhng s trn

3. ngha cc t vit tt: REF, SCADA, EMS, DMS, PLC, SOFT, LCD,BIL, IEC, GIS, OC, OV, BF, UF, UV, FR?

REF : (Restrict Eathing Fault) hoc (Residual Eathing Fault): (Chmt c gii hn) L bo v so lch chm t c gii hn, vng bo v lvng nm trong khong u ni so lch ca hai TI.

SCADA: (Supervisory Control And Data Acquisition): L h thng

gim st, iu khin v thu thp d liu t xa.EMS: (Energy Management System): L h thng qun l nng lngDMS: (Distribution Management System): L h thng qun l li

in phn phiPLC : * (Power Line Carrier): L truyn dn sng thng tin trn

ng dy ti in.* (Program Logic Control): Lp trnh iu khin Logic.

SOFT : (Swich Onto Fault Trip): (Chng ng vo im s c) L khing vo im s c th n ct ra khng c thi gian tr.

LCD: (Liquid Crystal Display): Mn hnh tinh th lng

IEC: (Internation Electrotechnical Community): Tiu chun k thutquc t.OC: (Over Current): Qu dngOV: (Over Voltage): Qu pUV: (Under Voltage): Km pBF: (Breaker Fault): (Li my ct) l khi rle xut lnh ct m my

ct khng ct c th chc nng ny (Trong Rle) s khi ng, gi tnhiu i ct cc my ct khc c lp my ct b s c.

UF: (Under Frequency): (Km tn s) Khi qu ti, tn s s gim thp,chc nng ny s thc hin sa thi bt mt s ph ti khng quan trng.

GIS: (Gas Insulation System): Mc cch in ca h thng kn.BIL: (Breaker Insulation Level): Mc cch in ca MC.FR: (Fault Recorder): Ghi li cc d kin s c, li, bt thng.

4. Quy nh v kim tra v x l nhit mi ni?i vi cc mi ni: Mt ngoi ca ng ni khng c c vt nt,

ng ni phi thng, phi c p ni ng qui trnh, cc hm p phnnhm v thp phi ng kch thc qui nh ca nh ch to. Trc khinghim thu a vo vn hnh phi c tr s in tr tip xc ca tt c cc


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mi ni. in tr ca on dy c mi ni khng c ln hn 1,2 lnon dy c cng chiu di v tit din.

o nhit mi ni v tip xc lo.o 1 nm / ln khi ng dy mang ti cao.o 3 thng/ln khi ng dy ang qu ti.

V mt s qui nh khc ca Cng ty, n v.Khi chnh lch mi ni hay im tip xc vi dy dn ln hn 15oC

th phi o 3 thng/ln v c k hoch bo dng nhng nu iu ny xyra i vi Z qu ti th phi sa cha ngay.

Khi chnh nhit gia mi ni hay tip xc lo vi dy dn lnhn 75oC th phi sa cha ngay.

5. Nu cc hng mc kim tra MBA:Nhn vin vn hnh phi cn c vo cc ng h t bng iu khin

kim tra MBA v ghi thng s vo s vn hnh mi gi mt ln.Mi ca t nht mt ln, nhn vin vn hnh phi tin hnh kim tra cc

hnh mc sau: Kim tra ting ku ca MBA phi bnh thng. Kim tra mc du cc bnh du ph phi . Kim tra nhit du, nhit cun dy MBA.

Kim tra tnh trng s u vo khng b rn nt hay chy du trncc u s phi nhn thy c.

Kim tra mu sc cc ht Silicagel cc b th. Kim tra h thng lm mt:

+ Tnh trng ng c qut mt lm vic tt.+ V tr cc van ph hp vi tnh trng vn hnh.

+ Cc mt bch khng b r r du. Kim tra v tr cc van ca ng ng ti bnh duph phi m. Kim tra tnh trng thanh ci v cc imtip xc cc u ct. Kim tra trang b phong cha chy y .

6. Vn hnh MBA qu ti bnh thng, qu ti s c:Qu ti bnh thng l ch lm vic xt trong mt thi gian no

(ngy, thng, nm) , trong c 1 khong thi gian MBA lm vic qu ti vkhong thi gian cn li ca chu k kho st, MBA mang ti nh hn nh mc.

Mc qu ti phi c tnh ton sao cho hao mn cch in trong khong thigian xt khng vt qu nh mc ng vi nhit dy qun MBA tng ng.

Qu ti s c l ch qu ti cho php trong mt s trng hp ngoi l(s c) vi mt thi gian hn ch khng gin on vic cung cp in nng.

Thi gian v mc qu ti cho php ty thuc vo ch vn hnh,tnh trng my, ni t my.

Thi gian qu ti bnh thng c xc nh ph thuc vo nhit lp


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du trn cng trc khi qu ti, bi s qu ti theo nh mc v kiu lm mt caMBA

Qu ti cng ln th thi gian cho php qu ti cng ngn, tr s qu tibnh thng da theo quy trnh vn hnh MBA. Nu tr s qu ti vt qu tr squ ti cho php th phi tin hnh a thm MBA vo lm vic song song (nu

c) hoc ct gim ph ti theo phng thc: ct nhng h khng quan trng trc,ri mi ct n h quan trong sau.7. Vn hnh ng dy v TBA theo thng t 12:

9.1. H thng in truyn ti vn hnh ch cnh bo l :Mc mang ti ca cc ng dy v trm bin p chnh trong li

in truyn ti trn 90% nhng khng vt qu gi tr nh mc;Kh nng xy ra thin tai hoc cc iu kin thi tit bt thng c th

gy nh hng ti an ninh h thng in;Kh nng xy ra cc vn v an ninh, quc phng c th e da an ninh

h thng in.

9.2. H thng in truyn ti vn hnh ch khn cp l:Tn s h thng vt ra ngoi phm vi cho php cho ch vn hnhbnh thng, nhng nm trong di tn s cho php i vi trng hp xy ra s cmt phn t trong h thng khong t 47Hz cho n 52Hz.

in p ti mt nt bt k trn li in truyn ti nm ngoi phm vicho php trong ch vn hnh bnh thng, nhng nm trong di in p chophp i vi trng hp xy ra s c mt phn t trong h thng in dao ngin p trn li in tm thi ln hn 10% so vi in p danh nh nhngkhng c vt qu 20% so vi in p danh nh.

Mc mang ti ca bt k thit b in no trong li in truyn ti hoc

thit b in u ni vo li in truyn ti vt qu gi tr nh mc nhng di110% gi tr nh mc m thit b ny khi b s c do qu ti c th dn n ch vn hnh cc k khn cp.

9.3. H thng in truyn ti vn hnh ch cc k khn cp khi tnti mt trong cc iu kin sau y:

Tn s h thng nm ngoi di tn s cho php i vi trng hp xy ras c mt phn t trong h thng in;

in p ti mt nt bt k trn li in truyn ti nm ngoi di in pcho php i vi trng hp xy ra s c mt phn t;

Mc mang ti ca bt k thit b no trong li in truyn ti hoc thit

b u ni vi li in truyn ti trn 110% gi tr nh mc m thit b ny khib s c do qu ti c th dn n tan r tng phn h thng in;Khi li in truyn ti ang ch vn hnh khn cp, cc bin php

c thc hin a h thng v trng thi vn hnh n nh khng thc hinc dn ti hin tng tan r tng phn h thng, tch o hoc sp in ph thng.

8. Cc trng hp cho php ng li hoc phi kim tra khi bo v MBA tc


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ng ?Cc trng hp MBA b ct do cc bo v khng c lin quan n h

hng bn trong my, ch cn kim tra s b bn ngoi my v nu khng pht hinthy hin tng bt thng g th xin kin ca KSH A3, gim c cng ty chophp ng li MBA, c th cc s c cho php ng li MBA.

Bo v qu dng pha 3 pha ca MBA tc ng.Cc trng hp sau phi kim tra, th nghim my trc khi a MBA

vo vn hnh: MBA t ct do bo v hi hay bo v so lch lm vic th cn phikim tra, th nghim my v phn tch kh tm nguyn nhn. Ch cho php ngli MBA vo lm vic tr li sau khi tm r cc nguyn nhn v khc phc cc hhng. Trong trng hp phi c s ng ca Gim c Cng ty.

9. Qui nh v vn hnh bt thng v s c MBA?

9.1. Trong khi vn hnh nu thy MBA c hin tng bt thng nh: chydu, mc du trong bnh du ph thp, my b pht nng phi tm mi bin

php gii quyt, ng thi phi bo co ngay vi lnh o v ghi ch y vo s vn hnh.9.2. i vi cc trng hp sau y phi tch MBA ra khi vn hnh:

+ My c ting ku mnh, khng u v rung mnh bn trong.+ S pht nng tng ln bt thng v lin tc trong iu kin nh mc.+ Du trn ra ngoi bnh du ph hoc van an ton lm vic.+ Mc du h thp hn mc quy nh bnh du ph v tip tc h thp.+ Mu sc ca du thay i t ngt.+ Cc s u vo b v, rn nt v phng in b mt hoc cn du.

9.3. Khi MBA b qu ti hoc nhit tng cao, nhn vin vn hnh phi xin

kin cp trn tm mi bin php iu chnh v gim bt ti ca my.9.4. Khi nhit du khng MBA tng ln n mc bo tn hiu, nhn vintrc ca phi tm nguyn nhn v bin php gim bt nhit bng cch:

+ Kim tra ph ti MBA v nhit mi trng lm mt.+ Kim tra thit b lm mt: Tnh trng cc qut lm mt.

9.5. Nu nhit MBA tng cao do thit b lm mt b hng m c iukin ct my sa cha th xin ct sa cha. Khi iu kin vn hnh khngcho php ct my th ch ngng ring bit thit b lm mt ng thi nhn vintrc ca c th iu chnh gim bt ti MBA trong khi vn hnh khng c thit blm mt.9.6. Nu mc du h hn mc qui nh nhiu th b sung du vo MBA.Trc khi b sung du phi sa cha ch r r, b chy du. Du b sung vo phil du mi c th nghim t tiu chun.9.7. MBA t ct do bo v hi hay bo v so lch lm vic th cn phi kimtra , th nghim my v phn tch kh tm nguyn nhn. Ch cho php ngMBA vo lm vic tr li sau khi tm r nguyn nhn v khc phc cc hhng. Trong trng hp phi c s ng ca Gim c cng ty.9.8. Trong trng hp MBA b ct do cc bo v khc khng c lin quan


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h hng bn trong MBA th cho php ch cn kim tra tnh trng bn ngoi my vnu khng pht hin thy hin tng bt thng g th xin kin iu min chong in li MBA.9.9. Khi rle hi bo tn hiu, trc chnh phi kim tra bn ngoi MBA vly kh phn tch.

+ Khi kim tra bn ngoi thy c du vt h hng s, thng du, kim trathy kh chy c hay kh c sn phm phn hu ca cch in phi bo covi iu min v Gim c Cng ty xin dng my.+ Nu kim tra khng thy hin tng trn th c th tip tc lm vic nhngphi theo di thng xuyn. Nu c xut hin kh trong rle th bo v tiptc bo tn hiu th phi bo ngay vi Gim c Cng ty v xin kin dngmy kim tra.

9.10. Tt c mi x l cc hin tng bt thng v s c MBA u phi ghiy vo h s MBA.

10. Gii thch khi u ngc cc tnh dng in 1 pha i vi mch cng t3 pha:Cng sut tc dng c tnh nh sau:

P=UAIAcosA+UBIBcosB+UCICcosC (*)Trong :

UA,, UB, UC l in p cc pha A, B, CIA, IB, IC l dng in cc pha A, B, CCosA, cosB, cosC l h s cng sut cc pha A, B, C

Nu c 3 pha u ng cc tnh th h s cng sut cos ca 3 pha scng du. Nu 1 trong 3 pha dng in u ngc cc tnh th h s cng sut

cos ca pha s tri du vi 2 pha cn li. Gi s in p cc pha l UP, dngin cc pha u nhau l IP, h s cng sut u nhau l cosTa c cng thc tnh cng sut tc dng khi u ng cc tnh l: P=3

UPIPcosNu u ngc cc tnh 1pha gi s pha C th theo cng thc (*)

P= UPIPcosA + UPIPcosB + UPIPcos(180+C)P= UPIPcos + UPIPcos - UPIPcos = UPIPcos

Do trong mch cng t ranh gii 3 pha nu u ngc cc tnh dngin 1 pha th ch s cng t ghi nhn vi sn lng thc t gim i 2/3 ln (chbng ch s ca 1 pha).11. Tc hi khi p lc kh SF6 gim thp :

Kh SF6 dng cch in v dp h quang. V th trong qu trnh VH,nu p lc kh SF6 gim thp s gy nh hng rt nghim trng n MC v thitb.

Trng hp kh SF6 gim thp Cp 1 (Alarm): Lc ny kh nng dp tth quang ca my ct b hn ch. Nu trng hp ny m my ct ct (do iukhin hoc bo v) lm p lc kh suy gim hiu hn gy nh hng n my ct


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nh: Khng dp tt c h quang, lm chy hng tip im, pht nhit gy nmy ct...

Trng hp kh SF6 gim thp Cp 2 (Lock Out): Lc ny kh nng cchin & dp h quang rt km nn MC s b kho c mch ng & mch ct. Nguyhim nht l trng hp lc ny xut hin s c dn n khng c lp c im

s c, dng s c vn duy tr gy h hng thit b, vt liu...; Cc bo v lc nykhi to ct cc my ct khc c lp im s c dn n mt in din rng.Hoc khi kh SF6 gim thp cp 2 (Lock Out) cn tin hnh c lp my ct xl dn n phi ct in cc my ct lin quan gy nh hng vic cung cp inv tnh n nh ca h thng.12. Cch x l khi MC SF6 c cc bt thng sau:

p lc kh SF6 gim thp:+ Khi my ct bo tn hiu p lc kh SF6 gim thp cp 1: Trc ca bo

co lnh o, trng trm v A3 cho kim tra p lc kh SF6. Xc nh nguyn

nhn gim p lc v tin hnh np kh theo ng mc quy nh theo quy trnhnp kh hoc xc nh tn hiu ch th nhm.+ Khi pht hin p lc kh SF6 gim thp cp 2, khin cho mch thao tc b

kho, trc ca bo co cho Lnh o, trng trm v A3 c bin php x l phhp vi cc thit b khc trong h thng v c bin php x l my ct cn thit.

L xo MC khng cng c sau khi ng hoc ct. Trng hp ny cntin hnh cng l xo MC bng tay tip tc thao tc, sau phi kim tra mchcp ngun v ng c cng l xo ca MC x l h hng.

Mch khng ng pha ca MC tc ng (ch vi cc my ct c b truynng ring tng pha): Phi kim tra v xc nh nguyn nhn dn ti mch ny tc

ng c hng x l thch hp.i vi MC chn khng yu cu ch yu l h thng sy chng ngng tbung MC phi lm vic tt. Khi c iu kin phi lm v sinh sch s tt c ccb phn mang in v cch in ca MC.

Li mch thao tc: C rt nhiu nguyn nhn c th dn ti khng thaotc ng, ct c my ct nh: mch ct b h hng, li lin ng, hng Rletrung gian ng ct x l cn phi xc nh c nguyn nhn li mch thaotc.

13. Cc hng mc kim tra MC SF6 ang vn hnh?

Trong vn hnh bnh thng, mi ca 1 ln NVVH phi kim tra MC v: Tnh trng bn ngoi gm: s, tip a, pht nng u ct (cam), ting ku ca MC. p lc kh SF6 : s thay i p lc kh khng c nhn thybng mt (ti cng T0mt).

p lc kh nn (i vi BT kh nn) hoc trng thi l xo phi vtr tch nng y (i vi b truyn ng l xo), ch th trng thi O/C


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ca MC phi tng ng vi tnh trng vn hnh. in p, dng in i qua MC.

Sau mi ln ng, ct bnh thng v s c phi kim tra ti ch cc mcsau:

+ MC ng hoc ct tt c 3 pha.

+ Cc hin tng khc thng: v ting ku, p lc kh SF6, p lc khnn.

+ Ghi s ln thao tc tng pha b m ca MC.+ i vi b truyn ng kh nn: Kim tra my nn kh phi t dng p

lc nh mc v t ng x nc ng van y ca xi-phng my nn.+ i vi b truyn ng l xo: Kim tra ng c tch nng dng sau

thi gian ln dy ct (khi MCng) v l xo v tr tch nng y .Nu qu trnh kim tra pht hin iu g bt thng phi bo ngay cho ngi

c trch nhim x l v ghi vo s theo di MC.

14. Mch in khng ton pha my ct TBA:G

CCACCB

CCCTCA

TCBTCCTCA

TCB

TCCBVG

52a52bCBCA

BCA+

52a52a52b


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Mch bo v khng ton pha

Ch thch:- 52a; 52b : Tip im ph my ct.- G : Rle trung gian- : Tip im ca Rle trung gian

- CC-A : Cun ng Pha A- CC-B : Cun ng Pha B- CC-C : Cun ng Pha C- TC-A : Cun ct Pha A- TC-B : Cun ct Pha B- TC-C : Cun ct Pha C

15. Cc hng mc kim tra TI, TU, CSV trong vn hnh TBA:Cc hng mc kim tra TI trong vn hnh:

- C chy du u ra s cp hoc th cp, cc mt bch ni, ng chth mc du.

- Cc u u s cp c hin tng nh la hay i mu do pht nhit.- ng s c b phng in, bi bn hay nt v.- Mc du trong ng ch mc du.

Cc hng mc kim tra TU trong vn hnh:- C chy du u ra s cp hoc th cp, cc mt bch ni, ng ch

th mc du.- Cc u u s cp c hin tng nh la hay i mu do pht nhit.- ng s c b phng in, bi bn hay nt v.- Mc du trong ng ch mc du.

Cc hng mc kim tra CSV trong vn hnh:- Cc u u s cp c hin tng nh la hay i mu do pht nhit.- ng s c b phng in, bi bn hay nt v.- Kim tra ch s ca b m CSV.

Lu vn hnh:- Trng hp dy ng th TU, TI b hng:

- Khi dy ng th ca TU, TI b t ngay ti v tr N (hnh v).- ch vn hnh bnh thng, mch dng cung cp cho cc thit b nh

r le bo v, cc ng h o lng vn hot ng bnh thng. Tuy nhin khi b


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t dy trung tnh th s c hin tng b di im trung tnh (ch xut hin khi phti ca TU, TI khng i xng) v iu ny s lm cho cc thit b o lng hocbo v lm vic sai.

- Khi phng in t pha s cp sang pha th cp ca TU, TI th gy nguyhim cho ngi v thit b, c th ph hng cc thit b nh r le bo v hoc cc

thit b o lng Cch x l: Tin hnh kim tra thng mch tng on mch th cp ca

TU, TI pht hin ch hng.

16. Cc lin ng c bn gia DCL v MC: iu kin c bn lin ng gia dao cch ly v my ct (cc iu kin

khc nh: p lc kh my ct , rle Trip & Lock out, rle gim st mch ct ....iu khng tc ng):

+ ng c my ct t xa th cc dao cch ly hai u phi ng.+ ng c my ct ti ch th hai dao cch ly hai u khi ct.

+ ng c my ct hp b bng in th my ct phi v tr vn hnhhoc th nghim.+ ct c my ct hp b bng c ti nt nhn khn cp th my ct phi v tr vn hnh.

+ ng- ct c DCL t xa hoc ti ch th cc my ct phi ct.17. Tc dng ca mch chng gi gi MC:

Khi thao tc ng MC, m ti thi im ng dy ang b s c (vd ct in ng dy cng tc, sau khi lm xong nhm cng tc khng thotip a lu ng ng dy) th xem nh ta ng MC vo im s c. Bo v stc ng ct MC, lc ny nu thiu mch chng gi gi m tay ngi thao tc vn

duy tr kha ng v tr ng hoc tip im kha MC b h th MC s ng ctnhiu ln, h quang sinh ra trong bung tip im ca MC duy tr v ko di lmnh hng n tui th tip im ca MC. V vy ngi ta thit k mch chnggi gi bo v MC.18. Bo v so lch thanh ci 87B tc ng trong nhng trng hp:

Bov so lch thanh ci (F87B) l loi bo v so snh pha. Mch dngF87B ly vc t tt c cc dng in ca cc ngn l ni vi thanh ci, Khi ch u dy bnh thng, dng in th cp i vo r le 87B Id xp x bng khng,r le khng tc ng. Trng hp b s c trong vng bo v (c gii hn bicc TI cc ngn a vo F87B) gi tr Id ln v r le tc ng i ct cc MC linquan.19. Cc nguyn nhn c th dn n bo v thanh ci tc ng nhm:

Khng a mch dng ca mt tuyn ng dy vo bo v thanh ci.Khi khng a mch dng ca mt xut tuyn ng dy vo bo v

thanh ci th dng so lch Id xp x bng dng in ca tuyn ng dy iuny c th lm cho r le tc ng nhm nu gi tr dng ti vt qu gi tr dngt ca bo v.

Vi r le s loi RED 521 c chc nng gim st trng thi mch dng.


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trng hp ny r le s xut tn hiu Open CT (Open CT c ngha l h mchdng a vo bo v)nu gi tr dng ti ca xut tuyn ln hn gi tr ci tca chc nng gim st trng thi OCT. Trng hp ny th chc nng so lch sb kho trong sut qu trnh duy tr tn hiu Open CT. Cng c th khng xut tnhiu Open CT nu dng ti khng t tr s ci t ca bo v relay.

u ngc cc tnh hoc u sai th t pha mch dng ca mt tuynng dy a vo bo v thanh ci:

+ Nu u ngc cc tnh, mch dng ca tuyn ng y a vo bov thanh ci th gc pha ca dng in xut tuyn ny cng pha so vi cc xuttuyn cn li v khi vn hnh bnh thng bo v s tc ng nhm.

+ Nu u sai th t pha bo v cng tc ng nhm do sai lch gc pha cso snh. V d a dng pha B v C o v tr cho nhau, lc ny gc lch phatng ng ca pha C (pha B) l 600 v dng so lch tng ln v bo v s tcng.

20. Nguyn l lm vic ca bo v 50BF, Phm vi tc ng ca bo v ny:

Chc nng 50BF c th lm vic hai ch : Ch lm vic ph thuc(External CBF) hoc ch lm vic c lp (Internal CBF) hoc kt hp c 2 ch nu trn (On, Int. or Ext.).

Ch lm vic ph thuc: L c khi to t cc tc nhn bn ngoia ti. Lc chc nng ny s tc ng i ct MC v iu kin sau thi gianBF.

Ch lm vic c lp cn tho mn cc iu kin sau:+ Gim st dng chy qua MC c bo v.+ Bo v c ci t 50BF xut lnh ct do nguyn nhn no .+ Sau khong thi gian BF nu dng chy qua MC nh hn ngng t ca

chc nng 50BF th bo v s xc nhn MC dc ct ra v t tr v. Nu dngchy qua MC vt qu ngng t kt hp vi thi gian BF ca n th chc nng50BF s tc ng i ct cc MC lin k trc v sau MC b li.

Phm vi tc ng.+ Tu theo chc nng 50BF c khi to t bo v Z hay MBA cc i

tng ct s khc nhau. Khi chc nng 50BF tc ng s i ct cc MC lin ktrc v sau MC b li trong vng bo v s cp. C th hiu khi nim vng bov s cp l vng bo v m r le tc ng ct MC khi xy ra s c bng mttrong cc chc nng c ci t khc chc nng 50BF.

+ Phm vi tc ng ca chc nng 50BF thng l rt rng, gy gin on

cung cp in.21. Gii thch chc nng SOFT (Switch onto fault trip) trong cc bo v rlek thut s:

Khi c s c Z, rle bo v tc ng ct MC, sau ng li MC bngtay hoc t ng m s c vn cn duy tr th chc nng SOTF (switch on tofault ) trong cc bo v rle k thut s ca cc rle bo v s lm vic ct tc thiMC.


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Nguyn tc lm vic ca chc nng SOTF l tc ng ct MC tc thi,khng kim tra hng sau khi ng li MC (bng tay hoc bng F79) m s cvn cn duy tr nhm m bo loi tr nhanh v chn lc phn t b s c khi hthng in.

a chc nng SOTF ca cc bo v k thut s vo lm vic th cna tn hiu khi ng t rle bo v v trng thi ng m MC ti b phn nhntn hiu vo ca bo v.22. Cc loi rle no khi cha gii tr c hiu rle th khng th ng liMC:

R le ct v kha (F86): Khi xy ra s c cc r le bo v s tc ng c lp im s c. i vi nhng s c m phm vi c xc nh c th v dnh cc s c ca MBA, s c vng II, III khong cch, th bo v r le s tcng ct MC thng qua r le F86. Khi r le F86 tc ng s gi tn hiu i ct MCng thi lm nhim v kha (Lockout) mch ng. iu ny l cn thit, bi vvi nhng s c thc s th cn phi c kim tra v x l dt im mi c

cho php ng MC vn hnh tr li.R le gim st cun ct ca MC (F74): Trong mt s trng hp c th

s dng r le gim st cun ct MC kha mch ng. Bi v khi cun ct bhng, nu xy ra s c hoc thao tc ct MC s khng thc hin c, iu ny rtnguy him nn s dng r le F74 kha mch ng ca MC.23. Cc loi rle no vn c th ng li c my ct ngay c khi cha giitr c hiu:

i vi cc bo v r le k thut s khi tc ng ct MC th s kch hotcc n chc nng sng (c hiu). Tuy nhin khi im s c c c lp, r le tr v nhng cc n led chc nng vn sng nhm gip cho NVVH nm bt

nhanh chng tnh trng s c. Khi r le tr v th cho php NVVH thao tc ngli MC.24. Cc rle khi mt tn hiu in p rle s lm vic sai l:

Nhng rle sau y c s dng tn hiu in p: F21, F67/67N, F90,F25/F79. Khi mt tn hiu in p th bo v s lm vic sai .

Cc bo v khong cch F21P, F21B : Khi mt tn hiu in p th bo vs lm vic sai do tng tr tnh ton ca r le c nhiu kh nng ri vo vng tcng (Z1, Z2, hoc Z3). Cc r le s c ci t kho chc nng khong cchv chuyn sang chc nng qu dng khn cp bng mt nh phn vo (BinaryInput) kim tra trng thi ca MCB cung cp p kim tra.

F25: Khi mt tn hiu in p th khng kim tra c iu kin ng bca h thng thc hin ho hai h thng in vi nhau.F79: Khi mt tn hiu in p th khng c in p so snh thc hin

chc nng AR nu c yu cu kim tra ng b.i vi cc r le c chc nng qu dng c hng th chc nng ny s

khng lm vic nu mt p kim tra a vo.* Lu cch khc phc:

Cn c mch gim st trng thi cc MCB (mini current breaker) cung


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cp tn hiu in p kim tra a vo bo v Rle.25. Mc ch, ngha ca vic dng rle bo v tn s thp:

lch tn s khi tr s danh nh chng t trong h thng in b mtcn bng cng sut tc dng gia ngun pht v ph ti. Nu tn s qu thpchng t trong h thng thiu cng sut tc dng, ngc li nu tn s qu cao

chng t trong h thng tha cng sut tc dng. sai lch tn s l mt c trng cho s n nh ca h thng chng li

nhng bin i cng sut tc dng trong h thng in. i lng ny cng bchng t h thng cng n nh. V vy h thng cng ln bao nhiu th thit b otn cng phi chnh xc by nhiu.

Khi tn s b gim thp chng t cng sut ca ngun in khng png c nhu cu ca ph ti. a tn s tr li bnh thng phi sa thi tngbc ph ti cho n khi lp li s s n nh ca h thng.

26. S nguyn l 87T:Nguyn l : Bo v so lch MBAda trn nguyn tc so snh bin

dng in gia hai u phn t cbo v.Theo s nguyn l ta thy:- Dng so lch MBA: Idiff = |It1 - It2| .- Dng hm: Istab. = | It1| + |It2 | .26.1.Trng hp MBA lm vicbnh thng v ngn mch ngoi thdng It2 ngc hung vi It1.

Tc l : It2 = -It1V ln : | It2| = | -It1|

a.Trng hpngn mch ngoi

v lm vic bnhthng

b.Trng hp ngnmch

trong vng bo v

Dng so lch MBA: Idiff = | It1 + It2 | = | It1 - It2 | = 0 (v It2 ngchng It1).Dng hm: Istab = | It1| + | -It2 | = 2It1 = 2It2.

* Nh vy trng hp MBA lm vic bnh thng v ngn mch ngoi th


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29. Cch kim tra pht hin hin tng chm t ngun DC?Cho ct dn tng mch trong thi gian ngn xc nh ni b chm chp

(trong 1 n 2 giy).Trng hp khng xc nh c chm t trong cc mch cung cp cho

ph ti in mt chiu phi phn on s c xy ra trn thanh ci hoc Accu. Khict in cc vt ny phi ch vic cung cp cho cc ph ti quan trng.Khi xc nh c mch b s c cng phi ti lp ngay tip tc cung

cp in (ngoi tr ng dy cung cp cho cc thit b khng quan trng) v tmbin php x l bng cch tch dn cc nhnh ph ti ni vo ng dy tmim chm t.

d dng xc nh im chm t c th dng n bo chm t hocthit b o lng bit chm t cc dng (P) hay m (N) ca h thng mtchiu.30. Cc tr s cch in ca h thng DC theo cc cp in p.

Rc ca tng cp in p:300K i vi ton b h thng in mt chiu .

1M i vi h thng lm vic ring lTheo QPTB ca nh xut bn xy dng nm 2001 th Rc ca tng cp

in p nh sau th bo tn hiu:20K i vi cp in p 220v10K i vi cp in p 110v5K i vi cp in p 48v3K i vi cp in p 24v

31. Thit b kim tra cch in thng xuyn trn thanh ci DC pht tnhiu khi cch in b suy gim:Rle kim tra chm t ngun DC l thit b hp b vi t chnh lu.Khi cch in DC b suy gim th n tn hiu ti t DC s sng .

32. Cch thao tc khi vn hnh h thng lm mt MBA ch bng tay(Manual)? Cc iu cn lu :

iu khin ti phng iu khin:+ Kim tra cc kha thao tc ng/ct cc qut v tr ct.+ Chuyn kho chn ch t ng/bng tay sang v tr bng tay.+ Bt cc kha thao tc ng/ct ca tng qut mt sang v tr ng, kim tra

ng c qut quay theo chiu kim ng h. Nu chuyn kha m ng c qutkhng khi ng phi kim tra ptmt cp ngun mch iu khin, ngun cungcp cho tng ng c.

iu khin ti t trung gian MBA:+ Kim tra cc kho thao tc ng/ct cc qut v tr ct.+ Chuyn kha chn ch t ng/bng tay sang v tr bng tay.+ Chuyn kha chn ch t xa/ti ch sang v tr ti ch+ Bt cc kha thao tc ng/ct ca tng qut mt sang v tr ng, kim tra


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19/58

Trn hnh v l th vc t ca in p v dng in dung trng thi lmvic bnh thng. Bnh thng c:

|0CA | = |0CB | =|0CC |0

C = 0CA + 0CB + 0CC = 0|A| = |B| = |C| = |Pha|0 = A + B + C = 0

Qua cc biu thc trn thy rng, tng dng in dung chy trong t v

in p ca im trung tnh u bng khng.Cu 2: Phn tch tnh trng khi chm t 1 pha hon ton trong mng

in 3 pha trung tnh cch t?Xt s mng in 3 pha trung tnh cch in i vi t c pha C chm

t trc tip v th vc t biu din in p, dng in dung ca n. Khi pha Cchm t trc tip, in p ca n i vi t bng khng Uc = 0, in p hai phacn li dch chuyn i mt vc t - Uc; tc l coi ti ch chm t c t thm mtin p - Uc. Trn c s c th xy dng c th vc t nh hnh b. Ddng vit c cc biu thc:

UA = UA UC = UABU B = UB UC = UBC

U C = UC UC = 0UAB = UA UB = UAB

Du phy pha trn biu th cho ch chm t.

CBACB

CAb)

a)

0

C

A

C

B


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- C

0A

B

CB

CA

-C

V dng in dung th nh sau: V in p hai pha khng s c tng ln ln,nn gi tr dng in dung ca chng cng tng so vi khi cha chm t, tc l

I CB = 3I0CB, I CA = 3I0CA; cn dng in dung pha chm t bng khng .

Dng in dung ti ch chm t s l:V vct: - I C = I CA + I CBGi tr dng in dung ti ch chm t khi chm t mt pha c xc nh

theo cng thc sau y.ng dy trn khng: ;ng dy cp: ;Trong : l in p dy (kV);

L l chiu di tng cc ng dy c ni in vi nhau(km).

T cc phn tch trn, c th rt ra cc kt lun sau:

1/ in p ca pha chm t bng khng, in p hai pha cn li tng ln ln(bng in p dy).2/ in p dy ca mng in khng thay i.3/ in p ca im trung tnh tng t khng n in p pha.4/ Dng in dung ca cc pha chm t tng ln, cn dng in dung ti

ch chm t tng ln 3 ln so vi dng in dung mt pha trc khi chm t.Cu 3: Phn tch tnh trng khi chm t 1 pha hon ton trong mng


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in 3 pha trung tnh ni t qua cun dp h quang:Cun dp h quang l cun cm c li thp t trong mt thng cha du

my bin p (trng ging nh my bin p in lc 1 pha). in khng ca cundp h quang c iu chnh bng cch thay i s vng dy hay khe h ca lithp.

b)

a)CB

CA

0

C

A

C

B

L

L

C

Khi chm t mt pha, chng hn pha C (nh hnh v), in p im trung tnhcng l in p trn cun dp h quang tng ln bng in p pha, trong cun dph quang xut hin dng in cm L (chm sau in p trung tnh 900). Kt qu lnti ch chm t c dng in dung v dng in cm ngc pha nhau (hnh b).Nu iu chnh in khng ca cun dp h quang thch hp, dng in ti chchm t bng khng.

Trong thc t vn hnh phi ng ct ng dy, dng in dung C thay i,

nn kh thc hin c L= C . Mt khc, phi iu chnh cn li mt tr s =L= C no cung cp cho rle tc ng bo tn hiu cho nhn vin trc nhtbit v kp thi sa cha.

Gi s mng in lm vic vi ton b ng dy m hiu chnh cun dp hquang sao cho C > L , tc l b thiu ( 1 = L= C ). R rng khi c mt s ngdy ct i th L gim i, khng m bo cho r le tc ng nn c th khngnhn bit c tnh trng chm t mt pha trong mng. Ngc li nu chn xl cacun dp h quang sao cho khi tt c ng dy lm vic IL > C ( tc l b tha)v khi 2= L- C . Khi c mt s ng dy b ct s km tng gi tr 2,cng lm cho rle d tc ng, d dng pht hin c chm t mt pha.

Tm li, trong li in ba pha c trung tnh ni t qua cun dp h quang,cn phi b tha IL > C .

Cu 4:Trnh by cc s phn phi ngoi tri dng trong trm bin p

?1. S 1 h thng thanh gp:

331


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k, cn phi ct cc ngun cung cp, do phi ngng lm vic cc thit b trongthi gian sa cha.

+ sa cha mt my ct ca ng dy bt k phi ct ng dy vh tiu mt in trong thi gian sa cha.

+ Ngn mch trn thanh gp s dn ti bv t ng ct tt c MC ni nthanh gp, v cc thit b phi ngng lm vic trong thi gian loi tr s c .+ Do nhng nhc im trn, s mt h thng thanh gp khng phn on chdng cho thit b c mt ngun cung cp. Vic phn on thanh gp s tng cng tin cy lm vic ca thit b mt h thng thanh gp. S phn on c xcnh bng s lng v cng xut ngun cung cp. a s trng hp s phn onbng s ngun cung cp. s ng dy c phn phi gia cc phn on saocho khi ct mt phn on s khng dn ti ngng lm vic ca cc h tiu thquan trng. Do cc h tiu thu quan trng cn c cung cp t hai ngun lyt hai phn on khc nhau

S 1 HTTG c MC phn on.

+ S mt h thng thanh gp phn on bng my ct (hnh v) c uim hn. Bnh thng my ct phn on MC c th ng hay ct. Nhng numy ct bnh thng v tr ct th phi t thm thit b t ng ng ngun dtr (TDD). Nh thit b TDD, my ct MC s t ng ng li khi ngun cung cpca phn on b ct ra. Nu my ct MC bnh thng ng v xy ra ngn mchtrn bt k phn on no th my ct phn on v my ct ngun ni vi phnon y b ct ra. Phn on cn li vn lm vic bnh thng. S mt h thngthanh gp phn on bng my ct c dng rng ri cho cc nh my in vtrm bin p c s mch t v in p bt k .

+ i vi nh my in, trong iu kin lm vic bnh thng, my ct

phn on lun lun ng, cn i vi trm bin p c th ng hay ct my ctphn on ny.- Nhc im: ca s mt h thng thanh gp phn on bng my ct

l khi s c hay sa cha mt phn on, cc ngun cung cp v ng dy nivo phn on phi ngng lm vic. Khi sa cha my ct ca mt mch no, mch y tm thi mt in .

1. S mt h thng thanh gp c thanh gp ng vng.- Nh phn tch trn, s mt h thng thanh gp c nhc im l

sa cha my ct ca mch no th mch y mt in. Nhc im ny c thkhc phc bng cch t thm mt h thng thanh gp ng vng MCv. h thng

thanh gp vng c ni vi mi mch qua mt giao cch ly vng- Lc ny my ct vng thay th cho my ct ca ng dy a myct ng dy ra sa cha .

- Khi h thng thanh gp lm vic c phn on bng may ct hay daocch ly , mi phn on t mt my c vng , hoc tit kim t mt my ctvng cho c hai phn on

- Hai ng dy D3 vD4 lm vic song song, cung cp in cho trm t-1Hai ng dy D2 v D5 cung cp in cho trm T-2, T-3, T-4. ng dy D1 v


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D6 lm vic ring r c ni n hai phn on khac nhau. Bnh thng tt cmay ct ng dy ngun cung cp v phn on u ng , my ct ng vngMCv v tr ct .

- gim s lng my ct c th dng s hnh 5-19c trong my ctvng v my ct phn on ch l mt. Nhng nn nh rng trong cng mt lcmy ct khng th lm hai nhim v ng thi. So vi s hnh 5-19a.b th s ny kinh t hn nhng vn hnh phc tp.TG

D1D2

S h thng 1 thanh gp c thanh gp ng vngDCLV

N1N2

MCV

DCLVTGV

S 2 h thng thanh gp .- S h thng thanh gp c mt my ct trn mt mch ch r trn hnh

v.- Trong s ny mi mt mch c ni vi hai h thng thanh gp qua

mt my ct v hai dao cch ly thanh gp. Cc mch ng dy cn thm daocch ly ng dy. Mt h thng thanh gp lm vic, mt h thng thanh gop dtr, v d TG-1 cn TG-2 d tr hoc ngc li. Cc dao cch ly ni vi thanh gp

lm vic c ng li, cc dao cch ly ni vi thanh gp d tr c m ra. Slin lc gia hai thanh gp nh my ct ni MCn.- u im ca s hai h thng thanh gp l ln lt sa cha tng

thanh gp m khng h tiu th no mt in, sa cha dao cch ly thanh gp camch no th mch y mt in, nhanh chng phc hi s lm vit ca thit b khingn mch trn h thng thanh gp lm vic, sa cha my ct ca mch bt kmch y khng phi ngng lm vic lu di.

- Sa cha bt k cc dao cch ly thanh gp no cng phi thao tc nhsa cha thanh gp v dao cch ly thanh gp ngng lm vic .

- Nhc im ca s hai h thng thanh gp l dng dao cch ly thao

tc ng ct cc mch dng in song song. nu thao tc nhm ln s dn n huqu nghim trng. Mt khc nu khng phn on thanh gp lm vic th khi ngnmch s gy mt in ton b. khc phc nhc im ny ngi ta cho vnhnh hai thanh gp, mi thanh gp c ni vi na ngun v mt s tiu th cnmay ct ni ng li lin lc gia hai thanh gp. Nh vy trong tnh trng vnhnh ny, h thng hai thanh gp phn on ging nh mt h thng thanh gp cphn on, trong my ct ni ng vai tr nh my ct phn on. Ch vnhnh ny c p dng rng ri cho cc thit b c in p t 35 kV tr ln.


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- Nhc im th ba s hai h thng thanh gp l khi sa cha my ctca mch bt k, mch y tm thi mt in. Dng s hai h thng thanh gps tn nhiu dao cch ly, b tr thit b phn phi phc tp v gi thnh cao nht li vi thit b trong nh do cp in p 6/10 kV ngi ta rt t dng s ny .

2. S hai h thng thanh gp c thanh gp ng vng . (hnhv)

D1S h thng 2 thanh gp c thanh gp vng

N1TG1D2

N2MCN

TG2

MCN2MCN1DCL2DCL1MCVMCD1MCD2DCLVDCLVDCLV


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- S hai h thng thanh gp c thanh gp ng vng khc phc cnhc im hai h thng thanh gp trn :

- Sa cha my ct ca mt mch bt k vn khng gy mt in d ch ltm thi. Cc mch u c ni vi thanh gp vng qua dao cch ly vng. Ngoira my ct ni lin lc gia hai h thng thanh gp chnh cn c my ct vng nithanh gp ng vng vi hai h thng thanh gp chnh. Trong mt s trng hp tit kim. Ngi ta khng t my ni thanh gp ring m ch s dng my ctng vng v thm mt dao cch ly ph na (hnh). Nhng s dng my ctng vng lm vic nh ct ni thanh gp ch thch hp khi bnh thng vnhnh trn mt h thng thanh gp. Nhng thit b bnh thng vn hnh c hai h

thng thanh gp th khi sa cha mt my ct no th phi chuyn tt c ccmch sang mt h thng thanh gp v my ct ni lc ny lm nhim v ca myct ng vng.

- S hai h thng thanh gp ca thanh gp ng vng m bo lin tccung cp in hn nhng tn nhiu dao cch ly, cu to thit b phn phi phctp. S ny ng dng cho cc thit b quan trng c in p t 110 kV tr ln .

3. S a gic.- Trong s a gic thanh gp c ghp thnh vng kn (hnh) gia hai

my ct phn on ch c mt mach v trn cc mch khng c my ct bo vring. Khi sa cha my ct bt k khng c mch no mt in. S ny c

my ct bng s mch nhng tnh bo m cung cp in cao hn s mt hthng thanh gp .- Tuy nhin s ny c nhc im l khi sa cha hay dao cch ly

thanh gp th a gic b h. Khi nu xy ra ngn mch mch khc khong kvi n th a gic c th b tch ra hai phn , v vy dn n mt s ng dy haymy bin p b mt in. Cc kh c in phi chn theo dng cc i khi a gicb h. Dng in ny ln hn dng in lm vic qua kh c in khi a gic knrt nhiu, v vy phi chn kh c in c dng nh mc ln .

- Cu to thit b phn phi ca s a gic phc tp v bo v role chocc ng dy, my bin p kh khn hn. V vy ngi ta ch s dng cc s a gic vi s cnh ln nht l 6.

4. S cu .- t im ca s ny l s my ct t hn s mch m tnh m bo

cung cp in vn khong km. S cu c p dung khi c bn mch .a. S cu c my ct pha my bin p (hnh v).- Trong s ny v pha ng dy khng c my ct m ch c dao cch

ly. Khi sa cha hay s c mt my bin p hai ng dy vn lm vic bnhthng. Ngc li khi sa cha hay s c mt ng dy th mt my bin p tm


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thi mt in. Sau y c th dungfdao cch ly ng dy tch ri ng dy bs c hay cn sa cha khi phc li s lm vic bnh thng ca my bin p.s ny ch thch hp cho cc trm bin p cn phi thng xuyn ng, ct mybin p (trong mt s trm bin p, ph ti thay di nhiu, ti nhng gi ph tithp ngi ta mun ct bt mt s my bin p gim tn tht cng xut trong

n) v ng dy ngn .b. S cu c my ct pha ng dy ( hnh)

- Trong s ny v pha ng day cao p ca my bin p khngt my ct. Nhng u, nhc im ca s cu c my ct pha ng dyhon ton ngc vi nhng u , nhc im ca s cu c my ct dt pha caop ca my bin p.

- u im: s ny l nhc im ca s kia, tht vy trong s ny, khi ngn mch trn mt ng dy no th ch c ng dy mt in, ccmy bin p vn lm vic bnh thng. Nhng khi s c trong my bin p th mtng dy tm thi b mt in. V vy s ny thch hp cho cc trm bin p

v chiu di ng dy ln. c. S cu m rng .

- Do u im ca s cu l kinh t v tnh m bo cung cp in tngi cao, nn ngi ta dng s cu cho c trng hp, thit b c nm mch nhhai my bin p v ba ng dy hoc ba my bin p v hai ng dy.

- Cn ch rng trong cc s cu khng t my ct pha cao p camy bin p th cn ct my bin p ngi ta phi ct pha h p, sau y tin hnhct my bin p trng thi khng ti bng dao cch ly.

- Khi xy dng thit b phn phi theo s cu cn phi ch n s phttrin sau ny, sao cho s cu c th tr thnh s h thng thanh gp.

Cu 5: Trnh by cc bin php gim tn tht cng sut v tn thtin nng trong li in?

Cc bin php ch yu gim tn tht cng sut v tn tht in nng trongli in:

gim tn tht cng sut, tn tht in nng trong li in:T biu thc: Tn tht cng sut:C th a ra cc bin php:

- Gim in tr R trn ng dy: phi tng tit din dy dn, dnn phi tng kh nng chu ng ca mng, ct: Phng php ny khng

kinh t.- Tng in p nh mc ca h thng. Do my pht in khng ckh nng pht ra in p cao ph hp vi in p yu cu, cho nn nng cao in p ngi ta xy dng cc trm tng p, v ph hp vicp in p ph ti ngi ta dng cc trm gim p.- Nng cao h s cng sut cos cc h x nghip bng cch hnch cho cc ng c lm vic non ti hoc khng ti.- Phn b cng sut tc dng, cng sut phn khng trong mng theo


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mt phng thc kinh t nht- My bin p vn hnh vi phng thc tn tht in nng t nht.

La chn s u dy hp l nht cho mng in.- Dng mng kn m khng dng mng h.

- Kim tra thng xuyn tn tht in nng trong mng.

Cu 6: Trnh by cc phng php iu chnh in p trong li in.

a. iu chnh in p bng cch thay i u phn p ca MF: m bo in p u ra ph hp vi yu cu ca h tiu dng. Khi ph

ti tng ln th phi iu chnh nng cao in p ca MF. Khi ph ti gim xungth ta phi h thp in p ca MF m bo lch in p khng vt qu gitr cho php.

b. iu chnh in p bng cch thay i u phn p ca MBA :in p thp nht xut hin trn thit b khi ph ti l cc i v in p

cao nht xut hin khi ph ti l cc tiu . Mt trong nhng bin php c bn

m bo in p cn thit trn thit b tiu th l chn u phn p ca MBA lthay i t s bin K ca MBA t c tr s in p yu cu ca ph ti.c. iu chnh in p bng MBA iu p di ti:

Vic thay i in p bng cch thay i u phn p, phi tin hnh ct in tuynhin trong mt s trng hp khng cho php ct in ph ti. V vy ngi tadng MBA c bit iu chnh in p gi l MBA iu p di ti.

MBA iu p di ti cho php thay i u phn p m khng cn phict in. Nh vy ta c th thay i u phn p ng vi trng thi vn hnh caph ti lun lun gi cho in p gn bng hoc ln hn in p nh mc.

Cu 7: Nu cc s ni dy ca TI, TU trong bo v rle ?a. S ni dy ca TI trong bo v Rle:1. S ni cc bin dng in v rle theo hnh sao hon ton.

- Trong s ny cc bin dng in t trn c ba pha, cun dy ca rlec ni vo dng in ba pha ton phn (hnh 1a). Dy trung tnh (dy v) bom s lm vic ng ca s khi ngn mch chm t hoc khi ngn mch 2pha . Khi h thng lm vic bnh thng v khi ngn mch 3 pha dng in I0 = 0v trong dy trung tnh (v nguyn tc) khng c dng in.

- Khi ngn mch chm t dng in chy trn dy trung tnh l:3 = + +

- S sao hon ton c th lm vic c khi ngn mch mt pha. Tuynhin, hin nay bo v chng ngn mch mt pha, ngi ta thng dng s hon ho hn c b lc thnh phn th t khng.

*


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**IAIBICIaIbIc

S hnh sao hon ton

2. S ni cc bin dng in v rle theo hnh sao khuyt.- Cc bin dng in ch t trn hai pha, cun dy ca rle cng ni vo

dng in pha ton phn (hnh 2).= - ( + )

hay =

- Nh vy trong s ny dng in Iv tn ti c trong tnh trng lm vicbnh thng v dy v bo m s lm vic bnh thng ca cc bin dng introng tnh trng ny. Dy v cn bo m s tc ng ng ca bo v khi ngnmch hai pha trong mt pha khng t bin dng in (pha B) v khi ngnmch nhiu pha .

- Khi ngn mch mt pha khng t bin dng in (pha B ca hnh 2) s ca hnh sao khuyt s khng lm vic, v vy s ny ch dng chngngn mch nhiu pha.

**

IAIBICIaIc

S hnh sao khuyt


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3. S ni mt rle vo hiu s dng in hai pha:- S ny cn c gi l s hnh s 8. Dng in i vo rle l:

= - tnh trng i sng: IR = Ia = Ic

Nh vy h s s : ksd =- S dng mt rle ni vo hiu s dng in hai pha c nhy:

Kn = ph thuc vo dng ngn mch.+ Khi ngn mch 3 pha dng in trong rle I(3)R= . I(3)NT (hnh 3b) trong

I(3)NT l dng in ngn mch 3 pha quy i v pha th cp ca bin dng in.+ Khi ngn mch hai pha c t bin dng in (pha A, C):

I(3)R.AC = 2I(2)NT.+ Khi ngn mch hai pha, trong mt pha khng t bin dng in (AB

hoc BC):

I(2)

RAB = I(2)

NT (hnh 3c)Nh vy hai trong ba trng hp ngn mch hai pha, s c nhy lnb hn khi ngn mch hai pha. y l khuyt im ca s ni mt rle vohiu s dng in hai pha.

*IAIBICIaIc

S hnh s 8*

b. S ni ca TU trong bo v rle:1. S ni cc cun dy theo hnh sao hon ton:

- C th dng ba bin in p mt pha hoc mt bin in o ba pha.S ni cc bin in p theo hnh sao vi cc rle ni vo in p

dy(a),in p pha (b), v in p gia ba pha v im trung tnh ca h thngin p dy.

- S c th cung cp cho rle cc in p dy, cc in p pha v cc


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in p gia cc pha v im trung tnh ca h thng in p dy (hnh 1: a,b,c).- in p t vo cc rle:Ua0 = ; Ub0 = ; Uc0 = ;

ABCABC0

S hnh sao hon ton.

2. S ni cc cun dy theo hnh ch V:S c to thnh bi hai bin in p mt pha ni vo hai in p dy

bt k ca mng s cp v c dng rng ri trong cc h thng in p 35kV

khi khng cn ly (dng) in p pha i vi t.ABC

S hnh ch V

3. S b lc in p th t khng .- S c to thnh bi ba bin in p mt pha hoc mt bin in p

ba pha nm tr c hai cun dy th cp, mt cun dy ni hnh sao c trung tnh

ni t, mt cun ni hnh tam gic h. in p t vo rle ni vo hai u tamgic h.(hnh 3a): = + + = ( + + ) = .

- Cng c th ly c in p U0bng cch ni t im trung tnh ca hthng, (v d ca my pht in hnh 3b) qua mt bin in p mt pha. Rle cni vo cun th cp ca bin in p. Khi chm t s dch chuyn in p U0 caimtrung tnh v trn cc cc ca rle c in p UR = . U0


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ABC

S b lc th t khng.

Cu 8: Trnh by nguyn l lm vic ca cc rle bo v dng trongtrm bin p?

a. Bo v qu dng: l loi bo v tc ng khi dng din qua ch t thitb bo v vt qu gi tr nh trc. C th chn bo v qu dng in thnh bov dng in cc i hay bo v dng in ct nhanh. Chng khc nhau chcch m bo yu cu tc ng chn lc v vng bo v tc ng. m bodng in cc i tc ng chn lc, ngi ta to cho n thi gian tr hon thchhp. m bo chnh xc chn lc cho bo v ct nhanh cn chn dng khing thch hp. Vng bo v ca bo v dng in cc i gm c phn t c

bo v. Vng bo v ca bo v ct nhanh ch mt phn ca phn t c bo v.Nhc im ca bo v qu dng l khng m bo c tnh chn lc cabo v trong cc li in phc tp c nhiu ngun cung cp.

b. Bo v dng in c hng: l loi bo v lm vic theo gi tr dng inti ch ni rle v gc pha ca dng in y vi in p thanh ci ca trm c tbo v. Bo v tc ng nu IR > IK v pha ca n ph hp vi trng hp ngnmch ng dy c bo v. Nh vy bo v dng in c hng l bo vqu dng in cng vi b phn lm vic theo gc pha ca dng in v in pti ch t bo v.

Trong bo v qu dng in c hng ngi ta dng rle cng sut nh

hng tc ng cho bo v v ch cho php tc ng khi cng sut ngn mch it thanh gp hng ra ng dy.c. Bo v khong cch: l loi bo v c b phn c bn l b phn o

khong cch, lm nhim v xc nh tng tr t ch t bo v ti im ngnmch. Thi gian lm vic ca bo v ph thuc vo quan h gia dng in vin p a vo phn o lng ca bo v v gc lch pha gia chng. Thi gianny tng ln khi tng khong cch t ch h hng ti ch t bo v. Bo v tgn ch h hng nht c thi gian lm vic b nht.

d. Bo v so lch: l loi bo v lm vic da trn nguyn tc so snh trctip dng in trn cc nhnh ca i tng bo v.

e. Bo v hi thng du MBA: trong MBA mi s c xy ra u lm chodu bc hi v lng hi ny c chuyn t bnh du chnh sang bnh du phMBA. Li dng hin tng ny ngi ta dng rle hi bo v cho MBA.

Rle hi gm 2 phao thy tinh 1 v 2, bn trong cha tip im thy ngnc c nh trn gi . trng thi lm vic bnh thng trong bnh cha rlehi ch u du MBA nn cc tip im ca phao 1 v 2 m. Khi c s c nhtrong MBA th du trong MBA bc hi hoc mc du h thp lm cho phao 1chm xung ng tip im i bo tn hiu. trng hp khi c s c nng du


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ngang hp nht bx ngi ta ta xc nh t l a/ha.Gi s ta c: a/ha=3, sau ta hytm t l hx/h, v d trng hp ny t l hx/h=0,3, tc l hx=0,3h, t ta cbx=0,9ha.

Trng hp t nhiu ct thu li th cc phn ngoi ca khu vc bo v

cng c xc nh theo cc cng thc trn. Cn phi kim tra iu kin bo v anton cho ton din tch cn c bo v. Vt c cao h x nm trong trm s cbo v nu tho mn iu kit:

D 8(h-hx) vi h 30mD 8(h-hx).P vi P>30m

Cu 10: Cho bit cng dng v phm vi bo v ca dy chng st?a. Cng dng ca dy chng st:- H thng thu st bao gm: b phn thu st (kim, dy), b phn ni t v

cc dy dn lin quan n hai b phn ny. Tc dng bo v h thng thu st tptrung in tch nh nhn b phn thu st, to nn in trng ln nht gia nvi u tia tin o thu ht st v hnh thnh khu vc an ton bn di, xungquanh h thng thu st.

- Dy chng st c dng bo v chng st nh thng trc tip vong dy ti in trn khng.

b. Phm vi bo v ca dy chng st:Phm vi ca dy chng st c to bi mt ct thng ng theo phng

vung gc vi dy chng st c honh : 0,6hp v 1,2hp.- p = 1 khi h 30m.- khi 30m < h 60m.

b-1: Phm vi bo v ca 1 dy chng st:h: l treo cao dy chng st.hx: l cao ca vt cn bo v.bx: l bn knh ca phm vi bo v ca dy chng st cao hx.

Phm vi bo v bx theo hx nh sau:* Vi dy chng st c treo cao h 30m.hoc thep phng php n gin:Khi

Khi* Vi dy chng st c treo cao 30m < h < 250m.Phm vi bo v theo chiu cao (mt ct ng) gim mt khong cch h

tnh t nh. Vi h tnh theo:b-2: Phm vi bo v ca 2 dy chng st:Khi 2 dy chng st t cch nhau S = 2R = 4h th mi im trn mt t

nm gia 2 dy dn s c bo v an ton. Nu S < 4h gia hai dy c th bo v


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c mt cao:Khi dy dn 3 pha ca ng dy ti in cng nn trn mt mt phng

ngang th iu kin ca dy gia vi cao hDD c bo v l khong cch Sgia 2 dy chng st phi tha mn iu kin:

b-3: cch xc nh phm vi bo v ca dy chng st ca ng dy tiin cao p: treo cao trung bnh ca dy dn thng ln hn 2h/3, do trong trng

hp ny vic v ton b phm vi bo v ca dy chng st l khng cn thit mthng thng ch cn xc nh gc bo v l .

l gc to thnh gia ng thng ni lin cc im treo dy chng st vdy dn v ng thng vung gc vi mt t qua dy chng st.

cng b th xc xut st nh vo dy dn v cng b:Vi hc l chiu cao ct in tnh bng mt, l gc bo v tnh bng . trng hp gii hn th dy chng st c th bo v c mt gc gh

bng trong thc t tng mc mc an ton, tc l gim xc sut st nh vngqua dy chng st vo dy dn, ngi ta thng chn = 20 25o cho ccng dy ti quan trng.

Cu 11: Cho bit cng dng ca cc loi ni t trong h thng?- Ni t lm vic: l m bo s lm vic bnh thng ca thit b hoc

mt s b phn ca thit b theo ch lm vic nh sn nh ni t trung tnhMBA, cun khng in, dao ni t.

- Ni t an ton: l bo v cho ngi khi tip xc vi cc phn v my

bnh thng khng mang in nhng khi cch in b chc thng in p cao xmnhp sang pha in p thp m khng gy ra tai nn in git. V vy ni t antpon cn c gi l ni t bo v. V d nh ni t mt u cun th cp TU, TI, ni dt DCL, MC khi sa cha.

- Ni t chng st: m bo tn dng in st xung t khi c st nhvo ct thu li, dy chng st, ng dy ti in nhm gim nh in p do stgy ra khng lm h hng cch in ca thit b. Ni t chng st c 2 loi: nit cho ct thu li, dy chng st v ni t cho cc thit b chng st nh PT(chng st ng), PB (chng st van).

Cu 12: H quang in l g? Nguyn nhn, tc hi v cc phng phpdp tt h quang?

- H quang in l hin tng phng in t duy tr trong cht kh vi mt dng rt ln (hng nghn A/cm2), nhit rt cao c th t n 100000C phntrung tm h quang v 3000 n 40000C phn b mt h quang.

- Nguyn nhn sinh ra h quang in:+ Do ng ct u tip xc ca cc kh c in.+ Do phng in trong qu trnh ngn mch.


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+ Do qu trnh ion ho cht kh gia hai u tip xc ca kh c in.- Tc hi ca h quang in:+ V h quang pht sinh ra nhit cao, do sau mi ln ng ct b mt

tit xc ca tip im thng b chy r.+ H quang c th pht sinh an cho gia cc pha gy nn hin tng ngn

mch nhiu pha. Trng hp ny thng xy ra khi thit b ng ct b hng bdp h quang.

+ Nu xy ra h quang in chp chn c th gy ra hin tng qu inp ni b lm hng cch in ca my in hoc hng cch in ca ng dy tiin.

+ H quang c th gy bng hoc t vong cho con ngi.+ H quang c th gy ra ho hon nu n pht sinh nhng ni c vt liu

d chy n.- Cc phng php dp tt h quang:+ Ko di h quang in: khi h quang b ko di th in p duy tr n cn

phi cao. Nu in p hai u tip xc nh hn in p duy tr th h quang s bdp tt nhanh chng.+ Chia h quang thnh nhiu h quang ngn: dng cc tm kim loi t song

song trong bung cha cc u tip xc chia nh h quang d dng dp tt.+ Dp tt h quang trong khe nh ca bung dp h quang: chy trong khe

nh, h quang b h nhit nhanh hn v cc phn tch in ca n khuch tnvo mi trng xung quang, dn n kh ion v h quang b dp tt nhanh chng.

+ Chuyn ng h quang trong t trng: h quang c coi nh mt dydn c dng chy qua. Khi h quang t trong t trng H th s c lc F tc dngln n. Nu hng t trng vung gc vi trc h quang th h quang b chuyn

ng tnh tin v b y vo khe h ca bung dp tt h quang. Khi t trngtrn, h quang chuyn ng quay, d dng c lm mt v kh ion. i vi khc trn 1000V, c th dng bin php dp tt h quang khe h v trong t trngnu trn.

+ Dp tt h quang trong du cch in: nu cc u tip xc c t trongdu cch in, khi h quang xut hin, di tc dng nhit ca h quang du bphn tch to thnh bt kh p sut cao lm cho h quang b ko di v b dp tt.

+ Dp tt h quang bng thi khng kh: h quang c lm ngui nhanhhn khi c lung kh chuyn ng c hng thi vo. Thi dc hay thi ngang voh quang to iu kin tip xc cc phn t kh vi h quang, dn ti khuch tnv lm ngui h quang d dng. Tt nht l thi h quang bng kh lnh t ccbnh nn kh. Bin php thi khng kh dp tt h quang c dng trong myct khng kh

+ Dp tt h quang bng cch dng nhiu ch ct: ct mch in vi dngin cng ln v in p cng cao cng kh khn v rng khi nng lng ln, inp phc hi cao, kh ion trong khe kh khn hn. V vy trong cc my ct incao p dng nhiu ch ct trong mt pha, in p cng cao cng nhiu ch ct.

+ Dp tt h quang bng mi trng chn khng: h quang b dp tt trong


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mi trng chn khng c bn in cao gp hng chc ln so vi khng kh p sut thng.

+ Dp tt h quang bng kh p sut cao: kh p sut cao c bn cch incao. c bit kh SF6 c th dp tt h quang ngay c p sut thng.

Cu 13: Cho bit cng dng v phn loi cc t bng iu khin trongtrm bin p ?

+ Cng dng:Cc t bng trong trm bin p dng lp t cc thit b nh r le bo v,

cc ng h o lng, cc sa c tn hiu, cc kha iu khin ng ct t xa MC,DCL.... l ni trung gian ni dy cc mch nh th mt cch chc chn, thunli cho vic th nghim, kim tra trong vn hnh. Cch ly cc thit b nh th vimi trng bt li. + Phn loi:

Ty theo nhim v c th m ta phn loi nh sau:

- T iu khin: dng lp t cc kha iu khin ng ct,hin th s phng thc vn hnh ca trm. lp t cc b bo tn hiu, ccng h o lng

- Cc t r le: phn ln c lp t cc thit b nh r le bov, cc hng kp u dy trung gian.Cc t u y ngoi tri ca thit b: l ni trung gian u cp nh th ca thitb ngoi tri vi cc thit b iu khin, bo v nh vn hnh.

Cu 14: Cch lp t t bng iu khin?- Cng tc xy dng mng t t phi chc chn.

- Cc t in v bng in phi c cn chnh trn cng mt ng tm vphi c c nh chc chn.- Qu trnh cu hoc di chuyn phi cn thn, chc chn. Dng dy luc hoc

dy xch phi m bo, trnh ri rt, va chm lm h hng t.- B tr, lp t ti nhng v tr hp l, d dng, thun tin cho vic vn hnh,

theo di, iu khin, cng nh truy cp cc thng s.- Lp t, u ni ng thit k v m bo tnh nng k thut.- Trong qu trnh lp t, trnh cc va chm lm nh hng n cc thit b,

kh c bn trong.- Vic lp t, u ni cc thit b trong t bng phi cn thn v ng thit

k.- Vic ni cc thit b vi thanh ci ca t phi dng bulong hay cht nh v.- Cc bulong ai c v vng m bng thp dng ni cc thanh ci vi cc

thit b u phi m km.- Lp ghp ng theo th t kt ni nu l t hp b.- Tt c cc thit b phn kim loi ca v t u phi c ni t.Cu 15: Cc b phn sau y ca MBA dng lm g: cc s ra, cc


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cnh lm mt, thng gin n du, qut lm mt, bm du, ng phng n,bnh silicagen ?

- Cc s ra: Cch in gia dy dn v v MBA,c nh khong cch giacc pha vi nhau v dy trung tnh, a dy dn t trong MBA ra ngoi.

- Cnh lm mt: Lm tng din tch b mt tip sc vi khng kh khnng trao i nhit gia du nng trong MBA v mi trng bn ngoi din ranhanh hn.

-Thng dn n du: m bo cho thng du chnh lun y du, cha dukhi mc du trong MBA tng cao do s dn n ca du theo nhit .

- Qut lm mt: lm tng hiu sut tn nhit ca cnh tn nhit- Bm du: dng bm du nng pha trn ra ngoi cnh tn nhit lm tng

nhanh chu k ca dng du tun hon, gi cho nhit trong MBA lun n nh.- ng phng n: Gii phng p lc tng cao qu mc cho php do MBA b

qu ti hoc s c ni b MBA.- Bnh silicagel: Cha ht silicagel ht m, ngn khng cho hi m lt vo

trong MBA v duy tr p lc kh quyn ln b mt du.

Cu 16: Nguyn l lm vic v cch lp rp rle hi (rle Buchholz)kiu hai phao ca MBA? Cch x kh trong rle hi trc khi a MBA vovn hnh:

Thng du MBARle hi

Thng du ph Thng du chnhThng du ph

123467


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a. Cu to1. V RL hi2. Np RL hi3. Cc

4.6 Phao5.7 Tip im i bo tn hiu, tc ng i ct MCb. Cch lp rp:RL hi c lp trn ng ni gia thng du chnh MBA v bnh du ph Vi

chiu mi tn trn rle hng v pha bnh du ph. Hai u rle hi c van, LcMBA vn hnh 2 van u v tr m. Ch ng li khi cn tho sa cha rle hi.y l loi rle c 2 phao t trong mt bung du kn, trong phao nm trn tcng khp tip im i bo tn hiu, phao nm di tc ng khp tip im ict MC cc pha MBA.

cho kh bc ra d dng thot t thng du chnh ln thng du phngi ta thng t np MBA hi nghing 20 v pha bnh du ph.

c. Nguyn l lm vic :

Bnh thng trong rle hi lun cha y du, khi c h hng nh hay btu c s c: Lc ny c nhiu bt kh c to ra , chy qua ng ni n bnhdu ph v ng li trong bung rle hi do lm cho mc du trong rle higim xung . Phao 4 c gn nam chm vnh cu chm xung v ht tip im lig ng tip im 5 bo tn hiu.

Khi c s c nng to ra lung kh mnh di chuyn n bnh du ph lmcho phao 6 chm xung v khp tip im 7 i ct MC cc pha MBA.

Khi mc du gim thp do c r r du trong MBA qu mc cho php, utin phao trn (4) tc ng i bo tn hiu , nu mc du tip tc gim th phaodi tc ng i ct MC cc pha MBA.

Sau mi ln rle tc ng ct MC cc pha MBA cn phi Reset bng tayti nt reset trn rle.


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d. Cch x kh trong rle hi trc khi a MBA vo vn hnh:Trc khi a MBA vo vn hnh cn phi x kh trong rle hi trch

tc ng nhm v qu trnh vn chuyn hoc np du hoc lp t trong rle c thc hi du. Khi MBA mang ti hoc nhit thay i th c th lm rle tc ngnhm.

- X van trn rle hi cho du v kh chy ra sau ng kn li (van nyc th c lp ti 01 ng ni nh t rle xung).

Cu 17: Du trong MBA dng lm g? Cc yu cu c bn i vi

du dng trong MBA ? Ti sao MBA c b i nc c ti th hai u thnggin n du, c hai ng h ch th mc du? Mc du trong MBA cao haythp tng ng theo nhit du c xc nh nh th no ? Nhit duca MBA c o bng cch no v o ti v tr lp du no ca MBA ?

a. Du my bin p c nhng tc dng sau:1. Cch in:

- Cch in gia cc vng dy, lp dy.- Cch in gia cc pha vi pha.- Cch in gia cc cun dy vi v v li thp.2. Ngm tm lm tng kh nng cch in cho cc vt liu ngm trong du:- Vi, giy qun quanh cc vng dy.- G chn gi cc cun dy.3. Lm mt cc cun dy v li thp my bin p:- Khi vn hnh, di tc dng ca dng in ph ti v dng in Phu-c,

cc cun y v li thp u pht nhit, nu khng c bin php lm mt, nhit cun dy, li thp s rt cao, ph hng cch in, hng my bin p.

- Khi c du bin p th nhit lng ny s truyn vo du v du truyn rangoi bng cch i lu b phn tn nhit xung quanh my bin p.4. Dp h quang:Khi trong my bin p c nhng tia phng in nh du bin p c th dp

tt, hn ch kh nng gy ra s c cho my bin p.b. Cc yu cu c bn i vi du dng trong MBA:

No Hng mc th nghim Du mi trong my Du trong vn hnh

1

in p chc thng,kV/ 2,5cmDi 15kV

15 n 35 kVDi 110 kV110 n 220 kV500 kV

30

35456070

25

30405560

2 Tang gc tn tht in mikhng qu, % 20oC

0,2

1


41/58

90oC 2,2 7

3Tr s axt mg KOH trong 1gdu khng qu.

0,02 0,25

4 Hm lng axt v kim ho tantrong nc.

Khng c 0,1 mg KOH

5 Hm lng tp cht c hc theokhi lng khng qu,%

khng c khng c

6Nhit chp chy kn oCkhng thp hn

135 Gim khng qu 5oCso vi ln phn tch

trc.

7- Khi lng cn khng qu, %- Tr s axt du sau xy hamg KOH trn 1g du khng qu

0,010,10

Khng thKhng th

8 Ch s Natri khng qu 0,4 khng th

9

nht ng m3/s khng lnhn 20oC 50oC

289,0

khng thkhng th

10Hm lng nc theo khilng khng qu , %

0,001 0,0025

11

Hm lng kh ho tan khngqu, %220 n 330kV500kV

1,00,5

2,02,0

c. MBA c b i nc c ti th hai u thng gin n du, c hai ng h

ch th mc du l ti v:Nh ta bit thng du chnh v thng du b OLTC l hai thng du

c ngn cch vi nhau v mi thng u c bnh du ph ring . S d hai thngdu c ngn cch vi nhau v: kkhi iu chnh in p tc l thay i s vngdy ca cun trung tnh cao p ti cc u tip xc c gy ra h quang in nn dlm du b bn v li d c s c ti cc im tip xc . V vy phi t b inc c ti trong thng du ring thun tin, an ton hn trong cng tc vn hnhcng nh trong qu trnh i tu sa cha my bin p c tt hn.

Nh trn ta xt cng dng ca du bin p nn ta bit c hai thng du

(thng du chnh ca my bin p v thng du cho b OLTC) u cn mcdu theo quy nh do cn c ng h ch th mc du 2 u thng gin n du m bo mc du c hai thng lun trong vn hnh .

d. Mc du trong MBA cao hay thp tng ng theo nhit du c xcnh:

Trn mi bnh du ph c lp t ng h ch th mc du ca my bin pv mc du b OLTC hin th theo nhit v c tip im bo tn hiu mc du


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gy ra chm t 1 pha, bo v s khng tc ng ct MC. Dn n nguy him chongi v thit b.B. Bc 2/5:

Cu 1: Trnh by yu cu v nguyn tc thc hin t ng ng ngund phng (TD):

- Phi t thit b TD khi ct ngun cung cp in lm mt in cc trang bin ca h tiu th hoc sa thi ph ti v khi c cc thit b ng ct ph hp.Cho php dng bt k bin php no thc hin TD phc hi cung cp in.

- Thng thng TD phi m bo lm vic khi mt in p do ngn mchhoc do bt k s c no phn t c ngun d phng.

- TD ch c tc ng mt ln v nu khng i hi nhng thit b phctp th TD phi kim tra c trng thi ct ca my ct phn t ang lm vic.

- Khi bo v rle ca my bin p v ng dy ngn tc ng i ct my ctca n pha ngun cung cp cng nh pha tiu th (v d i vi cc phn t

t dng ca nh my in). TD phi khi ng theo b bo v km in p ringhoc theo cc b tip im ph ca my ct pha tiu th ( tng tc tcng ca TD). Khi ct my ct pha ngun cung cp phi m bo ct ngaymy ct pha tiu th bng mch lin ng v bng tc ng tip theo ca TD.Khi c phn t d phng v phn t c d phng u nhn cung cp t mtngun in th khng yu cu TD phi khi ng theo bo v km in p.

- Sau khi ng ngun cung cp d phng thay cho mt ngun cung cpc ct ra, s TD ca cc ngun cung cp in t dng trong nh my inphi c kh nng tc ng khi ct nhng ngun cung cp khc ang lm vic.

- B phn khi ng ca bo v km in p kim tra in p trn thanh ci

cc trang b in ca h tiu th phi m bo bo v khng lm vic sai khi chymt trong nhng cu chy ca cun dy cao hoc h p ca my bin p. Khiptmt bo v cun dy h p ct ra th phi c mch lin ng kha s tc ngca b phn khi ng.

- Khi thc hin TD phi kim tra kh nng qu ti ngun cung cp dphng v kim tra s t khi ng ca cc ng c, nu c hin tng qu tikhng cho php v ng c khng th t khi ng c th phi sa thi ph tikhi TD tc ng. Ty theo ii kin thc t c th dng TD ca cc nguncung cp ang lm vic thay th hoc ph thm cho TD.

- mi my ct chu tc ng ca TD phi c b phn thng xuyn kim

tra mch thao tc ng.- Khi b tr TD tc ng n my ct phn on hoc my ct ni (dphng bng ngun cung cp khc ang lm vic) phi c b phn tng tc bov cho my ct trnh nhng trng hp ng my ct lc vn cn ngnmch.

Cu 2: Trnh by yu cu v nguyn tc thc hin t ng ng lp li

Z?


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a. Yu cu thc hin t ng ng lp li Z:

- Tc ng nhanh: thi gian tc ng ca TL cn phi cng nh cng tt m bo thi gian ngng cung cp in l nh nht. cc Z c ngun cung cpt 2 pha th tc nh nhanh ca TL l cn thit rt ngn thi gian khi phc

tnh trng lm vic bnh thng ca mng in. Tuy nhin thi gian TL b hnch bi iu kin kh ion hon ton mi trng ti ch ngn mch nhm m bot ng lp thnh cng.

- TL phi t ng tr v v tr ban u sau khi tc ng chun b cho lnlm vic sau.

- S TL cn phi m bo s ln tc ng nh trc cho n vkhng c tc ng lp i lp li. Ph bin nht l TD(L mt ln.

- Khi ng hay ct MC bng tay th TL khng c tc ng. Khi ngMC bng tay nu n b ct ra ngay lp tc bi bo v rle, chng t ng MC

vo ngn mch tn ti, lc ny chc chn vic ng lp s khng thnh cng.b. Nguyn tc thc hin t ng ng lp li Z:

Cc iu kin cn thit c th a chc nng t ng li vo lm vic l:

- Phi c r le F79 hoc chc nng F79 trong rle F21.

- Kim tra MC ng ct tng pha hay 3 pha.

- Thi gian ng li phi ph hp vi chu trnh ng m ca MC- i vi trng hp ng li 3 pha cn c TU ng dy kim tra ng

b.

Cu 3: Tnh tn tht cng sut trn ng dy truyn ti 3 pha ?1. Tnh ton cho ng dy c 1 ph ti.Tn tht cng sut tc dng trn ng dy dn in xoay chiu ba pha

c xc nh theo cng thc: P = 3.I2.R = 3(Ia2 + Ir2)RTrong :- I: L dng in ton phn trn ng dy.- Ia, Ir: L dng in tc dng v dng in phn khng trn ng dy- R: L in tr ca dy dn

S thay th ca ng dy:

RXS'S"S = P - jQjj


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Bit rng cng sut ca 3 pha (2)V: S2 = P2 + Q2

Vy:(3-1)

Tn tht cng sut phn khng trn ng dy c xc nh theo: Q = 3I2.X Tng t ta cng c:(3-2)

Tng qut:Ch : P, Q l ca 3 pha, U: in p dy.- V n v: nu P [MVA]; Q [MVAR]; S [MVA]; U [KV]; R [ ]; X [ ]

th S [MVA]; P [MV]; Q [MVAR] .Khi tnh ton theo cng thc (3-1), (3-2), cng sut v in p phi ly ti

cng mt im trn ng dy.Khi tnh ton mng in a phng v thit k s b mng in khu vc

vi mc chnh sc dng trong tnh ton k thut, tn tht cng sut c xcnh theo in o nh mc ca mng in. Khi tnh ton chnh xc s dng inp thc ti cc im tng ng ca mng in.

i vi mng in a phng ta s b qua thnh phn Qc do dung dn cang dy sinh ra.

2. Tnh ton cho ng dy c t 2 ph ti tr ln.12A S1 S2UA

Sb=pb -jqbSc=pc jqc

UCUbbc


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r1+jx1r2+jx2

S"2S'2S"1S"2SC

Sb

* Xt ng dy c 2 ph ti ti b v c (hnh trn) ta cn tnh ton ton btn tht cng sut trn ng dy .

- Tn tht cng sut trn on ng dy 2:v

Vy:


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hay l QCu = (S/U)2. XBc/ Tng tn tht cng sut tc dng trong MBA l: P=PCu +PFe2/ Tn tht cng sut trong MBA 3 dy qun.

Ging nh MBA 2 dy qun, tn tht cng sut trong MBA 3 dy quncng gm c tn tht khng thay iSFe v tn tht thay i theo ph tiScu.Vy tn tht st trong MBA l: PFe =Pkti QFe = ikti%.Sm / 100.V tn tht ng lc MBA mang ti nh mc:

PCum =PN. QCum = uN%.Sm / 100.Nu ph ti cun dy 2 v 3 khng phi l nh mc, m l S2 v S3 th tn

tht ng trong 3 pha ca 3 cun dy ca MBA c tnh nh sau:PCu =PCu1 +PCu2 +PCu3.

Trong PCu1,PCu2,PCu3 l tn tht ng trong tng cun 1, 2 v 3.PCu3 = S32.rB3/U2

PCu2 = S22.rB2/U2

PCu1 = ( S2 + S3 )2.rB1U2

Nu tnh ton khng cn chnh xc th trong cng thc tnhPCu cho tngcun dy ca MBA 3 dy qun ta c th dng chung in p nh mc bn cuncao p, v rng in tr ca cc cun 1, 2, 3 ca MBA u c tnh i v bncao p.

Cn cng sut phn khng trong 3 cun dy ca MBA 3 dy qun cngc tnh tng t nh trn:

QCu =QCu1 +QCu2 +QCu3.Trong :

QCu3 = S32.xB3/U2

QCu2 = S22.xB2/U2

QCu1 = ( S2 + S3 )2.xB1U2

vy tng tn tht cng sut trong MBA 3 dy qun l:P =PCu +PFeQ= QCu +QFe

3/ Tn tht cng sut trong MBA t ngu.

Cch tnh cng tng t nh MBA 2 dy qun v 3 dy qun, ngha l tnhtn tht trong my cng gm c tn tht st v tn tht ng. Ring phn tn thtng th cch tnh c hi khc mt cht. Vi MBA t ngu nh sn xut cho ta tntht ngn mch gia cc cun dy cao trung, cao - h, trung - h: P C-T, PC-H,PT-H. Cn phi tnh tn tht ng nh mc ca tng cun dy cao, trung v hp.

PCu(C) = 0.5(P(C-T) + P(C-H) - P(T-H))


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PCu(T) = P(C-T) - PCu(CmPCu(H) = P(C-H) - PCu(C)

(1)

Ch rng nh my cho tn tht P(C-T) c tnh theo dung lng nhmc, cn tn tht PC-H v PT-H th theo dung lng tiu chun ca MBA tngu, v vy trong biu thc (1) PC-H v PT-H l tn tht c tnh i theocng sut nh mc ca MBA t ngu:

PC-H = PC-H/u2 v PT-H = PT-H/u2trong u = (UC UT)/UCvi UC, UT l in p bn cao p v trung p. Vy tn tht trong MBA t

ngu l:P = PFe + PCu(C)(SC/Sm)2 + PCu(T) (ST/Sm)2 + PCu(H) (SH/Sm)2

trong : SC, ST, SH l ph ti ca cun cao p, trung v h p.Sm l dung lng nh mc ca MBA t ngu.

Cch tnh tn tht cng sut phn khng trong MBA t ngu cng tin hnhtng t nh trn.

Cu 5: Phng php tnh tn tht in nng trn Z truyn ti v MBA?

Ti liu tham kho: Li in & h thng in ca Trn Bch.1. Phng php tnh tn tht in nng trn Z truyn ti:Gi s ta xt ng dy c mt ph ti B (nh hnh v).

A R Bo

SB = pB jqB

Tmax; cos

Tn tht cng sut tc dng trn ng dy l: P = . R 10-3 = ( )2 . 10-3 R {kW, kVA, , kV} Q = . X 10-3 = ( )2 . 10-3 X {kVAr, kVA, , kV}Trong : UB : in p ti nt ph ti B, c th ly UB=Um.

SB : Ph ti in ti B.R : in tr tc dng ca ng dy.

X : in khng ca ng dy.

- Nu P, Q, S: Ly l MW, MVAR, MVA th khng nhn vi 10-3.

v P, Q,U phi ly gi tr ti cng mt im trn ng dy.- Tn tht nm thng tnh theo TPT ko di nm ti = 1h A = ( ) = (P2max . p + Q2max . q)

Trong :


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+ Um2 (tc l U2m): in p nh mc.+ p: Thi gian tn tht cng sut ln nht do cng sut tc dng gy ra.+ q: Thi gian tn tht cng sut ln nht do cng sut phn khng gy

ra.

- Thc t tnh ton thng gi thit th cng sut phn khng v cngsut tc dng gn ging nhau, c ngha cos ca ph ti khng i trong nm.Nh vy: p = p = v ta c CT sau:

A = P. = ( )2 . R. = .R.

- Trong , thi gian tn tht cng sut cc i ( ) nh gi thng k nhmt hm s ca thi gian s dng cng sut ln nht Tmax ca ph ti do .

c th xc nh theo kinh nghim hoc th lp t s liu thng k, cth:

= (0.124 + Tmax . 10-4 )2 .8760 (gi) = 0.3 + Tmax +ng thi c th tra theo th = f(Tmax) hoc tra theo bng.2. Phng php tnh tn tht in nng trn MBA:- Tn tht in nng trong MBA gm hai phn:

+ Phn khng ph thuc vo ph ti xc nh theo thi gian lm vic caMBA+ Phn ph thuc vo ph ti xc nh theo th ph ti, nu cng sut

MBA c th ph ti th dng Tmax tnh .- Tn tht in nng 1 nm tnh theo l: AB = P0.Tb + Pmax . = P0.Tb + PN . Trong :+ Tb l thi gian vn hnh nm ca MBA v (8500->8760)h.+ Smax ph ti cc i nm ca MBA.+ Sm : Cng sut nh mc ca MBA.

- P0: Tn tht cng sut tc dng khng ti, tra trong bng l lch caMBA.

- PN: T tht cng sut ngn mch.- Nu c n MBA nh nhau lm vic song song th tn tht in nng trong

n my l: AB = n P0.Tb + PN .


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- Khi cc my trong trm c dung lng khc nhau: Khi vn hnh songsong cc my bin p c dung lng khc nhau th ph ti phn b t l vi cngsut nh mc:

S1=S.S2=S.

S1 v S2 L ph ti m my bin p B1, B2 m nhn.Sdm1, Sdm2 L dung lng nh mc ca my bin p B1, B2.

Tn tht in nng trong trm bin p c tnh bng tng tn tht innng ca tng my:

A = AB1 + AB2 + ..+ = ACu 6: Nhim v v yu cu i vi h thng RLBV?

a. Nhim v ca BVRL:Nhim v chnh ca BVRL l t opngj ct cc phn t h hng ra khi h

thng in nhm ngn nga s pht trin s c lan trn v m bo s lm viclin tc ca cc phn t khng h hng trong h thng in v loi tr nhng tnhtrng lm vic khng bnh thng c kh nng gy nguy him cho thit b v htiu th.

Ngoi ra thit b BVRL cn ghi nhn v pht hin nhng tnh trng lmvic khng bnh thng ca cc phn t trong h thng in, tu mc m

BVRL c th tc ng i bo tn hiu hoc i ct my ct. b.Yu cu c bn ca h thng BVRL :Cc thit b BVRL tc ng i ct MC cn phi c 4 yu cu k thut c

bn sau:+ Tnh chn lc+ Tc ng nhanh+ nhy+ Tnh tin cy

I. Tnh chn lc: l tc ng ca bo v m bo ch ct phn t b hhng ra khi h thng in.

II. Tc ng nhanh: Cng ct nhanh phn t ngn mch s cng hn chc mc ph hoi phn t , cng gim c thi gian tt in p cc htiu th v c kh nng gi c n nh ca h thng in.

III. nhy: BVRL cn phi c nhy i vi nhng h hng v tnhtrng lm vic khng bnh thng c th xut hin nhng phn t c bo vtrong h thng in.

IV. Tnh m bo: BV phi lun sn sng khi ng v tc ng mt cchchc chntong tt c cc trng hp ngn mch trong vng bo v v cc tnh


55/58

trng lm vic khng bnh thng nh trc.Cu 7: Ho in l g ? Cc iu kin ha in, tc hi ca ha in

khng ng b?- Ho in l ghp song song cc my pht in vo lm vic chung trong

cng mt h thng.- Cc iu kin ha in (ho ng b chnh xc):

+ in p ca my pht phi bng in p ca li in (UF = UL).+ Tn s ca my pht phi bng in p ca li in (fF = fL).+ Th t pha ca my pht phi ging th t pha ca li in.+ in p ca my pht v ca li phi trng pha.

Th t pha ca my pht in thng ch cn mt ln sau khi lp my v hang b vo li in ln u tin.

- Tc hi ca ha in khng ng b ha ng b khng chnh xc: victhao tc ng cu dao ni MF cha c kch thch vo li in c in p U L

tng ng vi trng hp ngn mch t nhin ca li in. Ngoi tng trbn thn ca MF cn c cc tng tr ca cc phn t khc ca li in (MBA,Z) nn dng in xung chy trong MF khng vt qu 3 hoc 4 ln dng innh mc. Hn na dy qun kch thch c ni qua in tr trit t nn dngin xung qu gim rt nhanh. Phng php t ng b c php s dngtrong trng hp Ixg < 3,5Im.

Cu 8: H thng lm mt MBA c cng dng g? Phn loi cc h

thng lm mt MBA. Cho v d v cng sut ca mt MBA ph thuc vo ccch lm mt ca my ?

1. Cng dng ca h thng lm mt:H thng lm mt MBA c cng dng l to iu kin cho MBA c thmang y dung lng trong mi trng hp m nhit ca my khng vtqu tr s cho php nhm m bo tui th s dng cn thit ca my .

Tham gia lm mt my bin p, trc tin phi k n du bin p. Duhp th nhit lng pht ra t cun dy v li thp, nh vo hin tng tun honi lu nhit, chuyn nhit lng ra v my v b lm mt, t tn ra khng kh,c nhit thp hn. 2. Phn loi: Tu theo dung lng ln, nh ca MBA m MBA c thc lm mt bng cc cch sau:

a. Lm mt t nhin bng khng kh, i vi my bin p kh.b. Lm mt bng du, i vi MBA ngm du, loi lm mt bng du li

c th lm mt bng my dng sau:- Lm mt t nhin bng du:Loi ny du truyn nhit ra khng kh qua v my v b tn nhit.

tng hiu qu tn nhit, cn tng b mt tip xc vi khng kh bng cch vthng c hnh ln sng hoc gn vi cc ng tn nhit, hoc cc b ng tn nhit,hoc b cnh tn nhit.


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Nu my lm vic bnh thng th khi my bin p vn hnh, phn trn cachng nng hn phn di.

- Lm mt t nhin bng du kt hp vi qut gi thi khng kh ngoi vmy v b lm mt tng hiu qu lm mt.

Cc qut gi phi c t ng a vo vn hnh hoc t ng ct ra tu

theo mc ph ti v nhit lp du trn theo yu cu ca nh ch to hay theoQuy trnh vn hnh ca n v vn hnh.

- Lm mt kiu cng bc tun hon du qua h thng ng nc lm mt:i vi loi ny tuy khng cho php ng in my bin p k c ng

in khng ti, nu h thng lm mt khng hot ng. V ngay khi my bin pkhng ti, nu h thng lm mt khng hot ng, nhit ca my bin p vt qu tr s cho php.

3. V d v cng sut ca MBA ph thuc vo ch lm mt:+ i vi MBA 16MVA- 115/38,5/24kV- VINA TAKAOKA:

(hin ang vn hnh ti trm E54)

Cun dy Cao p Trung p H p

Cng sut (MVA) khi khng cqut gi (ONAN)

13 13 13

Cng sut (MVA) khi c qutgi (ONAF)

16 16 16

+ i vi MBA 25MVA- 115/38,5/24kV- TH C:

(hin ang vn hnh ti trm E49)

Cun dy Cao p Trung p H pCng sut (MVA) khi khng cqut gi (ONAN)

20 20 20

Cng sut (MVA) khi c qutgi (ONAF)

25 25 25

Cu 9: Cng dng phn loi v u nhc im ca cc loi iu chnh

in p ca MBA?Cng dng : Duy tr in p n nh theo yu cu ph ti.C hai loi iu chnh in p ca MBA: iu chnh in p lc khng ti

v iu chnh in p lc c ti (iu p di ti).iu chnh in p lc khng ti:u im:

- Thit b n gin, r tin.- Khng lm bn du khi iu iu chnh nc phn p.

Nhc im:- Khi iu chnh phi ct in my bin p, gy mt in trong thi gian


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iu chnh nc phn p.- phm vi iu chnh in p khng rng.

B iu chnh in p c ti (iu p di ti):u im:- Lc chuyn i u phn p khng cn ct in MBA.

- C th gi n nh in p, p ng nhu cu v thay i in p ca phti.

- Phm vi iu chnh in p rng.Nhc im:- Chi ph ch to tn km, phi thng xuyn theo di v bo dng.- D lm bn du ca MBA.

Cu 10: Nhit du ca MBA c o bng cch no v o ti v tr

lp du no ca MBA? Nhit cun dy ca MBA c o bng cch no?- Cch o nhit du MBA

+ o nhit du, dng mt bu nhit biu t trong thng MBA vc t ti v tr m nhit du l nng nht. Khi nhit du thay i s lmthay i p lc trong bu nhit biu lm quay kim ch th tng ng.

+ Nhit du MBA c o ti lp du trn cng ca MBA.- Cch o Nhit cun dy ca MBA:Dng mt cm bin nhit ni vi mt bin dng qua in tr phi hp,

dng in qua bin dng tng ng vi dng in ti MBA. Do n phn nhc trng thi nhit ca cun dy.

Cu 11: Gii thch nguyn l lm vic ca b lc du tun hon ca b

i nc c ti ca MBA ?Trong qu trnh iu p di ti ti v tr cc tip im chuyn i c phtsinh h quang, h quang ny lm cho du phn no b t chy v dn ti gimthi gian vn hnh. B lc du tun hon cho thng du b iu p c mc ch llc tp cht c hc trong du b iu p di ti.

Cu to b lc du gm my bm du, hp lc, h thng van v ng dndu. Du trong bnh du b OLTC c ht theo ng ng qua hp lc v tr vb OLTC theo mt ng ng khc. Hp lc, tu mc ch, yu cu m s dnggiy lc (lm sch du) hay s dng mn lc phi hp (lm sch, kh nc).Ngoi ra b lc cn c ng h p lc v tip im p lc ngn nga trnghp p lc trong b lc vt qu mc quy nh gy h hi cho ng c bm duhoc chnh bn thn b lc.

Cu 12: Trong trm bin p, cc loi mch in kiu kn sau y c

nhim v g?- Mch iu khin MC in dng iu khin ng ct MC bng in

t xa hay bng in ti ch khi tho mn cc lin ng ca MC.- Mch iu khin DCL dng thao tc tc ng ct DCL bng in


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t xa hay bng in ti ch khi tho mn cc iu kin lin ng ca n.- Nhim v ca mch iu khin qut mt l nhm m bo 3 nhm

qut mt lm vic 1 cch chc chn v an ton. Khi nhit ca du v cun dy110-35-22 tng cao n s khp tip im i khi ng qut lm mt MBA( khi du tun hon lu thng qua ).

- Nhim v ca mch iu khin b truyn ng i nc c ti ca MBAl m bo an ton trong qu trnh chuyn i nc phn p bng in t xahay bng in ti ch .

- Nhim v ca mch in th Cp ca my bin dng in l dng lytn hiu dng in tiu chun(1 hoc 5A) cung Cp cho thit b bo v rle vcho o lng.

- Nhim v ca mch in th Cp ca my bin in p l dng lytn hiu in p tiu chun cung cp cho bo v r le v o lng v cch ly thitb vi in p cao.

- Nhim v ca mch bo tn hiu s c dng bo tn hiu s c mt

cch chnh xc khi bo v rle tc ng hoc tn hiu khc khi c s c nhmgip cho nhn vin vn hnh pht hin kp thi v x l s c trong thi gianngn nht.

- Mch in tc ng ca r le bo v c nhim v tc ng khi c ngnmch hoc tnh trng lm vic khng bnh thng xy ra trong h thng in.

Trong nhng mch trn c nhng mch dng ngun mt chiu l:+ Mch iu khin MC ct in.+ Mch iu khin DCL+ Mch bo tn hiu s c+ Mch in tc ng ca rle bo v .

Nhng mch dng ngun xoay chiu:+ Mch iu khin qut mt.+ Mch iu khin OLTC+ Mch th Cp ca MBD+ Mch th Cp ca MBA.

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