Cu 1: Ph ti tnh ton l g?Cu 2: V sao khng dng cng sut nh mc hoc cng sut t tnh ton thit k cung cp in ?Cu 3: Biu ph ti l g ? v sao ta cn v biu ph ti ?Cu 4: V sao cho php my bin p qu ti ? cho my bin p qu ti 1,4 c nh hng g n tui th ca my khng ?Cu 5V sao chn tit din dy dn cao p theo iu kin jkt ?Cu 6: my ct lin lc trm phn phi trung tm thng ng hay thng m?v sao ?Cu 7:C khi no khng my ct thng m m phi thng ng ?Cu 8: chn my ct trm phn phi trung tm cn chn my im ngn mch? V sao ?Cu 9: V sao phi ni t bin dng ?cu 10 : h s s dng , h s ng thi , h s k m my v cc h s trong lun vn cung cp dng lm g , ngha h s , v sao phi s dng h s ?cu 11 : khi thit k chng st bng kim thu st phng in sm(ESE - Early Streamer Emission), ti sao li chn kim cp 3cu 12 : s khch bit ca cc loi s an ton TNS , TNC , TT , IT , ....cu 13 : iu kin no chn CBcu 14 : v sao cn thit phi tnh ngn mch 1pha , 2 pha , 3 phacu 15 : v sao cn thit phi tnh st pPh ti tnh ton l ph ti tng ng khng i vi ph ti thc t thay i v mt pht nhit , thng s dng la chon cp , cb , MBA .Cu 2: V sao khng dng cng sut nh mc hoc cng sut t tnh ton thit k cung cp in ?

thng cng sut nh mc c gi tr ln hn cng sut thc t m thit b yu cu ( vic ny th hin qua h s ti Kt MC u ngun ct.- Bo v chm t: Khi mt pha b chm t: U pha gim dn v 0, I pha tng dn ln cc i nu l li trung tnh ni t trc tip. Thng thng th do ngi vn hnh x l. Kim tra U cc pha xc nh pha chm t, ct loi ln lt cc khi hnh, ct n khi hnh no m ht tn hiu chm t -> khi hnh b chm t. Cc MC th h mi hp b bo v c th t ct DZ b chm t ra khi li.Cu 9:- Ni t bin dng l yu cu bt buc v: Khi th cp bin dng b h mch s sinh ra in p cao pha th cp bin dng gy nguy him cho ngi v thit b, khi c ni t s lm ngn mch ti im ni y -> bo v tc ng ngt mch -> An ton.Cu 15:Phi tnh ton st p m bo vic g? V d:- Cp in cho mt xng c kh. Khi cc ng c my cng c khi ng s gy ra st p tc thi. Ci ny cc bn phi tnh h s ng thi trc ri. St p ln s lm cho cc khi ng t mt ngun hoc gim ngun tc thi -> Khi ng c thit b ny th thit b khc hoc ton b h thng b tch ra khi lm vic. y iu ch yu l tnh st lm sao khng nh hng (nh tip im ht do b mt ngun ca rle, khi ng t...) n cc thit b ang vn hnh.Cu 1:Trnh by iu kin cho php MBA vn hnh vi in p cao hn in p nh mc? Vi ch vn hnh hin ti ca li in hin nay th in p nh th no? Ph ti cho php ca MBA nh th no?Tr li:a) Cho php my bin p vn hnh vi in p cao hn in p nh mc ca nc ang vn hnh:25% ph ti nh- Lu di 5% khi ph ti nh mc v 10% khi ph ti mc.6h/ngy) 10% vi ph ti khng qu nh mc.- Ngn hn (b) Ch vn hnh hin nay th in p thanh ci 22kV gi mc 23.1kV do cc MBA phn phi c in p nh mc pha s cp 12.7/22kV (NC nc 3) ang vn hnh qu p lu di 5%.c) Cc MBA trn ch c php vn hnh n ph ti nh mc.

Cu 2:iu kin vn hnh song song cc my bin p? Gii thch tng iu kin?Tr li:a) My bin p c php lm vic song song vi cc iu kin sau :- T u dy ging nhau.- T s bin p bng nhau 0.5%.hoc chnh lch khng qu- in p ngn mch chnh lch khng qu 10%.- Hon ton ng v pha.b) Gii thch: i vi cc MBA khi u vn hnh song song th cc pha tng ng pha s cp phi u ni tng ng vi li pha s cp, lc :- T u dy ging nhau, t s bin p bng nhau hoc 0.5%, hon ton ng v pha: in p pha th cp giachnh lch khng qu 0.5% (khng xut hin dngcc MBA khng lch pha nhau, gi tr khng lch qu qun gia cc MBA gy s c).10%:- in p ngn mch chnh lch khng qu mc mang ti gia cc MBA khng lch nhau qu 10%.

Cu 3:Nguyn l lm vic ca recloser? Phm vi s dng? Cch thao tc?Tr li:a) Nguyn l lm vic ca recloser nh sau: khi dng in chy qua recloser vt qu gi tr ci t, recloser s tc ng, c lp cc ph ti sau n trong khong thi gian tr hon v sau s t ng li. Tuy nhin, sau mt s ln ng li m gi tr dng vn vt gi tr ci t th n s t c lp hon ton cc ph ti.b) Phm vi s dng- S dng ng, ct cc ph ti v dng ti ng ct phi khng vt qu dng nh mc ca n.- Gii tr cc s c thong qua v c lp s c vnh cu bng cch phi chc nng t ng li v lockout.- Thit k i km vi DS hoc LTD to khong cch nhn thy phc v cho cng tc sa cha, bo tr li in.c) Cch thao tc:- Bng tay: thao tc ng ct thc hin ti t iu khin, khi cn thit c th ct bng so thao tc t cn ct bng tay trn my ct (tuy nhin khng th ng li c bng so).- T ng: khi dng ti qua recloser vt qu gi tr ci t, recloser t ng ct v t ng ng li theo lp trnh ci t sn.

Cu 4:Li ch ca LBS so vi DS? Khi thao tc ct LBS th ng dy c th xem nh l c lp c cha?Tr li:a) Li ch ca LBS so vi DS :- C th thao tc ng ct dng ti trong khi DS ch ng ct dng khng ti.- C th ng ct khi hai u ng dy khng ng p, DS ch ng ct mch ng p.b) Khi thao tc ct LBS th ng dy vn c xem nh l cha c c lp v tip im LBS l tip im khng nhn thy.

Cu 5:Cho bit trnh t c lp v ti lp my ct c DS cch ly 2 pha?Tr li:a) Trnh t c lp :- Ct MC.- Ct DS cch ly 2 pha.b) Trnh t ti lp :- ng DS cch ly 2 pha.- ng MC.

Cu 6:T b trn li in phn phi c cng dng g? Ti sao khi lp t b vi dung lng ph hp th gim c TTN? T b trn li phn phi thuc loi b no? Nu phn theo cch iu khin gm my loi?Tr li:a) T b l thit b pht ra cng sut phn khng b vo cng sut phn khng do ti tiu th trn li, nh iu chnh c in p, nng cao c h s cng sut v gim tn tht in nng trn li.b) T b lp t vi cng sut ph hp th ton b cng sut ca t b pht ra s thay th cho lng cng sut ca ngun do on ng dy t ngun n v tr m ph ti nhn cng sut phn khng ca t b s gim mt lng cng sut chuyn ti bng vi cng sut ca t v tng ng s gim tn tht in nng chuyn ti lng cng sut ny.c) T b trn li phn phi thuc loi b ngang, nu phn theo cch iu khin gm c hai loi: T b tnh v t b ng ng.Cu 7:Tc dng ca vic lp LA trn li in phn phi? Gii thch ngha ca k hiu MCOV ghi trn nhn ca LA? Li 22kV s chn LA c c tnh nh th no?Tr li:a) Chng qu in p do xung st lan truyn trn ng dy; chng qu in p do ng ct thit b hoc trng thi qu khc ca li.b) MCOV (kV): in p lm vic lin tc ln nht ca LA (MCOV: Maximum Continuous Operating Voltage), n v l kVc) Li 22kV chn LA c c tnh nh sau:- Um: 18kV.- MCOV: 15,3kV.- Class: 1.- Ix nng lng: 10kA.

Cu 8:Hy lit k nhm thit b c mc ch ci thin cht lng p? Nhm c mc ch bo v s c.Tr li:a) Nhm thit b ci thin cht lng in p.- T b.- AVR (my iu p trung th).b) Nhm thit b bo v s c.- Aptomat.- FCO, LBFCO.- Recloser.- My ct (kt hp vi h thng r le bo v).

Cu 9:Ch qu ti ngn hn cho php ca my bin p nh p no khi c s c?Tr li- Nu c quy nh c th ca nh sn xut th thc theo quy nh, cc trng hp cn li khi c s c my bin p c php qu ti ngn hn theo bng sau:

Qu ti theo dng in, % 30 45 60 75 100Thi gian qu ti, pht 120 80 45 20 10

Cu 10:B iu p di ti cc tc dng g, c lp t u?Tr li:a) B iu p di ti (OLTC) c tc dng iu chnh in p pha th cp ca MBT trong phm vi cho php khi my bin th ang mang ti.b) OLTC c lp t pha cun s cp (cun cao) ca MBT.

Cu 11:Hy cho bit nh hng ca vic my bin p lm vic khng i xng khi ti phn b khng u?Tr li:- My bin p lm vic khng i xng khi ti phn b khng u cho ba pha. Khi dng in khng bng nhau cc pha gy nh hng xu n tnh trng lm vic bnh thng ca my bin p nh in p pha v dy s khng i xng, tn hao ph trong dy qun v li thp tng ln, chnh lch nhit ca my vt qu quy nh.

Cu 12:iu kin cn thit thc hin ng kt vng h 2 pht tuyn trung th? iu kin cn thit thc hin kt vng kn 2 pht tuyn trung th?Tr li:a) iu kin cn thit thc hin ng kt vng h- Phi s dng thit b ng ct c ti c dng nh mc ph hp.- 2 pht tuyn phi cng cp in p vn hnh.- im u ni kt vng phi m bo 2 pht tuyn cng th t pha.b) iu kin cn thit thc hin kt vng ng th- Phi s dng thit b ng ct c ti c dng nh mc ph hp.- 2 pht tuyn phi cng cp in p vn hnh.- im u ni kt vng phi m bo 2 pht tuyn cng ng v pha. 30o.- Gc lch pha gia 2 im ha:- Chnh f 0.25Hz.lch tn s gia 2 im ha:- Chnh lch in p gia 2 im U 10%.ha:

Cu 13:Kim tra nh k m ng dy trung th ch yu ni dung g?Tr li:- Pht nhit cc mi ni.- Phng in, r in.- Cc nguy c v hin tng bt thng xy ra.

Cu 14:My bin th 3 pha c t u dy Dyn11 ni t s trung tnh h th c tc dng?Tr li:- m bo in p pha t gi tr ng thit k.- m bo my vn hnh an ton.

Cu 15:Trm bin th 3 pha gm t hp 3 my bin th 1 pha c t u dy Ynyn0, khi 1 my b s c th c th cung cp in bnh thng cho cc khch hng 1 pha thuc 2 pha cn li khng? Ti sao?Tr li:C th cung cp in bnh thng cho cc khch hng 1 pha thuc 2 pha cn li do i vi khch hng 1 pha th ngun cung cp in thuc tng my c lp khng b nh hng bi cc my cn li.

Cu 16:Cng dng ca bin dng in (TI)? Trong bin dng cun dy c cp chnh xc 0.5 s dng cho mc ch g, cun dy c cp chnh xc 5P20 s dng cho mc ch g?Tr li:- Cng dng ca bin dng in (TI): bin i gi tr dng in trong mch s cp c gi tr ln v gi tr danh nh ca mch th cp phc v cho cng tc o lng cc i lng in (cp danh nh mch th cp thng l 1A hoc 5A).- Cun dy c cp chnh xc 0.5 (CL 0.5): s dng cho mch th cp thc hin chc nng o m in nng.- Cun dy c cp chnh xc 5P20 (CL 5P20): s dng cho mch th cp thc hin chc nng bo v r le.

Cu 17:Cng dng ca bin in p TU?Tr li:Bin in p (TU) dng bin i gi tr in p ca li ang vn hnh v gi tr danh nh ca mch th cp phc v cho cng tc o lng cc i lng in hoc cp tn hiu in p cho h thng r le bo v.10 cu hi ny hi b nhiu , kh th tr li ngay 1 lc . ln sau hoc nhng anh ch em khc tr li .Mnh c my nh sau :

1/ Cac ng c 3 pha tai sao phai chon cap 4 loi?

Si th 4 lm dy ni t an ton , c mu xanh sc vng .

2/ Co th thay th Khi ng t bng Aptomat c khng?

Khng th v 2 th ny c chc nng bo v khc nhau . KT ( gm contactor + relay nhit ) ch bo v qu ti ; Aptomat / MCB / MCCB / CB c th bo v qu ti ln ngn mch (bo v qu ti khng tt bng KT ) .

3/ G thich ky hiu 4G10 va 3.70 +1.50?

Cp ny 4 li , 3 li lm dy pha , tit din 70mm2 , 1 li lm trung tnh , tit din 50mm2

4/ tai sao tinh ngn mach ha ap lai k ti tng tr cua DCL,Aptomat,Thanh Gop.con tinh cao ap lai bo qua?

U thp , cc tng tr ny tng i cao => phi tnh chn CB / MCB / MCCB chnh xc . U cao , cc tng tr ny li tr nn thp , c th b qua .

5/ Tai sao trong cac tu phn phi va tu ng lc lai dungaptomat ma khng dung cu chi?

V cu ch ch bo v ngn mch trong khi cc t ny cn bo v qu ti ln ngn mch , hn na nu xy ra ngn mch th sau khi sa cha / x l s c th khng phi thay cu ch .

6/ Vi sao khng cp in chiu sang t cac tu ng lc ma lai cp in tp trung tao tu chiu sang?

Cn phi tch ngun ring ng lc vi chiu sng trnh st p qu 5% lm n hunh quang / cao p ... tt khi khi ng . c cng sut ln .

7/ Vi sao cp tng cho tu chiu sang dung 4 loi,con cap cp in cho tng cum en lai dung cap 2 loi?

Cn cp ngun 3 pha , phn b u cho chiu sng , trnh lm lch pha nn dng cp 4 li cho t chiu sng . n l ph ti 1 pha => dng cp 2 li , c th l 3 li v dng 1 li lm dy PEN .

8/ Vi sao en si t cos phi bng 1 ma huynh quang cos phi bng 0,8?

n si t l ti thun tr => cos phi = 1 . n hunh quang dng ballast dy qun , c tnh cm , cos phi = 0,49 -> 0,52 , tnh c b n th 0.6 ch 0.8 l hi cao . Nu HQ dng ballast t hoc n compact , cos phi = 0.97 -> 0.99 .

9/ Quag thng en si t phu thuc yu t nao? tng quang thng lam cach nao?

Ph thuc nhiu yu t : mi trng khi / bi , tnh trng c / mi v.v... Tng quang thng bng cch dng n c cha hn ch tn tht .

10 / tai sao tu bu lo\ 3 pha lai u tam giac?cach nao kh in ap d trn tu?

u t gic khi mt 1 pha , vn cn kh nng b cho 2 pha cn li . Nu u Y , khi mt 1 pha th 2 pha ca t b h mch , ch cn b c 1 pha . T bn sn thng u t gic . Khi lo chuyn .Kh in p d bng in tr . Ngy xa t bn sn khng c tr x t nn phi c mch x , thng dng bng n , c khi l n neon trong t t b , Ngy nay th khi cn ; t bn sn lun c R x u sn .1. dc 3 pha cp 4 li th cho php (3 dy pha +1 trung tnh) vy c th mc theo 2 kiu v thm thit b bo v chng d dng dy trung tnh cng c.2. khi ng t = k aptomat ? khng hiu cu hi3. ko bt lun4. h p mnh tnh t phn bin p li ti phi khng nh? cn cao p th sao.5. t phn phi v t ng lc dng aptomat m khng dng cu ch. aptomat c chc nng (chng on mch = cu ch, ng ct mch = cu giao) vy th dng aptomat l ng ri.6. t tng chiu sng dng cab 4 li cho tng cm n dng cab 2 li.t tng dng ln v cn m bo cao v t t tng mi i n cc cm. do dng cab 4 li theo mnh va linh hot khi mn thay i chc nng vd dng 3 pha,1 pha. va m bo tin cy. cm n th si cap 2 mt nng mt ngui. cng phi tnh n kinh t nh. mnh c tin th lp cab to bng ci thng phi cho trm n khi rinh.hj hj.8. n si t l ti thun nn cos =1 ( gc lch gi u v i = 0 ). cn n hunh quang n c thm balast nn ti n khng cn ti thun na.9. quang thng th hin cng sut bc x hay sng nn vi bng dy tc n ph thuc vo cht liu dy tc,kh kem,v c cht lng thy tinh bng v in p cp