Thdng tin khoa hpc cdng nghe md THIET Bf AN TOAN TIA LUA KS LE VAN HAI KS PHAM VAN HIEU KS VU TUAN ANH Vien Khoa hpc Cdng nghe Md TKV Increasing coal productivity in parallel with ensuring working saf[.]
Trang 1THIET Bf AN TOAN TIA LUA
KS LE VAN HAI
KS PHAM VAN HIEU
KS VU TUAN ANH
Vien Khoa hpc Cdng nghe Md - TKV Increasing coal productivity in parallel with ensuring working safety
is one of the key targets in the automation process of the coal
sector For these purposes, the application of the intrinsic spark safe
equipment to the mining activities is essentiaL The paper introduces
some fundamental principles about the spark safety
NhCimg nam gan day trong
cac md than ham Id Viet Nam
da dua vdo dp dung eac thidt
bj vd he thdng do ludng dieu
khien tu ddng ed tfnh an toan
cao, trong dd ed cae thidt bj va
he thd'ng an toan tia Ida nhu
he thdng quan trac khf metan,
he thdng thdng tin lien lac,
dieu khien tu ddng, tU xa, he
thd'ng kiem soat nhan su trong
Id Tuy nhien, sU hieu biet ve
thiet bj an toan ndi chung va
thidt bj an todn tia Ida ndi rieng
cdn han chd Bai viet nay gidi
thieu ve nguyen tac an todn tia
Ida cdia thiet bi dang sdr dung d
cac md hien nay
1 Cac nguyen tac cd ban
ve an toan tia lilira
Thiet bj dien lap ddt trong
vung ed nguy ed ehdy nd cd
the phdt ra hd quang, tia Ida
dien hodc sinh ra nhiet lUpng
cao ed the gay bdc ehdy hon
hpp chat ehdy nd trong mdi
trudng xung quanh nd
PhUPng phdp dam bao an
todn de trdnh sU ed ehdy nd Id
ngdn chan sU xuat hien ddng
thdi eda hon hpp khf nd va cae
ngudn ed the gay ra ndng
lupng Idm bdc chay hdn hpp
do, bao gdm:
+ ChUa thiet bj ed kha ndng
gay bdc Ida vdo khdng gian
het sifc chac chan, dam bao
khdng gdy ra bdt ky nguy hai
nao tdi hon hpp khf nd (vd phdng nd)
+ Cach ly ngudn gay nd vdi hon hpp khf nd
+ Han chd nguon nang lupng phat ra tU cac thiet bj dudi mUe ed kha ndng gay nd hdn hpp khf nd (an toan tia Idfa)
Ta't ca cae phUdng phap ap dung cho cac thiet bj chd'ng chay nd deu phai tuan theo tieu chuan qud'c gia hoac qud'c te
Cae tieu chuan qui djnh each thiet ke va lap dat thiet bj cho cac nha san xua't va ngudi sd dung Tuy nhien, eac thiet bj
phai 6ugc cdc ed quan ed tham
quyen chap nhan va cap chdng ehi Trong ta't ca eac phUdng phap chdng chay nd, phUdng phdp ddn gian, hieu qua nha't
dp dung cho eac thiet bj dien, dien td, la phUdng phdp an toan tia Ida (Ex i)
Nguyen tac ed ban eda phUdng phdp an toan tia Ida Id han chd tinh trang sU ed, dat tinh trang sU cd dudi mUc binh thudng vd bidt tnJdc kha ndng sU
cd ed the xay ra Tdt Id, tia Ida,
hd quang hoac nhiet dp be mat eda mach dien lap dat trong
vung ed nguy ed ehdy nd 6ugc
gidi han tdi mdd khdng dd de lam bdc Ida hon hpp khf nd Cae thiet
bj dien lap ddt trong vung ed nguy cd ehdy nd, cung nhU cae kdt ndi ve dien gi&a eac thiet bj
vdi nhau, phai dupe thidt kd de giam thieu dien dp hd mach va ddng dien ngan mach den mdc tdi thieu, khdng gay ra sU bdc chay cho hon hpp khf nd, bang each lam hd mach hoac ngan mach, tiep dat, hoac bang each nung ndng cae thanh phan trong mach dien (de giam nang lupng phat ra ngoai)
Mach thuan trd la mach ehi
ed thanh phan trd khang, cae thanh phan phan khang, cam khang va dung khang khdng
ed hoac nhd khdng dang ke Nang lupng dien phat ra tU mach nay phu thude vao ngudn dien V va ddng dien Isc
bj gidi han bdi dien trd R Khd
cd the xac djnh dupe tUdng quan giu'a nang lupng bdc Ida tdi thieu vdi mach phat ra tia
Ida Cac phep thd da 6ugc thifc
hien va cho tha'y kha nang bdc Ida hdn hpp khf nd cdia tia Ida phu thude vao dien dp hd mach (Voc=V) va ddng ngan mach (lsc=V/R) Dudng dac tfnh bdc Ida cua mach thuan trd the hien tren hinh 1
Hinh 1 the hien dudng dac tfnh bdc Ida ed quan he vdi nhdm hon hpp khf nd da dupc phan loai theo tieu chuan Dudng dac tfnh cho thay vdi dien dp hd mach thap hdn, thi
edng suat ngudn 6ugc sd dung
an todn se Idn hdn Ode diem nay cho thay cdc thiet bj ed dien dp cap ngudn tU 20-30y difdc sd dung hieu qua nhat trong cdc thiet bj an toan tia Ida Ndng lupng ddnh Ida tdi thieu (MIE) Id khac nhau do] vdi tCfng loai nhien lieu, the hien bang ti le eda nhien lieu
CO trong khdng khf, ma d ti le
dd hon hpp nhien lieu vd khdng khf rat dd bj bdc Ida
KHCNM s d 4/2010* CO DifiN - T U D O N G HdA MO
Trang 2Thdng tin khoa hpc cdng nghe mo
2000
1000
500
200
100
50
20
10
inA
\ \ \
V
G r t
M i l l U l l U m ,pry,ttno CUrXCIltS
a p p l i c a b l e t o e l e c t r i c a l
a p p a n t t u s -with c a d m i i u n
z i i i c m a g n e s i u m o r
a l u n u n u t l i
u p C \
C'Llss I 4 & B
C l a s s i Lip D
10 20 50 100 200
Hinh 1 a) Dudng ddc tinh bdc Ida tdi thieu theo nhdm khi cho thiet bi dien dung trong
khai thac md (nhdm I) b) Dudng ddc tinh gidi h^n ndcao vd gidi han ndthap cua tdng loai khi
Neu ndng lupng danh Ida
thap hdn mUe MIE, thi nd
khdng the lam bdc Ida d bat ky
ndng dp hon hpp nao Ndng dp
hdn hpp khf chay nd giam dan
cho den mdt gia trj ngUdng ma
tai dd ndng lUpng bdc Ida
khdng the lam bdc Ida hon hpp
do ndng dp qua tha'p, gpi la gidi
han nd dudi eda hdn hdp khf, kf
hieu Id LEL (low explosive
limit) Ndng dp hon hdp khf
chay nd tdng dan cho den mpt
gia tri ngudng ma tai dd nang
lupng bdc Ida khdng the lam
bdc Ida hon hpp (do qua ft
d-xy), gpi Id gidi han nd cao eda
hdn hpp khf, ky hieu Id DEL
(upper explosive limit) (bang 1)
Bang 1 Gidt han ndthap vd
gidi han nd cao eiia mdt sd
chatkhi
Chat
chay
/^celylenoe
Ethylene
Methane
Propane
Hydrogen
Gidi ^
han nd
thap(%)
2,3
2,4
4,4
1,7
4,0
Gidi han nd cao(%) ioo(ti;
gian nd) 32,6
17 10,8 77,0
Cdn eU theo nang lupng bdc Ida tdi thieu, khf ehdy
6\jgc chia thanh cdc nhdm,
theo dd, thiet bj dien an todn
6\jgc chia thanh hai nhdm:
Nhdm 1 la cac thiet bj dien sd dung trong yung md cd khf clidy nd va nhdm II Id cac thidt
bj sd dung trong cac vung khdc ed nguy hiem ehdy nd
Cac nhdm khf chay nd va thiet
bj dien trong eac nhdm I va II
lai tiep tue 6ugc phdn nhdm
nhd hdn thanh cac phan nhdm
A, B, C, Cdc thiet bj an toan tia Ida dung trong md ham Id thudng Id cap bao ve Ex iai
Ex ibi va Ex i d , trong dd cap
Ex iaI Id cao nhat vd ed the sd dung trong khu vuc cd nguy
cd cao nha't (bang 2)
Mpt sd Ipi the eda phUdng phap an toan tia Ida ma cac phUdng phap khac khdng cd:
+ Sd dung 6ugc b hau het
vung nguy hiem (vung nguy hiem nhat)
+ Bao tri va cdn chinh thiet
bj dudi hien trudng, cd the thuc hien ngay ca khi khu vuc san xuat dang hoat ddng va
tham chf ngay ca khi mach thiet bj dang hoat ddng Mach
ed dien dp thap nen an todn cho eon ngudi
+ Khdng can phai cd bien phap bao ve dac biet cho day dien d hien trudng, ed the sd dung ddy cap dien eda thiet bj thdng thudng
Trong eac Cfng dung an toan tia Ida, cd ba thanh phan
chfnh phai 6ugc xem xet:
(1) Thidt bj an todn tia Ida (2) Hang rao an todn tia Ida (mach each ly an todn): la phan ket ndi giCJfia vung an todn vd vdng cd nguy ed ehdy nd
(3) Day ndi lien ket
- Thiet bj an toan tia Ida
Cdc thiet bj an toan tia Ida nhu bp chuyen ddi dau do khf do gid do nhiet dp, vd bat ky mdt thiet bj ndo "luu gid
nang lupng" deu phai 6ugc
cap chdmg chi thidt bj an toan tia Idtei sd dung trong mdi trudng cd nguy cd ehdy nd
- Hang rao an toan tia Ida (thiet bj an toan tia Ida td hap)
KHCNM s d 4/2010* CO DI£N - TUDdNG HdA Md
Trang 39
Bang 2 Cap bao vp an todn tia Ida
Exia Mach khdng cd kha ndng gay bdc lifa
trong dieu kien hoat dpng binh thudng vd khi mdt hoac hai sif cd xay ra
Sd dung 3 di-6t zener dd bao ve qua ap, neu c6 sif cd lam 2 di-dt zener tidng thi di-dt zener thQ 3 vin hoat dong binh thudng Exib Mach khdng cd kha ndng gdy bdc Ida
trong didu kidn hoat ddng binh thudng hoac khi mot sU cd xay ra
Sif dung di-dt zener de bao ve qua ap, neu c6 SLf cd lam 1 di-dt zener hong thi di-dt zener thU 2 van hoat dong binh thudng Exic Mach khdng c6 kha ndng gay bdc iCfa
trong dieu kien hoat dpng binh thudng Didm phdn gidi giOa thiet bj
dudi hien trudng vdi thiet bj
trong phdng dieu khien gpi Id
"hdng rdo an toan tia Ida"
Hang rdo nay cd tdc dung bao
ve cdc mach dien trong vung
cd khf nd bang each gidi han
dien dp vd ddng dien Idm viec,
cung nhu dien dp va ddng
dien sU ed eda thidt bj d mdc
an todn (an todn tia Ida) khi di
qua nd Cd hai kieu each ly an
todn Id "cdeh ly an todn bang
di-dt zener" vd "each ly dien"
Hai kieu cdeh ly nay khdc
nhau ve each gidi han nang
lupng gay nguy hiem tU cdc
thidt bj trong phdng dieu khien
den vung ed nguy ed ehdy nd
Hang rdo an toan tia Ida
phai dupe thidt kd va 6\jgc cap
chdng ehi phu hpp cho tdng
thiet bj an todn td hdp (he
thdng cdc thidt bj ndi vdi nhau)
de kdt ndi vdi cdc thiet bj an
todn tia Ida khdc trong vung
ed nguy ed ehdy nd Cdc thidt
bj an todn tia Ida td hdp Id
nhCmg thdnh phan chfnh eda
bat ky mdt he thdng an todn
tia Ida ndo bdi vi nd quyet
dvnh cdc thdng sd an todn tdi
da cho phep de ket ndi cae
thidt bj vdi nhau trong mdt he
thdng an todn tia Ida
- Kdt ndi cdp didn trong hd
thdng an todn tia Ida
Dien dp va ddng dien trdng
cdc mach an toan tia Ida Id
nhd, do dd nd cho phep cd the
sd dung cdp dien eda cdc thiet
bj thdng thudng khdc vdi dieu kien la cam khdng (dien cam)
va dung khdng (dien dung) eda cap nam trong gidi han an todn cho phep eda he thdng
an toan tia Ida Thdng sd eda cdp thudng la ddng nhat tai mpi diem, do dd ed the de
dang tfnh 6\sgc cam khang va
dung khdng Cfng vdi chieu dai cap eu the
Rao chan an toan tia lua Rao chan an toan la thiet bj kdt nd'i cdc thiet bj giua vung
an todn vd vung nguy hiem vdi nhau (chay den mUc tdi thieu nd), muc dfeh Id gidi han ndng lupng nguy hiem tU vung an todn di vao vung nguy hiem
khdng the lam bdc Ida 6ugc
hon hpp khf ehdy nd Ndng lupng dien vupt qud trong eac mach dien khi cd sU cd d vung
an todn ed the 6ugc ngdn
chdn bang cdeh: dua ndng lUdng vupt qua vd dat (tidp dja); chdn ddng ndng lupng sU
cd bang cdc phan td each ly
Nhu vdy, khi xay ra su cd, mdc dien dp vd ddng dien trong vdng nguy hiem dupc han che tdi mdc an toan
- Rdo chan an todn tia lua dung zener
lis lau rdo chan an todn
bang zener da dupe sd dung rdng rai lam thiet bj an todn trung gian ddp Cfng nhu cau Idn sd dung thiet bj dien trong
vung ed nguy ed ehdy nd cao Khi lam viec binh thudng rdo chan cho phep truyen tin hieu dien theo ca hai hUdng vd khdng can trd chdng Khi xay
ra SLf ed tdng dien dp (dp Idn tdi da 250V) d phfa vung an toan tdi, thi dan den xua't hien mdt ddng Idn chay qua eau chi, qua di-dt zener vd xud'ng dat Cau ehi ndy cd td'c dp chay rat nhanh de dam bao an toan khi sU ed di-dt zener xay
ra (di-dt zener bj ddt se din den nguy ed ndng lupng dien nguy hiem vupt qua dupc hang rao vdo vung ed khf nd), eau ehi khi bj chay se cdeh ly
vd dien gida vung nguy hiem (trong Id) vd vung an todn (mdt bang) Theo tieu chuan
an todn, cau chi khdng dupc phep thay the de trdnh Idm suy ydu kha ndng bao ve an toan cho hang rdo chan, mdt khi cau chi bj ehdy thi thay mdi
ca hang rdo cdeh ly
Khi xay ra sU cd, dien dp
hd mach (Voc) d phfa eau dau nd'i xudng vung nguy hiem eda
rdo chan an todn, 6ugc ghim
bang dien dp ghim eda didt zener, vd ddng ngan mach tai
eau dau ndy 6[Sgc gidi han bdi
dien trd gidi han Rlim Gid trj eda dien dp hd mach Uoe vd ddng ngan mach Ise se quyet djnh cam khdng vd dung khdng tdi da cho phep eda cdc thiet bj (ke ca cam khdng vd
KHCNM s d 4/2010* CO DlfeN - TV »dNG HdA Md
Trang 4Thdng tin khoa hpc cdng nghe mo
dung khang eda dUdng day)
trong vung nguy hiem dUdc
phep nd'i vao rao chan an
toan, dieu nay de dam bao
ndng lUpng eda Uoe va Ise
khdng the lam bdc Ida hon
hpp khf chay nd trong vung
nguy hiem
Tuy nhien, hieu qua bao ve
eda rao chan an toan phu
thupc vao viec ket ndi tiep dja
cd tdt khdng Vi theo nguyen ly'
bao ve nay, ndng lUpng eda
dien dp va ddng dien 6ugc han
che bang each tra nang lUpng
thUa ve da't eda vung an toan
thdng qua dUdng tidp dja rieng
Dien trd tiep dat eda rdo
chan an toan phai dam bao
nhd hdn 1Q, tUdng Cfng vdi
kfch thude day tdi thieu 4mm^
Rao chan an toan tia Ida sd
dung didt zener ddn gian, hieu
qua va re tien, song, ed mpt
sd han che:
+ Phai dam bao tiep dja tdt
+ Cac thiet bj cap trudng
phai 6ugc each ly vdi da't
+ Dien dp rdi tren rao chan
ed the gay anh hudng den
hoat dpng eda thiet bj
+ Viec ket nd'i khdng ddng
hoac cd dien dp dang cao se
lam ddt cau chi
+ Kha ndng loai trU nhidu
kem, nhieu thiet bj cd ket ndi
vdi nhau se gay ra nhieu dien
dp cho nhau, cd ca nhidu td
hudng tiep dja tdi
- Rao chan an todn tia Ida
dung cac phan tur cdeh ly
dien
So vdi dung zener nguyen
ly nay khac biet d chd tao ra
su each ly vd dien gida vdng
an toan va vung nguy hiem
bang each sd dung eac phan
td each ly nhu bien dp rdle
ghep quang (opto coupler)
Ta't nhien cae thidt bj theo dang nay cung phai tuan theo tieu chuan an toan quy djnh
va phai 6\Sgc cap chCimg ehi
Neu 6ugc thiet ke ddng thi
"hang rao an toan tia Ida dung phan td each ly" se dam bao dien dp dau ra phfa ndi tdi vdng nguy hiem ludn d mUc gidi han an toan cho dd dien
dp dau vao rat cao Hang rao each ly kieu nay cho phep mach thidt bj khdng can phai tiep dja an toan danh rieng va viec tiep dja cho mach de ddng eau chi bao ve la khdng can thidt nda Cae thdng sd an toan eda dien dp hd mach Voc
va ddng ngan mach Ise 6\jgc
xdc djnh tUdng tu nhu d "hang rao an toan dung didt zener"
NhCJrng Ipi the chfnh eda phUdng phap cdeh ly:
+ Viec ket ndi tiep dja danh rieng dam bao chac chan khdng can thiet va cac thiet bj cap trudng ed the ndi tiep dja true tiep xudng dat
+ Cae thiet bj cap tafdng hoat dpng d cap dien dp tdi da,
vi khdng cd dien dp rdi trung gian (khdng ke rdi tren day)
+ Mach tfn hieu va mach bao ve an toan cd the tfch hdp vao edng mdt thiet bj
+ Lap ddt ddn gian, dUa thiet bj vao hoat ddng ma khdng can mach tiep dja
+ Kha ndng loai trU nhilu dien dp tdt (do dau nhieu thiet
bj ed ngudn mdt chung)
- Rdo chdn an toan tia lua tdhpp
Trong cac he thdng an toan tia Ida hien nay thudng sd dung ca hai phUdng phdp tren
de tan dung ldi the eda ca hai phUdng phdp do dd ddn gian
hda viec lap dat thiet bj vd tang cUdng an toan
* Cac thdng sd an todn eda thiet bj an toan tia Ida khi ket ndi vdi nhau can dam bao theo nguyen tac sau (chi dp dung vdi he thdng ddn ngudn hoac nhieu ngudn nhung tuyen tfnh):
Ui < Uo li < lo, Pi < Po, Co ^
C i + Cc^p, Lo ^ Lj + Leap
Trong dd:
Ui: Dien ap vao cue dai UQ: Dien ap ra cue dai
li : Ddng dien vao cue dai lo: Ddng dien ra cue dai P,: Cdng suat vao cifc dai Po: Cdng suat ra cue dai Co: Oien dung ngodi cue dai (dien dung cho phep)
Q: Dien dung trong cue dai (tdng dien dung tUdng dUdng eda thiet bj)
Ce^p: Dien dung dudng ddy LQ: Oien cam ngoai cue dai(dien cam cho phep)
L; Oien cam trong cue dai
(tdng dien cam tUdng dUdng eda thiet bj)
Lc4p: Oien cam dudng ddy
2 Mot so he thd'ng thiet
bj an toan tia Ida dupc dua vao sijf dung trong cdc md ham Id Viet Nam
a) He thdng canh bao tu ddng khi metan an todn tia lua do Ba Lan san xuat:
Hau het cdc md than ham
Id vdng Quang Ninh da dUde dau tu lap ddt he thdng tu ddng quan trac khi KSP-2C
va KSG-10 do hang Carboautomatika (Ba Lan) san xuat, cac tin hieu dien vd thiet bj eda he thdng phan trong ham Id la dang an toan tia Ida (hinh 2)
KHCNM s d 4/2010* CO DifeN - Tl/DdNG HdA MO
Trang 5220VAC
BAI 220/50 VAC
Vi giao tiep Mach giao tiep 0l£
i
May tfnh
RS232
H H
Khdi mach
vi XLf ly trung tam
Mach clach ly quang
Vi giao tiep Mach giao tiep d.do Mach each ly
Phong Giam sat tap trung
Hinh 2.- So dd khdi ciia he thdng do khi tu ddng cCia Ba Lan
Oaudo
CH4,
CO, gio
Dau do CH„
CO, gio
Trong ham
16
Sd dd hinh 2 cho thay:
- He thdng ed nhieu kenh
do, mdi kenh giao tidp vdi mpt
dau do thdng qua vi giao tidp
each ly an todn tia Ida Cae
dau do ed the la dau do CH4,
CO, gid, nhiet dp
- Cdc kenh eda he thdng
each ly nhau hodn todn ve
dien, sd dung cdc phan t d
bien dp cdeh ly vd phan t d
ghep quang (opto coupler)
- Mach vi x d 1^ trung tam
eCia he thdng truyen nhdn dd
lieu vdi eac dau do thdng qua
vi mach giao tiep vd each ly
vdi vi ndy bang cdc phan t d
cdeh ly quang Do dd mach
nay cd the kdt ndi true tidp vdi
mdy tfnh vd vdi ngudn dien
khdng each ly
Nhu vdy, SLf an todn tia Ida
eda he thdng dUdc quyet djnh
bdi bidn dp each ly
(BACL50/33/12), vi giao tiep,
dau do ket ndi vdi vi giao tiep
va dudng day
a) Phan tich an toan tia Ida
cho mdt kdnh do
Cach kenh eda he thdng la gidng het nhau vd hoan toan each ly dien vdi nhau, do dd
de hieu rd 6\jgc su an toan tia
Ida eda he thdng ta chi can phdn tfch sU an todn tia Ida
eda mdt kenh Sd 66 khdi eda
mdt kenh ed the dupe bieu dien nhu sau (hinh 3):
Mach kenh do cdeh ly vdi mach VXL trung tdm bang cae phan t d cdeh ly quang (opto-coupler) vdi khoang each an
todn dam bao theo tieu chuan TCVN7079, nen mach nay khdng cd lien he gi ve dien vdi mach VXL, do dd trong qua trinh tfnh toan mach gidi han ndng lupng cap tdi dau do
6ugc dam bao an todn tia Ida
se khdng xet den mach VXL
vd mach each ly quang
Ngudn 220VAC dUpe ha xudng 33V thdng qua hai bien
dp each ly B A I , BACL va cau chinh luu de cap ngudn cho "vi giao tidp", ludi each ly cdia hai
BA1 BACL Ciu di-it
220VAC
T 100uF
220/50VAC 50/33VAC
M9Ch
h-Mschj-chuyin , , deh
ail tin I I ly an j
hi0u H to^" r
X
M^chcich
ly quang
VIglio flip
Mach
Mach VXL tnjng
Hinh 3-Sodd khdi mdt kenh do
(390+150)12 150n
Ph6ng€)DTT 1 Dirdih^mlb
Hinh 4-Sddd tuong duong mdt kenh do
KHCNM S6 4/2010* CO DrtN - TU DdNG HdA Md
Trang 6Thdng tin khoa hpc cdng nghe m o
bien dp dam bao dien dp each
ly tdi 500V han che nang
lupng dien d mdc an toan khi
hoat ddng binh thudng cung
nhu khi cd sif cd tang dp tU
ngudn 220VAC cd the bang
qua hai bien ap each ly tdi vi
giao tiep kenh do Tdi vi giao
tiep, ngudn dien nay dupe
chuyen qua mach han che
ddng dien va dien dp (mach
each ly an todn tia Ida) de cap
tdi dau do dudi ham Id, ndng
lupng dien sau mach each ly
an toan dam bao an toan tia
Ida Nhin tU gdc dp an toan tia
Ida, sd 66 he thdng eda mpt
kenh do ed the dua ve dang
tUdng dUdng nhu hinh 4
Dien dp hd mach Uco 6itgc
khdng che bdi 3 didt zener
33V, va ddng dien ngan mach
Ise 6\sgc khdng che bdi dien
trd 690Q Tfnh toan hai thdng
sd nay nhu sau:
Ddng ngan mach (bao gdm
he sd an toan)
lse= 1,5x[33/(390+150+150)]
«72mA (lo)
Dien dp hd mach (bao gdm
he sd an toan) Uco = 1,5x33 «
50V(Uo)
Tra dudng ddc tfnh ddnh
Ida tdi thieu U=f(C) vdi dien trd
(390+150+150)=690Q, xac
djnh dien dung cho phep
khoang 200uF(Co) Trong dd
tdng dien dung trong mach
khoang 150uF(Ci), nhU vay
dien dung tdi da cho phep eda
dudng day vd eda dau do ket
ndi vao kenh do la
200-150=50uF Thue te tdng dien
dung cdia dudng day va eda
cae thiet bj da'u vao kenh do
rat nhd, ehi cd vai uF(Ci
+Ccip+ Ci TB kh4c) do vay dam
bao an toan tia Ida theo dien
dung
Vdi ddng ngan mach lse=72mA tra dudng dac tfnh danh Ida tdi thieu L=f(l) xdc dinh dUdc dien cam tdi da cho phep Id O.'lH (Lo=100mH)
Trong dd tdng dien cam trong mach chfnh la cudn day eda bien dp each ly (Li nhd hdn lOOuH) cdng vdi dien cam dudng day vd dien cam dau
do (Lo^p+U aiudo) khoang lOmH
ed trj sd nhd hdn nhieu so vdi dien cam cho phep, nen mach
an toan dien cam
Cdc phan td va dUdng mach in trong mach each ly an toan (trong vi giao tidp) dam bao khoang each so vdi cdc phan td hodc dudng mach in trong ndi bd mach va so vdi cac mach khdc xung quanh theo tidu chuan TCVN7079, khoang each tdi thieu Id 6mm
b) Phan tich an toan tia ICfa cho dau do khimdtan CPC-2
Mach dien eda dau do CPC-2 la dang an toan tia Ida, mach tUdng ddi nhieu linh kien Tuy nhien, vi xet d gde
dp an toan tia Ida, nen mach dupc dUa ve dang tUdng dUdng va ehi xem xet ky cac phan td can phai khdng che
6e mach trd thanh an todn tia
Ida
Trong mach gdm ed mpt sd
bd phan lifU trd va phdt sinh ndng lupng can dUdc khdng che: bp ae quy, mach tao ngudn chuan cho sensor va mach bao edi, trong dd, bd ae quy ddng vai trd ca'p ngudn
cho toan bp mach vd nd 6ugc nap de bu dap lai ndng lUdng
bj hao hut tU may tram tren phdng GSTT TU ac quy cd the chia thanh 4 nhanh cap ngudn chfnh khac nhau can phai xem xet ve mdt an toan, trong do cd 2 nhanh cd chUa
cdc phan td dao ddng can phai khdng che dien dp, ddng dien vao va ra eda hai nhdnh
do, cdn cae nhanh khdc ehi xet dien trd tUdng dUdng, dien dung tUdng dUdng va dien cam tUdng dUdng
TU tram trung tam, dau do
6iigc cap ngudn va ddng thdi
cung la dudng tfn hieu truyen gida may tram va dau do Ngudn tU may tram di qua 3 didt vao mach dau do, theo tieu chuan trd khdng ra cdia dau do dupc coi la rat Idn, do
dd dung khang va cam khdng
ra gan nhU bang khdng
- Xet khdi mach ae-quy: Mach ae quy cap ngudn cho toan bp mach dau do vd nhan ngudn ndng lupng bd sung tu may tram Ddng dien
su ed mach 6ugc khdng chd
bdi eau ehi eat nhanh 0,25A
va dien trd 3,3Q, dien dp hd
mach 6ugc khdng chd bdi hai
didt zener 12V Vdi dien dp hd mach eda mach ae quy la 1,5x12V= 18V (tfnh ea he sd
an toan), xdc djnh dudng ddc tfnh U(c) thi dien dung cho phep(Co) trong mach Id rat Idn (tren lO.OOOuF), trong khi dd tdng dien dung tUdng dUdng eda toan bp mach nhd hPn nhieu so vdi gia trj cho phep,
do dd mach dam bao an todn
ve dien dung
Cau chi 0.25A ehi cho phep ddng sU cd Id 1.7x0.25 = 0.425A (sU ed cao nhat) vdi ddng su cd nay thi dien cam tdi da cho phep trong mach Id 6mH, trong khi dd tdng dien cam trong mach rat nhd (khoang 300uH) nen mach an toan ve dien cam
Oien dp va ddng dien cap cho dau do eda khdi mach ae quy dam bao an toan tia Id^
KHCNM s d 4/2010* CO DifiN - Tl/ DdNG HdA Md
Trang 7Tuy nhien ndu trong ndi bd
khdi mach ae quy xay ra su cd
chap mach thi tia Ida sinh ra
se rat nguy hiem do dd toan
bd khdi mach 6ugc 66 day
bang chat cdeh dien de loai
trd SLf ed nay
Cdc trj sd dien dung, dien
cam vd ddng tai eda todn bp
mach dam bao khdp vdi thdng
sd an todn tia Ida eda ngudn
ae quy Tuy nhien, trong mach
cdn mdt sd mach cue bd can
phai xem xet, vi cdc mach nay
ed kha ndng thay ddi thdng sd
ddng dien vd dien dp cue bd
cd the gdy mat an toan tia Ida
Dd Id cdc khdi mach: mach
cdp ngudn chuan cho sensor,
mach edi bao ddng
- Mach cap nguon chuan
cho sensor
Dien dp hd mach dau ra
cOa mach ndy 6ugc khdng chd
bdi 2 didt zener 5,6V, gid tri
dien dp hd mach tdi da Id (tfnh
ea he sd an todn): Us-eo =
1,5x5,6 = 8,4V Tra dUdng ddc
tfnh U(e) xdc djnh 6\jgc dien
dung tdi da cho phep eda
mach Id khoang 5000uF trong
khi dd dien dung trong mach
chi Id IIOuF do do mach an
todn tia Ida theo dien dung
Ddng dien tdi da xay ra khi
dau ra sau hai di-dt zener bj
chap mach Tuy nhien ddng
dien ndy bj khdng chd bdi cau
chi eat nhanh 125mA do dd
ddng ngan mach chi dat tdi da
Id Is-sc = 1.7x0.125 =
0,2125A tra dudng ddc tfnh
bdc Ida tdi thidu L = f(l) xac
djnh dupe dien cam tdi da cho
phep Id 1H, trong khi dien cSm
trong mach la lOOuH, do dd mach an todn theo dien cam
Cdc tin hieu dien dp vd ddng dien dau vao va dau ra dam bao an toan tia Ida, nhifng ndu xay ra chap mach trong ndi bd mach thi cd the phat sinh ra tia Ida nguy hiem
ed kha ndng lam bdc Ida hdn hpp khf chay nd Do dd, de loai trU sU cd nay thi toan bd
mach 6itgc " 66 day" bang
chat each dien (hinh 5)
- /Wac/7 phat chudng bao ddng:
Mach nay cung gan gidng nhu mach cap ngudn sensor, tuy nhien mach nay chi cd thanh phan cam khang Ddng ngan mach cua mach cung dupc khdng chd bdi cau chi 125mA, ddng ngan mach la 0,2125A, tra dudng dac tfnh bdc Ida tdi thieu mach dam bao an toan (vi cam khang eda mach Id rat nhd) Ddng dien phan khdng eda cudn ddy trong mach ed the sinh ra ddng phan khdng ed gia trj Idn
cd the gay huy hiem, nhung
nd bj triet tieu bdi 3 di-dt mac song song, do dd tfn hieu dao ddng cap ra cdi dam bao an todn tia Ida Cung gid'ng nhu mach tren, todn bd khdi mach
6ugc "66 day" chat cdeh dien
de trdnh sU cd chap mach trong ndi bd mach
- Mach CPU:
Ddng ngan mach (tfnh ca
he sd an todn 1,5): lepu-sc = 1.5x9.6V/(3.3+150)n = 94mA
Tra dudng ddc tfnh ddnh Ida
tdi thieu L = f(l) xdc djnh 6\sgc
dien cam tdi da cho phep la 120mH Trong dd dien cam eda mach CPU ehi khoang 200uH, do dd mach dam bao
an todn tia Ida theo dien cam Vdi dien dp hd mach tdi da tai dau ra eda mach ae quy la 1,5x12V = 18V(dUpe han che bdi cac di-dt zener 12V), xac djnh dudng dac tfnh U(c) thi dien dung cho phep trong mach la rat Idn (tren lO.OOOuF), do dd mach dam bao an todn ve dien dung
b) He thdng canh bao khi
do Nhat Ban san xuat
He thd'ng kiem soat khf tu dpng cLia Nhdt Ban (da lap dat
d Mao Khe) dp dung ddng thdi tieu chuan thidt bj vd phdng
nd vd tieu chuan thiet bj an todn tia Ida
He thd'ng cd ca'u true phdn tdn, tram trung tdm Id he thdng cdc mdy tfnh vd truyen thdng vdi cdc may tram cue bd dudi Id Cdc mdy tram trong Id
cd kdt eau dang vd phdng nd (Exd), kdt nd'i vdi cdc dau do dudi dang tfn hieu an toan tia Ida He thdng sd dung mang truyen thdng ndi tidp, tram gidm sdt tap trung (GSTT) tren mdt bang ehi kdt ndi cdp quang vdi tram cue bd dau tien qua kdt eau phdng nd, tidp dd tfn hieu truyen thdng ndi tdi eac tram cue bd phfa sau bang cdp dien vd tfn hieu dien Id an todn tia Ida Ngodi hai dang cdng an todn tia Ida ndy, cdn cd cdng kdt ndi dau vdo vd ra dang on/off sd dung cdc phan td cdeh ly quang
KHCNM s d 4/2010* CO DI$N - TV DdNG HdA Md
Trang 8Thdng tin khoa hpc cdng nghe m o
PRDMTER Phong giam sat'
May khach
Cap dien(cap xoan doi)
Hinh 5-Sodd khdi he thdng
Moi tram sd dung bien dp
each ly ha dien dp tU 127V
(380V) xud'ng 24V, sau dd
dUdc chinh luu va ca'p cho
mach CPU, va cac mach kenh
do (8 kenh do) Mach CPU va
cac mach ca'p ngudn kenh do
sd dung cac bp chuyen ddi
ngudn each ly DC/DC de each
ly ngudn vdi nhau va vdi
ngudn chfnh, dien dp each ly
eda cac phan td nay la 2,5kV
Cae bp phan eda may tram
each ly ve dien vdi nhau vdi
dien dp each ly Idn, do dd ta
cd the tien hanh phan tfch sU
an toan tia Ida eda tdng khdi
ddc lap Khoang each eda cdc
bp phan mach each ly nhau
dam bao theo tieu chuan
TCVN7079 (hinh 6)
- Mach cap nguon cho dau
do: ed 8 mach, moi mach cap
ngudn cho mdt dau do, vd eac
mach nay dpc lap vdi nhau
nhd bd chuyen ddi ngudn
each ly DC/DC, dien dp sau caehIyla12VDC (hinh7)
Oien dp 12V sau bd each ly DC/DC se chay qua mach han che dien dp va ddng dien (mach an toan tia Ida), dien dp
va ddng dien sau mach nay la
an toan tia Ida va dupc ndi den mpt khoang cau dau rieng (khoang cau da'u an toan tia Ida) Khoang eau da'u nay cd the md ra khi may tram dang hoat dpng de ket ndi tdi dau
do vi dien dp va ddng dien trong khoang nay la dam bao
an todn tia Ida Cdc thdng sd mach:
Uco = 1.5x12V = 18V (Uo dien dp hd mach tdi da)
Isc =J8V/24n = 0.75A (^
ddng ngan mach)
Tra dudng ddc tfnh bdc Ida tdi thieu vdi dien trd ndi tiep 24Q xdc djnh dUde dien dung cho phep la rat Idn (Uo tren 3000uF) va dien cam cho
phep tdi da 150mH (Lo) Tong dien cam va dien dung trong mach dudng day va mach dau do la rat nhd (U^p+Li aa=100uH C^p+Ci ad=10uF) nen mach nay dam bao an toan tia Ida Hdn nda nguyen ly' mach nay rat an todn neu xay ra sU ed qua dp (tdc la didt zener lam viec) thi cac bdng trudng se lam ngan mach trudc dien trd han ddng 12Q d dau ra vd ddng dien nay la 12V/12Q = 1A se lam ddt cau ehi 0.5A vd cdeh ly ngudn dien vdi mach an toan tia Ida
Cac mach ndy khdng can cha't "do day", vi nd dupc bao
ve bang vd phdng nd dang Exd nhifng khoang cdeh cdc phan tu trong mach vdn phai dam bao theo tieu chuan an toan tia Ida Vdi nguyen ly mach nay thi eac linh kien trong mach cd dp ben rat cao neu cd su cd thi thudng ehi can thay eau chi de phuc hdi lai
-K/jd7fT?ac/jCPL'(hinh8): Mach CPU thu thap dd lieu
tu cae dau do va gdi thdng tin
ve trung tdm gidm sdt thdng qua mang truyen thdng RS485 Cac dau do gdi tfn hieu ndng dp khf dang tfn hieu ddng dien tUdng tU ve CPU thdng qua cae mach cdeh ly
an toan tUdng tU nhU mach cap ngudn nhung cdc tin hieu
nay rat nhd va disgc han che
qua cac dien trd cd trj sd Idn nen cam khang va dung khang anh hudng den mach CPU gan nhu khdng dang ke
KHCNM s d 4/2010* CO DI$N - TIT DdNG HdA Md
Trang 9Mdi CPU cd mdt dja chi
rieng biet vd duy nhat trong he
thdng, khi ed yeu cau se gdi
dd lieu tra Idi ve may tram
Nhu vdy, mach CPU se ed 4
cap ddy de kdt ndi vao mang
truyen thdng eda he thdng, va
cdc dudng truyen thdng nay
deu dupe bd sung cac mach
an todn tia Ida Cdc cap dUdng
ddy ndy tUdng t u nhau, nen
chi can xet mpt dudng Dien
dp hd mach eda dudng truyen
tiidng 6ugc khdng chd bdi ba
didt zener 5,1V, vdi he sd an
todn 1,5 thi dien dp nay Id
1,5x(5,1+0,7) = 7,7V, tra
dudng ddc tfnh bdc Ida tdi
thieu vdi dien trd nd'i tidp la
66Q thi dien dung cho phep Id
rat Idn (tam Id'y Id lO.OOOuF)
Vdi tdng dien dung tUdng
dUdng trong mach CPU
khoang 150uF thi dien dung ra
tUdng dUdng eda mdt eda
truyen thdng Id 3,7uF Trong
he thdng ed tdi da 15 mdy
tram, do dd tdng dien dung tdi
da tren dudng truyen thdng la
15x3,7uF = 55,5uF, tdng dien
dung cdia dudng day tdi da ed
khoang 4,2uF (200pF/m x
14x1500m) Nhu vdy tdng dien
dung cdia ca he thdng ed tren
dau ra eda mdt eda truyen
thdng Id 55,5 + 4,2 = 59,7uF ,
nhd hdn nhieu so vdi dien dung
cho phep, nen mach dam bao
an todn ve dien dung
Ddng ngan mach 5V/66n =
76mA vdi he sd an toan la
114mA, tra dudng ddc tfnh bdc
Ida tdi thieu cam khdng cho
phep Id khoang 300mH Tdng
dien cam tdi da cd t h i eda
dudng day vd eda mach CPU Id
(14x1500mx1uH+15x100uH)
= 36mH nhd hdn n h i l u so vdi
DC/DC
127VAC
127/12VAC
l ± i _ — ^ pttias
lr9m sau
''^y phia\nr<K
>
CM ffis: •0) ,
Madi Ulu
Hinh 6-Sodd khdi may tram dudi gdc dd an toan tia ilia
0,5A 12n/5w 12n/5w I
— f
f-12/12V
s: 3 ^
n n ? I A
C a c h ly
D C / D C
1 ^
Mach aliu
do
Mciy tram
I
Hinh 7- So dd khdi mdt kenh do trong may tram
lOOmA' M n 33n
Cdeh ly DC/DC
-^
-^
12V/5V
Khoi mgch CPU 150uF 1
T
TTI^
"•CffOniA" "33n
y " Tai may trgm phia sau
100mA 33„
I I l^^v
33n ,
•'=>n'
JM
Tx
33n ' ' ' * ' "^^^ '^'"^
HZD-y phia tru'dc
Rx
Hinh 8-Sodd khdi mach CPU trong may tram
mdc cho phep, nen mach an toan ve dien cam
Can lifU y, cdc dien trd han ddng, didt zener gidi han dien
dp hd mach, didt triet tieu ddng phan khdng la cdc phan td chju tai chfnh khi ed sU ed, do do can phai dupe tfnh todn edng suat tUdng dng vdi ddng dien hodc dien dp khi xay ra sU ed cao nhat, vd nhdn vdi he sd an toan 1,5 Ndu khdng dupc tfnh todn ddng thi nhiet dp be mdt eda cac phan t d ndy sinh ra ed
t h i rat cao vd gdy nguy hiem vi
nd phSi chju qua tai./
Tdi lieu tham khao:
1 Practice Electrical Equipment and Installations in Hazardous Areas Geoffrey Bottrill Derek Cheyne G Vijayaraghavan Steve Mackay
2 Tieu chuan TCVN7079-0/11, lEC 60079-11
3 Tai lieu vS he thdng quan trie khi KSG10, KSP-2C cOa Hang Carboautomatika (Ba Lan)
4 Tai lieu v6 hd thdng quan trie khi Nhdt Ban
5 Ky thuat an todn trong cac him Id than vd didp thach, TCN-14-06-2006 4/2007
KHCNM Sd 4/2010* CO DI$N - TV DdNG HdA Md