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CARRIER RELAYlNG
f e re n c e i s t o
d i cat i o n s
current s
t i ve s e quen c e current s during e xt P rn a l
fault s .
The
sen s it ive
t w o
make c ontact s , RRP and RRG , and one break
c ontact , RRB .
the
act i on
c o i l , RRT , ene r g i z ed by the l o ca l b at t e ry
c ont r o l le d
c ontact s ,
c o i l , RRH,
t h e
c a r r i e r
c o i l s are
RRP and RRG , are he l d open by a magnet i c b ia s .
The re lay i s p re vented f r om operat ing when the
car r i e r
though the
Th i s
mean s
re ce ived
f r om
t h e
c a r r i e r t r ipping I s pre vente d .
The
b r i e f ly
t e rnal
of one o f the ZJ
z one
b e
i n i t iat e d
l ine by the c l o sure of one of the Z3 c ontact R .
Meanwh i l e , the d i r e c t ional and s e c ond z one im
pedance c ontact s
l i ary
e:i- z ing
r e c e i v e r
r i e r
has
o c curred
c a r r i e r
c l o s e d
cuit s
c o i l
at
thr ough Z l .
the
se c t io n ,
curred
l
.
would have
t
end
near e f t
c l o se d t o s t op c a r r i e r .
If an int e rna l -t w o -pha s e -t o -gr ound
a s sumed , the ground c a r r i e r start c ontact Io3 ,
and one
p re ve nt p o s s i b ie
o f
the
phase
re lays due t c
and the f l ow
of p o s i t ive
car r i e r
c ont r o l l ed r e c e iv e r re lay i s a
p o la r i z e d
d - e �e l ay p r o v ided
The se c ontact s are operated
o f
t w o
c o i l s ,
as
e xp l ained above by CSP and CSG
and
the
other
a c a r r i e r
c onne c t e d
i n the plate c i r cuit o f
r e c e i v ing
tube .
de - e n e r g i z e d and the make c ontact s ,
h o l d ing
c o i l , RRH ,
operat inf c o i l , RRT ,
that
as l on g as c a r .L' i e r i s b e ing
e ither r r om the l o c a l t ransmi t t e r o r
opp o s it e
end ,
RRH i. s e n e r g i z e d and
c omp l e t e
se quence
o �
summa r i z e d a s l" o l l ow s :
phase - t o -phase
fault
e l ement s .
imme d i at e ly a t b oth end R o.� the
c l o se and ene r g i z e the aux i
swit ch, CSP ,
st opp ing c a r r i e r and e n e �e
the
ope rat ing
c o i l , RRT , o .::' the car
r e l ay .
S i n c e the same ac t i on
at
the far end of the l ine , n o
i s
re ce ived and the c ontact , RRP ,
a t
b ot h e n d s c omp le t ing the t r ip c i r
thr ough
D
and
Z 2 .
Howeve r , the t r ip
one
e nd
ha s a l ready b e e n ene r g i z e d
If t h e fau l t had b e e n e x t e rna l t o
then t r ipping c ould not have o c
s ince
the
c a r r j_ e r ho lding c o i l , RRH ,
been e n e r g i z e d by car r i e r f r om the
the
fault
whe re D w ou l d not be
of the
pha se c ontact s
s t art c a r r ie r .
inc o r r e ct i n
t a c t i s c onne ct e d ,
l oad
w i l l
and n e ga
out
g round
phase r e lay s
g r ound
c l o se
w ith
s t op c a r r ie r .
bJ
e d
one an operat ing
at e s
and
Thi s
h o lding
d i s c onne c t e d f r om a s ou r c e of p ow e r at one e nd
in other w o rd s , be c ome s a stub end feede r .
Norma l l y , b oth
a fault
t ran smi t t e r w i l l be
at the end which is c onne c t e d to the s our c e o f
p owe r and n o c a r r i e r w i l l be r e c e i v e d f r om t he
is e n e r g i z e d e ven
other end t o int e rf e r e w i t h t r ipping .
is e n e r g i z e d .
the
the b r e ake r s on the
thi s condit i on ,
t a ined at one end unt i l
e vent s
may
be
s t ar t e d a t t h e o t he r .
A s Aume an in
j u A t beyond the
Car r i e r w i l l
c ondi t ion o f the
ab i l ity t o s e nd and r e c e i ve
F o r
n e c t e d i n paral l e l w i t h the c a r r i e r start e l e
ment s .
car r ie r
c e i v e r tube s at b o t h ends of the
t o
mi l l i amme t e r .
i s
t i on ing , the a l a rm
l iamme t e r doe s not d e f l e c t
whi ch mu s t be inve s t igat e d .
has
t h e minimum
r e l ay
t r ou b l e can b e obtained b e f o re
o c cu r s .
A t hre e -p o l e
f r om
c a r r i e r
rault i s
shown
" Ca r r i e r
w i l l c l o s e t o
If the g r ound
the n t h e
e n e r g i z e C S O and it s c ontact
CSP
thu s making
it
t o
s t op c a r r ie r .
t r ipping
c ontact s
e n e r g i z ing the
CSG
It wi 1 1 be n o t e d
that c a r r i e r i s n ot start
a t e ither e � d
unl e s s fau l t
a
s t art ing
e l ement
i s s igni f i c ant
in
o c cu r s
on s u c h
s t ar t e d a n d
On para l l e l
l ine s ,
i t
fau l t
p ow e r und e r go a quick
fau l t e d l ine open .
c a r r i e r t ran smi s s i on i s ma in
It
i s de s i r ab l e
t o che ck
c a r r i e r 9et t o d e t e rmine it s
t h i s
purp o se
a t e s t push but t on i s c on
Pre s s ing the te st
s i gnal which
i s r e c e ived
operate
an
a larm re lay
If the c a r r i e r set i s not fun c
i s n o t heard and
a
min imum operat ing
required t o operate t h e
s o
that
an
indi cat i o n
s in g l e -throw
a
c ommon
handle
t r ip
and
out - o f - st e p
Figure 1 .
in
The
On - of f "
and
prefe rence c o n
ope rat i on o f Io3
w i l l short
imp o s s ib l e
for the
Howeve r , the
Do
and
Io2 , w i l l
aux i l iary r e l ay t o
current ope r
(
)
fault
de t e c t o r
.
c a s e a l ine
b e c ome s
I f
a l ine ,
t h e c a r r i e r
s t opped only
i s p o s s i b l e t o have
r e ve F s a l
as
Unde r
it ha s had t ime t o b e
p e r i odi c a l ly the
a car r ie r s igna l .
push but t on s e n d s a
by the re
l ine se c t i on
and e n e r g i z e
a
the mi l
indi cat ing t r oub le
The a l arm
re lay
value in e x c e s s
o f
r e c e i v e r
o f
impending
a c tual fai lure
s w i t c h
ope rated
is
conne c t e d
in the
c i r cuit s ,
as
switch
i s
marked
opening
it
remove s
5
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