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CARRIER RELAYING
c arrier
superv i s i on
and permit s the
or
re lays t o operat e
HZM
s t e p - z one manne r .
The swit ch a l s o remove s the
t yp e s HRK or HRP ground
t e c t ion
i s avai lab l e
relays .
Out -of -Step Product i on
It i s often
de s irab l e
at i on of relays during
s o that t h e
s y s t e m can b e
t i on s where synchroniz ing
ab le .
The carri e r re l aying
means
of prevent ing
t r ipping during
s t e p c ondit i on s without impairing
to t rip
for int e rnal fau l t s
out -of - step
c ondit i on s .
d ifference between
a three phase fault . and an
out -of- step cond i t i on
l y redu c e s the voltage and
rent whe reas during the approach of an out - o f
s t e p
condit i on ,
t he
change s are c omparat ively gradual .
The
t ype
re lay s
HZM
operate on faul t s ,
but not on l oad
roniz ing
surge
swing s from which the
can
re c over .
However ,
out -of - step ,
the
type
separate
the
system .
b l o cking
in
the Type
b l o cking re lay
addit i onal
out - o f - step b l o cking re lay de
t h e Type T S 0 -3
s cribed in
I .
L . 4 1 -4 1 8 . 3 .
HZ
In
the
type
Carrier scheme , out -of - step
b l o cking is provided by us ing the t ype RSN re
lay inst ead of the type RS re lay .
In
t h i s s cheme ,
the d i stance
operate s imu l t ane ou s ly f o r a three phase fault
if
they are to
ope rate at a l l , whi le
out -of - step the Z3 ope rat e s first , f o l l owed by
Z2 and then Z l .
As the system
t he
" in -phase "
p o s it ion , the e l ement s
in the opp o s it e orde r : that i s , Z l , Z 2 , Z3 .
To pre vent
t r ipping during
is ne ce s sary to arrange for the c l o sure of the
three c ontact s
A, B, C, and for the
relay
back c ontact , RRB , t o ope rat e a n
6
HZ
type
:n the c onven t i onal
re lay and ground pro
through back-up
ground
t o prevent the ope r
out -of - st e p cond i t i o n o
separate d at l o c a
e quipment i s avai l
system provide s a
out - o f
t h e abi l ity
o c curring during
One
fundament al
is that a fault sudden
increase s the cur
voltage
and
current
are
u sua l ly
set t o
o r synch
syet em
when the system
goe s
re lays operat e t o
HZM
To provide out - o f - step
Carrie r s cheme ,
an
HZM
require d , such a s
is
e l ement s a l l
during
returns t oward
re set
out - o f - step , it
re ceive r
add i -
t i onal
b l o cking re lay
cuit .
Thi s b l ocking
re lay mu st have a s l ight
t ime -de lay
so that it doe s not
circuit be fore t ripping on a three pha se fault
can oc cur .
On the other
the t r ip c i r cuit during an
t i on bef ore the s e c ond
ated .
The out - o f - step b l ocking c ontact i s de s i gna
ted a s X2 ,
and is c onne cted
cuit
a s shown in Figure
it are three c ontact s , A , B, C, whi ch are
back c ont act s on the aux i liary swit che s
C ,
ope rated
by the
Z 3 carr ier star c �ng
tact s
of the d i s t ance
iary c onta c t or
switche s , CSA, CSB ,
The
make c ontact s
of the se
serie s
with the back c ontac t , RRB , of the re
c e iver b l ocking
relay, and energize the c oi l ,
P , o f a pendulum t ype t ime -de lay re lay ,
l ow e r c ontact s make and energize the c o i l
the X2 b l o cking re lay .
three of the
Z3 carrier start contact s c l ose ,
the back c ontac t s ,
A , B , C , and X2 , open
t rip c i r cuit aft e r
a 3 t o
c ontact X2 , opens by virtue of all three
c ontact s , A , B , and C , c l o s ing through RRB
energize the P c o i l and i n turn, the X2 c o i l .
If the e le ct ri c a l
center i s i n s ide the pro
t e cted
l ine s e ct i on , and in other case s whe re
the
two voltage
source s appear
phase , the d ire c t i onal and
at each end
of the l ine w i l l be c l o sed .
s t op s carrier
( pre viou s ly started by the
c ontact ) .
This energize s
RRT t o a l l ow the � ontact RRB
t o open .
Thi s
de -energize s
lay, P , whose spring arm begins now t o o s c i l l
at e , a l t e rnat e ly
c l o s ing
c ontact s , P .
Thi s
ke eps the
gized .
Afte r
the amp l itude
the
pendulum
has
de c reased
value , it w i l l
not strike e ithe r
tact s and X 2 w i l l re set .
in cyc l e s ,
and the
t ime de lay
the pendulum
re lay should be l onger
t ime during
which
b oth dire ct i onal
"point in "
which
depend s
" s l ip cyc l e "
the
of the
t o open the
t r ip c i r
open the trip
hand ,
i t mu st open
out -of - st e p cond i
e lement , Z 2
i s
ope r
in the t ri p c i r
1 .
I n para l l e l
with
thE
A, B ,
c on
re lays thru the auxi l
and
CSC .
swit che s are
in
who se
of
Every t ime that
al l
the
cyc le de lay . Back
4
make
t o
18 0 °
out
of
impedance e l ement s
Thi s
Z3
the pendulum re
the
b ot t om and t op
X2 c o i l
e ne r
o f
vibrat i on of
to a
certain
of i t s c o n -
Thi s a c t i on
oc cur s
introduced by
than the
e lement s
upon the length of
system .
It i s de -
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