practical switched distance relay
TRANSCRIPT
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7/25/2019 Practical Switched Distance Relay
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1
ANAI,YSIS A}ID
PROIECTION
OF
POI{ER
ST$'U-TS
COURS.
PRACETCA.T
flTTCEED
DIST.INCE
BEtAl
3Y
P.T.Slrchenouglr
D.Sc.
a
I
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a=
ccr.;[E$Ts
I.
Iatroduction
2.
libo CharacteriEtic
,.
hd-uclple of
Measr:reroents
4.
-
Practical
8e1ay
5.
Qrcration
of hactical
Belay Geaeral
6.
Operatioa
of
Pcactical
Relay
Dtai1
6.1. Cucrent
inpute and
startlng
eleoenta
6.2
D.c. srltchlng
6.5
Phage
selectl.otl
6.4
Pbase
ehtftinA
6.5
Zoue
tluers
6.6
Phase
couparator
6.7
blpptag
and
fla6g1log
6.8
Povec
swi-Bg
block{ng
6.9
Srritch
-
oB
-
to
-
fault
6.10
lfeutral
cmpeneatior
7.
AppJ.i.catlo
7.L
Relay
settlngs
7.2
AddltLonal
featurea
Appeod{-s
SJ-uptl;fled
treatnent
of
t}re
expanelo
of
a
do
ot^nsL
for a
lbase
to
grourrtl
fanlt
trltb
a erosr
polar .rcd
relay.
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a
-2-
1.
Introductioa
'
Dtstance.protection ig
?rlso
bowa as
l4redance
protectla'
fbig
ls
because relays
of this
type
are
gensitlve
to cbangrr
-
i-a
polrer
systen i4redaace.
Uhen
applLed
to
a feedet
tborcfola
such
a
relay
rllL
detect faulte which
cause
a fall
of
ltr1ndsoc
nhlch
ls
rrlthin tbe relayr s range
of neasuio@tr
lbe
nartm
i-upedance
'*Lich
when
neasured
by the relay
trlll
cause
lt
to
operate
ls
called the
reach.
Relays
of this
tSrpe
usually Lrve
geveral
zryr
of
ncaaureoot,
ia
geaeral
tbre. Faults occurlng
Ls
tbe
f,lrst
zolc osuta
aolaal1y
llstaataneors
olnratlm-of
tbe
ralagr,
rihllat
tbc
'',
olnratloa of zones trro aail
threa
ls
tlne del4red.
&1r
1r
tllusttated in
flgure
A be}m.
I,qe
L
usueffy
crtadr
to
about 80/o of
the
flrst
feeder.
thlg
anrnrc
thet
om tl
I
.
tlre
ueasureneat
of
qrateo
paraoetera,
toletancc
La
thc
lahy
-'
-',
lnpedaace
settbgp
and
errors
ln
tlre
aslooleted
GPrr
gd
t' r.l'
.
,
caruot cause
tbe
relay
it
locatlo D
to
olnretr lr
toal-..'::..:;.::..1r':,
for
farrlts
Jnat
bryond clrsclt
brsaker
E.
Ia
aililltl&r
1tr16i,:,r-.::i
':.'
z@es of
p:rotectlsr
a,re
usus.Uy
illractim
r,
thSt
trl
ttr
.
't
,
'i,
reIry
la
oaly senqitlve
to
chang;g
ln
lnpedscc
of
tb.
ftdlE
,. *,,.
,
ita
oe dlrectlo
fron
tbe
relayLng
point.
Zoc
214
unrlly
'
.'-
",ri,
set
to
abort
5CD6
fato
the
aeood
fccder
od aor
11r
rtt
r'.:'.i,,;':'il'
about
N6
Lnto
the
thlrd feeder.
&e frnctlm
of @ra
zorS
2
r.r.' I
zort
I
Fro
A
2
and
5
is
to'back-up
protectiolr
at
potrata
E
od
.
A
clrsuit
breakers at
thege
loiatl.ong
f,atl
to
tutp
fe
tf,I,
faults,
tlen
the
ot,lret
proteetlon
rrtUl
cause
H.lptlgl
o{l''i
orn circuit
breaker
af,ter
a zone
2
oc
5
tLoc
dal4r.
1[he
cbaracteristlcs
of
a nbo
relay are
gbora
f
flgura
E
llf
are
plotted
on
t'he
iolndance
plane.
':,r.
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Introduction
cont...
Frc
B
tbe
relay
ls set
to
protect
a
Llne
the
angl.c
of r&loh
fr
e..j
.
,
il|he
inpedance eettlngp
of
z@ea
.L,
2
and
,
are
Z.
lr
-ii^a-Cl
:J.
phase
elrsteo
aad
E
ig
earth.
Qnrs
a
J
zoia
relay
rould
eleseertg.
llhe
type
of
relay
nhlch
ls
the
subJcct
of
thlr
fcofidi
oaly
oae.
three
startbgi
eloentg
ouo
ltct
lbee
te{oh
aa
Lupedaace
reach Zs
Ln
flgure
C
arc
rrrcil
flrrw
toi
this neesur{.ng
eleoont to
the
correot
f,slit ooillti$J
is
lrrova
aa
lhasa
gelectl@.
Secodltrr,
tJrs
sona
gslf
iacreese the
reach
of
the
ueasuriag eloot
st
tbt
of
,
elapsed tt-oes
b'y
predeteralned
anouat .
ec
aitrut{p"
svitched rlay
is In
temg
of
slze
aad
coet. Orc
ls irr
t$ms
of
perforoamce.
2.
llho
Relay
The
neasursmert
characterlstl.c
of
a
do
rslry
1r lhcn-
IIre
inpedance eettlngp
of
z@ea
.L,
2
and
t
are
Z.
lr
-ti.il^o|-
:J.
A
firll
di.stace
relay nould
hsve nsasrslr
elmtl
tc
flb-
fault codl.tlou, tbat
ls
A
-
E, B
-
E,
C
r
E, A
-
1't'-.$;:+i;
-';.,
C
-
Ar
rhere
A,
B and
C
arr
the
phase
dcalgnstlcof
I'Sli.r,.
flgure
0.
trtre
circle
has a dlaneter
4
and
tbe aCl,r o(:
inpedance
ls e.
|ftre
relay
uust olnrate
lf lt
ucraurf.'i
inpedaace
lnside the cl.rcle
aad
be
stabl,e
for
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F
rc
C
,.
'
Prlnciple
of
l'Ieasurenent
ft
is a
property
of
a
circle
-
figure D
-
that
lf
1laeg
0B
and
AB are
dranrr
fron each
Frf'D
of^a
dlameter
0A and
tf
B
ls
o
flre clrcle
goo
llbls
propert5r
caa
be
oade use
of.
ff
a
phage
cooFarator
ls
taken
and
arrangeil
so
that
ttr
*
p":tS"t
If
the
phase.alsl?
betneen,
itc
tno
tnpt
lr
thaa
9O-
aad
aot
present
tf
tlre
ptraae
srgle
Lg
lelr ttn
tf the
tro
lngrta are
chogelr
cor"rectly,
tbe
ilerl.cc
trttl
I
as
aa
lnpedance
ielay.
In
ft6ure E,
e
is
the
rorrce
voltagc
of
Zs
Zc
-rX"
e
Yr
F
gr
Frc
E
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the
systen,
Z"
the
source
impeda,nce
at
F.
and
Yf,
dd
h
*" the
voltage
to
the
rel'ay.
h=
Thus
for
any
fault
ft,
at
tbe
4-
4.
(fu+b+BO=O
.'.
vF
4
bound
4-
vF
'+
F"
and
V,
4.
PracticaL
Relay
Figure
1 sbons
distance
relay,
as
follors:
4.1
Input
Ctrcuits
4.1.I
Cur=ent
faput
transactors
4.L.2
Voltage
Connections directly
to
4. .,
DC supply
ac/*,/ac convertor
or dc-dc
convertor
1i:l'::.]
Tf
Ze
is the relay
reach,
that
is
the
fault
imgedance wtrlch
just
causea
oper'dtion
then
the
fault inpedance
of
a fault
current
which
rvill
be
supplled
ary
ttre
clrcler
0B
ls
b
*d
l3 le
vF
t
of
Z*+AB
-?A=
O.'.A3
=%-%)
the
phase
selector
So
tf
the
phase
comparator
ia
g:iven
signals
t
*U
+
-
\
tbe rclagr
'rd11
neasure
a^sr
ue
reqrrLre.
so
the signals
tre
ca,n
tke
a,re
:-
-
UR
rdrere
h,
1"
a
repllca
lnlndalrce
nltbfn
tlre
rrlegr.
llhe
above
relay
1s
terned self-polarlsed
bccauae
the
quantlty
T"
le
taken
fron
the
failteil
phase.
Eowever,
for
faults cloge
to
the
relay
locetlo
YD
rdLL
b. sE
LL
gi
.:
Y?
-
IZD
rill
be
latge.
Dlfficulty
Ln
neasuraeat
could
bG
s4|cfootd'
sl.nce
n6st faults a,ri
r:abalancea,
iuat
ls
aot
J
phasel
tbtr
poltitilgg-'''''
voltage
ca,n
be
taken from a
healtby
phase
aacl
cuttsbfy
bs a
hl,fhir,'.;i,,'
Such
a
relay
is
sald
to
be
cross-polarlsed.
lblc
tcchiquo
ber
ttra
'
advantage
tlat lf
tlre
conect
phale
le
chogn tJreu
fc eff
rnbrlrcdl:1
,-
faults,
the
reach
of
the relay
nhllgt staylng
the
sae
alog
t&c
cba,racteristlc
aagle
will
increase
al@gi
thc
reslgtive
a-rc.
llhll
'
'
'''-
:
gfves
the
relay a
gtcater
tolerance
to
arc
and
toner
footlng
relblFdir,
'-
.',:-
the
block
diagraa
of
a
gractLcal
srftcbcd
-
-.'.":1;;
tbe
t5rpe
P:ftS.
llre
prlnclple
elmt
l31t
.,-.r
.:.
.
,
(rz)
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4.2
4.1
4.4
4.5
4.6
Starting
elenents
(s.1,
s:
and Sc)
Phase
selecting
net
'"rork
D.C.
sritching:
circuits
Signal
processingi elenent
lbis
arda
lfiase
shifts
the
restraint
and
polarisi.ng
voltaSee
to
sjruulate
the
replica
impedance.
'Zoae
tiners
These
alter
the
relay
teach
at the
expiration
of
zoe
2
and
zone
5
times.
Conpa.rator
rbnn{nes
the
phase
relatlonship
betneea Vn
and
Yr
-
llrlfrplas
and flaggtng
clrcuit
Srrltcb
-
on
-
to
-
fault
clrcuit
Porer svtng:
bl6qkrng
circult
(PSts)
Operatlo
of Practlcal
Belay
lbe
basl.c
operatlolr
of
the rlry
ls
ea
follova
:'
Startlng
eleoente
detect
tbat a
faglt
has
oGglrt1cd.
Drfc frilt
c.-
be
either
i.nslde
or
outslde
the
otber z@ts
of
protcotlc
4.'l
4.8
4.9
4.10
,.
of
the
relay.
Signale
frm
tJre phase
rtarten
actrtl .
rrcd
'
'.
relagrs
i3
tire
pU"i"
selectim
nodule.
Ib,lc c@ctt
th
f ry
of
tle
phase
cmparator
to
the correct
sl8nels.
Operatlo
of,
'
the
starter
also
eaerglses
thE
d.c.
snitcbtat
nodule
sd
r
rpe{
relay consects
the
d.I.
supply
to
the
$aee
cosparatol
ee
?ql.'
tlners..
lf
the
fault
fs
G-zoneltrthe
phese
cooparator
rllt
'ii.',"':r.l
aend
a trlp
signal
to
the
trtp
aa{
flagd 8
nodute.
l[rtr
wf,:r,'::..',,
the
trtpprns reray
to
be euergtsed
and-elso
cmectc
tJrc-flr8$l4|l.:.,,.
clrcgit
to a
sf;t
frm
each
phase
ttartr
for
a
ghort
tlD.
,.,..
:.ir.:
llhe
rota,qy ladicators
which
alle
assocleted
rlt'b
thoac
fhr . ,
.-
,
,.
,.
starterc
ntrfch
detected
the
fault
rdll thea
operatc.
If tbl.,
tj....'.-:.
,
fanlt
ls
not
in
zore
1,
then
nhea
the
zcra
2lfrer
opcrrtfrr-i:i;i; ;:{1,
ault lE
not
Itr
ZCE1e
I,
EAeB
llllell IIl
zcBa I
r,IEE slrB.s--5t-
..,.,.--.'-:,;:{.:,.:i,
ttre
reach
of
tJre
r'elatr
riLL
be ertendad.
tf
the fltrlt tr
ln^..-.=,.1,''+.tlij:"
zcre
2
and
has
not
beelr
cleared
W
tlll
tlne
by
ot'bsr
fE
irii
L
"*.
2,
on
oyre=atiln
of
t,lre
zme
5
tlnsr
sgafn
pwl*il:.i:g'::
that
the fault
b'as
aol
been
clearcd
by other
lnotectl.o.
:
r.'
;
llben
the
curleat fa1ls to
uomal.
Ioad
oar.zero and
tbe
lryit{
-
,
voltage
is
restored,
the relay
qr:J.ckly
resets.
:
:.;-:,i:;.t
.
:-."j
':::.:
irrli:i::
.
., ..::::-*:
:l'
:
.
;,il..njir
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5.
cont...
A
fourth
zoare
of
protection
can
also
be
incorporated.
Strls
is effectively
the
starter
circle.
A
zone
4
tiner
is
required
and
at the
end
of
its
operating
tine
trippi.:og
is
pe:rattted
i.f
any
starter
is
picked
up
or
if directional
plotectioa
is
requlred
the
restraint
voltage
circuit is
opened.
[hls
results
in
the
relay
beconing
a
simple directional
elenent.
(fZ
fs
conpa,red
now
only
with the
polarising
voltage).
The
dlrectionaL
zoe
4
characteristlc
is
showa
in
figrrre
F.
Frer
the
phase
startbg eloents
can
bc
either of
tihe
rndcr
lnpedaace
or
slnple
orelcumEat
tJrp.
&e
chotce
of
rnirr
i-upedaace
or overcurrcnt
atarterg deparila upcr
the
r;rata
to
be
protected.
Orelcr:rent
starters aae cbceper
rad
fartrr
than
the under
lupedaace
ty?e,
hrt
u
tf,e
cur-slt
l"n
tlc
bealtlry ohases
increasei aignlflcantly
durfngi
a feultr
tJlcn
'.'
lf
lncorzect
phase
selectlou
ls
to
be
arolileil
slthcr
tbr
@ercrErent
starter
would
nead a
hrgt
settLng
or
rrudcr
fspeCrmr
etarters
sboutd
be
useal.
Under
lulndaace
lhasc
starttrr
thAfld
also be
r:sed
lf
[s
rn{n{nnrm
fault
cnnot
ic
].eas
flren
tte
Bq-{nnn load cunerrt.
Detailed
Operatio
6.
5.1
e
Cnr"cent
lnput
clrcuits
and stastlng:
clcoeato.
:
Flgura
2 shwa
tbe cuneat
Lqnrt
clrgult.
therc
ls
oc *"h.
:,-;'.
,
lnput
ctrcutt
pr
lhase
and oe for
thc
ncutra.l
ol.roult.
Slf,;'
,.
is
connecterl l.a
the restfiral
clrcul.t.
Sach
trlfnt
copllll.tiQ,,,r.'-,.
trangactors
La
sedes.
A
transactor
or
qusdratura
cnrtut
.1
.,,.,.
,;1
:,.
trarisfoDBer
has
an outlnrt voltage rblch
leadg
tbc
lnlnrt
at
ti','.::-.':.
b5r
90"
and
is
tlLrectly
ptopotti."r'1
to
Lt.
lbe
ortlut
${
q
-
cin-
tlrerefore
be considlred
to te
v
=
fr1/;9o
or
Y
=
XIISQ.
-"
,,.
..
Thls signaL
is
the=efore
the
voltage
nUfcU
rould be
ttevelolrll
r:
across
an
impedance
Z,
in
uagrritude.
this
slutrlates
the
na,gnitude
of a
repllca
impedance,
that
ls
the relay
gettlug'
or
reach.
the
value
of
this
setting
can
be changpd
-
-'
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6.L. cont...
by
chang:ing
the constant
K.
Coarse
charrges
are
nade
\r
neans
of
taps on
the
prirnq'
winding
and
fine
changes
by the we
of
a
potential
Civider
connected
across
the
seconda:ry
windlng.
Fhe
second
transacio= is
connected to the startirg
unit.
the
output
frou
the
transactor is
used
either
for
overcurrent
Eeasurenent
or
in
conjuaction
rrith
a
volta6e
input
for
uuder
iupedance
neasu:eraent.
The
overcusent starters
have
cugeat
seltings
of
5Fri
to
lOA
rate
-
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10/37
5.2
cont...
eircuit is
to
provide
a
time
deLay
between
starters
pick{ng
up
and the
sw'itching
of
the d.c.
onto the
neasuringi
urlit.
Ehls ls
reguired
where capacitor
voltage transfomers
aure
used
'rl.tb
r.rnderimpedance
starters.
the
tine
delay
is
required
to
ealtule
that
transients
generated
by the Cfllrs
have
dled
away
beforo
phase
selection
is
carried
out.
6.t
Phase
Selector
Circuit
-Ftgrrre
4
ls
a
cllagran of
the
p[rase
""l"cto"
eirauit.
Its
inputa
3
3-
Secoada.lry
voltage
of the line
ilr
A,
B, C
&
tr;
tde
TZ
slgnals
fron
p[ase
A, B aad
C
tapgt
trarsactolg
and
tJrc
IZ signal
frm
the
transactor
in
the reslthral
clr"sutt
for
ncotral
cmpensetlo;
a
signal
fro
each
plraee
gtarter
drich
Lr
plcted
up.
Ite
outpnt ts
a
resiralnt
vollage
Vo,
a
pola,rLsJlg
voltegs_Tp-
aDd
tbe
co:=ect
cmbiaatioa
of
IZ
slepatE
accordl-ng
to
the tablc
belc'
\z
Vn-&
a
0nboa,.O
.'.
vR
=
gts
TAIIIA
.6.
-
.G
B-C
AA
L-tt
A-3
.3-C
c-A
A-3-C
Ypn
A-r
C-I{
A+f,
3-N
A-Il 3+X
c-[ B-x
c+I[
A-3
C-A A+B
B-C
A-3
3+C
C-A
B-C
C+A
C-A
3-C
C+A
6.4
Phase
Slfti''g
(Sfgraf
Proceesing
l{odule)
After
Fbase
eelection
the
restraint
voltaga
and
lnlac:t-slrlq
voltrSt
uust
be
plase
shifted
to cooplete
tbe eLEulatl@
of
tlrc
tpdggl
repllca lqentLoed
ln
sectlo
].
&e
Dapltudc
of
tbls
lgtillol
Uieaance
nas
Ueea
set
b3r
tbe-cu:r?at
Lagtrt
trangaatcrar
tblt
frr
+al
V
gtgnal
is
iq
reattty
I-
I
zl.
lf
tbo
rslay
le
-to- c
rr '
,,'
to an rry.aot""
zle
taet
ie."oie
ior
Ilbasc
to
phage
fanltl El
,
for
phase
to
grornd
faulta
m
cer{read
llnec
Z'e
"AU
tr,ta4qq,y1t
the
rertraLnt
and
polarisLng
slgnals
sust
be
phpe
shr{t'il
r'foilldlrr'
lhe
range
of
adJus-tneut
of
tfre
iefry
1g
fro
tO'
to
85-'-
,
,
.-.1:,,.5"'
llheu
the relay is
operatin8
af@g
ltg
chsractertstfc
48lsr
lbA
'':i:''
fro
the
ffgure
be1ow
re
cul
gee
ttrEt
V"
'r
lft'
.;-:,..
'::
'.
e-re
-
7/25/2019 Practical Switched Distance Relay
11/37
i*,iase
a;.r*:i.iqq
i$igr:ai
Pxocessi-:lg
l"'ieriri":i
co;rr-,
.
So
fron the figure
for
say
z
pbase
A
aa
angle e
to
ground
fault
rrittr
V^.
uust
be
pbase
shlfted
by
90
-
e
leadtag
aled
%
tnc
plarlrlng:
vtftaep nust
be
phaee
sblftad^I50-
l.eading.
Silra
as
thc
satl8p
of
relay
adJusfuerrt
ls
to
10'
to^85"
ligELng
tJrc
oortreepodlag
phase
sbtfts for
Vo
and
Vp
are
60' to
5'aad
fro
120-
to 55-
leadllrg
respectivety.
1[hus,
the
quantlties
nhich h.8Ta
baG
selected
l"n
the
phase
eelectlm
nodule
a,re
appll.ed
to t'b.
1srr.
ehlftJ.rrt
nodnle.
Eere
each ls
lgoleted
b5r a
voltagu
tE&tf68.
Flgurc
5
gbors
tha
eigDgl
proceaalng
nodule.
&e
fbrrr
afiftf.ne
s
carrled
out as
PrEdor1gly
dclcribed
and
tbr
rotrrlnt
voltaga
tg
agplled
to
I
ettlmratfre
Lfmuftc
Ear&cd
9,
Y,
Ed
C.
Ihege
ane
Urougbt
lnto
operatLo
rdren tbc zora 2
ed
5
tt-urn
operat.
KC
f;
flre zoJI
ertaaeloa
featurc.
llhls
le
qflfl.nrt
G
sectl@
?.
Tbe
cotact
Z, opelra lf
a zoe
4
tt-Eer
te
fltrt4
,
at
tlre
end
of
zclrra
4
tl-ue
anfi
glvcg
tJre
relay
a
dlrectlcrl'
cha.racterlstlc
as
shour
ln
flg;; f.
':'
"'
6.5 Zoue
,| fuoers
,..,.
.
]'::
llbese
ace
sJ-uple
B.C. ttuers as
ghor1u
La
Ftgp$
6 atoil
ubo
tba' :
set
tige itelry
oa
each
has
e4rired
Lt
cloees Lts
outlnt
q@tlct.
"
'
Thls
svitcbes
an
atteauator
lnto
the regttaLut
voltagp
ot'toult
::-
rrhlcb
has
tbe
effect
of iacreaslng
the
dlaaeter
of
the
do
clithr
that
is
lncrcasing
the
reach
of
ttle
reIay.
'
,l
'
6.6
Pbase
Coparator
.
trbe
phase
cmparator
block
dlara
ls
flur
8. be
phstc
gigea-I
V?
ar:,d
tbe signal
-fr
ata
edded
by aa
op'eratloal
"1x-
sqtr","6ssves
fn
phase
*tth
the
regult
are
ganereted.
&rti',;f,:
=:
;$"'#;';"
?fi
f l'' iil
nii"i'; ;;;
;
:;;;' 6-I*:'
"
.'
phase
with
the
polarislng
voltae
a,re fed
tnto
the see6d
loft
t
of
tfre
phase
comparator.
lbe
outgrt
of
this is
a
rectaagU.lar
wave
vilh
a sark space
ratio
of urrity
yben
the
pbage
qn61o
betneen
the
h*o
input
q..natities is
0".
If
the
angle 1s
lrgA
than
9Oo
then tEe
rnark
space
ratio
increases
and
for
angteg
gireate=
than
lOo
it
becoues less
then
unlt5r.
-
7/25/2019 Practical Switched Distance Relay
12/37
'.;*i:iiia^cator
*1ni",,
lhis
change
is
detected
by the
integrating
circuit
and
level
detector
ruhich
foIlow
it.
\.lhea
the
relay is in
the
restraired
condi.tioa,
that is
the
alr8le
is Iess
tnan'9Oo
the leve1
detector
output
is
zeto.
For
an
olnrate
condition the
integrator
outprt
vill
be
positive
and
hence
tlre
level
detector
will operate
the output
relay.
6.7
trlppins
and
Flagglng
Module
Figureg shows
a diagrau
of the
trlpptng
sa ffzggllrl
clrsnit.
'dhen
any
starter
detects
a
fault,
the
d.c.
srrtchilg;oduh
is
energJ.sed.
this
causes
contat'a'to
op r.as
thti
ootrot
te
on
tbe
relay
rdeich
is
uged
to
$rltch
the
d.c.
supply to
tbe
neaaurlrg
circults.
-:
'
.t'',
In
the
baalc
node
of
operatlo the
Ibr. L
fu
ta
ald
th. r
i1,,;
.
flag control
Lg
not cmected.
llhen
the
phrre
ooperrte-r{rt1f,h.,...
tbat
a
fault is
rdthta
tJre
relay
reacb
thr H.pplng rtglrl,flFil-.+,,
thlg
cllcutt
is
a
+JOV d.c.
al8nrr
and
tibla
ocr1gtlo
i&1
tglD:li.;,.
:
relay
and
tha
aurJ'ltaly
rIay
yhtcb
ls ln
pardfd
ultb.lt..
:"fbi'i
aurlllary
relay
operates
cloaJ-ng coatacte
AI
eld
12.
Clolur.:gE*
,,.
AI
eaergJ.seg
tbe flag
relay FC
for
a ehort ttne
nhlcb
lr
solnolJ0l;
by
t&e
ierles
capaciion.
tlben
the
cotact
FC
oloc.t
or rlir.ff.t.
tbe coi1s
of the
rota,rry
ladicators
A, 3, C, Z2
ann
Z,
Ll
to
the
zero
volt
a1.1.
L
+7O
as]f
g{8'a41
fm
qr
ltera
nLtcb
bas operated
ls
app[ed
to
tlrc
reapecttvc
lotrry
uhen
tbe
startets
operate,
so
nbca
cotact
SC
clorcll
:
l"adlcators
co:reegodtng
to
the
fatrlt
co
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7/25/2019 Practical Switched Distance Relay
13/37
5.8
Power
Swing
Slocking
lbansient
power
swi:rgs ean occur on
s;'steus
that appear
to
a
distance
relay
as
faults. fl:e function
of
the
power
strl:rtg
blocki.rrg
nodule
is
to
preveat
such
spr:rious
operatlon. Its
operating
charaiteristic
is
identical
to
an
r:nderimBedance
starfer
as
shovrn
in
figure-
G.
x
-x
This
feeture can oaly be applled
to
relays
uhD mch
etrrtG "
a.re
fitted. Sl.nce
porerrrings
are
ugually balanced tbe
o6ltod.E
of one
$rase
only
ls
requlred. Ore
slgDals
usod
by tha
pomclt
t 8
blockrng
nodule are taken froa
th,e
phaae
B rmder{,4ndoot ltarta8t
so the tno
characterlstlcs
track
perfeetly,
..
.r,
The
prlaciple
of
operatlon
ls
to
ne'esure
tbe
traagtt
tl^uc
of
rbl-.,,.'..
r
locus
at the
dlsturbaace
betreen
the
powerarlqi
blocldng:
ot 4L' '":.,.
and the
r,hase 3
rraderLro6redance
gtarter
clrcIe.
If
t&lr
11
6ffrtrr
than
a
preaei.
tlne
then
trlppLrag
ts
blocked.
A
selcatot tttlt&:,'.
allorls
blockilg of
Eppl:rg
in zoe
{,
zmes
7&
4;'
toaa.
2
L
r,&-*
"-.'.
or
zones
Lr
2,
J
and
4.
Operatlm
of
the
astra.l
startehol@-,;,":
,-:.-:'
ove:rldes
aff
-pdrer
srrfDg
blocw"g
aa
Ltg
operatlo
lndlcctrt'::''t\1ffi--f:'.'1i1,
zero
sequeace
cureat
Ls
florJag,
nhtch reenltg
o$ fro
ra
ea,rth
fault.
6.9
Srdtcb
-
or
-
to
-
fault
-
featr:re
ff
a
fault
ls
preseat
on
a
systen
when
lt is
enatElc6dt
should
be
lnstanta,neous.
lbls
is
becauee
the
uort
UkG\t
of
suctr aa occuraace
is
the
presouc
of eaathltrg
c1o1n.
eltl::l .:r
circult
lnitiates
tripping
lmediately
aay
start:r
pl.cll
try
1l
ac
voltaB
was
aot.preseat imedlate\r before
tlre
starte
p1O4;:
up.
A
dlagran
is shona in flgilre1o. Oae
of tro
nodu Olr:
operation
can
be selected
by
a ll"lc. [he
first
operBtot 6
a
tine
delayed
basis.
If
a fault which
causea
sterbee
ptctqt
occurs within
JOO
nsec
of line energtsation,
Lmedlete
tirl,pgfng.
is inj.tiated. In
the
seeond
node,
tf
tbe
ac voltage supptl,cd
to
the
relay
(3-C
volts) is
less than
approxinately 5.Gr ac
tJra'
the
plck-up
of
arry
starter
will
canrsre
imedlate
tripplngi.
Potrl tyrrl3
SlcrtrrO
CHtaeif&rrtc
udol
rnPcotuc,,
re4rc *,
c,hAAaaT3et3tra
-
7/25/2019 Practical Switched Distance Relay
14/37
Lj
i
':i
coa'1
.
'
,.
A tine
delay
on
reset
is
fitted to
thls circuit
to
ensure it
always
operates
in
one of the tvo
nodes
outlined.
Oece the
relay
has
been engeri.sed
at
ful1 line volts'
the
switch
-
oD
-
to
-
fault circuit
is
readered
lnogerative
for
about
25
secontls
when
the
a.c.
voltage is:educed
to
ze o.
This
ensures
corect
operatim
&rri'g
auto-reclose
Eequences.
-ff
a
busb3'r'yT
ts
r:sed,
the
reJ.ay
nll.l.
be
enelg[sed
at
full
systeu
volts
before
its
assocl.ated Line clrcult
breaker ls
elosed.
To
enable
cor:rect
oper"ailon
La
sucb
an
lnstance
aa
anrillary contact
on
the circnit
breaker
is
used
to
supply
a.c. voltage
to a te:rnlnal
on
the relay at
ttre
iletant
dlen
the
circrdt
breaker
is
closed.
.
6.10.
Neutr"al
Copenaatioa
The
neutral
cmpeasatl.oa
for
overAead
ltnes
needs
oaly
bc
scalar,
as
t&ete
Ls
aot
uucb
dlffercrlce
ln
feult
angl.e
betmca
lbase
to ohase
faultg
and
phase
to
grounit
faultg.
Oa
cebleg hor*ever,
vectorlal
coopansatlo
la
rcqnlrcd.
&a
relay ty:pe
pt'tC
hae
an
ortre
uodulc
to
1rgrlde
thl'g
ccganrtlGo
6.11
tr\r.se Patlnre
Modnle
(V[
Suporrrfslo)
If oe
of
the ftses
betrsen
tJre
rysto
voltap
tranfolucr
ot
ttre relagr
blons,
thea
f
a fault
occurs
arytrbcaa
o
t}e
ryrte
'
11htcb
catrsea
the
gtartlng
cloqrta
to
olnratc
tdrc
eelagr
oro
nls-tr1p
becanrge
of
tbe agparant
aellrcrilo
of volts
et I'tr
-
terutnals.
Oae
nagr
of
pri,v"ntfag
gicU
nfs-ta{pplng
lt
to.
g1;Dlt
I
a
relay
vhtch
detelts
tbc
fallure
or
blorlng:
of e
YlE ntfl
-A
tnblbtie
operatio
of
the
rclay
rnrtaatV'
&it
aot
rrtll
of,
cotrtno ueaa
tUet the relry
cabnot
trlp for
ary farilt.
UndC
theea clrcungtanceg
zoae
oe faultc
rJ'tl1
be cleafed
by baok-Up
protectlo.
'
7.
Appllcattco
?.1
Belay ScttLag
AdJrrstnelrts
FigurE
?
ls
a
pbotoga$
of
a relay
tyP
Pf i
-
.
I',"..-.,.,
tb,e
gtarter
settlng;
"i"
*
the
rnler
-tupeOanoc
starlter
no0u'fuli',-,'
lt-.,
:
mrnbers
lC,
LL
aad
12.
ltodule
U ia
tlre-netrtral
ovleraurrnat
-Q$$i'--
lBbe
eoarge
aud
line
zone
1 Eettlngp
are
oa
tlre currot
fnFrt
.'
:
'-.t.'.,',
sodnle
mrmber 14
aad a,re
malked'lZ
and
El
reepectl'vely.
&o
zone
1
reah
can
be
ugltlplied
by
a
factor
set
6
a
c6l3|1col
Cl:
,
l*
'
nodule
5.
tbl.s
factor
is
0.1 for
very short
ffnesl ffi-il
ilO.
t
.'
''
Arr
idinity
positio
is
also
present
on
thls sritch.
&r
tbl'r
setting
the restraint
voltage
is
reucved
frm
the treasrElrgi
cletult.
lhis
causes
the relay
to
behave
as a
ptuely
itLrectlonal
dcslor
a.nd
is
ueed
dgring
connissioaing
io check
the
eorrectnesr
of
connections
usin6
load
cr:rrent.
@
-
7/25/2019 Practical Switched Distance Relay
15/37
|
.L
cont..
"
lIodule
5 also
carries
the zone
2
ao:td
zone
J
setiings.
llhese
are nultipliers on
the sverall
zone 1 setting
a;rd
are
narked
K2
e.nd KJ
respectively.
fhe
control
on nodule 5 rm.rked
e aetg
the
relay
cha.racteristic
angl-e.
tbe
zone
2
arrrtd
J
ti.ners
are set using
poteationeterE on module
.
The
fi:actions
of
the other nodules are iut follows:
ModrrLE
7
is
the
trippi:tg
and
flag8:i:cg
nodule. It
ca'rrl.eg
a
-rotary
indicator
for
each
pbase.
Indlcatio
obtaiaed
for
different
faults is shosn
in
the table
belotr.
Fau].t
A.G
3-G
A.B
3-C
c-A
I
pb.
f1aeglng
A
B
AB
BC
CA
A3C
1hls
nodule
also bas
a
s1;"1tch
for
resetlrng
indlcatio.
Module
I is
the
povet
EugPltrr
nodule 2
ls
the
d.c.
srltclr.fqg;
uodule,
uodule
J
is
the
a.c.
svltchtag
oodule
atrd
oodule
4
houses
tbe
lhase
comParator.
7.2
Addltl@al
Feafi:res
Soue
applicEtLong
of
a
distance
relay
rcqqlre
featr:res
only
uentioned
up
to uor.
l[bege
are
zoa
1 ertension
and e-ternal
flag
coatrol.
lhsrc
dre selFeral
schenes
t*d.ch
use
tbcse-trc'o
uhlch
bsre
be$
choien.
7.2.L
Auto
Recloslrng:
As
illustrated
La
ftgure
A,
zoae
1
usgally
onlgr
covers
8fl$
of
afeederlength.IauaryapplicatloDscle4rEracaof8lrlt''.b
the
end 2Gf/6
b
zone
2
tlne
I's
rnacceptable.
If
no
nsrnq
gf
sienal1lng
betneen
lllrE
euds ls
aval.Lable
sln8le
sbot
auto
re-lostng
can
lmprole
the
situa,tion.
About
WA
of
faulta
m
overhead
lines
a,re
of
a
tlansleat
nature,
th&t
ts
tl|
they
afC
clea.red
quickly, then
on
te-enrsi.sation
of
the
clrcgltr't&o
fault
will no loogsr
be
Present.
.
Figure 11
shows
schenatically
a,n
auto
reclosing;
appucatla.
llhen
a.ny
starter
detects
a
far:lt,
the conrnaon
starter
1,ratrEat
contact
oirerates.
This is ar=anged
to
g:.ve
a
JOT
stgnal
t-o
the
zone
i
e:rtension
relay
input.
Zone
1 is
nog e=teniled
b5r.
an alount
set on
the
KC
poteationeter
(not
stroun
1n
flgure
7)
which
is
located
on
nodule
5.
lbis
extension
is
aLlorved
to
exist
for
150
nSec
a:rd
is
controlled
by
a,n
ilte-ra.I
tiaer.
-
7/25/2019 Practical Switched Distance Relay
16/37
The
anor:nt
of
the
extension
is
usually
set
to
be
just
beyoad
tbe
next
circuit
breaker.
Under
these
circumgtances faults
in
the
nert
protected
zone
aay
be
cleared
by breaker
A
but
this
causes
Iiitle
inconvenience
as
this circr:it
breaker
is
reclosed
after a
short
tine delay.
If
the
fault
was
tra,nsient
the
systen
rvil1
now
be
healthy. fhe
auto reclose
tiBlngi
sequence
will
not
al1ou
a
second
zoae ]
extension
for
a
flxed
line
so
if
the
fault
nas
perslsteat
it
will be
cleared i:e
zoe
1
tine
of relay A
if in zone
I
zoaa
2
tine of
relay
A
tf in
tJre
od
zoae
aad
in
zone
1
tine
of relay 3
if ln
tlre
zoae
1 of
that
relay.
An
lnput
from
relay A
to the
auto reclose
ralay
rril1
preveat
auto reclosing
if
relay
A
tp*ps
a fault
in
zme
2.
7.2.2
Penissive
Ove:reachrng Schene
Fi6urel2
shows
the
d.c.
circrrlt of
a
penolssive
ilve:=eacb,
tranrfer
trippireg schene.
lbls
utlllses
a
couualcatlor
chanel
betucar
tvo
llne
eadi.
Thlg
ls
usually
a
casler
slgla1
lngreagcd
@
t;ba
porer
ll e. The
node
of operatlo
ls
ae
folloug.
lf
the
cartls
channel
is
out of
serrlce
ttren
trlp relays
85
a,re oly
enrrgl$d
for
faults
in
the
protected
eectidr nbelr tbe zo;e
2
o@tact
fnFl
.
operates
9{
'lrfeU
ia
tu:ar sna?letea
the
elrcui.t
to
rclqra
S6 f
,
contacts
96-t,
86I-1 alrd A5-1
etc.
With
ca:rlet
ln
gswlco
'
howeve ,
zoae 1,
which
ls
set
to
about
Vq"
&
the
grotccted
ltrre
rrtll
caf,ure contact
S6LI to
close
for
all
faulte I.n
tJrc
protected
}[ne
plus
faults
up
to
26
ortrlile.
tblppfng
cs@ot
,
'-
occur
horever unlege a ca,r=ler
glgnal
is
recelvsd froo
sod D.
:'::.:
-
ltrle
slgnal rILL cause
95
r
2
to
operate
lncdlate\r.
lhit
ulll
'..
cause circuit
breaker
H.ppf.ng
and
also
suerglsc
elaot
rc r&la&.'
.',,
rrlLl
cause
the
relay
to
flag.
,,
.il,:;,
.
:-
.:.
'
I
bansnrlsgloa
of ca,rler
is
talttated
by tbe como
gtarter
lqlEt
r'
,
i
contact
on
relay 3.
Ibls
a:rao6enent
ls
ca1led
perrlaal.tr
:
.
uadeneach
becauge
zme
I
hae a
rgtrch
Ln elcegg
of
tJret
$h{oh
'-
is
required hrt trlpptng
is
only
per:oltted
tn
zoe I
ttoa
for
..'
i,,.r.._,.d$
:
a
reach
',*rich
is
leis
tJran
thls-
ana
ts
deter:oLrred
by
ca,lrllt
'
,.,r
ii,,
trarrscissloa fron
relay locatioa
B.
t,'','..,"i,.
'
tbe
abonre
tno
schenes
erre oly
tvo
of
nry
alrd art
ilcacr:lbrd
;:.
*;'.1',
,.,,,.
here
to
lllugtrate
the
r:se
of
the tno
facltttles
natl.Gcdr
,.,,'rr.i;,;-,
:'
zoe 1 ertensl.on
and erte:rral
f1a6
control.
.
,
:.;_,.;,t.
i.r.:
-
"
a'+i:ltl:$'-
;'
.
lt.
j,
I,jl,
".
t"'::,'
,
.r.i+r,:*:r,,jr,ijij..
,
..:l
,
-
7/25/2019 Practical Switched Distance Relay
17/37
-
AFi}ENDIX
SIMPLIFIED
TREATI4ENT
OF CIRCLE
EXPANSION
FOR EARTH
FAULTS
ON
SOLIDLY
EARTHED
SYSTEPI
AND HEALTHY
PHASE
POLARISATION
1.
Geometry
of
a
circle.
l.I
Consider
the
circle
in
Fig.
I:-
Fig.
l.
Its
centre
is
at
point
(a,
b)
and
it
hae
a radiue
r.
Any
point
P on
its
circumfererce
is
described:-
pZ+qZ=rZ
(i)
The
co-ordinatee
of
point
P
are
(x,
y).
x
=
a+p and
y
=
b
+
q
Subetituting
in
(i)r
(x-a)2
+
(t-O)t
=
tZ
and,
,2-2r"
+y?
-Zyb
=
"2
-a2-a2
(ii)
-
7/25/2019 Practical Switched Distance Relay
18/37
Page
2
-
Appendix
Fig.
2.
L.2
Consider
nou
Fig.
2.
A
circle
centre
C
hes
a
diameter
0A'
It
ig
a
property
of
a
circle
that
the artglc
of interecctiqr
of
eny'tuo^
chorde
nb
ehA Og
is
a_right
angle (90o) rtrera
theeG
chorda
inturaet
tha
sare
dianetar
0A
on
the
circr.rmferencs.
2.
Application
of
l.
to a dietarne
relay.
SeIf
polarised
relay.
Fig.
,
Let a trensmiseion
line
have
inpedarpc
Z
=
R
+
JX
aa
in
Fig.
l.
Lrt
thr
driving
voltage
be V.
I
=
U.
If
there
ia a fault
at
F,
then thc lmpcderrcc
to
z
the
fault ie
Z.
A
seley
at
point
A
vill
bc
cncrgiacd
rlth
voltage
V
end
current
I.
If
the
relay
ia to
detect the
fall
in
lirc
iapedarrcc bclor
a velr.c
ZR
,'
-l
,
'"
i""i.i
;;aair.gi,
than
if
qr.rantitiee
Vp
and
I
'are
takcn rg
followr
?-
-',i:
i'.--:
relay-rill
de[ict
a
feU of inpcAanco"belou
a aet vrlus
rith
thc addftltltl,':':i.-,,,
propirty
of
recogniairq
the
direction
of
the
fault
(feU
in
tqcdrnr)'fro ,.j,.,,,
the relaying
point. . .
,--.',-.'':;
,.'''
'
-ar:
This
is
a
sirplification
in that the
va.Iue
R
inclu&a
line,
earth eird
fult
'
I
'
resi9tanceandthevalueXisthetotalIoopinductance.Itigststd
thet the
source
ie
solidly
earthedr
'
-
7/25/2019 Practical Switched Distance Relay
19/37
A
diagram
on
the
ZR=
RR
+
impedance plane
is
shoun
jxn
0=relayangle
Page
3
-
Appondix
in
Figure
4
=
line
angle
=
Tan-l
Xx
G
Figure
4
u:
-.^
0A
(Zn)
is
the
setting
of
the
relay in
ohms
at
en
angle
g.
_+
The
vector
sum
0A
=
0B
+
BA
ean
be represented
by
ZR
=
fg
*
t-
VR
*
Zf,l
a
\I
t
Thie
rEans
thet
the.inpedence
to
the
fault
Zg
can
be
npasured
by
sxeaindql
tha
ph.sg
angle
betueen
VR end
Vp
-
Zp
'r
rf+'i
or
betseen
vg
and
vp
-126,
Zp
being
a reprica
ispedance
cithin
thc
ralay.
It
should be noted
here
that
it
ie
only
the
angle
betueen
thage
tuo
qlsrtltt6
that
is
nou of
significance
and
not
thiir
megnitudas.
gnce
thc
vector
subtraction
YB
-
IZn
hae been
done,
any
signai
in
ptraae
uith
the
rcrullrnt
of
thrs
subtraction
can_be
conpared
rrith
any
signal
in
phase
uith
vpe
urirg
I
phaee
comparator..
If
the
angle ia greater
tian
goo
th
quantitiSi
vo
gio
|
/
are
the
result
of.a
system
inpedanci
Zg
shich
ia
leee
than
thc
ratay"arttfng
:",.: l
lF
("::^Figuri.5)
heni:e
operatlon
of
the
relay ie
raquircol'*-.ngr;
oF
reaa
than
90o
rysy|ling
of
a
syetem
iapedance
greater
thari
Zj
ard
trnc;
reqriring
relay
stability
Ftgut
5
)lo'
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7/25/2019 Practical Switched Distance Relay
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Page 4
-
Appendix
3.
Mho
relay
operating
characteristics.
Fully
cross
poJ.arised
earth
fault
relay.
Syetem
agsumed
solidly
earthed.
l.I
System
vith reactance
only
(Figure
6).
The
vector
Ve
is
replaced
by
another
vector
Vp
in a croas
polarirad
relay-
(sometiilea
cal]ed
sound
or
heelthy
phaae
polarisation).
Thia
vector
is
derived
of eourse
from e healthy
Phese
by the
phaac
selection
netvork.
Consider
a
phase
A
to
ground
fault.
The
polarising
qulntity
tekcn
in
the
relay
type PYTS is
Eg
phaae
ehifted
by
600
leedt
i.e.
U,=Eg/.60=-EA
Initially let tht
source reactance
be
zero.
Quantities
to
be,
conpared
are
Vp end Vg
-
IR ZR
Zg
(Xp)
is
relay
setting
In
Figure
7,
for
angle
0.{8
to
be 90o
TanS=
I
TEiT
Real oart
-
Imaginary
part
oA
=
-Iqigrg .
BA
ReaI
part
I
Ff$rsc
6
::.
-
-
_
_
@
a
aa
:..:..
:'
,.
t
-
7/25/2019 Practical Switched Distance Relay
21/37
Page 5
-
Appendix
0A
is
Vp
:
-Eg
(1
+
j0)
BA
is
Vp
-
IpZp
Vp=E4 ;IR:
Vs
-16
Zii
=
Ea-EnjXn
Rp
+
jXp
E4
Rp
+
jXp
""L
f
ve
-r*ze
|
=
Iq.
lurl
.:
o
lmao. HeeI
EA(r-
if
the
angle betyeen
Vg
-IjZj
and Vp is
90o
Real
part
of
nunerator of VX
-
IpZX
=
0
jxR
)
=
ER
(RA
*
f
-
.it*
(Rr
-
jxF)
)
I
rf
a
.a
Rp
+
jXp
,'.
np*xf
-XRXr
:
o
Conparing thia
yith
(ii-;
*
page
I
end
it
rapreacnte
a circlc
orl
an
inpedance diagram treating
RF erd
Xp
.s vraieblas.
x RF
y:xF
and
2Xpb
=
XgXp
.'
.
ZRga=0
.. a=0
and12
-b2-.2
=o
tL2
..r=o
.'.
r
-
XR
z
The
above
shoue
that
the
nfio
circle
hes radiu
ft
rnd
lt tqrhn-'r
1",,;,.,'
f
"
i;i..,
.:,
,
the
origin.
(Figure
8),
i.e.
the
diamter
of
t'hi
circle
Xtr
lr rqff:ri.j:.
to
the
relay
reach along
ite
eherecteriatic
angla..
: :,1,:,
.,ir;
,
'
.- :r.r
.;
jjrXe
a
b=Ig
2
Flgurc f
-
7/25/2019 Practical Switched Distance Relay
22/37
Page
5
-
Appendix
Figure
9
3.2
Assune
nov
source
impedance
X5.
&xr
Lel
V.p
=
eg
ZSO
=
-EA
(f
ti0)
ae
before
.
But
Vg
=
En
(Rf
+
jxf)
tr6-?llfr-.1x5
IXp
=
En
jXn
Rf+jlf+jXs
.'
.
Vp
-
IXZp
=
EA
.
(Rr
+
ixf)
-
ixn
n'
tf,p*jfri-i;1-
=
EA
.
(Rr
+
jxr) (Rr
-
j (xp
*
Xs))
-
jxn
(Rr.-
J(x6
+
x5))
=EA.
np"xp+XpX5-Xn(x.r+X5)
+
j--
RF
*(xr*x5)2
Real
part
of nr.merator
=
0
-
8c
P3$
5
.'.
np
"
xpz
*
xfXs
-
ft(xp
+
X5)
=
0
i.e.
Rp2
*
XFZ
+
Xp
(X5
-
Xn)
-
XnXS
=
Q
ngz
*
XgZ
+
Xp
(X5
-
Xn)
=
XgX5
2b=X6-X5
b =XR-XS a=0
T
,2
ta2
:
x6x5
,2
=
XpX5
+
(Xn
-XS)z
_:4_
=C-
xnXs rx{
T
7-T
+
XpX5
-
7/25/2019 Practical Switched Distance Relay
23/37
Page
7
-
Appendix
)
-
XR
+
XpX5
r-T
.)
=
(XR
+
X5)'
_T_
r=
Xp+X5
T
+
x-z
J
4
Figun
10
If
rrs
let
Xq
in
Fig.
l0
=
0
thcn
it
is
idcnticel to
Fig.
8.
Ih.
influence
oF tne
e6urce
inpedarns ie
to
incrcarc ttre
diantar
of tha-
circle
but not to
affect the
reach Xg.
Fig.
13 ehouE
the
expanaion
of
thc cheracterietlc rith
thc rcloytrq
Erantitiea
superinpoeed uhre
the
courcr
end
linc
arc a &Gd
to
hrw
resistance
and
reecterrce.
.
vith
Reaistance and
Reactsrics.
Fignrc
Il
Vp
=
Eg
Z60
-
-Ea
=
E"
(-l-jo)
vR
=
Ea
(Zl.
r
Rf+jxJ
Z5+7,y+Rpr+jXs
IZp
=
Ea
ZR
Qr
4,-
Z5+Zg+RC'+jXo
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24/37
Page
I
-
Appendix
Vp
-
IZp -
Ea.
(ZL
+
Rf'
+
jXo)
-
ZR
79+7y*RFi+jXo
-
Ea
(Rl
+
jXL
+
RF'
+
jXo
-
Rg
-jft)
R5
+
jXg
+
R1
+
jXt
*
Rg'
+
jXs
Rg
+
Rpl
-
Rp
Xg+XO'=XF
=Ea.tp+jXp
-
RR-jxn
ffi;x1
=Ee.Rr-RR+j(Xr-Xn)
re)
-
Ea.
[nr
-RR*j
(xs
-x6fl
t*s*Rr
-
j (x5+xpfl
Denominetor
ReaI
part
of
nurprstor
is
(Rf
-
RX)
(R5
+
Rp)
*
(Xf
-
Xn)
(XS
*
Xg)
=
0
.'.
*rt+Rp
(R5
-
Rn)
-
RsRR
*\FZ +
rf
(Xs
-
xn)
-
XgX5
=
e
i.e.
Xpz
+
X6
(X5
-
Xn)
*
RF2
+
R6
(R5
-
Rn)
:
X5Xg
+
R5
R6
Conparing
uith
y2
-
zya
*
rz
-
zu
=,2
-oz
-"2
2b=(X6-XS)
b:Xp-X5
T
2a:(Rg-RS)
e=Rg-R5
,2
-b2
-"2
j2=x5xR+R5Rx
=
(Xn
+
XS)z
4
=
XSXR
+
R5 Rg
*
(XR
-
xS)2
*
(Rn
-
Rs)2
_-:_
_r
,,
*
(Igi-ls,)-
4
Exainining Figure
12,
Point P,
the'relay
reaeh
i"
6i*F
i.e.
(Rn
-
RS
+
RR+
RS
),
(Xn
-
X5+
Xp+X5
ZZTT
=RRTXR-Zp
-
7/25/2019 Practical Switched Distance Relay
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Page
9
-
Appendix
Again,
whilst
the
diameter
of
the
circle is
bigger the
reach
remeina
the
same,
and
letting
(.5
=
0
the
diagram
simplifies to
Figurelo,
i.e.
s=a.
b=Xp
It is
stressed
that
this
treatment
is
a
simplification
of
the
practical
conditions
but it
serves
to
indicate
hou
a
mho
relay
uith
caoas polarisation
is better
equipped
to
cope
uith
resiative
faults
than
a self
polarised
relay
beeause
the circle
dianpter
ilrcreeseg
for
unbalenced
faults
rrithout
affecting
the
reach atong
the relay
characteristic,
and
the expansion of the
characteristic
is a
function
of
the
aource to
line
inpedanee
ratio.
Figure
12
Figure
lJ
tr
i
i.
i
a-
,.
t
r
I
'
l:
t.
-
7/25/2019 Practical Switched Distance Relay
26/37
no0
--'l
I
I
I
I
I
fl
i
?'
(,>
f
f
o
dl
ni
(n
tl
r
nl
n
l=r
l8
lr
Ite
l'-.
P
r
D
tr
r
o
('l
x
v
.D
o
p
D
3
ur+
5g
P
.P
rf)Ul
o1
:g
I
ro
I
r1
rf
ll
It
c
rq
1l
t
f;n
AB
S''t
io
flflfl
9Z
-
7/25/2019 Practical Switched Distance Relay
27/37
l:
Jr
iirii
r,j
'
ri;f;
'
'i:i
|
.
.
i'ti;
-:
;t
.,1*i
ri:i
Freupe
2
C uecexr
lxpur
Crecurr
-
7/25/2019 Practical Switched Distance Relay
28/37
i.
F
IoUfiE
3E
Vonalro^-
tGHrro
erll.lrhl
,-l
,tl. ,-olf.1c
F
or
I
R unJct' ,-'pr.lan..c
al.e*a^F
rt
r
l3
i:
i..
h
t"
I..
l'"
::
ta
ta
I
t
i
-
I
araaa-tl
illtornaBtSlll
Ph- Ph
Co,^ll.:----
Frr-utE f 6
Valr al-r'on
I
rrl
t
I
I
t
I
,
I
u
I
It
a
a
I
I
t
L
ra
ta
ril
ta
:
a
a
t
o
Ir
ti
'caeh
,..rilL
...raffiali
tor-iltltE
l.orlStttl
ll1t
ra,
at
at
la
arl
at
.-'
.fa
ta
ta
tt
O_t
fl^-
A
3
Ph
Fo"tls
-
7/25/2019 Practical Switched Distance Relay
29/37
N
l-r
t
o
ou
-ii
--l
t
I
I
I
I
I
I
I
I
__t
z
9
t-
u
ut
J
r
u)
r_
ql
P9
-l
(}U
+
lrj
c
J
d
u-
*-
"*t--'*r#:fo
-
7/25/2019 Practical Switched Distance Relay
30/37
FIC
5-
.PI{ASE
SI{IFT
AND MULTIPLIER.
CIRCUITS.
4@
L,l$1+vs.
-lr.
(Di)
8lr-r
[r-'ol
+l3Y.
'\'
RCA
ito-Es'
(rrr.rrr,t
C
-r
)
RcA
J''-Ag:
(t.rra
od-cr)
c-l
A-g
3-t
c-A
A-3
-
7/25/2019 Practical Switched Distance Relay
31/37
)
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