Practical Switched Distance Relay

7/25/2019 Practical Switched Distance Relay

1/37

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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


2/37

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.


3/37

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.


4/37

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


5/37

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


6/37

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)


7/37

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


8/37

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

-

-'


9/37

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


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


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.


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


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


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.

@


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.


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

,


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)


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

'


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'


20/37

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


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


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


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


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


25/37

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.


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


27/37

l:

Jr

iirii

r,j

'

ri;f;

'

'i:i

|

.

.

i'ti;

-:

;t

.,1*i

ri:i

Freupe

2

C uecexr

lxpur

Crecurr


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


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


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


31/37

)

r

I

lut

Dt

iRr

Tl:i

EDr

R

Br

:t)

iQ

ttt

lRl

le.

E-l

t

9r

bzg

F|G,

6

z*.

lt,{lc,,-

qc.ss'f.

faov.

ot.

7a.A'lrrce

3#e

Ct

lzc

(a)

lzr

&r)

4

Czr)

O.2D

Ao'g.

o.3

.e

r,otit.

-


32/37

c\

(tt

tl


33/37

Itn

lxr

ls

e

elr

'qlfi

t-

o

lo

Tt

r'

D

q

tn

N1 II

ill

ad

ig

c

Iq

d

IT

+

E

$t

ir

l

't

3

o

c

o

.{

J

0p

Ai I

rn

r

r

{

;

d

..

,f,

Bf

dgi

ffr

nliil::$

o

t t I

hJ

e

t

i;

d

s

ii

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d;

Pr-,

n{-

;o

?

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TI

I

;

o

I

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1


34/37

*rftE11'

o.fo

PAr.lCf

t


35/37

-

3g

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Documents

Practical Switched Distance Relay