Barzam A.B. Automation in Electrical Power Systems (Системная автоматика)

CE.A.PTER

TEN

10-3.

Power Supply to Consumers After

Tripping

of

Busbars

and Automatic Reestablishing

of

Substation Connections

If

the

tripping

of

the

busbars, being

at

a

short-circuit

fault,

interrupts

the

power supply

to

consuners,

then

successful automatic

reclosure of

the busbars

nust

ensure

reestablishment of

the

voltage

across

the

consumer

term.inals.

To

achieve

this object, when

the

busbars are

at a short

circuit,

tbe differential

protection must

only trip the supply connections,

while

the connection

suppiy-

ing

power

lrom

these

busbars

to

tbe

consumers

must rem.ain

srritched on.

The

lmm

dif.

proteetion

Fig.

10-1.

Discriminating

prohibition

oI

automatic reclosing of

terminations'

q'hen

the busbar differeai,ial

protection

repeats

its

operatioii

sensitive

protection

wbich operates

during

insillation

testing

must be discri-

miuated

against

load

currents. The

operating

time

of

the ARC device emplo-ved

b-v the

breaker

through which the

testing

is

performed should

be

sufficient to

transfer

the consumers'synchronous

load,

if

any,

to operation

w-ithbut

exeita-

tion or

trip it

by

the

instant

the

voltage

is applied to

the

busbars.

The

reestablishment

of

normal

connections of

the substation after

the ope-

ration

of

the

busbar

differential

protection

is

by

means of

the

ARC devices

installed

on

the

breakers

of

the

lines

and transformers

t10-31.

During

the

first

functioning

of

tire

busbar

differential

protection

no

puise

to

prohibit

theopera-

tion

of

the

termination

ARC

devices

is

given.

The first

to

close

is

tbe termina-

tion whose

ARC

device

has

the smallest

time setting.

THREE-?EASE

ARC

OF

TRAN6FOR}TERS

AND

BUSBARS

DOe

SATR

and

holds

itself

closed u'ith

its contact

2TR-L

until

conract,

l?R-S

elo-

ses.

AJter

the operation

of the

busbar

differential

protection

the

busbars

become

deenergize!

and

reial' 7AR

resets

before

the

contict

of

reiay

SATR

has closed..

Re1a5'

4AR,

the

contacts

of

which

prohibit

ARC

operation"bn

the

other

termi-

nat.ion-q,

is inoperat'ive.

The

breaker whose

ARC

time

is

shortest

recloses.

if the

short

circuit

on the

busbars

has

eliminated

itself the ARC

devices

of

the

other

terminations

operate

in

-ceguence

and

re-qtore

the

initiaj

connections

From

busbor

Cz//ereniial

proiection

Closing

ctnuil

0pentn-e ctrcuit

Clostno

cLrcuit

0penino

time

of

reclosure

from

tlre

ARC

device

of

the

operating

protection,

the

If

t,he automatic reclosure

is

successful,

no

prohibiting

pulses

arefed to

other

terrrinations

and,

if it

is unsuccessful,

the differentiai

protection

of

busbars repeats

its

operation

to

prohibit

automatic reclosures

of

tire

other

minations

and

trips the

elosed

breaker.

The

sensitivity

of

the differentiai

event

of

reclosure

to a

persisting short

circuit

on

the

first

termination.

The

principle

underlying

the

ARC

prohibition

circuit

is clear

from Figs

10-1

of the

substations.

If the

short

circuit

on the

busbar.s

persists,

the

busbar

diffe-

qential

protection

repeats

its_o_peration.

contact

I.A,R*.1

close*.

and.

as

b]- this

time

tire

contac,t-of.

relat,

SAf

f

is

ciosed

(this

rela\:

rras

deenergized

after

tbe

first

operation

of

tiie

busbar

differential

protection)

the

relal'

{AR

frn"tions.

The

contacts

of

lelay

44R

make tlre

circuit

and

prohibit

ARC of all

trrniin^ti-

of

this

contact

must

be

greater

than

the

of the first

terminationl

i.e..

it,

should

time

of the

ARC

device,

the

breaker,

the

ter-

pro-

and t0-2.

When

the

busbar differential

protection

operates

for the

first

time,

I

se the

relay

4AR. This

circuit is

broken

by

the

coutact of

relal' SATR

whose

be

equal to

the sum

fault

ciearinE

time

bv

the

busbar

differential

If during

testing

the

sensitivlty

of the

main

selt

of the

differential

protection

the

case

of a

persisting

short

circuit,

J- L

?

No.

{

l,lo.

2

/to.

J

Fig.

10-2.

Decentraiized

lgo]ribition-

oI

autcmatic

rec.losing

oI terminatiots

uiren

tlie

busbar-differential

protection

repeats

its

o*pe.ration

Iatter

functions and instantaneous

A t,-4 rD UtftDcu tu ult

contact

2'TR-2

opens

the

circuit

of

reiay

___v-v4,

v,

r(

l.vl

qt

sensitive protection

to trip

the

busbars

in

2!*

CEAFTER

TEN

Iil

-

4.'

lAutomatic

Reestabli"fri"g,of

P

ower

Station

Connections

When a

short

circuit

of busbars persists

due

to

a failure

of the

breaker

at

one

of

faulty

phase terminations.

when

the immediate

automatic

reclosure

is

unsuccessful.

When

the

back-up

device

of

the

breaker

lunctions

after a failure

of the

bre-

aker

of

an autotransformer (transformer,

generator-transformer

unit)

and

after

its

damage.

tor'mprove

ttre

se-nsrtffit1'

of

thgtusbar

diff-erenlial prolection

use is

maele

of an

auxiliary protective.

element

having

an operating

current

rn'hich

is

not

t

The

ARC

p.rohibiting

circuit

of the

brcaker

of termination

No.

3

can

be made

in

the

it

is

first to

be closed

Iess

than

THREE-PIIASF

ARC

OF

TRANSFORMERS

AND BUSBARS

discriminated

against

-

unbalanee

currents from

external

faults

ancl

hunting.

This

eiement

operates longer

than

the

complei,e

ARC

cycie.

goJng

lines

onl,v is necessary,

as tire

dutv

personne]

can

be responsibie

for

the

subsequent

closure

of the

generators

and

the generator-transformer

units.

10-5.

Three-Phase

ARC

of Translormers

The

ARC devices

of

transformers

are intended

to recover

the

power

supolv

after

emergencrt

trippinE

of a feedinq

transformer

for anv callse .,i,h"" thari'in-

The

AFC devic.es

of transformers.differ

mainif in

the

starting

aad blocking

*tT;,r1;;

ng

ol

att

ARC

d.euic:e,

i*tn the

moin

o,

o*r,-up

protection

deui,ce

on th.e

transformcr

tunctions.

pronrot€'s

its autonatic

reciosurr

v:hatevel

the

fauli

(internal

faults

included).

A

disadvantage

here

is

tha{ the

fauity

transformer

mayreclo-"e

wjth

t,he

risk of additiorrat

dapage.

This

method

may iiod

irs

appli.

ea[ions rn'here

u-se

is

made

of

quick-aeti^On

protection

unitS

or

s'bere proviSiin

is

made fs1

-speedilg

up

tlp

action of the back-up protection

units afier

the

ope-

ration

of

tbe

AFC devices.

ARC

prohibittng

in

operatiorz of

the

signal el-em-ent

ol

the

oil

pressure

protecti.on

is

u.sed

to

prevent

aut,omatic

reclosure

in

the

case

of internal damage

to

trans-

rormers.

tne

slgnal element

oI tlre

oll

pressurc

protection

function-q at the pre.-

sence

of

gas

in

the

relal:

or in case of oiJ leakage.

\Vhen

external

short

circuits

occur.

the

signal

element

misoperate-s far

more

rarelv

than the

tripping

ele-

ment.

Therefore,

prohibition

of

ARC operation

by the

signalling

contact of

trinni

the

transformer

breaker

for

anv

reason.

exceot

internal f

u pur a

Ltug

'uime

oi ihe

ARC

devices

shouiri

be

somewirai.

grearer

i,han

tire

of the

signal element

of tlie

oil

pressure

protection (3

to

5 s).

324

f

uuu

auls

ul

t

- I t n -- _

,l

tAn are

by the

ARC

device

(the

o

time

of ARC

device No.

3 is

ting

time

dzo

C}I.A,PTER

TESi

\4lhen

Dower

so

evice

to

be

used

should

be selected

to

THREE-PEASE

ARC

OF

TRANSFORI\IERS

AND

BUSBARS

operations

on

the

lines.

When

a substation

is

equipped

*'i*uh

autotransforners

ali the

above-mentioned

with

regard

to the

use

of

ARC devices

for

transformers

remains

valid.

10-6.

Conclusions

1.

ARC devices

are effective

when

adopted

for the

automatic reclosing

of

b_reakers

placed

in the

circuit

of pou'er

transformers (autotransformer-s),

after

t-hey

have tripped

short

circuits.

or.after

malfunction

of

the

protective rblaying

devices

and

v'hen

the tripping

is

inadvertenlil:

performed

by

attending per-

I

sonnel.

2. The

circuits

of

the

ARC devices

used

on the

transformers

are similar

to those

of the

ARC units

emploi'ed

bv transmission

lines.

3.

A-fter

operation

of

the

differential

protection

of busbars

and

tireir

deen-

ergizing,

the

busbars

can

be reenergized

with

the

aid of

the

ARC

devices

instal-

Ied on the

breakers

of the

outqoing

t,erminations

(feeders).

4.

The

percentage

of

successful

transformer

and busbar

automatic

reclosures

is about, the

same

as for

transmissior.r

lines

(more

than

60

per

cent

on the statis-

tical

data).

5. After successful

testing

of the

busbars,

it

is better

for

the

normal supply

to

ihe subsiation

to

be automaticall-v

reestablished.

Such

automat,ic

Oevi'ce!

are

appiied

in a

number

of

power

s-vstems..

ij.

Ar:toma'r,ic recJosure

of the'busba'rslwith

tbe

qee-qt;ablishmeni-

,;i

t.hr,

pri-

marv

circuit

of the

before-fau1t,

service

at.

porver

stations

complicat.es

tbe

ARC

circuit

as it. is nec.essar\:1o

prevent (in

a number

of cases)

asyn-chronous c.onnec-

tions

of the generat,ors.

lfre final

decision

as to

the

automatic

reestabiishment

of

the

normai

service

connections

should

be

based

on the

anah,sis

of tire local

service

conditions.

10-7.

Review

Question-s

6.

Ho3'

do

you

explain

the

successful

operation

of t,he

ARC

devices used on

busbars

7-

Hou'is

tlre nature

of

t,ite load

connected

to

ti-re

substation

busbars taken into

account

('rvbether

it^is

asynchronous

or s5,ns[s6rous)

rvhen

applyrns

,tnC

devic,u.

to

" "t.p-aoio-n

transformer?

8.

Io{

step-don'n

substations

the

differential

busbar

protection

onl

the breakers

When

.{ly .buqbars

be reenergized.withoui

p,reliminaiy

inspection

of the

equipment?

UI

327

the

transformer

at

the

substation

and

respective

-voltages

or the pernissible

suit the

actual

operatirrg

conditions

of

ensure

synchronous

corrnection

of the

asvnchronous

connection.

When

the

transformer

is^used

to

su

Iv

svnchronous

mot,ors

or

s

chronous

capaclf,ors,

operation

of t

evices

must

be

coordinated with

the

I

t

ratroD

or with

the

required

to

trip ihis load,

as in the

case

with

the

A

has

.L--l-:--- rr__,

rl -

:

---------

rrreulirug.

rl,taJ/-

rne

aLrenorng

.

personnel

tmmedratel5'

reclose

the

transiormer

alter

it

been trippe

d

b5' tire

protection

unit?

Clt

cr.pter

El,et:en

AUTOMATIC

TRANSFER

TO

RESERVE SUPPL-I* AtsD

EQUIPMENT

which

bring

in

the

stand-by

suppiy

and

reduce

the

suppiy interruption time to

Iess than

t to

2 s.

One

of

the

first

ATS

systems employed

in the

power

systems

of

tbe

USSR

for the

house

circuits of the

Gorky

power

station was proposed

by

the author

in

1930.

The selJ-starting

of asynchronous

motors

(with

a

phase wound

and squir-

rel-cage

rotor)

is

possible

and

permissibie.

This

has

been

corroborated

bf

the

ATS

service

experience

and the

respective theoretical

anaiysis

t11-{1.

The first

ATS

devices

deiigned

for the station-service installations

wele

made to function

only

s'hen

internal

faults occurred

on the

power

transformers

or on the

house-

circuit

generators.

Later the service

offered by

the

A?S

devices

was extended to

cover l:usbar

faults,

as

busbar short

circuits

often self-cleared

after

deenergi-

zing-

This factor,

as mentioned

previouslv,

determines

the suceessful busbar

reclosing*.

AUTOMATIC

TRANSFER

TO

FNSBRYE

SUPPLY

A]VD

EQUIPMENT

11-1.

General

To

make

the

power

guppl.r'

to tire.con$lmers

more,

dependable,

the-v

are

sup-

plied

from two

sides.

In

this

case

a fault

at.

one

of tlie

supply'

uniir

-and

jis

tripping

willlot

stop

tbe

suppl-v

to

the

ccnsurners,

as t,hey *itt'U.

fed

through

thg

intaCt

linl.:s of t.hc nn\rro!-

epeton

Al

+Jro

o+:r- *i*-. {'!.^

a==-- -:r

p

I

-r,

(

i

n

;

;;;;'"

;

i

;;.

il

il ;ii:

ilil

fi l'

".:.

;;;

Jl,-"iJ

il. u"01,:i

I

#ffi

;

ffi

of

the

poFcr

circuits

into

a

ring

svstem

"nd

paraliel

operation

tf

transformers,

'

makes tire protective

relaying

poT

campiicateri-

The'operating

conditions

for

tlte

equipment

uorserr,

due

tG

the increase

in

the

short-circuit

currents

and

1ys

t,

.. Tire.r}-se

g[

a

se{iiplalize,l

F'o1'el

suppl-v

s1'sl"m

marerially

simpiifiestfre

proLective

reialing,

adds

tu

ifs

ieltabie

opefat,ioc,

increases

the

residlai

lolta_

ges

across Lhe

husbars

of

tle suppll

distributi6n

.s5rst€rB

and

decreas-ei

i.

creates

t.he

requircd

operating

cond

main

disadvantage

of

a

-sectionalizt

'

when

a fault.

qccurs

on

the

suppll'

u

rially

by

the

automatfc

transfer

of

the,

basic elements,

through

which

tiong

are tripped.

"i-

Under

norliai

condition-s

tire stand-by

sodrces

lcay

!*

switched

off or

bel

.1

'..onder

vohage

and;gggry

no

load.

.

.,

:.

1

.

-.----.*

--.

"-

.,

'

.'

.'.

'

.

frr,other

instances,

tle

stsn&ht-suultes

ma.y

be

partiall-v-

loaded,

i.e., t,hp

'

,.

'

wlrol',e.hcad

of

the

eonsumer

is

shared

arDotrg the- two

('or

more)

ge$eratiug

units

and

these

units

perform

stand-by functioni.for

each

other.

Manually

placing

a

stan&by

unit fnto

actiotr

c,auses

a

prolonged

interrup-

'

ti.orr

to.the

ir:"lt

*pply

and, as

a

rrie,

"nr"G

ine:p"qd""t.o

pri"-rr""

n"it

g

e

nolnal process.

sumers

is

materiaily

improveri

by

the

When

a

stand-by

unit carries

its

ioad.

then. if

this unit

is

connected

to

a

persist,ing

short

circuit

on

the

busbars

oi the

power

soluce

being remedied. the

iault

wiII

extend

to the loads

supplied

by the stand-b1' unit.

To

mitigate

tjre ef-

fect

of such

operatiou,

provision

is

made

for

introduct,ion

of

a

speeded up

protec-

tiorr

aft,er the

ATS

operation

to ensure

the

quick

disconnection

of

the stand-by

unit together

witb

its loafu from

t.he busbars

of

the

circuit being remedied.

'

Another solution,

whlch

prevents

the

extension

of

e

persistiug

busbar

short

circuit to the

Ioads

of

the

stand-by unit

when the

busbars

are

reenergized,

is the

':iointopelationoft.br.ATsandARCdevices.\1'henalat}tocsnrsont.hesupp}y.

ing circuit

elemenis

and their suppil-

to the

consumer is interrupted, the latter

-

ts

disconnected.

from the

maiu

source

of

power

and transferred

t,o

the

stand-by

'

-

soutr.e. Thus,

t}re-ATS

operation takes place

onlv after

the faultl" e.lementr'is

tripped

both

at

the

side

of

the

main

source of

power

and at

the

sid.e of the recei-

ving

busbars

of

the

corrsrrmer.

If

a short

circuit

occurs

on

the

consumer's bus-

bars,

no

ATS

operation t;rkes

place.'Ihis

operation is prohibited

by

the prot.ec-

.

tion responding

t.o busbar faults,

or

the

ATS

device

cannot

be triggered:. It, is

.

'..

t,he

AffC device

on

the

supplying

connectlons

that functions

'.

When

a

short

cirtuit

on

the

busbars

(or

on

the

lines

run

from the

busbars

.

.''

to the

corsumer

if the failed

line is

not

deenergized) clearsr-.the

power

suppiy

,,/'

reistorcs.

If tbsdu.ult

persists

the

brtaker

closed-b-v

the ARCdevice is

trifrped

.

suppiy transformer

is

operating, the

ATS

device closes,

and if it

is

the

overcur-

'

t€rt protection

the

ARC device

functions.

Automatic

reciosure

of stand-by

supply lines

allows

the

suppl-v

circuit

t,o

Liu€sjs

eensidercd as+rlaet-upreastre,

and

doernot;€trpersetitr*he

erseof

ra.R€

devices

on

them.

A

deenergized

line is

reclosed fron

the

AFC

device, and

if the

automatic

reclosure

appears

unsuccessful

the line is

automaticaliy

tripped

at

'

With

&10-kV

insta

on the

busbars

sometimes

e

successlu AfS and ARC

operations at short

on

tbe

fact tbat duri

were

deenergized.

-

circuits

rr

leads

use

of

aul,omatie

transfer devices

(ATS)

h^ +^ ^-

gE

&U

EI

* --: ^L --i

!5

trrDq

rt r

:- aL^

I

Ill

|,uts

/1

t circuits

the isol

CEIAPTER

EI,E\EN

AUTOMATIC

TN.ANSFER

TO

RESER\;E

SUPPLY

AND

EQUIP}I.ENT

21

transfer

the

ioads

to

a suppl;,

from

anot_

"ownttload.

[or

backing

up

the

suppiy

to

the

consu_

reration

of important

mechanisms

of

the

n

-place

of the

constant

idie

running

of

tching

on

of

stand-b-v

feed

pumps,

diaft

c.

is provided.

cver

to

a

staud-by

power

source

is

done

eration

of

communication

and

remote_

rf

the

a.c.

supply

at

the

power

station

or

rtus

under

normal

operaling

conditions.

lined

through

the

uie

of

an-

AT_S

device

bv power

svstems

to

ensure

service

u,ith

: *'ithout

further

capitai

outlav.

A so_

de.,'ice (ADR)

has

beln

develoneti

t1t-zl.

^+i^-. ^f r----I

uLrur.r

ur Lr.aIIstormer

suEstatlons

to

the

faulted

section

of

the

main

supply

Iine.

,

t-vpe

relal's

such

as

cunent,

'uojt"g.,

,s

over

5

years

obtained

from

the

USSR

t1r-31

is given

in

Table

{{-1.

aique

is

an

important

meats

irr

impro_

wer

systems.

'Ihe

number

of succes-"fu}

A!=s

o_perations

totals

90-95

per

cent.

ATS

devices

is

determined

bV

hou.

q.

are

reestabiished

after

reenergizing.

Thi

and

whether

the

electric

motirs

r^7in

str

ckly

the

before-fault

productivity

is

obtainea.

ti

I

an

ATS

device

is

anything

but

successful

if

the

co

T'q {-tf-.-9n.t"ting

ratings

become

critical

during

tbe

starring

time

wit}r

re-

sultant

outage

of the

production

pfocess

The

above

circumstance

is

a difficult

problem

to

solve

with

regard

to

.the

choice

of the

lufPlrl

circuit (multi-sour".

ritppty

without

ATS devices

or radial

supply

with

ATS

devices),

protective

reiayiirg-

deyices,

characteristics

of

the

motors

and

loads,

commutation

apparatus,

cbntiol

circuits

and blocki"g-

a*ices.

ii-2.

ATS

Device

Circuits

upplied

from

cornm.on

busbars_

Fig.l1_l

rtion

s'ith

t,wo

step-do*-n

transfoimers.

rn

busbars (iighting

circuit,

electrical

)se

no

limitations

on

the

operating

time

application

of voltage

1.5-Lo

2.5 i

after

transfofmers

are

cooijec.ied

to

a

c,f,rnulcil

"iJ::r:?:t

,i'"1'

are

as rorrov,s

:

being

open.

different

sections

s.ith

breaker

sJ

.

(2)

One

of the.t,ransformers

(transformer

71.

for

inst,ance)

is

connected

to

the

two

sections

with

breaker

,SJ

being

closed.

tr"nsform

er

TZ is

disconnecteci.

Under

such

conditions

the

ATS divice

assures:

The

use

of

the

tran-qformers

as

stand-b-v

units

v,ith

respect to

eacir

other,

when

thel'

operate

into

different

seciions.

'

---

Automatic

transfer

of a transformer

as

a

stand_bl,

unit

when

onl;,

one trans-

forrner

is

in

operation

and

is

tripped

due.to

a-fault.

Automatic

reenergizing

in

the

-case

of

a

short,

circuit

on

the

busbars

of

the

sgctio,n

during

parallel

operalion

of the

transformers

with

tiie

section

breaker

closed'.Such.operation

Fal'be

advisable

in

order

to

balance

better

the

loads

oI

the

translormers

and

reduce

losses.

Reenergizing

of

section

/,I is

not provided

in the

case

of a sbort

circuit

w-iren

t'ralsJ+rmer49

isJripped

arrd

breaker

,9,1

is

closed.

Se.c,tiron

/r::cannbtFe

reeneF

gize-q

when

transformer

TI is

switched

off

and

breaker.Sj

closed..

Llnder

these

conditions

the

required

reclosing

can

be performed

bv

rn

-tRC

device

rn,hich

:l:::. Jl.: .r.h_.

'11?d-by

prote9ii9n,,oi.

rh;

;;;;r"r;"',

;;;;;;;;r.

Tffi

;;;;;:

and the

ARC

device

are

not

shown

in

Fig.

LL-l).

The-o

tion

of

the

stand-b

9YIUg

f

\

or

COIIS

Table

11-1

Data

on

Five

Years

Operation

of ATS

Devices

Where

installed

Periodicity,

year

numirer

Of

set-)'ea

rs,

Ii*

successfu

l

operation,

oi

Substation

translormers

(apparent

re-serve]

Transmission

lines

Transf

ormers

of

staljon

seryice

(apparent

reserve)

Stat.ion-service

motors

lntersection

breai<crs

for

station-

service

(non-apparent

reserve)

ElerseefiO!

breaEers

of

substa

_

(non-apparent,

r.eserve)

Otitcr

oEjects

of

service

..\!l

instailarions

5.945

1 6,

Eg5

17,046

39,795

3,753

8,316

26,

g8g

112,629

J{

94

.9

Q4

,l

99

.54

q7A

89.2

98.2

96.06

51.2

87.3

46.3

s8.0

54.0

.fo.c

810.0

t r8.0

J..f

4.7

2.7

'l=

I. '

4.4

1-l

,J.

C

I

successful

|

\nsuceessfu)

opera!ton

I

operation

of

relays

3AR

and

4Ak

from

the

operating

current,

iisconnec'oing

'ui

instance),

u'hile

opere-

$i*

r*I

\s;

\

o

$

&$i

r\':

*E$i

r

-1

ql*

AUTO}IATIC

TRANSFER TO RESERVE SUPPLY

AND

EQUIPMENT

tion of

the

differential

and oil

pressure

protective

units

cancels

the

operation

of

the.ARC device,

and

the

ATS device is allowed

to

function.

The ATS

device operates as follows:

Whatever

the cause of

tripping the breaker 32

or 54

(a

short

circuit

on

the

busbars

iucluded),

the auxiliar-v contacts

of

the breaker-s

break and open the

coils

of relavs

.Z

and

2

(rela)'s

with

deiayed armature dropout).

After

the

coils

are

deenergized,

tbe

relaSr

contacts open in

1.5

t,o

2

s.

Thus,

after tripping

the

breaker

52

or 54. rela-r, 3 or

4 closes

for

1.5-2

s

and

in

its

turn closes

the

section breaker and

the

breakers of the

power

transformer

(if

the latter has

been

tripped

open).

The

ciosing circuits of

the breakers ,S2

and 54 are

*'ired

through

the

auxili-

ary

contacts

of the breakers S/

and

SJ

(the

auxiiiary contacts close

after

t.he

breakers,9T

and SJ ciose). This connection is

provided

to

prevent,

t,he

closing

of

the

three

breakers simtrltaneousll-

which

may

overload the storage

batter5'.

The

coil circuits of

relays

3 and 4 open

1.5 to

2

s after the working

transformer

is

ciisconnected,

thus

promoting

a

one-shot

ciosing

of

the

section

breaker

and

the breakers of

the stand-b-v transformer.

The one-shot

ATS

in the

case

of a

short circuit on

tbe

busbars

of the section

being

remedied is obtained

b1'

ma-

king

the

breaker control circuit

capable

of

blocking against

muiti-shot

closures.

With

operating times in

excess

of 0.5 s

it is

practicable to

realize

tlie pro-

tective

relaying of

the

section

breaker

asd

the

power

tiansformers with

an acce-

lerat.ed

action

after

the

operation of

the

ATS device.

,,As

an

exanple.

Fig.

11-1

i]lustrates

a possil'Ie

crrcuit.-foi

a,ac,eierating.,the

operation oi the

overcurrent

protection

of

the

section breaker.

\['ith the

ilreaiter

55

tripped

open,

the

coii of rela1,' 5

carries a

current,

and

the contact

of

the rela-v

is closed. After

the

breaker

has

been closed

manualll'

or b_v the ATS

device to

carr],

a short

circuit burden,

cunent relay-s

6

function

and close time

relav

7.

The

}atter

completes

the accelerated action

circuit in 0.1 to

0.2 s. If

reiavs

6

and

7 do

not functiorr

after ciosing

the breaker,SS, the protection

acceieraiing

circuit

is opened

after a certain time

by

the

contact of reiay

5 and

oniS'the

selective

protection

remains.

The

use

of the

above-described

circuit

for

acceierating

the

operation

of tlie

overcurrent

protection

of

the section

breaker

is

permissibie

if the

current

relal's

fail

to

operate due to the self-starting

curents after closing the section

breakei.

Discrimination against

these

currents

may

sometimes

lead

to un*'anted

desen-

sitization of the

protective

system.

When this

happens,

the

operating time

of

the acceleratedprotection

is

set

to

about

0.5 s

[11-4]

or use

is made of

an au.ri-

Iiary

curren"

cutoff

isolat,ed

against

the

starting

currents,

but

operating

from

the shor't-circuit

currents

wiren

a

fault occurs

on

the

busbars.

The

breakins

eireuitof

this

cutsff

isnormaLlyopen

and is

autonnatically

closed

a

certain timi

after the

section

breaker

is

closed

manually, remotely,

or by

the

ATS devie.e

(i.e.,

this

circuit

is controlled

by

the

contact

of relay.f).

If

each of the

transformers

is not furnished with

an individual

ARC

device

be

irerformed

by the

A

device.

For

this, the

.J.aJ

9Ee

9JQ

g.:

@

=6o

=

.5'- o

EE*

qa-

--

=@

O+-

E

Or=

-, C.E

s

.=

tr=*

r

=e:i

6

:,.,

i

6

,iE

7

o'-

-

l.;-e9

o

>iJ

r

EsF

€.'

-c

urh

ts

v'

trJ2

^

-::-

::X

6.S-;

=

@'=-

/ loo

F

t'=

C sE-

a--

o

hc=

vx-

=

-6ri

a e..

i

p!:;

L

.:*

>Ji-

_+-=!^

e,LO:

.2

IE:

E

?

*-;F

E._5*-

c';aE

.T

5E:

\

o

_c)

sti

circuit

on

one

of the

sect.ions wil

T?N

a7

nofnFA

vt

vLIvI

I

JJ.l

CHAPTER

ELE1IEN

action of the

back-up

protection

of the

transformer

(or

the

back-up

protection

of the transformer

should

have two

time-settings.

the'smaiierto

lrip

tne

section

breaker

and the

greater

to

disconnec,t

the

traisform.t

Aii.;

the

sections

are

separated

and

the

transformer

feeding

the

short

circuit'on

the

faultS'r."iion

l*

clisconnected,

the

ATS device

functio*ns

and

breaker

,S5

reestabiisiiei

thu

.,rottr-

ge

across

the

deenergized

section

at

the

expense

of

the

section

intact.

\4rhen

the

breakers

,9.I,

52.

S3 and

S4'ale

openea

*"nu"fiy-

ana

ir

case-c

u'hen

such

disconnections

deenergize

one

of t,he

sections.

as perfoimed

by

*i.1"-

ke,

(i.e.,

the

ATS

device

is not

disconnected

deliberatet5),

in.

IiS

aer,llce

vti]

her

section.

rper

(bridge)

I

is

provided.

This

discon_

ire

control

ke1-

sri.itch

tiisconnectins

tire

Ling

current.

TIie

circuit

has

signallirre

rf the

ATS device

and

the

path

if a

ctol

I

after

the

breakers

.Si

ind

,S.?

have

\.J U5L? tl ,

ATS

deuices

oi

power

transformers

^supplied

lrorn

d.i..t'f

erent

power

sources

flg

t1-2).

The transformers

I-l

and,

T2 aie, s,orking

units'and

thl

transformer

TB

is

a stand-bJ,

one.

-The

power

suppi5,

to tire

transformers

is

flom

djffcreni

sources (for

instance.

from

different

ieit,lons

of

the

geoeration

l,oitage).

Tire

from

the

above-described

circuit-

in

tiiat

transformer

becomes

disconnected.

but

re

se,ction,

'*lhate-,,ei

t-ne

reascn

ma1,

be

.

s

'are

di*sconnected

or

at fault.

\r-oltase

iarl

relav

7

makes

the

breakers

of

tirit

^" ,T1..

pic\up

se,t.ti{s

of

voifage..trl,o7t1l.}lX*hril

as

practicable

(30

ro

409i1

oi

L') rn

order

to limit

the

reach

zone

in

the

case of

voltige

dips

drrring

a

short

c'ircuit

on

tire

outgoing

lines

and

also

to

discrimirrate

ag.ainit

voltaie

d;;;.

during

the

subseguent

lelf-startings

of the

mot,ors.

The

*uiiiog

of time

relar.

P

is greater

t,han

the

operating

time

of ti,. protection

againsf

shJrt

,i;rujt;;A;

ring

in

the

zone

of residual-r'oltage

rvhich

is

less

ttrai

30 to

40

per

cent

of

L:r,.

The voltage

relavs

are

connected

Io

different

phases.

The

conta"i*

of tbe

rela's

are

connected

in

series.

This

connection

prer,ents

false

operation

oih.n

r".;I

the

f uses

blou.s.

The

use

of the

ATS

circuit,

shoq'n

in

Fig.

t1-2

may

be permittecl

ri'hen

the

loads

are asl'nchronou'',

iighting

or

heatingZo"..

Utnno

the

ioad

is

stnchronous

the

ATS device

*Y.i,te

sipplti*nt*a

"itit

rq*pment

that

prevents

as3'nchro-

nous.app)ication

of the

r.'oftige

from

the

stana-by

source

to

the

busbars

across

urhieh

tlreveltage

is

maintaiied

b1.

the

coastiotipchronoo.:*utor-"

r,rith

iive

f

ield.

q

o

,i

o

rDl

@

(Jb

=c

CF

?f6

r-9

FFc

b

-b6E

,@_

o ,H

q

rx

E*i

tr

if:

=Fo

Y6E

tso

CP*

.-

,=

=

c:

E*=

A)

/,

EK

L

16

E*il

L

^

,-T

;

-c

Ee

-6

Ei;-

c

EF

.-

e..e

>

Fc

'r

>'-

"

49?

<

E6

*

.o*

lo

-

lL

.E

.3E

v

i:=

.L

el

c>

s=

!bl

F<

AI

.;

>'

F

c)

E

6

\

tr

s

I

qJ

l^

R

\

tD

,S

\

\*

\E

qb

c\

\

s

q)

t;

E|o$

The

circuit

ailou's

for

the

stand-bJ'

source-

Use

instailation

of a

relav

is

made

of

one

reiav

i.

across

a

fault

occurs

on its circ.rri

are

not

showa.

The

protection

units

installed

on tlie

section

breakers

ave

clr-

336

CEAPTEN

DLE]rEN

AIITO}IATIC

TRANSFER

TO

RESER\-E

SUPPLY

AhiD

EQUIP&fENT

337

power

sources

ser\re

as

stand-bv

units

for

each

other.

\47hen

section

is

deenergized

the

asvnchronous

motors, coasting

for a short

time

due

to the

accumulated

energ5,

maintain

the voltage,

for

ihich

reason

the

actionbf

the

protection

mav

be

some-

what

behind.

To

spced up

the

operat.ion

of tire

ATS device, rvhen

the

sunnlv

trans-

former

is disconnected,

rvhatevei

ih.

c"use

may

be

(u'lten,

for

instance.

an operator

opens

the

breaker

at

t,he suppll'

side

bv

rnistake),

the

circuit

assures

the tripping

of

the

section

breaker

throuelt

tire

auriLiar!

contacts

of the

breaker

found

at

the

suppIS'

side

of

the

working

transformer.

\\rhen

the

section

is

deenersized.

the

tripping

of

the rvorliing

transform"er

mav

be

obtained

through

the voltage

reia_v

connec-

tion

circuit

siiown

in Fig.

11-3.

This

makes

it possibie.

to

increase tire pickup

sett,ing

oJ tlrd'voltage

rela5'

1s

Ltpicxup

:

65

96

of

l.he

rated

voltage.

Tlie time

relal' Zfr picks

up

ri'hen

the

voltage

across the

section

busbars

and the

current

flows

in the

circuit

of

the

suppl,v

transformer

disappear.

This protects

against

improper

disconnection

of

the

working

trans-

former

due to

false

operation

of tire insLru-

FiC.

l1-3.

Connectjon

oI

r.olt,age

lelar,

rvhich

indicates

lrcl-current

in'sunpi!

connection

case

of biown

fuses

rhe

ci

rcur,

*#TJ

";;1n5'",rffT*t?*i,'Jt'jr3'xt,,il

current

in the

main

suppl-v

circuit issuffici-ent

to

make

the

current relav

func-

tion.

The

cJroice

of the

current

relay should

be such tirat

it

holds

t,he

contacts

open

at

the

minimum

load

and that

its

coil is

sufficient])'

heat

resistant

t.o'

withstand

t-h.

maximum

possiblc

operating

currents.

When

the_

wo1\ing

transformeri

are supplied

through

transmission

lines

eq]]pped

s'ith

ATS

devices,

the

operating time

of the

st*arting

eiement

of the

{+S devicrwith

a vo}tage

rela5'

6nd a

ciuent relay

must

ne

}reator

than

f,lie

total

time

taken

to

clear"

the

short

circuit

on

the

r'rppi),

Iine-and

reclose the

breaker by

the

ARC

device.

Tltus, the transfer

to

-the

stand-by

source

is

performed

onl-rr in

the

case

of unsuccessful

automatic

reclosure.

"If

the

line

Fig.

11-4.

1,3

-

voltage

relays;

Circuit

of

ATS

device

of

porver

transmission

.2

-

tirDe

relal;

I

-

delayed

reset

relay;

s

_

6

-

Jumpers

lines

signalling

relay;

time

of

the

undervoltage

protection

is

generally

isolated

against

the

operati

t lttt

"

wnen

[ne

A'1

s

ched

off.

99-9n7A

ts tripped

for

soms

reasonr

the

voltage

protection

must

be

swit-

338

CEAPTER

ELEVEN

AUTOMATIE

TRANSFER

TO

RESERVE

SUPPLT

AND

EQUIPMENT

339

6

ygl^tage

transformer.

Delaved

reset

rela-v

4

ensures

one-shot

operation

of the

ATS device.

If

the

supply

line

is furnished

with

a

two-shot

action

ARC device

installed

from the

side

of substation

,4 and

if after

the

second

ARC operation

the

iine

remains

under

voltage

the

return

of

the

substation

to the

main

po!\,er

source

is

best performed

manualiy

(locatly

or bv

means

of a remote-cbntrol

device).

(t)

device

using

ri'eight actuators

(a)

and

circujt

supplied

with rectified

alternating

current

(b)

Figure

t1-5b

illustrates

the

circuit

of an

ATS device

used

with

one-shot

ating

elements

are

combined

in

one relay

2ATR

with

an armature

reset

delay

_

To^improve

the

reset-to-pickup

rat

relay

2ATR

is

controlled

bv-the

contac

ATR

rared

for

110 volts

isLbout

f0 vr

mes

disconnected.

Its

auxiliary

contacts

make

the

b5'lupplv

breaker.

which

hai

been.

prglTe+

b5,

the

contact

of

rela-v

ZATy.

To

accelerate

the

operation

of the

ATS

devrces,

the

ttippi"g

of

the

main

pos'er

source

breaker

must

be

speeded-up.To

thi-s

end.

the

iirg.'"*.

shorx,n

in

{igt'

1l-1

and

11.2

have

circuits-which

i.tio.*

ruch

trippioe

o";."tions

$,hen

'uhe

breaker

at the

suppiS

side

of the

main

.u;plj'

tt"n.toril"t

T.

Jo.". It is more

compiicateti

ro

accelerate

the

acrion

of

erb'alri;;.*pi;"

jil;;r;;A;;

-"upplied

from

the

main

poyel-

sources

over

relari;-\'

il;;-it*slission

lines.

The possibilities

are

ls

follows:

(a)

To

protect

the

suppl5'

lines..use-maI,

be

made

of

a iongitudinal

diffe-

rential

protection

which

iiips

the

line

from

both

sraes

in

the

case

of

a

short

circuit.

(b)

Use

ma_v be

made

of

a

device

for

the

breaker

at the

supply

line

side

is

c

stance

l.Uuickl-v

acting

prot.ection

(a

cu

(c)

Tire

line

mal'

beJurnished

wirh

connects

the

line

from

both

sides

in

the

based

on

the

principle

of

protection

r*,it

ternal

short

circuits.

(d)

Use

ma1'

be

made

of der.ices

$,

real

porver

flou'*s

in

the

line.

Examples

e

operation

indication

rvith

the

aid

bf a

:

zing

a decrease

in the

frequencl

and

th

The

best

results

are

obiainei

b_,v

usi:

both

on the

lines

suppl5;ing

the

substa

p-orler

to

the

parallel

]oads.

This

ma]

the

time

relal-,

incorporated

in the

ATS

ment

of

any

type,

to

0.5

s.

i1-3.

A?S

Devicesgs"$

by

Substations

Supplying

Synehronous

Loads

G)

Fig.

11-5.

Circuit

of a.c.

ATS

of

ATS

device

.irrith

r.oltage

relal'

A

typical

scheme

used

to

su

power

to

many

industriai

enterprises

is

nted

b

own

substations

over tu,o

trunk

lines.

Co"or.iia

ra*i^-^ ^f ^^_^-_*^^_-r_

l-.-_l

to

each

trunk

hne

are

o?

ltotaJ.l.ti

L!\'eerl

t,nem.

the

case

of

an

phase

rectifier

b"ds;"t

;;;;;;"; ; i#;"Ir;ilir;;;i";;;.

Generally

this

breaker

is

open.

It is

clbsed

bv

the

ATS

device

in

22*

CIIAPTER

ELEVEN

interruption

in the

suppil,-

to the

section

after

the

supply

trunk line entrance

is

disconnected.

The use

of two

trunk lines

allows them

to

be

used

as stand-br,

Iines

with respect

to each

other,

providing

that

each

section has

a transmissioii

capacity

srrfficient

to

carry

the loads

of both sections.

This

power

supply s-v-

sten

of

industrial

consumers

allows

simple-type protection-

units

ana efS

devices

to

be

useC,

the

high-standard performance

of

*'hich

has

been

conobo-

rated

by

their

application

Ior many

years

on

the

station-service

instaliati-

ons

[1r-5].

During

aa

ATS cycle, the

synchronous

motors

connected

to

the

deenergi-

zed

section

}ose their

slmchronism

with

respect to

the

stand-by source.

ATS

operation ma-v

be

permitted

either

after disconnection

of

the

svnchronous load

oi af t,er

removal

ol its

excitation

and the

transfer

to starting

bperation.

Both

duties

may

be

checked

by the

fact that

the

voitage

across tf,e

tusbars

of

the

backed up section drops

to

a

value

at

Ieast

lower than

65

per

cent

of

the

rated

wnlf l.p Thrrc fho nnorof inn af +ho AT'Q .lorriaa oftar f-i^-in^ *!ra l,-^^1,^- ^+ +} ^

4vu

vr

uuv

t\rv uvrrvv

qruvr

urrlJpru6r

u49 llgqaEl au ugg

main

suppl;"

entiance (foi

insiance,

af"er

ihe

opera*r,ion

of

proiee^uive

reLa-ving

s.vstem) rnust wai.t

for the

voltage

to

drop to the

specified value.

Asynchronous connection

of

an

excited

synchronous

load from

an

ATS

de-

vice

may

not be

recommended

for

the

following reasons:

(a)

Asynchronous

connection current

is many

times

the designed nominal

current of

a synchronous

motor, this

connection

may resuit

in damage

to

the

motOr

[11-6].

(b)

Fossible

asynchronous

operation

which'may

cause the synchronous

mo-

tors

supplied

from

the

other

(intact)

trunk

line to lose

their synchronism, i.e.,

disconnection

of the

two

production prooess

fiow }ines being

supplied

from the

two

trunk

lines,

w-hich

often

cornpletely destro5's the

production process-

(c)

Crrtain

types

of synchronous

motors do

not permit

resynchronization

after asyncbronous

connection

rn'ithout

additional measures being taken

(an

example

is

excitation

removal

and

its subsequent reapplication after recovery

of

the voltage,

or short-time

unioading

of

th'e

motor). Low-speed

synchrooo*

motors

of

piston-type

compressors

have sueh

peculiarities

tl1-?1.

To

speed

up

the

operation

of

ATS

devices,

when

carr-r'ing

slnchronous

Io-

ads, the

ATS

device

circuit

must incorporate

elements

which indicate any in-

terruption

in

the power

supply

from t,he

main source

and remove,

simultaneous-

11,'with the

tripping

of

the

entrance from

this source,

the

excitation

of

the syn-

chronous motors being

connected

to the

given

section

of

the

distribution

sub-

station.

When

necessar]',

the

above-mentioned element

must

give

a

short-time

unioading

to the s-vnchronous

motor at the side

of

the

mecbanism being driven

by

this motor.

Complete

disconnection

of the

synchronous

motors

with their subsequent

manual reclosure

cannot be regarded

as a satisfactory solufion

of

the

problem,

since

the

prolonged

shutdown

of

important

mechanisms

driven

by slnchronous

AI]TOMATIC

TRANSFER

TO

RESERVE

SUPPLY.AND

EQUIP]TfENT

341

which

has

its s;mchronous

driving

motor

connected

to the

second

section

of the

distribution

substation,

shutdowi

of

one of the

mechanisms

can

sause

no d.istur-

bance

to

the production

process.

As

mentioned

above,

elements

that

can

indicate

an

interruption

in the power

supplS',to

qny

of the

distribution

substation

sections

may be'real

fower

irty;

controlied

b5r

the

operation

of an

underfrequency

relay

tri"-ri

-or-"

,5r.y

,..prir:

-

sive

to

freguenc-r'

change rate

or

on" trsponding

to

ihe

d.ifference

between

the

freq_uenr.ies

of

the

two

iections

of the

diitribution

substation

t11-sl.

It

should

be

remembered

that

the

voltage

reiays

*"iii"g

for

the voltage

drop-across

the

deenergized

section

pay

not

Function

for

a

fois-time

v'hen

the

synchronous

motors

aie

not

tripped

"od.th*ir

fields

are

not"discharged,

i;;

the voitage

wili

be

maintained

by

the

coaiting

synchronous

motors

(for"several

seconds).

In

order

to

speed

up the

operation

of

the

ATS device

started from a voltese

reiay. provision

should

be

made

for remor:a]

of the

excitation

J

th. =:*;h;;:

nous.rnot,ors

(or

for

their

disconnection)

after

the

action

of tire protectoi

on

the

suppl-ving

line

or tbe

transformer,

w-ith

the

breakers

of

the

main

and stand-bv

suppi_v

entrances

being

tripped

at

the

same

time.

I

1-4..

ATS

Device-s

with

Standard.ization

Contrcl

Sta{.ions

motors

wually

results

in disturbance to

the

production

This may be

ltrecl only

w

utoown

mecnan r

one.

ror

out.

Its

auxiliary

contacts

IL-BC-I

open

the

circuit

of

,he

circui'i

ior

ciosing

t,he

cont,actor

R-EL found

stand-by

supp)v

entlance).

After the

armature

rops

nnn hc r^A

yrrlJarED

the

tiistribution substation

sections

works

into same

Iine as

the

mechanism

in

the

circuit

of

Entrance

2

(a

Barzam A.B. Automation in Electrical Power Systems (Системная автоматика)

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