IEEE TRANSACTIONS ON POWER APPARATUS AND SYSTEMS, VOL. PAS-88, NO. 6, JUNE 1969

500-kY AC Substation Design Criteria

Summary of Industry PracticesIEEE COMMITTE REPORT

Abstract-In order to determine major trends in 500-kV substationdesign practices, a survey was made of ten major electric utility sys-tems in the United States and Canada. These findings are presentedin tabular form for easy comparison of design features. Majorvariations in data are identified by an asterisk and are explained inthe accompanying discussion following the tabulation. These datashould be invaluable to those companies having 500-kV systemsunder study and will serve as a permanent record of the state-of-the-art. The Working Group has prepared similar data on Hydro Que-bec's 735-kV system and American Electric Power Company's 765-kV system, which will be published in a separate report.

INTRODUCTION AND CONCLUSIONS

THE 1960's will be remembered as the decade that saw the500-kV story unfold in the electric utility industry of the

United States and Canada. The first systems were placed inoperation in 1965, and since that time all ten surveyed have ac-

cumulated sufficient operating experience to confirm the validityof their design in varying degrees of satisfaction. Since the survey

was undertaken, additional systems have been placed in serviceor are in advanced stages of design (Fig. 1).These data generally represent the latest design criteria of the

participating agencies. They do not necessarily mean that allstations constructed by these companies conform to the exactcriteria, since individual circumstances usually require some

design change or modification. Indeed, some companies used morethan one design and changed criteria with experience and to meetspecial conditions.

This design information represents a Herculean effort on thepart of the companies which pioneered in this field; and the suc-

cessful operation of these systems is a tribute to the designers,the constructors, and the equipment manufacturers who partici-pated in this exciting venture. This summary should be an

invaluable reference and guide for the whole industry, and espe-

cially for those companies contemplating 500-kV design. It is notintended, however, that this information be used as a substitutefor an independent engineering study of the total situation in-volved. Although these data reflect the individual design phi-losophies of the ten agencies involved, they could not possiblyshow the alternatives considered or give the reasoning behindthese decisions. Therefore, the committee members cautionprospective designers against the temptation to use this informa-

Paper 69 TP 45-PWR, recommended and approved by the Sub-stations Committee of the IEEE Power Group for presentation atthe IEEE Winter Power Meeting, New York, N. Y., January 26-31,1969. Manuscript submitted September 13, 1968; made available forprinting November 7, 1968.Members of the Working Group of the Transmission Substations

Subcommittee of the IEEE Substations Committee are: Paul R.Dolan, Chairman; L. M. Berry, R. R. Blanchard, 0. R. Compton,C. L. Donaldson, Jr., G. E. Hertig, W. J. Leister, E. R. Taylor, Jr.,J. A. Maneatis, L. M. Gordon, J. B. Oliver, R. J. Perina, E. S. Raila,H. N. Scherer, P. H. Shoun, R. F. Stevens, G. W. Supplee, E. York,and C. E. Zanzie. Former members who contributed are: W. G. Case,H. E. Lokay, D. A. Mitchell, V. P. Rader, and E. R. Snyder.

tion verbatim and out of context with the total design settingfrom which it is taken. Certainly every number listed and ev7eryvalue shown would require an explanation far beyond the scopeof this report. For additional information on the individual systemdesigns, it would be best to first review the supporting bibli-ography referred to and then follow up with the particular com-pany involved.

DISCUSSION OF MAJOR DIFFERENCES IN DESIGNCRITERIA TABULATIONS

Allegheny (by G. B. Hoffman)

Supporting Bibliography:[1] W. C. Guvker, J. E. O'Neil, and A. R. Hileman, "Right-of-

way and conductor selection for the Allegheny power system500-kV transmission system," IEEE Trans. Power Apparatusand Systemns, vol. PAS-85, pp. 624-632, June 1966.

[2] W. C. Guyker, A. R. Hileman, and J. F. Wittibschlager,"Full-scale tests for the Allegheny power system 500-kVtower-insulation system," IEEE Trans. Power Apparatusand Systems, vol. PAS-85, pp. 614-624, June 1966.

[3] A. R. Hileman, W. C. Guyker, R. W. Powell, W. A. Richter,and J. WI. DeSalvo, "Insulation coordination in APS 500-kVstations," IEEE Trans. Power Apparatus and Systems, vol.PAS-86, pp. 655-665, June 1967.

[4] A. R. Hileman, W. C. Guyker, H. M. Smith, and G. E.Grosser, Jr., "Line insulation design for APS 500-kV system,"IEEE Trans. Power Apparatus and Systems, vol. PAS-86,pp. 987-994, August 1967.

[5] G. B. Hoffman, A. R. Hileman, and W. C. Guyker, "Alle-gheny power system 500-kV system design," Proc. 1965American Power Conf., vol. 27, pp. 962-970.

[6] G. B. Hoffman, J. K. Dillard, and A. R. Hileman, "Selectionof line insulation for APS 500-kV system," CIGRE, Paper410, 1966.

[7] "Report tests on designs for 345 500 735 kV," ElectricalWTlorld, pp. 50-51, 102, November 1, 1965.

American Electric Power Service Corporation (by H. N. Scherer,Jr.)

Equipment:Item C.3: A 1600-ampere disconnecting switch was selected,

since this was greater than the maximum line interchange currentexpected in the future and would also be greater than the maxi-mum installed transformer capacity connected to the 500-kVlines.The 500-kV stations are not really substations but are 500-kVlines feeding 500/345-kV transformers that are then tied to the345-kV station buses.

Item E.1: Lightning arresters were specified on the basis of60-Hz sparkover and seal-off voltages and maximum line dis-charge thermal capacity. 384-kV is above the maximum dynamic60-Hz overvoltage that can occur on this system. It is AEPgeneral practice to select the lowest rating arrester that cani be

854

IEEE COMMITTEE REPORT: 500-KV AC SUBSTATION DESIGN CRITERIA

Fig. 1. 500-kV and above tranismission systems in the Uniited States and Canada, in serviceor to be completed in early 1970's. All lines that are not designated are 500 kV ac.

used on our 60-Hz systems with the aim of achievinig the lowestpossible BIL for the transformer.

Arkansas Power and Light (by R. W. Toler)

Electrical Station Design:Item B.3: This phase spacing was utilizedl to allow the in-

stallation of three 500-kV phase transpositions in the substationl.

Supporting Bibliography:[8] J. T. Henderson and R. W. Toler, "Low profile pedestal bus

design used in SCEC-EHV substations," presented at theIEEE EHV-AC Transmission Conf., Richmond, Va.,October 4-6, 1965.

[9] R. N. Newsom, S. B. Nickelson, R. W. Toler, MI. S. AIerritt,H. A. Riesch, and F. W. Smith, "Staged tests on the TVA-SCEC 500-kV interconnection between Johnsonville andWest Memphis," IEEE Trans. Power Apparatus and Systems,vol. PAS-86, pp. 1389-1399, November 1967.

Bonneville Power Administration (by R. F. Stevens)

Electrical Station Design:Item B.3: The 20-foot phase spacing is electrically adequate

and is adopted for economy of space and, more importantly, tominimize length of crossover buses.

Item B.6.e: The height of the main bus above ground is only23 feet, the same height as the bay bus. This is for reasons of

convenience and economy and also provides a lower profile. Thismakes it necessary to bring two phases of the bay bus "up andover" where they connect to the corresponding phases of the mainbus. It is these crossovers that account for the 41-foot heightshown under item C.4.e.

Supporting Bibliography:[10] R. F. Stevens, I. T. Davies, and M. N. Marjerrison, "BPA

500-kV transmission-line and substation design," IEEETrans. Power Apparatus and Systems, vol. PAS-85, pp.687-695, June 1966.

Keystone Project (by C. E. Zanzie)Electrical Station Design:

Item C.4.a: A bundle of three conductors per phase was usedfor substation bay downeomers to minimize corona in the areawhere conductors run parallel to the leg of the backbone strue-ture.

Ultimate Substation Layout:Item A: The maximum open-line voltage of 650-kV is a cal-

culated value based on the following situation. Since it would bepossible to have two lines connected in series between source andline open end, a figure of 260 miles of 500-kV line was used to cal-culate the maximum open-line voltage. The condition of no loadbetween source and the line open end was used. There are no re-actors in the Keystone 500-kV system.

8.5)

500-

kVSAC

Substa~tion

11lc

Lric

ali

Dcsign

(Cri

teri

a

Alt E1

ItENY

ALEI

ARK.

Pt

L.BP

AKE

YSTO

CON

PD-i

tOI

E3'CR

CO.

TVA

IfP

(Co.

RL

ECSR

ICIA

Si

ESKI

__N_

A.'

Minimum

Clearance

'Transrnession

(Metal

tofe

tal)

Stationsm

(Peners'ting

Stations

1.Phase-to-phase,

ft.

2320

20l(

I2-

PO-20n

2r-a

2.Pi

vse-

Lo--

roun

d,ft.

P115IT,-(1113_______

3.Al

enve

enoiiv

-L'i/

111s

idi

vilvi

lie

Cl______

~~~31

_30

Va

stI'

f)aram

eters

I.0)rireit

rain

me32

0030

336c

3000

OA3%

3--

-IotO

-77-c

4CQ

~~~~~

~Cri

_-O

'4

2.Ty

,pe

(rig

id,

tension)

Rigi

dTensioi-

Rigi

dRi

gid

Rigil--

Pigid

Rigi

d-e

sici

Tension

Tens

ioi

d_

3.Ph

ase

spacing,

ft.

2823

35*

20*

2525

2526

2525

___________________________

25(Rkrs.

______

______

_____

4.Mi

ax.

distance

between seipports,

ft. ~~~~~~~56100

-Sta.

ARi

ng53

43Li7

89

C0

Ea.

57__

5.BIL.

kV18oo

1530

I80

1550

iSOC

180

180

100

i00

2551

_

6i.Co

iidu

ctor

sa.

iiberpe

rph

ase

12

i1

11

13

23

h.Ci

aivi

eter

,in

ches

5'RS

1.65

4,5,

6CR5

5IR

54.5

4-1/

28*

1.762

i.68

ie

c.Ty

pe60

61-1

,620

49mcmii

Altuhe

Altu

he4"

Allute

Altu

beAl

lute

2156

memi

l2,034.5

mcmii

249

nccc

til

AlAl

loy

tube

ACSRE

S____

ched

uie

80AC

SR6"

Allute

5005

AlAlloy

d.Subconductor

spacing,

inches

18

18

431'

12

e.((ieight

shov

egr

ound

ft.

(VSupport)

6029

30V5

~23:_____

4753-/C

6o

_____

___

~~~~~~~~~~~~~~~~~~~

J~~~~~~~~~

saLsics.)~

~~~~~~~~~~

~~~li-v

L-!(-I

.L.ii

rrev

itca

liij~

",2O

(131

01iI30A

C,0

0/40

0__

___0

0119

3C17

'Tv-p

(1ensiot

rigi

d)RIij'Tl

cr7ie

PigiJ

CclooenseioliI

iierirCeso

3.9

1__

_iC

~~~~~~

~~~~~~

~~~~~~

~~~~~~

~-igid

Piii

_____

__

iS*ad

l ay

widt

h.ft.

-90

00__

_10

0___

nL5

0-)

100

4.ayconductors______

-.imPer

-ner

phas

p12rs

__

1.Di

amet

er,

inches

SJPC)C,e

i,

5CR

.P1

__

12I

ui__

~~~~

~~

~~

~~~~~~

~~~~

~~~

~~IRS-_L_

j,5

4.51

c.u25

3-1/

i

Cfe

Co(-il

-1,

2040

1(iw

iA11tile

A1.

iCt91il

Clci

Slib1

1li

345

ii1

Alte-

lbeAC

APAAIA1

A535,0AC11)01

TikI

I:.

IiSiii

Alti

be411063V

d.`J

iitc

ondu

icto

r,spseSci

inclhes

ii11.3

.1

Heig

htat

ove

grosind

ft.

(@Su

ppor

t)S

0315

9~

32_

__~

i1.

10232

D.Pn

suil

ator

s

1.Su

spen

isio

nCon

24Un

its

24un

its

2211nits

25Unitt

26Un

its

30-35

Units

30UnitE

IilE

5-3/

4ii

x10

'5-3/41'

x10

f6-3/411

ail

5-3/4ii

xloll

5-3/411

x10

l5-

3/411

x10"*

3li5-3/411

x10

"

*See

discuission.

H z zrn p H;p ~- CI z

50(-cc\[

ACSubst-tion

Elee

tric

alCDa

esigns

Critit

'ia

ALLE

.JGI

IEAP

Ott'AR

.5.

'5PA

-~,

Sat

.i(

!CC

0".7-.

ipCC.

[1.

"LEtC

-PICA

iTA

10`

DESI

SuIp

port

5Un

it~aper-ds

iTtY

'it,

'apered

IIuniit

')'n

itpi

t'it

ntIC)at

Stat

ion

Post

"L:t

ic'

oat

tant

ion

',os

tatu

rSt

atio

nSt

Citatiosna

'iia

)'tn

atCa

itti

o3.''i"

"'c

lt

,inch

es

33e

3_Sw

itch

int'

a sip

e,tn

-10

15:

'St(In5 IC

kna

',T't

CCII'T

['IL'apM

na.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~)O

. 10

e

i.Tr

ansf

orme

rAr

ea______

1.tI

rans

form

erconnection

Rigi

d_1C-nsi-or

Rgi ot

_Rig

i-d~

Rigi

d-RigidefitenireicRgi

(Tension/Rigid)

___e

nsio

n___

____

sioTenior__igid

2.Me

thod

sofco

nnec

ting

CoSpare

Reno

vei

Sparc

once

,Re

move

IRemoveSpar&

1-sPe

ove&

Reov

eS&r-

IaSparereBPusSSparc-anusSpare

ius

spar

e(no

spare,

spare

Repl

ace

Repince

Replace

3-Nto

Spar

ebus,

remoie

&replace)

3.e.c

rtianry

(ius)

one

None

Rigid

Rigi

dRi

gid

orRi

gid

Rigi

dRi

gid

Rigi

dC~one

(none,

rigid,

tension)

Ins.

Cable

e-rtiary

Reactor,Area

on''__

_one

1,

Reactor

connection

-or-

,eliNonse9

a._Y-pe

(rigid,

Tension

_______

Rigid_______

_______

Rigid

Rigid

Tens

ion

Rigid

___o

ne___

t.

Phase

sp'cing,

ft.

76__

2.1.',inina,m

distanice

f'rorr

reactors

tofe

rrou

snl

ater

iais

,ft

._____

IaT

_______

3.CMethod

ofswitching

AC-

Disc.Sw'sa.

ACe

inACt'

per-

AC"

per

Air

eintt

1i

Reactor

tos.

RCa'

etor

ton.

tin

lay

ing

T.'ype

Directionat

DirectionaT

Diri

ctio

nat

Phas

eCoi'._

Plr.

aonqp.ttri.)

Dire

ctio

naT

Phas

Coat

.th

asr

Corap.

T-Ce

tCt

'tic

Dire

cito

nni

Coinparison

Conp

aris

onCo

nrp'

iris

onPi

stan

nc'i

Pj1Drie.

Pisi

.P

neContactno

n'(P

iidendnt)

n./diar:ct

Sura.

Pir.

Corn

p.t'o'.eparo'.

,tgtRIn

Rita

ysra

a'r

nnid

T'rct'fr

n.i)

e'raisair

crit

Ce

I0

_______________

~~~~ri

-Pcaunt

('-ace

aup)

a'C

i.OR

2.Ch

anne

lPT~

T-TPItC

tPLC'

PT'

"141IC

(tni

ttil

)iT,(

TLC

iCC_,tW

LaC1.

Conm

muni

cati

ons

for

disp

atci

-Ci

lSihield

ieOHC

Shie

id"~P

A',tAtaI

nail

ire

PLC

it''C

iChicl

:PS:',

HShield

Ct'tSttCii

ing

area

load

frej

uenc

y,'

Sire

sand

t%ires

t%irc

tine

C".

'ire.-

administration

Carrier__

1.Control

cabie

Shie

ided

,Gr

d.Unshielded

Unsh

ield

edSh

ieil

den

Shie

Tded

'Tnshielded

tUns

hiel

d-d

Shii

elde

dShielded

(shielded,

unshieaded)

aito

then

-ds

except

for

aud-

den

pressure

rela

ycir

cuit

s~

A.

Transformers_______

i.'Typ

eAuto

Auto

trar

s-Au

totr

ans-

Auto

tra-

ns-

Aato

(2zaics)

Auto

tran

s-A-

uton

tran

s-Autotr

ans-

3Windnie

Auto

tran

s-fo

rmer

former

dorm

er-forner

formic

forn

acr

fors

erS.

311

catin'

,"

A21

0SiC

~~~

~~~~

~~~~

35C2

10'C

/C/i

5/0

90SC279/350

360

118046

00145

046004

75060

/~~

2oo12CC

450/

600/

750

5500

+ti,

1'12

CC3)0/51T

50ST6288360

'CCpC

ollo

CC5eoTDCi

2:TS

Ctt/2c0

3.Vt

olta

ge,

Cck5CC/138

n5o

o/16

1/13

.R,

CC23

0S

CC5o623885.25'

500/

lr1/

13'2

C00/23C

/115

5-'

5CC

/3lt

5/T3

.2~~~~

~~~~~~~5

00/1151/

13.5 2

5/SiT.

1-51/

5CC

230/I3.8

525/

238/

28.2

9'25/23t/a3.8'

D-eita

i'ap

/s5-0/o

/13.8

34_

__._

41.Single

orth

ree

pDhnse

3RlInse

Single

Sing

leSingle

7Ra

niks

ofSi

ngle

"3

t,ia0g

cSi

ngS

Sinigle

Single

&3

Cingle

Phas

e?haie

Phas

e2~

Phas

e_5.

BIL,

klvwinding

&13

CCWi

ndin

g13CC

1425

514

125

S142

5a

55C

1675

Winding

11425

S'indin."

1425

1675

Wind

ing

1300

iWinding

bushing

1550

Rushing

1800

Bushing

iiso

Bush

ing

1590

0'u

shin

g&Ru

shin

gC.

~~~~~criinry

rating,to

neT~~

~~~~~~

~~~~~~

~~~~~~

""""'

~~~~

353O

to13

352

3535

30cT

hra

5CA

35No

ne13.5)

(Rea

ctor

Pond)

Rati

ng)

e.

Circuit

'm-rakers

!one__

I1.mi

n.ratit",

t'J,

A35

,000

________

35,000

35,000

38.0

0030

,000

35,0CC

35,000

-3iCCC0

35,000

2.ISP,

kiC

1OC

1500

155C

aC15

001500

1CC0

1CC

1550

*See

discussion.

I_____I__

g to tI., 0 z t Si)z0

m

Pt Pt PIt 0-3

C.T 00

5(0(-1.1VAC

Substationl

Ele

2t'lic

daD2

eign

Critel

iimi.

AILE

(ill

ENY

ALP

ARK.

P.L.

BPA

KM'-fST0

ELOC'

(DRO

P0

1'Fl

SCPE

COVA

VLP

C(.

3.CuLrrent

Yrat

ing,

A30

0030

0024

0030

002500

3000

3000

3000

2000

x~~

~~00__

4.Sw

itch

iing

sirge

resi

stor

(closinlg)

Yes

Yes

Yes

Yes

a'Ye

sYe

sYes

Yes

C.Di

scon

nect

Swit

ches

1.lorizontal

or

vert

icnl

I"er

tica

lfi

oriz

onta

lVertical

Vertical

'.er

tica

lVe

rtic

alcr

tic

al.e

rtic

alIo

rizo

cnta

l-!l

oriz

onta

:Irenk

Doub

leFr

eak

Hori

zont

alan

dCe

nter

Rota

-Douible

End

Vertical

tion

Treak

Reac

hVe

rtic

alReach

Vert

ical

Freak

2.itL

,kV

T56Y0

1550

1800

1550

1800

1800

1800

1800

1800

1a.

eSwitc

hoen

a5

613,6"

Vert

.15'

i4,-10ol

17'

(Mietal

to17

-1/2

'(2

)9'

-8"

17-1

/2'

clearance

~~~~

~~~~

~~~~

~~~~

~~~~

~~~~

~~~~

~~15

'Vert.

feic

tal)

lforiz.

Reach

17-1

/2'

ci

_~~~

~~~~~~

16,'ertciReachl

3.Cu

rren

trating,A

3000

i6oo0'

_3000

2400

kl25

000_

oo1000

3000

3000

3000

20OIl

4.surge

supp

ress

ing

No.0

.o.o

Provisions

For

.'o.'o

.0To

riZ.

Mc.-

resi

stor

Future

Yes~ Vert.Reach-1l'o

5.~y

peof

oper

ator

3Pole,

3Po

le,

Mlot

or3

Pole,

Motor

3Pole,

Motor

3PloleManual

3Po

le,

Moto

r3l

Poie

,cl

,anu

alSiagle

Pole,

3Pole,

M'ot

or1

3Po

le,

I,anual

'01c

tr3Po

le,M

otor

Mianual

Hydr

auli

cna

eum

atic_

Shun

tReactors

lonJone

one

_one

1.Voltage,

kM50

0&13.8

553p&34.5

________

027

.652

3455n13.40

11.47

_______

2.T4

mind

ing

1STI

,kV

1425

t110

1350

C200

1800

Ic11

01550

511

01550

",110

1(75

~-110

Neutral

3.Singlc

or

mreP

hase

T-ot

hco

thSingle

Single

Sing

lcSingle

'hr

e_E.

Ilig

htni

ngArrester

Ratings__

__

1.Rank

376

384

kV*

410k:

396

kV42

0k.

,44

4k

480

kV,

4311

kM.420

k'.7

44Ick4

1307

-f4f8__

2.Shunt

reac

tor

(_500

k.l')

l4on

e42

0k.

'41

0k.

!lo

ne48

0kV

,43

1k'.

460

k'I4(

6~kV

492kV_____

F.Series

Capa

cito

rs',

one

-lone

None

________

one

None

______

________

n1.

kotae1.00

k.,

525

k'.__

____k___

-2.

BILt

IV__

1800

1800

1600

3.M'

inim

umc

clearance

a.

Phase

to

phase,

ft._

17

22-1

121

b.Ph

ase

toground,

ft.

______

1216.

15_

__

___

______

C.Insulators

a.Cmp

port

SIJ

nit

6Iinit

5ni

Stationi

Lo.t

__

______

Stat

ion

Past

Sta-

tion

ilo

st________

______

t.'S

nium

aleakage

dis-

tance,

inches

350

432'

3O__

Pote

ntia

lTransformers

&Co

upli

ngCouipling

Capa

cito

rCoupling

Coupling

Coui

plin

gCoupling

Couipl

inig

Coupling

Devi

ces

Capa

cito

rCapocitor

Cascade

Pote

ntia

lCapacitor

Capacitor

Capacitor

Capa

cito

r'a

paci

tor-

Capa

cito

rand

Rot.

Tlra

nsfo

rmer

IPotential

Potential

SCascade

Devices

Devices

~~~~~~~Device________

1.',

olta

ge,

kV31

8P

to50

030

0LtoI

500

500

500

525

52300

Lto

N287

LtoS

2.Rinding

FIL,

RI16

751550

1T06

1800

1800

1550

,3.

'shing

'IET,

k.16

001

Cc1800

oclan

lCt25

1800

1100

1800

Rous

ing

'See

discussion.

I's I-0 zx I'd2 z F6- F-i c's q ;D ct:z 35

;rl .r c4 )J2

,

Q512-

zI c.

500-kV

ACSu

bsta

tion

Ultimate

Layo

utand

Envi

roma

lent

alPactors

ALLEGHENY

AEP

ARK.

P.&

L.BPA

KEYS'i'ONE

ON'I

'.HY

DRO

PE

SCE

CO.

TVA

VEP

CO.

I.ULTIMAIE

SUBS

I:AT

ION

IAYO

IJ'T

_A.

H4ig

hVo

ltag

e,kV

Nominal

500

500

500

525

0050

0500

5-25

5Q0

--

Maximum

550

550

550

550

550

550

550

550

550

525

Maximum

Open

Litne

55665

0*55_

05Y

600*

550

L.Low

'oltage,

kVNominal

138

345

161

&11

523

023

023

0220

220

161

Maximum

145

362

51241.5

253

242

230

230

169

C.Ba

sic

Switching

Sche

meRreaker

&1/

2Ri

ngCo

nver

t-Ri

ngCo

nver

t-Straight

Pus

Brea

ker

N1/2

Prea

ker

1/2

Breaker

N1/

2Ring,

Main

&Breaker

&1/2

500

kV&

tibl

eto

tible

toRi

ngBus

Transfer

Zig-

138

kRB_reaker

&1

2Br

eake

r&

1/2

Breaker

&1/

27.,

gD.

No.

and

Capa

city

of4

P2@

1P40

03

P4@

66

44

@2

R2@

Tran

sfor

mer

Bank

s35

0MVA

each

600M

VA/B

ank

1@

800

900M

VA/R

ank

650M

C/A/

Pank

900M

VA/

300I

/A/

750

orlOOMYVA

10OOM'VA/Bank

1200

MVA/

Bank

750M

VA/B

ank

Bank

Bank

per

Hank

E.No

.of

Transmission

500

kV4

210

86

148

G08

88

Lines

Low

Volt

age

10-1

38kV

21

345

12@

161&/or

128

188

1210

122

0kV

16P

161

kV12

11(_

F.Capacity

ofTrans-

500

kV17

0013

001500

1200-1500

2400

2000

2000

2400

(Sum

mer-

1000

2000

1000

mission

Lines,

MVA

'lhe

rmal

)Lo

wVo

ltag

e250

(138

kV)

(345

kV)6

00(161

kV)300

300-400

400

600

600

230

kV-636

800

200

400

(Summer-

_|hermal)

II.

ENVIRONMENTAL

(ACTORS

_A.

Maximum

Elev

atio

n,ft

.11

0012

003000

5400

1000

_2000

2000

4000

1000

3500O

B.Te

mper

atur

eRa

nge

-20

to100OF

-10

to11

0°F

0-1200F

-30

to110°F

-40

to13

0OF

-C0

to10

5°F

0to

115OF

0-110°F

-20

to110°F

-30

to110°F

C.Max.

Desi

gnWind

Vlel

ocit

yNo

100mi/h

Wind

NoNo

100mi

/hWind

Rare

57mi

/hNl

ind

100mi/h

Wind

90mi/h

Wind

100mi/h

Wind

and

Gust

Fact

or1.

3Gust

1.25

Gust

130mi/h

Gust

130mi

/hGust

D.Earthquakes

Noea

rthq

uake

s(To

NoYe

sNo

Mino

rYe

sYe

sLight

(To

but

designud

0.2g

Str.

0.2g

Str.

for

mino

rmin-

Desi

gnDe

sign

ing

falls.

_E.

Degr

eeof

Contamination

Ligh

tto

Mode

rate

toNone

Moderate

-Moderate

Mini

mum

Moderate

toModerate

toLight

toLight

toand

Type

Moderate

(Tea

vy1

-Possible

Heav

yHeavy

Heavy

HTeavy

Indu

stri

alHT

eavy

Cont

ami-

Agri

iclual+l

Agrioiultural

Industrial

niat

ioh

from

Indu

s-tr

ial

Power

Plant

Coastal

Pog

_

*See

discussion.

IEEE TRANSACTIONS ON POWERI APPLTRUlS.ANDI) SYSTEMS, JUNF 1969

The condition of 650-kV at any open-line ternminal will occuronly during the time after closing the line source breaker and be-fore application of load. It is contemplated that the condition willoccur not more than 3 minutes a year, average, with a maximumperiod of 15 minutes, which might occur once every 10 years.

Ontario Hydro (by L. M. Gordon)

Equipment:Item B.4: Ontario Hydro has only a single 500-kV linie;

hence high-speed reclosing cannot be used, and this removes themajor need for closing resistors. The line surge withstand wasdetermined by other factors and is sufficient to enable the line tobe picked up without using closing resistors. The circuit breakershave provi;sion for adding closing resistors if necessary when thesecond line is added and high-speed reclosing is used.

Item E.1: Lightning arresters purchased for protection of the500-kV windings of the Hammer and Kleinburg autotrans-formers have switching surge characteristics designed to protect1675-kV BIL windings. These arresters are constructed with twotaps, rated 480 kV and 432 kV rms, and designed to provide a15-percent margin between the maximum switching surge spark-over and the switching surge strength of the transformer whenconnected on the 480-kV tap (full arrester). The 432-kV tap wasprovided so the protective margin could be increased in thefuture when dynamic over voltages on the 500-kV systems areexpected to reduce.

Pacific Gas and Electric Company (by J. A. Maneatis)

Electrical Station Design:Item A.3: This clearance represents the height of the miiain

buses above grade and is based upon the height of the cross busrunning under and connected to the main bus, plus the nominalphase to phase clearance from the cross bus phases to the mainbus phases (28 ft 6 in + 25 ft + 6 in = 54 ft). Roadways crossunder main buses only and run parallel and between adjacentcross bus bays.

Item B.6.b: The use of 8-inch IPS aluminum tube for themain bus was based upon the requirements for current carryingcapacity (4500 amperes) and mechanical strength and deflectionconsiderations. Because of the bus and bay arrangement, onespan of main bus in each bay is 75 feet between supports. Toeliminate additional supports, meet deflection criteria, and pro-vide margins of safety for short-circuit forces, schedule 40, 8-inchaluminum pipe was selected.

Item C.3: A bay width of 150 feet was utilized to permitsatisfactory termination of multiple parallel 500-kV lines enter-ing the bus from the same direction. Pacific Gas and Electric 500-kV transmission lines are of the single-circuit flat-configurationtype with phase conductors at 43.5- and 50-foot separations. Inpractically all cases these lines enter the station at an angle andterminate on separate lineside dead-end structures.

In addition the 150-foot bay arrangement provides adequateclearances to accommodate 500-kV series capacitor banks locatedat the line terminations.

Item D.1: The use of 30 and 35 insulator units in suspensionand dead-end strings was selected on the basis of adequately with-standing switching surges up to 2.3 per unit under wet or con-taminated conditions. Stations in normal environments, consider-ing the long, dry California seasons in the Pacific Gas and Electricservice area, were equipped with 30 units with provision foradding more. Stations in severe environments, such as is found incoastal plant locations, were equipped with 35 units.

Item D.2: The use of a 6-unit post was selected on the basisof adequately withstanding switching surges of 2.3 per unit underwet or contaminated conditions. This number of units provideda means of obtaining the desirable leakage distance by utilizingthe standard type of units available at the time.Equipment:

Item F.4.a: The use of a 6-unjit post was selected on the basisof adequately withstanding switching surges of 2.3 per unit underwet or contaminated conditions. This number of units provided ameans of obtaining the desirable leakage distance by utilizingthe standard types of units available at the time.

Item F.4.b: Because of the long, dry California seasons in thePacific Gas and Electric service area, deposits of dirt, argiculturalsprays, salt water spray, and other contaminants are not washedoff by nature, except during the rainy season. By experience withour 230-kV and lower voltage systems, it has been necessary toprovide substantially more leakage distance for insulators thanwould normally be required. 432 inches were extrapolated fromour 230-kV system and were considered the minimum for supportinsulators.

Southern California Edison Comparty (by P. R. Dolan)

Electrical Station Design:Item D.1: Thirty 53/4- by 10-inclh insulator uniits per string

were selected for the substation suspension insulators in order tomeet the minimum 60-Hz requirements dictated by the degree ofcontamination in the area. Included in this number are threeunits added to provide the substation with a 10-percent marginabove the transmission lines.

Supporting Bibliography:[11] P. R. Dolan and A. J. Peat, "Desigi; of the first 500-kV

substations on the Southern California Edison Companysystem," IEEE Trans. Power Apparatus and Systems, vol.PAS-86, pp. 531-539, May 1967.

[12] P. R. Dolan and E. W. DuBois, "Design criteria for theSouthern California Edisorn Company 500-kV system,"Proc. 1964 American Power Conf., vol. 26, pp. 844-853.

Tennessee Valley Authority (by Pauil H. Shounl)Electrical Station Design:

Item B.6.d: The two-conductor strain bus supports the fixedcontacts of breaker isolating pantograph switches, and the 3-foot7-inch spacing was required to ensure proper operation of theseswitches under winds up to 90 mi/h or gusts up to 130 mi/h.

Item D.1: At generating stations, 32 units are used invertical insulator strings and 26 units in horizontal strings tocompensate for contamination resulting fromn the large coal-burning power stations.

Equipment:Item C.4: Our main and transfer bus switch scheme required

that long sections of bus be de-energized by means of disconnectswitches; therefore, these bus sectionalizing switches (verticalbreak or center rotational horizontal) are equipped with resistorsto limit switching surges. The vertical reach, breaker-isolatingswitches are not so equipped.

Ultimate Station Layout:Item A: The design level for rmaxirnum open-line voltage is

600 kV at the remote station. The 600 kV include the maximumsource voltage plus the Ferranti effect on the line upon energizing.

860

IEEE COMMITTEE REPORT: 500-KnV Af SUBSTATION DESIGN CRITERIA

Supporting Bibliography:[13] R. M. Milton, H. H. Leech anid R. C. St. Clair, "Tennessee

Valley Authority's 500-kY system-step-down substationdesign," IEEE Trans. Power Apparatus and Systems, vol.PAS-85, Ppl 36-46, Jai-nuary 1966.

[141 T. M. Swingle avid H. I. Dobson, "Tennessee Valley Author-ity's 500-kV systeImi-communications," IEEE Trans.Power Apparatus and Systems, vol. PAS-85, pp. 47-53,January 1966.

[15' A. C. Pfitzer and G.M. VWilhoite, "Tennessee Valley Author-ity's 500-kV systemn transmission line design," IEEETrans. Power Apparatus and Systems, vol. PAS-85, Pl'28-35, January 1966.

[16] F. Chambers, 0. S. C. Hamiimer, and L. Edwards, "Ten-nessee Valley Authority's 500-kV system-system plansand considerationts," IEEE Trans. Power Apparatus andSystems, vol. PAS-85, pp. 22-28, January 1966.

[17] C. McCord, L. R. Sellers, and E. R. Snyder, "TVA'sJohnsonville 500-kV switchyard," Proc. 1964 AmericanPower Conf., vol. 26, pp. 1061-1073.

[18] R. C. St. Clair, "Pantograph disconnects save on 500-kVsystem," Electrical World, pp. 48-49, May 29, 1967.

Virginia Electric and Power Com),pany (by 0. R. Compton)

Equipment:Item B.3: The entire initial 500-kV project was designed oni

the basis of the ultitnate needs. It was decided that 1700 MVAwas the maximum loading of long 500-kV lines without seriescapacitor compensation. Since we were designinig for our ultimateneeds, the 2000-ampere switches are adequate.

Item C.3: Disconinect switch current rating was selected tomatch the associated circuit breaker eurrent ratings.

Supporting Bibliography:[19] C. L. Wagnler, J. AIM. Clayton, F. S. Young, and C. L.

Rudasill, "Insulation levels for VEPCO 500-kV substationequipment," IEEE Trans. Power Apparatus and Systems,v-ol. 83, pp. 236-241, March 1964.

Discussion

Frank W. Smith (Tennessee Valley Authority, Chattanooga, Tenn.):The summary of data presented in this paper will be of lasting interestand value to utility engineers concerned with the design of 500-kVsystems. In preparing this paper. Working Group 64.1 has performeda real service to the industry.

The interest of this paper lies both in the similarity of the pr acticesof the several utilities represented and in the contrasts which appear.Explicit reasons are presented in the text of the paper for many ofthe practices whieh at first glance appear unusual. However, onemust also conclude that basic differences in philosophy are reflectedini some of these contrasts. The spread in basic insulation levels, thedifferences in protective margins, the utilization or nonutilization ofcontrol cable shielding or surge suppression resistors on switchesrepresent degrees of liberalism or conservatism in the engineeringapproach of the several companies. Each of these philosophies servesa useful purpose to the industry as a whole, and we may predict thatas time goes on, extremes will tend to become means as experienceproves wherein the optimum answers lie. This is as it should be.

This paper also provides a dramatic illustration of the vast progressin communication between utilities, both private and public, whichhas been taking place over the past several years. Better transporta-tion and communications facilities are partly responsible, and these,too, are products of engineers. But perhaps we can also assume thatrelations between engineers as human beings are on the upgrade;that we are recognizing more and more that in spite of differences inthe structures of our parent organizations, we are all striving for thesame objective: the betterment of the lives of those in our time and ofour posterity. If this spirit cannot only be continued but lcommu-nicated to other factions of our world community, we shall all bericher for it.

IEEE Working Group: Because of the nature of the working groupassignment covered in this paper, we had not expected formal dis-cussion. However, several verbal and informal discussions were re-ceived; and Mr. Smith has in his prepared discussion summed upvery eloquently most of the discussions received. His comments aremuch appreciated and, we think, quite appropriate. He mentionedthe matter of improved communications and human relations involv-ing engineers having different design philosophies and backgrounds.This is an interesting observation and, in working with this group,one could not help but be intrigued by this truth. Even when we werediscussing extreme variations in design criteria, you never once hearda member of this working group criticize another or his company forthe apparent discrepancies in design philosophy. These engineerswere much aware of the fact that there was more than one good solu-tion to an engineering problem-that there were good men on bothsides of a controversy.The objective of this paper was to record and report design criteria

and not to recommend or propose design. Since the presentation ofthis paper, however, feedback from industry has already indicatedthat some design standards and criteria are being revised. This ap-plies especially to the rating and application of lightning arresters.Some companies have been conservative and reluctant to place muchreliance in arresters as surge-limiting devices, but they are liberaliz-ing their viewpoints as modern arresters prove themselves in service.The matter of surge-suppressing resistors and secondary circuit

shielding remains a very controversial subject; but additional study,experience, and tests should soon provide a better analysis of theseinfluences and their significance. Basic insulation levels and electricalclearances are items that are at present under special study byappropriate technical committees. More uniformity and standardiza-tion are indicated and should result in considerable economies to theindustry; however, standardization has its limitations too, sinceenvironmental factors and system operating requirements will varyconsiderably and necessitate continued variations in design criteria.

Manuscript received Fehruary 18, 1969.

861

Mantiscript received April 2, 1969.