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For optimal performance,it is very important that thebusbars arrive at their destination undamaged and free ofcorrosion.To be able to guarantee this, Nedal Aluminium B.V.hasput together its packaging specifications with great care.In consultation wit h the client, a choice can be madefrom three packaging qualities:

Quality C lass IIINedal packs the busbars,per diameter, in stable packages,in which the bars are stacked without distance blocks.The bars are deburred, chips are removed from insidethe bars,and they are fitt ed with a plastic seal,so that nointernal contamination can occur.The bars are alsocoated with a thin layer of oil, for conservatio n purposes.

Quality C lass IINedal clusters the busbars into stable packages.D istanceblocks ensure that the bars are not able to knock againsteach other.W hen the bars are to be transported over longerdistances (transpor tation by sea),t hey are oiled, andpackages are sealed completely in a plastic co ver.

Quality Class IIdentical to Class II,but :for optimal prot ection and conservation,N edal packseach (completely oiled) busbar in plastic, and,eachpackaging unit is placed in a wooden crate.

For further info rmatio n about packaging,please feel freeto request a copy of our packaging conditions fromNedal Aluminium B.V.

PACKAGING GUARANTEES QUALITY

Nedal Aluminium B.V.

Groenewoudsedijk 1Postbox 2020

3500 GA Utrecht N etherlands

Tel. +31 (0)30 - 292 57 11

Fax +31 (0)30 - 293 95 12

E-mail:sales@nedal.com

Website:ww w.nedal.com

NEDAL BUSBARS FORHIGH-VOLTAGE STATIONS

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NEDAL ALUMINIUM

As the first D utch Aluminium Processing Industry,since 1 938, Nedal

has specialised in the development and production of extruded

aluminium profiles.

Nedal supplies its quality products to clients all over the world.

Thanks to our many years of experience,modern production

techniques and,particularly,our cl ient-oriented ap proach,our cl ients

find us a valued partner.

Nedal supplies special aluminium busbars for the power

connections in open-air switching stations in high-voltage systems.

In these strategic points in the power supply,t he busbars are a veryreliable alternative to cable connections,a nd they are attractive in a

technical and economical sense too.

NEDAL BUSBARS STRONG POINT S

The natural qualities of aluminium give the busbars manyadvantages.

Nedal aluminium busbars are lighter and have a greater stiffness than cables with t he

same current transfer capacity- this facilitates larger free spans;- which require fewer points of support (and foundations);- the load on the foundation points is lower than is the

case with cables impose a lower load on supports,switches and

transformers than shunted cables do in the event of short-circuiting

are good conductors, thanks to the skin effect:a busbarssurface has a current density that is relatively lower thanthat of a cable.

are permanently corrosion-resistant possess excellent electric conductance properties

have a smooth surface are maintenance-free have a very long life span

Technically perfectedThe excellent quality of Nedal busbars is the result of manyyears of experience,co mbined with cont inual research andproduct development.

Client-oriented solutionsNedal offers tailor-m ade solutions.The busbars specificationsare fully adapted to suit each individual clients requirements.

Maintenance-free and environmentally fr iendlyThanks to aluminiums natural propert ies,aluminium busbarsrequire hardly any maintenance.Because corrosion is not anissue,costly conservative treatment s and coatings,w ith theirgreat impact on the environment, are unnecessary.Of cour se,t he fact that aluminium busbars can be recycledalso benefits the environment.

Tailor-madeNedal ensures that its busbars possess the optimal specifica-tions and metallurgical properties required for each

individual situation.After consultation with the client,N edaldetermines the alloy and dimensions required.Throughoutthe productio n process,the specifications are monit oredclosely.This starts at the melting process,and extendsthrough to packaging and dispatch.

CALCULATION OF SPECIFICATIONSACCORDING TO KEMA PROVISIONS

Using the booklet in this brochur e,yo u can calculate whichspecifications the busbars used in your projects must meet.The guidelines and methods of calculations have beendetermined by KEMA (Dut ch quality-control institute forelectrical material and appliances).O f course, the specialistsat Nedals Technical Centre will be only too please tocalculate these specifications for you,o r offer you advice onthem.

In the m elting furnaces,t he alloy

required is produced pr ecisely

The alloy leaves the casting pit in

the form of billets

The billets are homogenised before

busbars are extruded from them

Precise measurements and checks

throughout the production process

guarantee an optimal product

Nedal extrudes the busbars from

one piece,exactly according to the

dimensions required,up to lengths

of 28 metres

A protective packaging ensures that

the busbars arrive at their destina-

tion undamaged and ready for instal-

lation

NEDAL BUSBARS FOR HIGH-VOLTAGE STATIONS

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T

EC

H

N

ICA

L

S

P

EC

IF

IC

A

T

IO

N

S

N

E

D

A

L

B

U

S

BA

R

S

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DETERMINING BUSBAR CROSS-SECTION

This par t of o ur documentation describes a metho d for determ ining the r ight choice ofbusbar cross-sectio n.This metho d w as for mulated in co-operation w ith K EMA in A r nhem,

the N etherlands.

It is assumed t hat t he client know s the follow ing details:The nominal current during normal operationThe required short-circuit currentThe applicable centre-line distance between busbarsThe maximum span between two busbar supports.

Based on these details a correct choice of busbar diameter and wall thickness can be madeusing the method described below.

T he dimensions of a busbar are m ainly determ ined by tw o physical loads, i.e. t he ther maland mechanical loads on the busbar.

MATERIAL PROPERTIES

The alloys listed below, w hich comply w ith EN 755-2, are t hose mo st comm only used forelectrical busbars.Alloy 6101B T6 has more mechanical strength but less electricalconduct ivity. If higher electr ical conduct ivity is required, alloy 6101B T7 can be used.

H ow ever, t his alloy has less mechanical str ength. O f cour se busbar s made o f o t her alloyscan also be supplied. Please contact N edal A luminium B.V. for fur ther infor matio n about t hepro per t ies of t hese alloys.

THERMAL CAPACITY OF BUSBARS

The thermal capacity of a busbar is mainly determined by: the env ironment: temperature and solar radiat ion t he no minal cur rent the maximum busbar temperature as determined by the cl ient.

W hen the amount of heat absor bed by the busbar is t he same as t he amo unt of heat itemit s, equilibr ium is reached. In this situatio n the busbar t emper ature w ill remain constant.The current at this point of equilibrium is the current-carrying capacity of the busbar.

This heat balance must be considered under normal operating conditions and under theextr eme condition o f a shor t-circuit. D uring a shor t-circuit ext r a heating of the busbar s

may occur in a short space of time.

Normal operating conditionsIn this docum entatio n the allow able curr ent w as calculated in accor dance wit h D IN 43 670w ith an ambient t emper ature of 35C , a final busbar t emper ature of 80C , an absor ptio ncoefficient o f 0.6 and a solar r adiatio n o f 600 W /m 2.

The allowable currents for the busbar dimensions and standard aluminium alloys availablefro m N edal are given in table 2 and table 3.

It can be seen from the t ables t hat w hen using aluminium alloy 6101B T 7 for a curr ent-

car r ying capacity o f 3000 A , t he minim um busbar dimensions (diamet er/w all t hickness) o f100/10, 120/6 or 160/4 are acceptable.

For different ambient temperatures or final busbar temperatures the current carryingcapacity can be det erm ined using t he load facto r fro m figure 1.

Specific gravity

Youngs mo dulus E

Str ess corr esponding to t he yield point (R)

Ult imate tensile strength (Rm)Elongation

Coefficient of linear expansion (0 - 100C)

Electrical conductivity (at 20C)

Property

kg/m 3

N /mm 2

N /mm 2

N /mm2

%

K -1

MS/m (m/mm2)

Unit

6101B T6

2,700

70,000

160

2158

23.5x10 -6

30

Alloy

6101B T7

2,700

70,000

120

17012

23.5x10 -6

32

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E x a m p le :A t a n am b i en t t e m p e r at u r e o f 3 0 C an d a fi n al b u sb ar t e m p e r a t u r e o f 6 5 C , t h e c u r r e n tcar ry ing capac i ty f rom t a b l e 2 o r 3 has t o be m u l t i p l ied by a f ac to r 0 .86 .

I f, u n d e r t h e se c o n d i t i o n s , a b u sb ar h as t o b e se le c t e d fo r a n o m i n al c u r r e n t o f 3 0 0 0 A , t h em e t h o d i s as fo l l o w s. T h e f ic t i ve l o ad o n t h e b u sb ar i s 3 0 0 0 : 0 .8 6 = 3 4 8 8 A . Fr o m t h e t ab l e( 6101B T 7 ) i t can t hen be seen th at po ssib le cho i ces fo r busbar d im ensions ar e 1 20 /10 o r160 /5 .

Fig u re 1 . C u r re n t ca r r y in g ca p a c it y a s f u n ct io n o f a m b i e n t t em p e r a t u re a n d f in a l b u s b a r t e m p e r a t u r e .

Short -c i rcui tU n d e r sh o r t - c i r c u it c o n d i t i o n s t h e f in al b u sb ar t e m p e r a t u r e m u st n o t e x c e e d 2 0 0 C , b ase do n an i n it i al t e m p e r a t u r e o f 8 0 C . H i gh e r t e m p e r at u r e s c an a ffe c t t h e s t r u c t u r e o f t h ealum in ium al loy , w h ich r esu l t s in changes i n i t s m echan ical p r o pe r t i es. D u r ing sho r t - c i r cu i t st h e t e m p e r at u r e w i ll ge n e r al ly r e m ai n b e lo w t h e a ll o w ab l e t e m p e r at u r e o f 2 0 0 C , b ase d o na b u sb ar t e m p e r a t u r e o f 8 0 C d u r i n g n o r m al o p e r a t i o n .

A f t e r de te r m in ing t he busba r c r oss - sec t i on t he cu r r en t dens i t y du r i ng a sho r t - c i r cu i t can bed e t e r m i n ed . T h i s c u r r e n t d e n si t y ( J) c an b e d e t e r m i n ed f r o m t h e s h o r t - c ir c u i t c u r r e n t I k an dthe c r o ss- sec t i on o f t he b usbar .

Ta b le 1 . C u r re n t d en sit y (J) a s a f u n ct io n o f m a t e r ia l t y p e a n d d u r a t io n o f t h e sho r t - c ir cu i t cu r ren t

5 5

0 .4

0 .5

0 .6

0 .7

0 .8

0 .9

1 .0

1 .16 5

6 05 55 04 54 03 53 0

2 0

1 0

65

60

55

50

45

40

35

30

20

10

1 .2

1 .3

1 .4

1 .5

1 .6

1 .7

6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 1 0 5 1 1 0 1 1 5 1 20

B u sb a r t e m p e r a t u r e (C )

Am

bienttem

perature

(C

)

Load

factor(A

)

0 .5

1 .0

1 .5

2 .0

3 .0

5 .0

D ura t ion o f t heshor t -c ircui t curr ent (s)

1 1 8

8 3

6 8

5 9

4 8

3 7

Je ff( A m p . / m m 2 )

6 1 01 B T 6

1 2 2

8 6

7 0

6 1

5 0

3 8

Je ff( A m p . / m m 2 )

6 1 01 B T 7

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MECHANICAL CAPACITY OF BUSBARS

The busbars diameter and wall thickness are not determined on the basis of the currentcarrying capacity only.The sag as a result of normal and exceptional loads must also be

taken into account.

In accordance w ith the har monisatio n do cument HD 637 Pow er installat ions exceeding1 kV a.c., busbar s must meet mechanical requirement s that have been derived from thefollowing loads and operating conditions:

Normal loads taking into account: the busbar s mass ice lo ad w ind lo ad

These loads determine the sag of the busbar under normal operating conditions.Theamo unt of sag depends on t he stiffness of t he busbar. If t he busbar s diameter and w allthickness are determ ined, the sag under no r mal oper at ing condit ions can be deter mined.This can be important for the design of a switchyard.

The sag resulting from the mass and span length of the busbar can be determined fromfigure 2.

Figure 2. Busbar sag as function of span length (as a result of the massof the busbar itself)

Exceptional loads, taking into account: sho r t -cir cuit fo rces sw itching fo rces.

O nly forces on t he busbar dur ing shor t -circuits are considered below, since these forcesare the determining factor in most cases.

In a three-phase system w ith three busbar s in the same plane, the greatest for ce duringshor t -circuits will occur in the centre busbar. Electr omagnetic forces w ill occur betweenthe conductor s as a result of t he shor t -circuit cur rent .The busbar must have a cert ain

stiffness to absorb these forces.The required section modulus was determined inaccordance with the simplified calculation method of IEC 865.

Sag

(cm)

Span (m)

50x4

50

x8

40

x6

40

x4

63

x3

63

x7

80x10

80x4

100x10

100x5

120x15

120x4

200

x20

200x5

220x1

0

220x4

250x

10

250x

4

300x

15

300x

4

350x

15

350x

8

400x

15

400x

10

160x4

160x15

126 8 10 14 16 18 20 22 24 26 28 30

0

50

10

15

5

20

25

30

35

40

45

AL

f

B

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Based on the requir ed shor t -circuit curr ent and phase-to -phase distance, theelectromagnetic force per metre busbar can be determined using figure 3 and figure 4(depending on t he alloy used).W ith this data and the required span length the requiredsection modulus can be seen.

The calculations are based on: a tw o-point support for the busbar a factor of plasticity of 1.4 automatic reclosing after the shor t-circuit.

DETERMIN ING THE BUSBAR DIAMETER ANDCROSS-SECTION

W ith the r equired nom inal curr ent car r ying capacity and t he required section modulus oneor more suitable busbar dimensions that meet both requirements can be found intable 2 or 3.

Example of determining a busbar dimension:

Criteria:

Inormal : 4000 A nominal current during normal operation

Ik : 50 kA shor t-circuit current

aphase-phase : 4 m phase-phase distance Lmax : 12 m span length, distance between suppor ts

Al alloy : 6101B T6

The following busbar dimensions (diameter/wall thickness) are acceptable for the requirednominal curr ent of 4000 A: 120/15, 160/8, 200/5 and 220/4 (see table 2).

Using figure 3 it can be deter mined that , at the given shor t -circuit cur rent , phase-to -phasedistance and span length, the required section mo dulus is approxim ately 100 cm3.Among

ot hers, the follow ing busbar dimensions meet t his requirement: 120/12, 160/6, 200/5 and220/4.

Busbars 120/15, 160/8, 200/5 and 220/4 meet bot h the current carr ying capacityrequirements and the requirements from the dynamic shor t-cir cuit load. Busbar 220/4 isthe lightest in weight but is vulnerable due to its small wall thickness.Therefore a choiceshould be made between 120/15, 160/8 or 200/5.

A fter det erm ining the diameter and wall thickness, the client s choice of busbar may bebased on the following: w eight saving standardisation o f busbars to be used (possibly a preference for 120 mm type) sag of the busbar as a result of busbar mass (see figure 2) curr ent density in the busbar as a result o f short -circuits (see table 1) ease of wor king on the busbar (it is easier to weld termination pieces to busbars with

greater wall thickness)

Changing assumpt ions or parameters can be discussed w ith KEMA , if required. O pt imisat ioncan lead to significant savings, not just on busbar mater ial but also o n suppor ts, e.g. lighterinsulator s, suppor t st r uctur es and foundations.To this end, KEMA has advanced calculat ion

methods and tools at its disposal.

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40

40

40

50

50

50

50

63

63

63

63

80

80

80

80

80

100

100

100100

120

120

120

120

120

120

120

160

160

160

160160

160

200

200

200

200

200

200

200

220

220

220220

250

250

250

250

250

300

300

300

300

300

300

350

350

350

350

400

400

400

4

5

6

4

5

6

8

3

4

5

7

4

5

6

8

10

5

6

810

4

5

6

8

10

12

15

4

5

6

810

15

5

6

8

10

12

15

20

4

6

810

4

5

6

8

10

4

6

8

10

12

15

8

10

12

15

10

12

15

1.2

1.5

1.7

1.6

1.9

2.2

2.9

1.5

2.0

2.5

3.3

2.6

3.2

3.8

4.9

5.9

4.0

4.8

6.27.6

3.9

4.9

5.8

7.6

9.3

11.0

13.4

5.3

6.6

7.8

10.312.7

18.4

8.3

9.9

13.0

16.1

19.1

23.5

30.5

7.3

10.9

14.417.8

8.3

10.4

12.4

16.4

20.4

10.0

15.0

19.8

24.6

29.3

36.3

23.2

28.8

34.4

42.6

33.1

39.5

49.0

7

9

10

15

18

20

24

26

32

39

49

69

83

96

119

137

169

196

246290

245

299

350

444

527

601

696

597

732

862

1,1061,331

1,815

1,457

1,722

2,227

2,701

3,144

3,754

4,637

1,584

2,311

2,9983,645

2,339

2,889

3,425

4,457

5,438

4,074

5,990

7,828

9,589

11,276

13,674

12,574

15,448

18,220

22,190

23,310

27,552

33,666

3.7

4.3

4.8

6.2

7.2

8.2

9.6

8.1

10.3

12.3

15.6

17.3

20.8

24.0

29.7

34.4

33.8

39.3

49.358.0

40.9

49.9

58.3

73.9

87.8

100.2

116.0

74.6

91.5

107.7

138.3166.4

226.9

145.7

172.2

222.7

270.1

314.4

375.4

463.7

144.0

210.1

272.5331.4

187.1

231.1

274.0

356.6

435.0

271.6

399.3

521.8

639.3

751.8

911.6

718.5

882.7

1,041.1

1,268.0

1,165.5

1,377.6

1,683.3

940

1,040

1,120

1,150

1,270

1,370

1,540

1,230

1,400

1,550

1,700

1,720

1,900

2,080

2,350

2,580

2,320

2,520

2,8603,140

2,440

2,700

2,950

3,340

3,680

3,960

4,300

3,110

3,450

3,760

4,2804,710

5,520

4,170

4,540

5,160

5,690

6,200

6,650

7,410

4,070

4,920

5,5906,170

4,530

5,030

5,470

6,220

6,860

5,290

6,370

7,250

7,920

8,560

9,370

8,230

9,100

9,880

10,530

10,130

10,850

11,740

970

1,070

1,150

1,180

1,310

1,410

1,590

1,260

1,450

1,600

1,850

1,780

1,970

2,140

2,430

2,660

2,390

2,600

2,950

3,240

2,510

2,790

3,040

3,450

3,800

4,090

4,440

3,210

3,570

3,880

4,4204,860

5,700

4,310

4,690

5,330

5,880

6,400

6,870

7,660

4,200

5,080

5,7806,370

4,680

5,200

5,650

6,420

7,080

5,470

6,580

7,480

8,180

8,840

9,6808,500

9,400

10,210

10,880

10,460

11,210

12,130

du(mm)

wd(mm)

m(kg/m)

452

550

641

578

707

829

1,056

565

741

911

1,232

955

1,178

1,395

1,810

2,199

1,492

1,772

2,3122,827

1,458

1,806

2,149

2,815

3,456

4,072

4,948

1,960

2,435

2,903

3,8204,712

6,833

3,063

3,657

4,825

5,969

7,087

8,718

11,310

2,714

4,034

5,3286,597

3,091

3,848

4,599

6,082

7,540

3,720

5,542

7,339

9,111

10,857

13,430

8,595

10,681

12,742

15,787

12,252

14,627

18,143

A(mm2)

I(cm4)

Z(cm3)

In(A )

In(A )

6101B T6 6101B T7

du = external diameter

W d = w all t hicknessA = cross sect ion

m = mass per unit length

I = second moment

Z = sect ion modulusIn = current carrying capacity

Table 2 Current Carrying Capacity of available Busbars (metric)Busbar temperature 80C at ambient temperature 35C

Legend

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11/4

11/2

2

21/2

3

31/2

4

5

6

8

10

12

40

80

160

40

80

160

40

80

160

40

80

160

40

80

160

40

80

40

80

120

160

40

80

120

160

40

80

120

160

60

80100

120

140

160

40

60

80

100

20

30

40

6080

1.16

1.54

1.93

1.40

1.87

2.50

1.87

2.56

3.83

2.96

3.92

5.12

3.89

5.24

7.35

4.67

6.42

5.51

7.67

9.76

11.54

7.49

10.62

13.85

16.87

9.71

14.68

18.68

23.28

18.24

23.2326.13

31.17

34.76

38.26

20.81

28.05

33.05

39.55

17.10

22.48

27.53

37.5545.48

8

10

12

13

16

20

28

36

48

64

80

98

126

162

210

200

262

300

400

486

553

631

859

1,071

1,248

1,170

1,689

2,069

2,462

3,691

4,4025,062

5,867

6,406

6,905

6,713

8,827

10,218

11,949

7,988

10,367

12,543

16,70019,833

4

5

6

5

7

8

9

12

16

17

22

27

28

36

47

39

52

53

70

85

97

89

122

152

177

139

201

246

293

337

402462

536

585

630

492

646

748

875

493

640

774

1,0311,225

938

1,077

1,206

1,076

1,240

1,432

1,337

1,562

1,898

1,792

2,051

2,326

2,189

2,529

2,957

2,504

2,919

2,832

3,302

3,703

3,980

3,531

4,149

4,672

5,080

4,238

5,095

5,583

6,102

6,237

6,7777,203

7,719

8,068

8,303

7,146

8,132

8,712

9,258

6,977

7,888

8,574

9,69910,502

969

1,112

1,245

1,111

1,280

1,479

1,381

1,613

1,961

1,851

2,119

2,402

2,261

2,612

3,054

2,586

3,015

2,925

3,410

3,824

4,111

3,646

4,285

4,825

5,247

4,377

5,262

5,766

6,302

6,442

7,0007,439

7,972

8,333

8,603

7,381

8,398

8,998

9,562

7,206

8,147

8,855

10,01710,846

Pipe Size(in)

Schedulenumber

42.20

42.20

42.20

48.30

48.30

48.30

60.30

60.30

60.30

73.00

73.00

73.00

88.90

88.90

88.90

101.60

101.60

114.30

114.30

114.30

114.30

141.30

141.30

141.30

141.30

168.30

168.30

168.30

168.30

219.10

219.10219.10

219.10

219.10

219.10

273.10

273.10

273.10

273.10

323.90

323.90

323.90

323.90323.90

du(mm)

3.55

4.85

6.35

3.70

5.10

7.15

3.90

5.50

8.75

5.15

7.00

9.50

5.50

7.60

11.15

5.75

8.10

6.00

8.55

11.15

13.50

6.55

9.50

12.70

15.85

7.10

11.00

14.30

18.30

10.30

12.7015.10

18.30

20.65

23.00

9.30

12.70

15.10

18.30

6.35

8.40

10.35

14.3017.50

wd(mm)

431.05

569.09

715.18

518.43

692.16

924.33

691.02

946.88

1,417.05

1,097.76

1,451.42

1,895.17

1,441.05

1,941.13

2,723.49

1,731.45

2,379.29

2,041.41

2,840.51

3,613.22

4,275.08

2,772.81

3,933.59

5,130.91

6,246.69

3,595.62

5,435.90

6,918.42

8,623.67

6,756.43

8,234.999,677.36

11,544.22

12,874.22

14,169.53

7,707.39

10,389.50

12,239.02

14,648.74

6,334.84

8,325.85

10,195.23

13,908.7116,845.22

A(mm2)

m(kg/m)

I(cm4)

Z(cm3)

In(A )

In(A )

6101B T6 6101B T7

Table 3 Current Carrying Capacity of available Busbars (inches)Busbar temperature 80C at ambient temperature 35C

du = external diameter

W d = wall thickness

A = cross sect ion

m = mass per unit length

I = second moment

Z = sect ion modulus

In = current carrying capacity

Legend

7/31/2019 201206110932275 p We w

10/11

0

10

20

30

40

50

60

70

50

100

150

200

250

300

350

400

450

500

SectionmodulusZ

(cm

3)

Short-c

ircuitcurrentIk(kA)

a=

1m

L=

6m

L=

8m

L=

10

m

L=

12m

L=

15m

L=

20

m

a=

2m

a=

3m

a=

4m

a=

5m

a=

6m

6101BT6

Figure

3.

Sectionmodulusasfunctionofshort-circuitcurrent,phase-to-p

hase

distance(a)andrequired

span(L).6101BT6

7/31/2019 201206110932275 p We w

11/11

0

20

30

40

50

60

70

100

200

300

400

500

600

700

800

900

1000

SectionmodulusZ

(cm

3)

Short-c

ircuitcurrentIk(kA)

a=

1m

L=

6m

L=

8m

L=

10m

L=1

2m

L=

15m

L=

20m

a=

2m

a=

3m

a=

4m

a=

5m

a=

6m

10

6101BT7

Figure

4.

Sectionmodulusasfunctionofshort-circuitcurrent,phase-to-p

hase

distance(a)andrequired

span(L)6101BT7