Epoxy Resin ImpregnatedPaper Bushings

17.5 kV to 800 kVup to 31,500 A

BS EN ISO 9001

TRENCH (UK) LTD - The site at Hebburn in the north east of England has pioneered the design and

manufacture of bushings for transformers and switchgear since 1929 and is a worldwide supplier to

equipment manufacturers and utility companies. In the early 1970's we developed Epoxy Resin Impregnated

Paper bushings for use in a wide range of applications and have become the international specialist for this

type of product, which accounts for over 40% of production. Epoxy resin is superior to resin-bonded paper

by offering lower partial discharge activity, a lower power factor and better thermal stability. Our products

are designed and manufactured to BS EN ISO 9001 as well as IEC and ANSI where appropriate.

Facilities Include● Products designed and manufactured to customer requirements.

● All bushings impulse tested as standard.

● Unique high voltage testing.

● Research and development and dielectric type testing to all national and international standards

up to 4MV impulse, 2MV AC, lMV DC in wet and dry conditions.

● Insulation studies and large-scale simulations.

Transformer Bushings● Full range of designs for outdoor or indoor use.

● Oil and SF6 connections.

● Insulation types include ERIP, OIP and RBP.

● OIP condenser bushings (type OTA) for medium/high power transformers

Switchgear Bushings● Solid insulation system for SF6 insulated switchgear giving unrivaled mechanical and electrical

performance up to 550kV.

Insulation Components● Total design and manufacture to customer requirements using epoxy resin, glass fibre and

composites for all types of electrical insulators.

After Sales Service● Comprehensive refurbishment facilities.

● Loan of steel transit frames for 300kV and 420kV bushings.

● Check testing

● Full reporting service

● Re-gasketing.

● Major refurbishment.

● Re-certification included.

● Covers bushings manufactured by other companies including English Electric, Ferranti, Micanite,

Reyrolle and VA Tech.

1

The epoxy resin impregnated paper range provides the very highest standard inbushing technology. Every product is impulse tested as a routine so you can beassured of high reliability and a low cost. With over 30 years experience in the fieldof oil free bushing applications our engineers can support all your through lifeneeds.

TRENCH (UK) LTDis a quality registeredcompany.Its managementsystems have beenassessed and complywith BS EN ISO 9001.

2

CONTENTS

Type HETA Voltage Range 17.5kV to 36kV

High current bushings for transformer to phase

busbar isolated connections

Type ETG Voltage Range 72.5kV to 800kV

Bushings for transformer to gas insulated

switchgear connections

Type EGA Voltage Range 145kV to 525kV

Condenser bushings for direct connection between

metalclad SF6 switchgear and outdoor equipment

3-6

7-8

9-10

Epoxy Resin Impregnated Paper Bushings

17.5kV to 800kV up to 31,500A

Features

● Central aluminium conductor cast in one piece without joints.

● Main insulation : vacuum impregnated epoxy condenser.

● Solid filling available : permits mounting at any angle.

● Thermal stability : excellent.

● Partial discharge : less than 10pC at 1.5Un.

● Freedom from oil leakage from the transformer in the event of porcelain breakage.

● Current transformer accommodation can be provided on request.

● Test tapping : standard.

● Designs available to cover IEC, ANSI and other International Specifications.

● Voltages from 17.5kV to 36kV and current from 6300A to 31500A

The bushing flange dimensions and design ofbushing terminals can be adapted to specificrequirements of the transformermanufacturer or to provide interchangeabilitywith existing bushings.

Type HETA Voltage Range 17.5kV to 36kV

High current bushings for transformer to phasebusbar isolated connections

3

FLAN

GE

PLAT

E TH

ICKN

ESS

STRI

NG

LEN

GTH

MIN

IMU

M C

REEP

AGE

LIN

E M

ETAL

(Tra

nsf.

end)

LIN

E M

ETAL

(Air

end)

FLAN

GE

LEN

GTH

PORC

ELAI

N L

ENG

TH

AIR

END

LEN

GTH

TRAN

SFO

RMER

EN

D L

ENG

TH

TOP

PLAT

E D

IAM

ETER

FLAN

GE

BOLT

HO

LE D

IAM

ETER

NU

MBE

R O

F FL

ANG

E BO

LT H

OLE

S

WEI

GH

T (k

g)

MAX

. PO

RCEL

AIN

DIA

MET

ER

FLAN

GE

DIA

MET

ER

FLAN

GE

BOLT

CIR

CLE

DIA

MET

ER

FLAN

GE

GAS

KET

SEAT

DIA

MET

ER

TRAN

SFO

RMER

EN

D D

IAM

ETER

PRO

TEC

TED

CRE

EPAG

E

CAN

TILE

VER

WIT

HST

AND

(kN

)

TIG

HTN

ESS

TEST

24

HO

URS

(bar

g)

TOTA

L LE

NG

TH

PART

IAL

DIS

CH

ARG

E (k

V)(1

0pC

Max

.)

LIG

HTN

ING

IMPU

LSE

WIT

HST

AND

(VO

LTS)

POW

ER F

REQ

UEN

CY

WIT

HST

AND

(kV)

- 1

MIN

.

REFE

REN

CE

CU

RREN

T (A

)

MAX

. PH

ASE

TO G

ROU

ND

(kV)

RATE

D V

OLT

AGE

(kV)

Un17.5

24

36

Up125

150

200

Ir63008000

1000012500160002000063008000

1000012500160002000063008000

100001250016000200002500031500

Uy17.5

24

24

Up50

70

95

26

36

54

1.4

1.4

1.4

4

5

4

5

4

5

L665675

695705

765775

795805

865875

895905

9551135

L1290

310

305

325

320

340

375

L2375385

395

460470

480

545555

565

615760

L3165

250

335

L48090

100

8090

100

8090

100

125

L5130

130

130

180300

REFERENCE PERFORMANCE

Voltage Mechanical PORCELAIN

DIMENSIONS (mm)

L6165

185

165

185

165

185

220

L720

20

20

25

L8205

290

375

430

650

870

160

240

320

D1250290330400460550250290330400460550250290330400460550660820

D2255300340410470560255300340410470560255300340410470560670830

D3290350400450535620290350400450535620290350400450535620720930

D4335400450500590680335400450500590680335400450500590680780980

D5445500545625685780445500545625685780445500545625685780900

1070

D6300350395470535630300350395470535630300350395470535630750920

d1520

22

1520

22

1520

22

n212

16

12

16

12

16

24

6988

10513316820785

107126161192241101126149185230288364502

Minimum Oil Leveln2 holes

D3 D4

5

d

L7

L

L2L1L6 L4 L3 L520

D6 D5D1D2

L8

90°

Figure 1

Type HETA Voltage Range 17.5kV to 36kV

High current bushings for transformer to phasebusbar isolated connections

4

40

T2

a/2

20

aA1

85A3

A2

20

85

40n4 Holes

t

t/2

T1

T3

n3 Holes

Figure 3

Type HETA Voltage Range 17.5kV to 36kV

High current bushings for transformer to phasebusbar isolated connections

40

a/2 20

aA1

85A3 A2

2085

40n4 Holes

t

t/2

T1

T3

n3 Holes

Figure 2

NU

MBE

R O

F H

OLE

S

HO

LE P

ITC

H

THIC

KNES

S

SPAC

ING

LIG

HTN

ING

IMPU

LSE

WIT

HST

AND

VO

LTS

(kVp

)

WID

TH

NU

MBE

R O

F H

OLE

S

HO

LE P

ITC

H

THIC

KNES

S

SPAC

ING

WID

TH

REFE

REN

CE

CU

RREN

T (A

)

ARRA

NG

EMEN

T

RATE

D V

OLT

AGE

(kV)

Un17.5

24

36

Up125

150

200

Ir63008000

1000012500160002000063008000

1000012500160002000063008000

100001250016000200002500031500

Fig23

4

23

4

23

4

A1180120150200120150180120150200120150180120150200120150200240

A2160250290340430530160250290340430530160250290340430530610700

A325

25

25

a60

50

605060

50

605060

50

6050

60

n364684664684664684688

T1150120150200300350150120150200300350150120150200300350400480

T2

75100120140190

75100120140190

75100120140190220250

T33025

3025

3025

30

t506050

506050

506050

60

n46468

12146468

12146468

12141616

REFERENCE TERMINALS (FIGURES 2, 3 & 4)

Air End Transformer End

5

1.2

1.1

1.0

0.9

0.8

0.7

0.60 10

010

20304050

20Tc - To(K)

To - Ta(K)

RATI

NG

FA

CTO

R 'R

'

30 40 50

SA

SO

Connections to Bushing - Section SA and SO

Fig. 6 identifies the connections made to the bushing; these are the air end SA and the

transformer end SO. The reference conditions for the bushings are based on defined

values of current density in the copper connections as follows:

SA = 1.5 A/mm2

SO = 2.5 A/mm2

Operating the bushing at higher air temperatures will demand some decrease in the

value SA while restricted conductor temperature rises will demand some decrease in

value SO. When requested we can advise on specific values.

Selection Procedure

1. Select voltage class (creepage may influence decision).

2. Determine (TO - TA) and (TC - TO) : bushings to IEC 137 allow (TC - TO) = 30K. Other

specifications may reduce this to 20K or 10K.

3. Refer to fig. 5 for rating factor ‘R’.

4. Divide maximum system current by factor ‘R’. This gives minimum current rating in

terms of the catalogue reference temperatures.

5. Add any overload and proximity effect.

6. Select next highest Ir value from catalogue list.

1. HETA 36/200 class.

2. (TO - TA) = 10, (TC - TO) = 20

3. R= 0.82

4. eg 8650A max, therefore

8650/0.82 = 10550A

5. NOT REQUIRED

6. Therefore Ir = 12500 A

Current Rating- Factor ’R’.

The bushing nominal current rating Ir is based on one set of temperature conditions

typical of those found in power transformers connected via phase isolated bus-duct

systems. These reference conditions are:

Oil temperature TO = 90°C

Air temperature TA = 70°C

Max. conductor temperature TC = 120°C

Therefore TO - TA = 20K

Therefore TO - TO = 30K

Consequently, the rating factor ‘R’ for these conditions is defined as 1.0. For other

temperature conditions refer to fig. 5 for the appropriate value. Use of this factor in

determining the correct bushing is described below.

Example

Figure 5. - Rating factor selection chart.

Figure 6. - Connections to bushing.

Type HETA Voltage Range 17.5kV to 36kV

High current bushings for transformer to phasebusbar isolated connections

Figure 4

40

a/2

20

aA1

85A3 A2

20

85

40n4 Holes

t

t/2

T1

T3 T2

n3 Holes

6

Features

● The design is compatible with the requirements of IEC 1639 for the GIS to transformer interface. Other dimensions can be provided on request

● The ETG bushing range is provided for a full range of operating ratings to IECand ANSI Standards

● Epoxy resin impregnated paper insulation. Vacuum impregnation of the condenser core gives excellent partial discharge performance

● Oil free solid insulation provides no fire or explosion risk with the bushing

● Design allows for differential expansion across normal operating temperature range

● lnsulation is gas tight and when combined with an effective sealing ring system will provide <10-5 torr litres per second Ieakage

● Connecting flange is also gas tight and incorporates a self grounding test tapping for through life capacitance and tan delta measurement

● Non-standard CT accommodation and corona shields can be provided on request

● All bushings are electrically tested with a simulation of the service arrangement,preventing oil contamination of the gas side

Description

The epoxy resin impregnated paper range provides the very highest standard inbushing technology. Every product is impulse tested as a routine so you can beassured of high reliability and a low cost. With over 30 years experience in the fieldof oil free bushing applications our engineers can support all your through lifeneeds.

The bushings detailed show our product range which is suitable for connecting oilfilled transformers directly to SF6 metalclad switchgear or ducting.

for detailssee opposite

Type ETG Voltage Range 72.5kV to 800kV

Bushings for transformer to gas insulatedswitchgear connections

7

d3

L3 L2

L4

n2xm2

n1xm1t1

d4

S2sealing surfaceRmax

enclosureflange

contact areaon bushing side

bushingflange

6.3

S1 d9

t2d8 L7

d2

L

TRANSFORMER ENDSF6 END

L4 L1E

L5

D1

D3 D4 L6n3xm3

D2

INTE

RNAL

DIA

MET

ER O

FG

AS S

IDE

SEAL

ING

FAC

E

INTE

RNAL

DIA

MET

ER O

FG

AS S

IDE

ENC

LOSU

RE F

LAN

GE

INTE

RNAL

DIA

MET

ER O

FG

AS S

IDE

ENC

LOSU

RE

OU

TER

DIA

MET

ER O

FG

AS S

IDE

TERM

INAL

NO

. OF

HO

LES

x D

IAM

ETER

GAS

SID

E TE

RMIN

AL P

CD

GAS

SID

E LE

NG

TH

GAS

SID

E TE

RMIN

ALTH

READ

DEP

TH

GAS

SID

E TE

RMIN

AL T

HIC

KNES

S

OVE

RALL

LEN

GTH

MAX

IMU

M P

HAS

E TO

GRO

UN

DVO

LTAG

E (k

V)

LIG

HTN

ING

IMPU

LSE

WIT

HST

AND

VO

LTAG

E (k

Vp)

POW

ER F

REQ

UEN

CY

WIT

HST

AND

VO

LTAG

E (k

V) 1

Min

.

SWIT

CH

ING

IMPU

LSE

WIT

HST

AND

VO

LTAG

E (k

Vp)

RATE

D C

URR

ENT

(A)

RATE

D V

OLT

AGE

(kV)

Ur

72.5

72.5

123

123

145

145

170

170

245

245

420

525

800

Up

325

325

550

550

650

650

750

750

1050

1050

1425

1550

2050

Us

*

*

*

*

*

*

*

*

*

*

1050

1175

1500

Ir

1250

2000

1250

2000

1250

2000

1250

2000

1250

2000

2000

2000

2000

Up

140

140

230

230

275

275

325

325

460

460

630

680

800

Uy

42

42

71

71

84

84

98

98

142

142

243

303

462

L

740

1010

1050

1120

1190

1560

2410

2560

3595

L4

330

520

770

1050

1340

L2min

30

125

L3min

20

25

*

t1

70

110

*

n1x m1

4xM12

*

d2

99

139

60

d3min

250

300

450

540

630

S1max

200

220

450

540

500

S2min

260

280

510

600

630

t2

285

305

535

640

720

d8

315

335

565

690

764

d9

16

20

23

n2xm2

8xM12

16xM12

16xM16

28xM20

L7

25

30

30

33

33

L5

150

220

200

355

L1

260

340

380

450

570

1160

1210

1900

E

30

300

600

D1

90

110

145

200

329

487

D3

250

290

400

500

600

D4

290

335

450

560

660

n3xm3

8x15

12x15

12x20

12x24

16x24

L6

18

22

25

D2

90

110

175

200

d4

200

220

450

540

500

REFERENCE RATING GAS SIDE DIMENSIONS AND TERMINOLOGY AS IEC61639 TRANSFORMER SIDE

GAS

SID

E FL

ANG

E PC

D

EXTE

RNAL

DIA

MET

ER O

FG

AS S

IDE

FLAN

GE

EXTE

RNAL

DIA

MET

ER O

FG

AS S

IDE

SEAL

ING

FAC

E

GAS

SID

E FL

ANG

E FI

XIN

GH

OLE

DIA

MET

ER

GAS

SID

E FL

ANG

E TH

ICKN

ESS

MO

UN

TIN

G F

LAN

GE

HEI

GH

T

TRAN

SFO

RMER

SID

E LE

NG

TH

MIN

IMU

M E

ARTH

BAN

D

TRAN

SFO

RMER

SID

E D

IAM

ETER

TRAN

SFO

RMER

SID

E FL

ANG

E PC

D

EXTE

RNAL

DIA

MET

ER O

FTR

ANSF

ORM

ER S

IDE

FLAN

GE

TRAN

SFO

RMER

SID

E FI

XIN

GH

OLE

S N

O. x

DIA

MET

ER

TRAN

SFO

RMER

SID

EFL

ANG

E TH

ICKN

ESS

TRAN

SFO

RMER

SID

E TE

RMIN

ALD

IAM

ETER

GAS

SID

E FI

XIN

G S

CRE

WS

NO

. x D

IAM

ETER

Type ETG Voltage Range 72.5kV to 800kV

Bushings for transformer to gas insulatedswitchgear connections

8

Type EGA Voltage Range 145kV to 525kV

Direct connection between metalclad SF6 switchgear and outdoor equipment

The bushings in the EGA range are suitable for connecting outdoor equipment to

SF6 metalclad switchgear or ducting and may be mounted vertically, horizontally or

at any angle between.

The primary insulation used in this range of bushings is condenser graded, epoxy

resin impregnated paper - ERIP. The bushings are intended as alternatives to

conventional gas- filled porcelain. Use of ERIP provides a compact bushing design

which is completely free of oil. The lack of oil or pressurised gas in the bushing

greatly minimises the risk of fire or explosion.

Used extensively for many years, ERIP has a proven reliability record in many

applications and is virtually free of partial discharges at test voltages.

The cast epoxy insulation has inherent gas tight properties and combined with an

effective sealing ring system provides security for the gas environment and a gas

leakage rate of <10-5 torr litres per second is guaranteed. The design caters for the

effect of differential expansion across the normal operating temperature range.

The connecting flange is impervious to gas and incorporates a self grounding test

tapping for capacitance and tan delta measurement during periodical maintenance.

The bushing flange dimensions and design of the SF6 terminal can be adapted to

suit the specific requirements of the SF6 equipment. The design of the outdoor

terminal can also be adjusted to suit connections to the outdoor equipment or

overhead lines.

Condenser bushings for direct connection between metalcladSF6 switchgear and outdoor equipment

9

L

L1 L2

L5100

d1

ZxiD3 D2 D1

d2

L4 L3

OU

TDO

OR

END

TER

MIN

AL D

IAM

ETER

SF6

END

TER

MIN

AL D

IAM

ETER

FLAN

GE

FIX

ING

No.

OF

HO

LES

x D

IAM

ETER

FIX

ING

FLA

NG

E O

UTS

IDE

DIA

MET

ER

FIX

ING

FLA

NG

E P.

C.D

.

SF6

END

INSU

LATI

ON

DIA

MET

ER

OU

TDO

OR

PORC

ELAI

N C

LEAR

ANC

E

FLAN

GE

HEI

GH

T

SF6

END

LEN

GTH

SF6

END

INSU

LATI

ON

LEN

GTH

OU

TDO

OR

LEN

GTH

TOTA

L LE

NG

TH

MAX

IMU

M P

HAS

E TO

GRO

UN

DVO

LTS

(kV)

LIG

HTN

ING

IMPU

LSE

WIT

HST

AND

(VO

LTS)

POW

ER F

REQ

UEN

CY

WIT

HST

AND

(kV)

SWIT

CH

ING

IMPU

LSE

WIT

HST

AND

(VO

LTS)

RATE

D C

URR

ENT

(A)

RATE

D V

OLT

AGE

(kV)

Un

145

170

245

300

420

420

525

525

Up

650

750

1050

1050

1425

1425

1675

1800

Us

-

-

-

850

1050

1050

1175

1300

In

2000

2000

2000

2000

2000

4000

4000

2000

Up

275

325

460

460

630

630

740

860

Uy

84

98

142

173

243

243

303

303

L

2040

2280

3195

3405

4465

4465

5090

5610

L1

1670

1870

2690

2900

3860

3860

4400

4810

L2

370

410

505

505

605

605

690

800

L3

290

330

400

400

500

500

585

660

L4

200

200

300

350

400

400

400

400

L5

1250

1450

2150

2320

3200

3200

3740

4150

D1

140

160

220

270

329

375

375

375

D2

290

290

400

532

532

532

532

532

D3

335

335

450

570

570

570

570

570

d1

40

40

40

60

60

80

80

80

d2

160

160

160

170

203

220

220

203

Zx diam i

12x16

12x16

12x23

16x18

16x18

16x18

16x18

16x18

REFERENCE RATING DIMENSIONS

Terminal and flange dimensions may vary to suitrequirements of both SF6 and outdoor equipment.

Type EGA Voltage Range 145kV to 525kV

Condenser bushings for direct connection between metalcladSF6 switchgear and outdoor equipment

10

Trench® Austria GmbHPaschinger Strasse 49Postfach 13A-4060 Linz-LeondingAustriaPhone: 43-732-6793-0Fax: 43-732-671341

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Trench® ChinaMWB (Shanghai) Co., Ltd.No. 3658, Jiancheng RoadMinhang, ShanghaiPeoples Republic of China200245Phone: 86-21-54720088Fax: 86-21-54723118

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Trench® LimitedBushing Division432 Monarch AvenueAjax, OntarioCanada L1S 2G7Phone: 905-426-2665Fax: 905-426-2671

Trench® LimitedCoil Product Division71 Maybrook DriveScarborough, OntarioCanada M1V 4B6Phone: 416-298-8108Fax: 416-298-2209

Trench® LimitedInstrument Transformer Division390 Midwest RoadScarborough, OntarioCanada M1P 3B5Phone: 416-751-8570Fax: 416-751-6952

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Trench® France S.A.16, Rue du Général CassagnouB.P. 70 F-68 302St. Louis, CedexFrancePhone: 33-3 89-70-2323Fax: 33-3 89-67-2663

Trench® Germany GmbHNürnberger Strasse 199D-96050 BambergGermanyPhone: 49-951-1803-0Fax: 49-951-1803-224

Trench® Switzerland AGLehenmattstrasse 353CH-4028BaselSwitzerlandPhone: 41-61-315-51-11Fax: 41-61-315-59-00

Trench® (UK) LimitedSouth DriveHebburnTyne & WearNE 31 1 UWPhone: 44-191-483-4711Fax: 44-191-430-0633

Trench Facilities

www.trenchgroup.com

The Trench Group is your

partner of choice for electrical

power transmission and

distribution solutions today;

and for the development of

your new technology solutions

of tomorrow.

E 322.30Subject to change without notice (05.2006)Printed in Canada.