Composite Insulators

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Introduction

Trench Germany – the former MWB, founded in 1946 - is a recognized world-wide leader in design and manufacture of high voltage equipment for electrical and industrial systems.

In its long history - while experiencing several insulation mediums, e. g. epoxy resin, traditional oil-paper-

Basic Structure of Hollow Composite Insulators

insulation - Trench Germany decided to focus on SF6-gas as insulation medium for its whole product range.

Along with this decision, Trench Germany introduced as one of the first manufacturers the composite insulator technology for hollow composite insulators already in 1980.

Flange

FRP-tube

Silicone Housing

This type of insulator consists of a tube out of filament reinforced plastic (FRP) for the mechanical support and a housing out of silicone rubber to withstand environmental attacks.

Until today more than 10000 units up to 800 kV are in service all over the world under the most differentenvironmental conditions.

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Our primary intention was to use the hollow composite insulator for Trench Germany products only.

Therefore installations typically cover free-standing SF6-gas-insulated instrument transformers and bushings.

Application

Application of 420 kV Current Transformers under different environmental Conditions

Location with heavy pollution: The insulator (originally grey) is covered totally with a layer out of high conductive minerals. Nevertheless the insulator surface shows excellent hydrophobicity.

Due to the increasing importance of composite technology for high voltage devices, Trench Germany now delivers devices, Trench Germany now delivers devices, Trench Germanycomposite insulators directly to users for a wide range of high voltage applications:

Location with less pollution accumulation on the insulator surface

• Instrument Transformers

• Circuit Breakers

• Disconnectors

• Post Insulators

• Lightning Arrestors

• Bushings

• Cable Terminations

Polluted Insulator Surfaces:While on porcelain water penetrates totally into the hydrophilic pollution layers, insulators with silicone sheds still have a very good water repellency due to the hydrophobicity transfer.

Clean Insulator Surfaces:The degree of water repellency on hydrophobic silicone rubber is much higher compared to hydrophilic porcelain.

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If the surface of a high voltage insulator is hydrophobic, the leakage currents as well as the surface discharge activities will be reduced significantly.

In co-operation with its sub-supplierTrench Germany developed a special high quality silicone for its insulator sheds.

Features

This silicone provides not only a hydrophobic surface when it is clean; it also transfers its hydrophobicity quickly into and onto pollution layers which may accumulate on the surface.

Therefore – even under worst pollution conditions – the insulator shows excellent performance withoutany failures.

A cleaning process is not necessary.Tests on Trench Germany insulatorswhich have been in service under severe conditions for many years prove that the transfer properties remain unchanged.

Hydrophobicity

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Until today no standard existed for dimensioning a composite insulator’s creepage distance .

IEC 815 for ceramic and glass insulators often is applied. However, this standard does not refer to

hydrophobic surfaces and the transfer of hydrophobicity under pollution.

Due to these hydrophobic properties it is possible to reduce creepage distances according to the customers’requirements.

Mechanical StrengthThe mechanical tasks of a composite insulator are fulfilled by the FRP-tube.

The tube data (winding angle, wall thickness etc.) are calculated carefully,

based on a many years’ know-how and with the help of special software.

This results in an outstanding mechanical strength.

Trench Germany current transformers after Los Angeles earthquake in 1994.While porcelain equipment was destroyed almost totally, these current transformers were still ready for operation.

Trench Germany dimensions the creepage distance based on its 20 years experience, considering the individual electric and climatic conditions of the operation location.

Creepage Distance

The Trench Germany insulator is:

• earthquake resistant

• resistant against vandalism

• explosion proof

• easy to handle during transport and installation

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Unique Single Mould Method

Trench Germany uses a unique method to assemble silicone sheds:

One shed is moulded on top of the other. The mould rotates, therefore the shed gets an inclination also on the lower side.

There are no moulding lines on the silicone surfaces which might influence the pollution and erosionperformance.

Moulding Principle

With the single mould method the seamless insulator can be designedexactly to different requirements for shed geometry or shed distances … without dependency on special tools.

This provides the greatest flexibility with respect to meeting a wide range of customers’ requirements.

Moulding Equipment

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Internal diameter 120 150 174 190 190 240 248 250 288 300 340 350 500 756 762 770

I.D. (mm)

Outer diameter 130 180 198 206 257 272 312 308 362 516 790

O.D. (mm)

Insulator length one stack up to 4620, cascading possible

L (mm)

Typical FRP-Tube / Shed Data

Preferred types are printed in bold. Additional data on request.

Trench Germany was one of the first manufacturers to apply composite materials to high voltage hollow composite insulators.

Today, the hollow insulator is a well Today, the hollow insulator is a well Todayestablished product within the world-wide high voltage industry.

Having installed more than10,000units, Trench has accumulated valuable experience with all fcaets of electrical and mechanical design, material selection, production and testing of composite insulators.

This experience extends to many different climatic zones as well as for

all high voltage levels. To this point To this point Tin time, no ageing of our composite insulators has been reported.

With this background, Trench is able to guarantee a high lifetime expectation for all of its composite insulator products.

Lifetime

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

Trench® Brasil LtdaVia Expressa de Contagem, 2685Contagem, Minas GeraisCEP 32370-485BrazilPhone: 55-31-3391-5959Fax: 55-31-3391-1828

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

Trench® High Voltage Products Ltd., ShenyangNo. 2 Zhengliang Er. RoadJing Shen Xi San StreetDao Yi Economic Development ZoneShenyang 110136 P.R. ChinaPhone: 86-24-89722688Fax: 86-24-89737200

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

Trench® LimitedPower Line Carrier Division815 Middlefield Road, Unit 6AScarborough, OntarioCanada M1V 2P9Phone: 416-291-8544Fax: 416-291-5581

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 205Subject to change without notice (05.2006)Printed in Canada.