Ten Reasons to Specify Trench COTA Bushings

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Transformer Bushings Type COTA

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Paper/Foil Oil Condenser

The extremely high dielectric resistance obtained with the proven Trench paper/foil oil condenser provides superior impulse protection and high resistance to steep transients. The Trench design ensures that COTA bushings will last the life of your power transformer.

today, including vandalism, earthquakes and heavy pollution. In addition, Trench COTA bushings with a composite insulator can weigh nearly 50% less than other brands of bushings, making them ideal for mobile substations.

4 Shatter Resistant In-board EndsEvery Trench COTA bushing is offered with a shatter resistant inboard end insulator. These insulators are less susceptible to damage from handling. They will not shatter like porcelain preventing major transformer repair costs. Trench inboard end insulators have 25 years of proven field experience.

ratings to 3,000 amps. Now almost all medium power transformers through 100 MVA can have all draw lead bushings. The Split-Conductor draw lead feature allows shorter installation times and ensures factory tested transformer lead connections.

7 One-Piece Porcelain(Glued Porcelain) All Trench COTA bushings, through 161 kV offer, as standard, one-piece porcelain. On request 230 kV COTA bushings can be provided with onepiece porcelain. For 230 kV bushings and above multiple pieces of porcelain are used and to ensure the best possible joint between the porcelain pieces a special gluing process is used. This gluing process eliminates the use of gaskets, which can deteriorate and cause the bushing to fail.

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Porcelain Cemented to Flange(46 kV and above)

This unique process ensures high cantilever strength and eliminates the possibility of oil leaks where the porcelain meets the flange.

5 Embedded End Shield(46 kV and above) High voltage bushings require an end shield to control the electrical field strength at the in-board end of the bushing. Instead of mounting this shield externally, Trench embeds the shield in the epoxy-resin inboard end insulator. This provides a more uniform distribution of the electrical forces and reduces the required clearances. The embedded end shield provides greater interchangeability with other bushings, making Trench COTA bushings the ideal replacement bushing.

3

Optional Composite Insulator

For more than 15 years, Trench has offered transformer bushings with outdoor composite insulators. Composite insulators are proven to provide solutions to many of the problems faced by the industry 2

6 Split-Conductor(Super Draw Lead) Historically bushings through 69 kV only offered a draw lead rating of 400 amps. Today, using the Trench Split-Conductor in COTA bushings you now have draw lead

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3 45

6 7 8 9 10

As we have seen in item 6 Trench COTA bushings provide extremely high draw lead capabilities. This is accomplished by eliminating the threaded joint inside the top terminal and replacing the threads with Multi-contacts. The multi-contacts are made from high-grade beryllium copper alloy, silver-plated and installed inside the bolted top terminal.

9 Multi-Contacts

10 Quality

11 1 Top terminal 2 Multi-Contact

Everyone talks about quality; nearly everyone is ISO 9001 certified including Trench but that is not the whole picture. Quality starts at the beginning, it starts with the design. When you compare a Trench COTA bushing with other brands you will find quality design features not offered by the others. These include O-ring gaskets instead of flat gaskets, compression springs not in the bushings oil, the interior of all castings painted, easy to read prismatic oil level indicators and stainless steel test tap caps just to mention a few. Quality is the reason Trench offers the only standard three-year bushing warranty in the business. 85 years in the bushing business and still growing, Trench, the quality choice for bushings.

3 Retaining pin with locking device 4 Central tube5 Split Conductor upper part 6 Mounting flange 7 Gasket surface flange 8 Split Conductor lower part 9 Epoxy insulator 10 End-shielding 11 Bottom terminalSplit-Conductor COTA150... COTA900

Top terminal Draw lead stud

8

Bolted Top TerminalEnd of draw lead cable

Multi-Contact Retaining pin with locking device 4 Fixing screws

Distance to gasket of flange see outline drawing

Unlike other bushing designs, where the top terminal is threaded onto the bushing the Trench COTA bushing utilizes a top terminal that is bolted to the head of the bushing. This feature eliminates the requirement to check the top terminal for tightness, increasing reliability and provides a truly maintenance free bushing. 3

O-Ring gasket Bushing head

Terminal ID

Top Terminal COTA Draw Lead Bushings

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Trench FacilitiesTrench Austria GmbH Paschinger Strasse 49 Postfach 13 A-4060 Linz-Leonding Austria Phone: 43-732-6793-0 Fax: 43-732-671341 Trench Brasil Ltda Via Expressa de Contagem, 2685 Contagem, Minas Gerais CEP 32370-485 Brazil Phone: 55-31-3391-5959 Fax: 55-31-3391-1828 Trench China MWB (Shanghai) Co., Ltd. No. 3658, Jiancheng Road Minhang, Shanghai Peoples Republic of China 200245 Phone: 86-21-54720088 Fax: 86-21-54723118 Trench High Voltage Products Ltd., Shenyang No. 2 Zhengliang Er. Road Jing Shen Xi San Street Dao Yi Economic Development Zone Shenyang 110136 P.R. China Phone: 86-24-89722688 Fax: 86-24-89737200 Trench Limited Bushing Division 432 Monarch Avenue Ajax, Ontario Canada L1S 2G7 Phone: 905-426-2665 Fax: 905-426-2671 Trench Limited Coil Product Division 71 Maybrook Drive Scarborough, Ontario Canada M1V 4B6 Phone: 416-298-8108 Fax: 416-298-2209 Trench Limited Instrument Transformer Division 390 Midwest Road Scarborough, Ontario Canada M1P 3B5 Phone: 416-751-8570 Fax: 416-751-6952 Trench Limited Power Line Carrier Division 815 Middlefield Road, Unit 6A Scarborough, Ontario Canada M1V 2P9 Phone: 416-291-8544 Fax: 416-291-5581 Trench France S.A. 16, Rue du Gnral Cassagnou B.P. 70 F-68 302 St. Louis, Cedex France Phone: 33-3 89-70-2323 Fax: 33-3 89-67-2663 Trench Germany GmbH Nrnberger Strasse 199 D-96050 Bamberg Germany Phone: 49-951-1803-0 Fax: 49-951-1803-224 Trench Switzerland AG Lehenmattstrasse 353 CH-4028 Basel Switzerland Phone: 41-61-315-51-11 Fax: 41-61-315-59-00 Trench (UK) Limited South Drive Hebburn Tyne & Wear NE 31 1 UW Phone: 44-191-483-4711 Fax: 44-191-430-0633

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.

www.trenchgroup.comE 322.61 Subject to change without notice (05.2006) Printed in Canada.