Transformer Bushings IEEE/ANSI Standard, COTA 150 COTA 2050

Transcription

1 Transformer Bushings IEEE/ANSI Standard, COTA 150 COTA 2050

2 Application Trench bushings, Type COTA, are designed for application on liquid filled power transformers and reactors. They are used to connect the power transformer or reactor to overhead lines or exposed bus in either outdoor or indoor conditions. Connection to the transformer winding leads can be accomplished by one of three methods: Bottom connected via a fixed conductor. Connected via a copper draw lead cable(s) supplied with the power transformer. Bottom connected via Trench s all copper Split-Conductor draw lead. (Up to 1300 kv BIL) The method selected depends on voltage rating, maximum through current or user preference. Connection to the power system is accomplished with an industry standard threaded top terminal. Applicable Standards Trench bushings Type COTA, are designed to meet or exceed the following industry standards for liquid filled power transformer or reactor applications: Design Active Part The active part of the COTA bushing is constructed of oil-impregnated paper with layers of aluminum foil. The position of the foil layers is computer optimized to ensure a homogenous electrical field, radially and axially controlled, providing extremely high dielectric resistance. The Trench active part design ensures that COTA bushings will last the life of your power transformer. Housing The housing is constructed of a head, outdoor insulator, mounting flange, ground sleeve (COTA 250 and above) and epoxy or fiberglass insulator, held together by either a central tube or a fixed conductor. Pre-tensioned cone spring washers provide mechanical stability over the entire temperature range, ensuring a leak free bushing with the highest possible mechanical strength. COTA bushings are sealed exclusively with 0-Ring gaskets and each bushing is hermetically sealed with its own independent oil reservoir. The interior of the aluminum castings are painted. Head The cast aluminum head contains an oil expansion chamber with an oil level indicator. The design of the head allows the bushings to be shipped and stored horizontally and mounted as follows: COTA 150 and above draw lead models and fixed conductor models above COTA 200: vertical to a maximum inclination of 40. For greater inclination, contact Trench for special instructions and limitations. ANSI/IEEE Standard C IEEE Standard General Requirements and Test Procedure for Outdoor Power Apparatus Bushings ANSI/IEEE Standard C IEEE Standard Performance Characteristics and Dimensions for Outdoor Apparatus Bushings IEEE Standard C R2002 IEEE Guide for Application of Power Apparatus Bushings COTA 150 and above draw lead models and fixed conductor models above COTA 200 COTA 150 and COTA 200 Fixed conductor models: vertical or horizontal 2 T R A N S F O R M E R B U S H I N G

3 Outdoor Insulator The outdoor insulator is either a high-grade electrotechnical porcelain or an insulator constructed from a explosion-resistant fiberglass epoxy resin tube with molded silicon-rubber sheds. Porcelain Insulators The standard porcelain insulator on COTA bushings is ANSI No.70, light gray. Brown porcelain is available upon request. One-piece porcelain is standard on COTA 150 though 750 and optional on COTA 900 and When the height of the bushing makes it necessary to use more than one porcelain element, Trench uses a special gluing procedure developed to ensure that the porcelain elements will exhibit the same level of performance as a single porcelain element. On bushing style COTA 250 and above, the porcelain insulator is cemented to the mounting flange using special cement and sealed with an 0-Ring gasket. To protect against corrosion, the mounting flange surface and porcelain that is in contact with the cement is treated with a special coating, ensuring a trouble free interface. Alternating sheds Porcelain insulator Portland cement Mounting flange O-Ring gasket Silicone Rubber Insulators Silicone rubber insulators used by Trench are specifically designed for use on high voltage bushings. These insulators demonstrate superior electrical and mechanical characteristics not found in other types of insulators. The physical properties of the silicone rubber provide many advantages over conventional porcelain insulators. The silicone rubber insulator has demonstrated superior performance in earthquake prone areas. Porcelain insulator Typical design COTA 250 COTA 900 Fiberglass - reinforced epoxy resin tube Silicone rubber sheds Portland cement Mounting flange O-Ring gasket Silicone rubber insulator Silicone Rubber insulator Typical design COTA 250 and above T R A N S F O R M E R B U S H I N G 3

4 Design Mounting Flange The mounting flange is a high quality aluminum casting, machined to exact dimensions, ensuring an excellent seal between the bushing and the transformer. Integrated into the mounting flange of COTA bushings through 69 kv are test taps. Above 69 kv the mounting flange is equipped with a voltage tap. Sealing cap Epoxy insulator Embedded End Shield (Draw Lead COTA 250 though 1175) Sealing cap Test Tap COTA 15O COTA 35O Oil plug High voltage bushings require an end shield to control the electrical field strength at the inboard 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 the Trench COTA bushings the ideal replacement bushing. Current Path Voltage Tap COTA 550 and above Shatter Resistant Inboard End Every Trench COTA bushing is offered with a shatter resistant in-board end insulator. These insulators are less susceptible to damage from handling. They will not shatter like porcelain preventing major transformer repair costs. Trench in-board end insulators have 25 years of proven field experience. The lower end of the COTA bushings (COTA 200 and below) are protected by an explosion resistant fiberglass-reinforced epoxy-resin tube or (COTA 250 and above) by a shatter resistant cone shaped vacuum molded epoxy resin insulator. Two current path options are available: Fixed conductor Current path via conductor that is fixed in place and has the active part wound on the conductor. The fixed conductor is either solid rod or a tube, depending on the specific bushing design. Draw lead Current path via the transformer s cable(s) to a silver-plated copper terminal through multi spring contacts to the copperalloy top terminal. Or via Trench s copper Split-Conductor draw lead through multi spring contacts to the copper-alloy top terminal. These insulators are designed to be installed during the intank drying process of the active part of the transformer and can withstand temperatures up to 130 C. 4 T R A N S F O R M E R B U S H I N G

5 Fixed Conductor When a fixed conductor bushing is selected the connection to the transformer winding leads will be at the bottom of the bushing. The terminal configuration at the bottom of fixed conductor bushing will depend on the current rating and/or the desired application and the requirements of the ANSI/IEEE Standards. Draw Lead Cable(s) When the application is less than 800 amperes, draw lead cable(s), provided with the transformer, can be used. For recommendations on selecting the draw lead cable(s) for COTA bushings refer to the Trench COTA Instruction Manual. When applying draw lead cable(s) on bushings with a vacuum molded epoxy resin insulator the embedded end shield provides for a simple, space-saving assembly without additional shielding or barriers. Refer to the Trench COTA Instruction Manual for additional details on this feature. Top Terminal 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 providing a truly maintenance free bushing. The top terminal is designed to accept either a draw lead terminal or the Trench s Split-Conductor. On fixed conductor COTA bushings the top terminal is an integral part of the bushing s conductor. Top terminal Lock pin 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 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 provides increased safety for personnel, shorter installation times and ensures factory tested transformer lead connections. For Split-Conductor applications the termination of the transformer or reactor winding leads will be at the bottom of the bushing. The type of termination required will depend on the maximum through current, operating voltage and mounting position. Additional measures (shielding, barriers, etc.) may be required. Contact Trench for available terminals and shields for your specific application of the Split- Conductor. Split conductor upper part Mounting flange 4 Hex-socket screws M10 with disk spring washers torque 17 ft.lb. (23 Nm) Split conductor lower part Epoxy insulator Bottom terminal Split-Conductor & Top terminal T R A N S F O R M E R B U S H I N G 5

6 Cut Views Top terminal Top terminal Draw lead stud Oil level indicator Head housing Oil level indicator Head housing Insulator Active part Insulator Active part Name plate Test tap Voltage Tap (COTA 550 and above) Air escape plug (COTA 1050 and above) Mounting flange Mounting flange FRP tube Grounding sleeve Test tap (COTA 350 and below) Conductor Epoxy insulator Bottom terminal Typical design COTA 150 & COTA 200 Fixed Conductor Typical design COTA 250 COTA 1175 Draw lead 6 T R A N S F O R M E R B U S H I N G

7 Quality Top terminal Oil level indicator Head housing Insulator Active part Voltage Tap (COTA 550 and above) Mounting flange Grounding sleeve Epoxy insulator Name plate Air escape plug (COTA 1050 and above) Test tap (COTA 350 and below) 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, 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. Standardization Trench COTA bushings were developed to promote the concept of standardization. The designs detailed in this catalog will cover nearly 100% of the bushing requirements for liquid filled power transformers or reactors rated through 2500 MVA, three-phase, 2050 kv BIL. (Excluding high current bushings for GSU transformers) All COTA bushings though 900 kv BIL are designed for operation, without de-rating, to an altitude of 10,000 feet. COTA bushings above 900 kv BIL are offered with altitude ratings based on the BIL rating of the specific bushing. Example; a COTA 1050 may be rated for 10,000 feet while the same bushing rated at 1300 kv BIL will only be rated for operation at 3,300 feet. COTA bushings (COTA 200 and above) have as standard, extra-creep porcelain in accordance with the heavy contamination level as described in the IEEE Guide for Application of Power Apparatus Bushings, C R2002. Bottom Terminal COTA bushings present a level of standardization that will reduce inventories while meeting the most demanding requirements. Typical design COTA 550 and above Fixed conductor T R A N S F O R M E R B U S H I N G 7

8 COTA Technical Specification Sheets C Style Number 150-H AG F AG H DG4-01 Drawing Number 025D001A 025F002A 025S011A Current Path (copper) draw lead fixed draw lead Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,500 2,700 3,000 CT Pocket Length (inches) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance. (Inch) Approximate Weight (lb.) Mounting vertical vertical/horizontal Vertical Style Number Drawing Number 200-H AG D001A 200-F AG F002A 200-H DG S013A Current Path (copper) draw lead fixed draw lead Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,500 2,350 3,000 CT Pocket Length (inches) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance. (Inch) Approximate Weight (lb.) Mounting vertical vertical/horizontal vertical Style Number 250-H AG H AG F AG3-01 Drawing Number 046D001A 046S004A 046F003A Current Path (copper) draw lead draw lead fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,400 2,000 3,000 CT Pocket Length (inch) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance (inch) Approximate Weight (lb.) T R A N S F O R M E R B U S H I N G

9 COTA Technical Specification Sheets Style Number Drawing Number 350-H AG D002A 350-H AG S008A 350-F AG F002A Current Path (copper) draw lead draw lead fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,400 2,000 3,000 CT Pocket Length (inch) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance (inch) Approximate Weight (lb.) Style Number 550-H AG F AG F AG3-01 Drawing Number 115D002A 115F001A 115F002A Current Path (copper) draw lead fixed fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,400 2,000 3,000 CT Pocket Length (inches) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance. (Inch) Approximate Weight (lb.) Style Number Drawing Number 650-H AG D002A 650-F AG F002A 650-F AG F001A Current Path (copper) draw lead fixed fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,400 2,000 3,000 CT Pocket Length (inches) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance. (Inch) Approximate Weight (lb.) T R A N S F O R M E R B U S H I N G 9

10 COTA Technical Specification Sheets C Style Number 750-H AG F AG F AG3-01 Drawing Number 161D001A 161F001A 161F002A Current Path (copper) draw lead fixed fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,400 2,000 3,000 CT Pocket Length (inches) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance. (Inch) Approximate Weight (lb.) Style Number Drawing Number 900-H AG D003A 900-F AG F003A 900-F AG F005A Current Path (copper) draw lead fixed fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,600 2,000 3,000 CT Pocket Length (inch) BIL (kv) s dry (kv) s wet (kv) Min. Creep Distance (inch) Min. Arcing Distance (inch) Approximate Weight (lb.) Style Number Drawing Number 1175-H AG D002A 1175-F AG F001A 1175-F AG F004A Current Path (copper) draw lead fixed Fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 1,600 2,000 3,000 CT Pocket Length (inch) BIL (kv) 1,175 1,175 1, s,dry (kv) Wet switching impulse (kv) Min. Creep Distance (inch) Min. Arcing Distance (inch) Max. Altitude (feet) 3,300 3,300 3,300 Approximate Weight (lb.) T R A N S F O R M E R B U S H I N G

11 COTA Technical Specification Sheets Style Number 1675-F AG F AG F AG3-01 Drawing Number 500F001A 500F005A 765F001A Current Path (copper) fixed fixed fixed Insulation Class (kv) Max. L to G Voltage (kv) Max. Current Rating (A) 2,000 3,000 2,000 CT Pocket Length (inch) BIL (kv) 1,675 1,675 2, s,dry (kv) Wet switching impulse (kv) 1,175 1,175 1,450 Min. Creep Distance (inch) Min. Arcing Distance (inch) Max. Altitude (feet) 5,000 5,000 3,300 Approximate Weight (lb.) 2,119 2,120 3,040 T R A N S F O R M E R B U S H I N G 11

12 Trench Austria GmbH Paschinger Strasse 49 Postfach 13 A-4060 Linz-Leonding Austria Phone: Fax: Trench Brasil Ltda Via Expressa de Contagem, 2685 Contagem, Minas Gerais CEP Brazil Phone: Fax: Trench China MWB (Shanghai) Co., Ltd No Jiangcheng Road Minhang, Shanghai, Peoples Republic of China Phone: Fax: Trench Fushun Dong Er Dao, Shuncheng District, Fushun, Liaoning Province, Peoples Republic of China Phone: / Fax: Trench Limited Bushing Division 432 Monarch Avenue Ajax, Ontario Canada L1S 2G7 Phone: Fax: Trench Limited Instrument Transformer Division 390 Midwest Road Scarborough, Ontario Canada M1P 3B5 Phone: Fax: Trench France S.A. 16, Rue du Général Cassagnou B. P. 70 F St. Louis, Cedex France Phone: Fax: Trench Germany GmbH Nürnberger Strasse 199 D Bamberg Germany Phone: Fax: Trench Switzerland AG Lehenmattstrasse 353 CH-4028 Basel Switzerland Phone: Fax: Trench (UK) Limited South Drive Hebburn Tyne & Wear NE 31 1 UW Phone: Fax: Trench Limited Coil Product Division 71 Maybrook Drive Scarborough, Ontario Canada M1V 4B6 Phone: Fax: Subject to change without notice E Printed in Canada