1ZSC563-AAA en, Rev. 4 Resin impregnated paper bushing, oil to SF 6, type GSBK Technical guide
This Technical Guide has been produced to allow transformer manufacturers, and their designers and engineers, access to all the technical information required to assist them in their selection of the appropriate transformer bushing. The guide should be used in conjunction with the Selection Guide to allow the optimum selection to be made. The technical information pertaining to bushings manufactured by ABB has been divided into separate documents, with one document for each type. The information provided in this document is intended to be general and does not cover all possible applications. Any specific application not covered should be referred directly to ABB, or its authorised representative. ABB makes no warranty or representation and assumes no liability for the accuracy of the information in this document or for the use of such information. All information in this document is subject to change without notice.
Table of contents Standards 5 Design 5 RIPCOAT 5 Test tap 6 Testing 7 Routine testing 7 Type tests 7 Special tests 7 Transportation and storage 7 Dimensions 8 Electrical data 9 General specifications 9 Connection details 1 Draw rod system 1 Fixed bottom contact 11 SF 6 side terminal 11 Standard end-shield 11 Conductor loading 12 Overloading of bushings acc. to IEC 12 Short-time current 12 Ordering particulars 12 Recommendations for positioning 12
1ZSC563-AAA en, Rev. 4 5 Standards Design RIPCOAT The GSBK bushing is designed and tested according to IEC 6137 and IEC 61639. GSBK is a Resin Impregnated Paper (RIP) bushing intended for immersed oil SF 6 service. The bushing can be mounted in any direction from vertical to horizontal. The insulation core of the GSBK is produced by winding crepe paper onto a center tube, with aluminium foil insert for electrical stress control. The manufacturing process is optimized to give a partial discharge free bushing with low dielectric losses. As a current conductor, GSBK uses the center tube, which is moulded into the RIP core. The outer terminal is fit to the center tube by a bolted joint. The bottom contact on the transformer side is mounted by a draw rod system or by a bolted joint. Water uptake on the RIP bushings during transport, handling and storage leads to increased dielectric losses. At site this means that the bushings might need to be dried before assembling leading to delays. A water barrier "RIPCOAT" has been developed to solve this problem. The time to reach critical dissipation factor has been stretched by a factor of up to 8 by using RIPCOAT compared to bushings with an unprotected oil-side. Actual time depends highly on level of relative humidity and temperature. Outer terminal RIP core Mounting flange Test tap Center tube gsbk_2 Fig. 1. Transformer bushing type GSBK oil SF 6 connection.
6 1ZSC563-AAA en, Rev. 4 Features Solid Seals the transformer Benefits Reduced risk of fire. No restriction in mounting angle. Oil leakage from the bushing eliminated. Reduced risk of fire. Risk of oil leakage from the transformer reduced. Non-brittle materials Protection of people and equipment. Easy handling. Safe transport - even when mounted on the transformer. High earthquake withstand. Light weight, compact Easy handling, small space requirements inside transformer, low life cycle environmental impact. Test tap The outer conducting layer of the condenser core is connected to an insulated test tap on the flange. During operation the protective cap must be fitted in order to ground the outer layer to the flange. The maximum test voltage is 2 kv, 5 Hz for 1 minute. The maximum service voltage is 6 V. Voltage tap is available as on request. The maximum test voltage is 2 kv, 5 Hz for 1 minute. The maximum service voltage is 6 kv. The test tap and voltage tap have dimensions according to IEEE, potential tap type A. gsbk_18 Fig. 2. Test tap. Test tap adapter For permanent connection of the test tap to the measuring circuits, a test tap adapter (catalog number 2769 522-C) is sometimes required, for example if the IEEE dimension standard for measuring tap is not used.
1ZSC563-AAA en, Rev. 4 7 Testing Routine testing Type tests Special tests The bushing is routine tested according to IEC 6137 and IEC 61639. The tests include measurement of partial discharge quantity, tan δ, capacitance and power frequency voltage withstand test. On each bushing, an external pressure test is performed and the tightness between the gas side and the oil side is confirmed. An individual routine test report is issued with each bushing. The routine test is carried out at room temperature with the bushing immersed in transformer oil. Type tests have been performed according to above standards and are available on request. A number of tests not specified by the above standards have also been performed and summaries are available on request. Transportation and storage The bushing is wrapped in a sealed moisture-proof wrapping material together with a drying agent upon delivery. The protective wrapping shall not be opened if the bushings are intended to be stored. The protective wrapping can be re-sealed, or a similar sealed moisture-proof wrapping can be used, together with a drying agent.
8 1ZSC563-AAA en, Rev. 4 Dimensions D4 R1 Ø 87 Shield SF 6 side Ø 87 R58 R1 17 72 R58 R58 R1 R1 L1 L5 D1 GSBK 17 GSBK 245-55 Flange SF 6 side 1.6 D7 x n1 L L3 L4 D5 D6 L2 D2 Flange oil side D1 x n2 D8 D9 Fig. 3. Dimensions. D3 gsbk_4 Dimensions are subject to modification without notice. Type GSBK Rated current (A) Dimensions in mm Cat. No. 1ZSC... Space for current Net Test tap Voltage tap 6 kv transformer (mm) mass (kg) L L1 L2 L3 L4 L5 17 16 917-AAA 917-ABA 3 68 147 52 75 2 3 378 -AAB -ABB 6 78 177 52 15 2 6 378 17 25 917-ACA -ADA 3 96 147 52 75 2 3 378 -ACB -ADB 6 113 177 52 15 2 6 378 245 16 9245-AAA -ABA 3 114 189 77 92 2 3 663 -AAB -ABB 6 128 219 77 122 2 6 663 245 25 9245-ACA -ADA 3 152 189 77 92 2 3 663 -ACB -ADB 6 171 219 77 122 2 6 663 362 16 9362-AAA -ABA 3 178 2285 15 135 2 3 943 -AAB -ABB 6 198 2585 15 1335 2 6 943 42 16 942-AAA -ADA 3 24 234 15 19 2 3 943 -AAB -ADB 6 231 264 15 139 2 6 943 55 125 955-AAA -ABA 3 258 2535 15 1285 2 3 943 -AAB -ABB 6 294 2835 15 1585 2 6 943
1ZSC563-AAA en, Rev. 4 9 Electrical data Ratings GSBK 17 245 362 42 55 Rated voltage IEC (kv), U m 17 245 362 42 55 Rated phase-to-ground voltage IEC (kv) 98 141 29 242 317 Basic Insulation Level (kv), BIL 75 15 13 1425 1675 Dry switching impulse level (kv), SI N.A. 85 15 1175 13 Routine test 1 minute dry (kv), 5 Hz, rms 365 56 63 68 75 Rated current (A), I r Note! Higher current ratings are available on request. 16/25 16/25 16 16 125 Rated frequency (Hz), fr 5/6 5/6 5/6 5/6 5/6 Temporary over voltage (kv), IEC 6137 clause 5.1 17 196 29 336 44 Space for current transformer (mm) 3/6 3/6 3/6 3/6 3/6 Nominal capacitance between conductor and test tap C 1 ±1 % (pf) General specifications Application: Classification: Ambient temperature: Immersion medium on switchgear side: Max pressure of medium on switchgear side: Immersion medium on transformer side: Oil level in transformer: Max. pressure of medium: Angle of mounting: 496/656 5/622 45/494 346/424 286/352 Transformers Resin impregnated paper, capacitance graded, completely immersed bushing, temperature class E (12 C) according to IEC 6137 +4 C to -4 C, minimum value acc. to temperature class 2 of IEC 6137 SF 6 gas. Max daily mean temperature +75 C. 75 kpa (over pressure) Transformer oil. Max daily mean oil temperature +9 C. Max temporary oil temperature +115 C. Not lower than 3 mm from the bushing flange. 1 kpa (over pressure) Horizontal to vertical Test tap: Dimensions according to IEEE, Type A. Max. service voltage 6 V. Voltage tap: Capacitance C2 of test tap: Conductor: Markings: Dimensions according to IEEE, Type A. Max. service voltage 6 kv. < 5 pf Integrated tube conductor Conforming to IEC Condenser core D1 D2 D3 D4 D5 D6 D7 x n1 D8 D9 D1 x n2 Cantilever load Max operating load (kn) 188 18 146 187 335 35 16 x 8 335 29 15 x 12 2 4 188 18 146 187 335 35 16 x 8 335 29 15 x 12 2 4 188 18 146 187 335 35 16 x 8 335 29 15 x 12 2 4 188 18 146 187 335 35 16 x 8 335 29 15 x 12 2 4 214 26 146 187 565 535 16 x 16 45 4 23 x 12 2 4 214 26 146 187 565 535 16 x 16 45 4 23 x 12 2 4 214 26 146 187 565 535 16 x 16 45 4 23 x 12 2 4 214 26 146 187 565 535 16 x 16 45 4 23 x 12 2 4 266 256 146 187 69 64 2 x 16 5 4 23 x 12 2 4 266 256 146 187 69 64 2 x 16 5 4 23 x 12 2 4 31 29 146 187 69 64 2 x 16 5 45 23 x 12 2 4 31 29 146 187 69 64 2 x 16 5 45 23 x 12 2 4 355 342 146 187 69 64 2 x 16 55 5 23 x 12 2 4 355 342 146 187 69 64 2 x 16 55 5 23 x 12 2 4 Test load (kn)
1 1ZSC563-AAA en, Rev. 4 Connection details Draw rod system The draw rod system offers the following advantages compared to other connection systems: No hand holes required in the transformer tank. Easy bushing installation and removal no connection work inside the transformer at site. No special supports required in the transformer as is the case with plug contacts. Perfect guiding of the bushing into the transformer. The lower end shield may be fixed to the contact and will thus be correctly positioned with respect to the lower end plate of the bushing. The center tube of the bushing is used as current conductor. The transformer leads are fitted with cable lugs, which are bolted to a bottom contact. This contact is pressed against the bottom end of the bushing tube by a steel draw rod. The upper end of this rod is bolted to a compensating device, which consists of a spring and is so designed that it gives the required contact pressure at all temperatures. The draw rod is divided at the level of the flange. If required by the transport conditions, an additional joint can be positioned below the flange. This must be stated in the order. The lower part with contact end shield can then be secured to the cover during transport and storage of the transformer. Bottom contacts with 4 threaded holes for cable lugs are available. The bottom contacts are made of copper in one piece. To this bottom contact there is a suitable end shield, cat. No. 1ZSC9993. Special bottom contacts are available on request. Catalogue number for draw rod: 1ZSC9994. Threaded hole M8 for pulling wire L 25 Additional joint on request 6 L2 64 45 H1 min 2 gsbk_23 Fig. 4. Draw rod system. M12 (4x) gsbk_24
1ZSC563-AAA en, Rev. 4 11 Fixed bottom contact The fixed bottom contact (Cat. No. 1ZSC9992-AAE) uses the same bottom contact as in the draw rod system, i.e. it is made of copper in one piece and has 4 threaded holes for cable lugs. The fixed bottom contact system also uses the center tube as a current conductor but it is secured to the center tube with a pulling ring instead of the draw rod. The pulling ring is made of aluminum and is threaded on to the center tube. The bottom contact is then fastened to the ring with six M1 bolts. Standard end-shields with Cat. No. 1ZSC9993, is suitable for the bottom contact. 64 45 gsbk_25 gsbk_21 M12 (4x) Fig. 5. Fixed bottom contact. SF 6 side terminal The dimensions on the SF 6 side terminal fully comply to IEC 61639 and include 4 threaded holes for GIS connection. The terminal is fitted to the top end of the conductor tube by means of bolts, screwed into a pulling ring. The terminal surface for GIS connection is silver plated. Special terminals are available on request. Fig. 6. SF 6 side terminal. gsbk_22 gsbk_26 Standard end-shield The end-shield is made of aluminum and coated with insulating epoxy paint or 3 mm of pressboard. The design enables easy installation and should be used with standard draw rod bottom contact, or with the fixed bottom contact system. Cat. No. 1ZSC9993-AEA 1ZSC9993-AEB Coating Epoxy paint 3 mm pressboard
12 1ZSC563-AAA en, Rev. 4 Conductor loading The GSBK bushings fulfill the temperature rise test requirements according to IEC for the currents in the table below. The rated thermal shorttime current (I th ) is calculated according to IEC 6137. Contact the supplier for current ratings for GSBK in oil - oil applications. Bushing GSBK Rated current A Short-time current (I th ) ka, rms 1 s 2 s 17 16 57 4 1 17 25 88 63 156 245 16 57 4 1 245 25 88 63 156 362 16 57 4 1 42 16 57 4 1 55 125 57 4 1 Dynamic current (I d ) ka, peak Overloading of bushings acc. to IEC Short-time current If the conductor for the bushing is selected with 12 % of the rated current of the transformer, the bushing is considered to be able to withstand the overload conditions stated in IEC 676-7 when following the directions: for long time and short time emergency loading the oil temperature must be 115 C max. and the daily mean oil temperature must be 9 C max. For overload conditions other than the above-mentioned IEC overload, contact the supplier for permissible currents and temperatures. The rated thermal short-time current (I th ) is calculated according to IEC 6137. Ordering particulars When ordering, please state: Type and catalogue number for bushing Connection details: fixed bottom contact or draw rod Catalogue number for shield on oil side Additional accessories or modifications Test required, in addition to the normal routine tests gsb_16 Nameplate Recommendations for positioning The maximum stresses in the oil at the surface of the shield and the parts surrounding the bushing must be limited to the normal values for insulated conductors and other similar components in the same transformer. The withstand voltages in a specific case depend upon many factors beyond the control of the bushing manufacturer. Therefore the configurations and distances given in the table and figures are only intended as guidelines.
1ZSC563-AAA en, Rev. 4 13 D3 D4 3 E 1 /3 x L4 max min R5 L4 Type GSBK E (mm) L4 (mm) d3 min (mm) d4 (mm) 17/16/.3 3 52±1 3 22 +3 17/25/.3 3 52±1 3 22 +3 17/16/.6 6 52±1 3 22 +3 17/25/.6 6 52±1 3 22 +3 245/16/.3 3 77±2 45 45 +5 245/25/.3 3 77±2 45 45 +5 245/16/.6 6 77±2 45 45 +5 245/25/.6 6 77±2 45 45 +5 362/16/.3 3 15±2 54 54 +5 362/16/.6 6 15±2 54 54 +5 42/16/.3 3 15±2 54 54 +5 42/16/.6 6 15±2 54 54 +5 55/125/.3 3 15±2 54 54 +5 55/125/.6 6 15±2 54 54 +5 R gsbk_7 Fig. 7. Recommendations for positioning. 55 5 45 Radius (mm) 4 35 3 25 2 3 35 4 45 5 55 6 65 7 75 Fig. 8. Recommended minimum distance R, for standard shield at 1 minute power frequency (rms) test. U (kv) gsbk_19 R25 R296 8 265 R35 Fig. 9. End shield. gsb_14 R9 Ø 142 Ø 258 R32 gsbk_9
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