1ZUA 2751-212

Oil Impregnated Paper Bushing, Type AB, Oil to AirPTAB-AOA804IZUA 2751-212Technical Guide138 kV, IEEE Std C57.19.01-2000This Technical Guide has been produced to allow access to technical information required to assist in the selection of appropriate apparatus bushings.Unless otherwise specified dimensions given in this document are in inches.2ABBTable of ContentsType AB Design (4)Voltage Tap (5)Testing (5)Bushing Loading (5)Recommended Positioning (5)Table 1: Minimum Electrical Clearances (5)Ordering Details (6)Style and Option Numbers (6)Table 2: Voltage Class Designations (6)Table 3: Current Rating Designations (6)Table 4: Airside (top) Termination (6)Table 5: Draw-lead Connectors and Designations (7)Special Requirements (7)Table 6: Electrical Data (7)Bottom Terminal Connection (8)Table 7: Suggested Draw Lead Cable Ratings (8)Top Terminal Connections (8)Explanation of Functional Style Number (9)Sample Draw Lead Connectors (10)Top End Construction of Type AB Bushing (11)Dimensional Data (12)Table 8: Lower End Dimensions (12)Table 9: Flange Dimensions (13)Table10: Top End Dimensions (13)Table 11: Termination Dimensions (15)Draw-rod Connection Details (16)Notes (17)ABB34ABBType AB DesignThe bushing is built up around a central conductor tube or rod on which the condenser body is wound.The upper and lower insulators, mounting flange, flange ex-tension, spring assembly, sight bowl, lower support and clamping nut form an oil tight shell to contain the condenser and insulating oil. The sealing between components is accomplished with oil-resistant “O-rings” in grooves and/or oil-resistant flat fiber reinforced gaskets.The space between the shell and the condenser is filled with high-grade transformer oil. This oil is part of the insu-lating and cooling systems of the bushing. Above the oil,there is a gas space to provide for thermal expansion of the oil. The gas space is filled with dehydrated nitrogen gas.The oil level in the bushing can be monitored by visual in-spection of the sight bowl. The sight bowl is prismatic to enhance observation of the oil level.The mounting flange and flange extension are high strength corrosion-resistant aluminum.The lower support is designed to accept a variety of op-tional terminating devices such as standard threaded studs,NEMA blades, or draw rod system.The upper insulator is a one-piece high quality porcelain with sheds designed for maximum performance. Type AB bushings are designed to meet or exceed “Heavy Creep”requirements (44mm/kV L -G) as described in IEEE Std C57.19.01-2000.Type AB bushings meet or exceed the cantilever test re-quirements for interchangable/circuit breaker bushings per table 8 of IEEE Std C57.19.01-1991.Type AB bushings described in this document are suitable for use at angles of up to 60° from the vertical position.Type AB bushings are designed and tested to meet or ex-ceed the requirements of the IEEE standard.Type AB bushings are designed and tested to meet or ex-ceed the seismic requirements of the IEEE Std 693-1997.See Installation and Maintenance Guide, IZUA 2751-213prior to installation or use.Figure 1. Cutaway view of a Type AB bushing 138 kVMOUNTING FLANGEUPPER PORCELAINFLANGE EXTENSIONTOP TERMINALSIGHT BOWL VOLTAGE TAPLOWER PORCELAINCONDENSERSHIELDSPRING ASSEMBLYABB5Distance of Grounded Edge from Live PartsWithin the angle of 0°-45° from the end of the ground sleeve,the “Radius A” shall be a minimum of 0.125" (3.175 mm).Within the angle of 45°-60° from the end of the ground sleeve,the “Radius B” shall be a minimum of 0.25" (6.35 mm).Distance of Grounded Flat Surface from Live Parts “S” is the minimum distance from bushing live parts to a large smooth surface such as a tank wall or core clamp.Shielding of Exposed ThreadsWhen applying these recommendations, all exposed threads must be shielded using a static shield assembly,bolting collar assembly or other appropriate shielding method.Distance of Grounded Flat Surface from Live Parts “S” is the minimum distance from bushing live parts to a large surface such as a tank wall or core clamp.Figure 3. PositioningVoltage TapThe bushing is provided with a Type A (Normally grounded)voltage tap as per figure 1 of the IEEE Standard C57.19.01-2000. This tap is connected to one of the inner foil elec-trodes of the condenser. In the factory, the voltage tap is tested at 20 kV , 50/60 HZ for 1 minute.Under normal operation, this tap is grounded. If the voltage tap is used in conjunction with a potential/monitoring de-vice, the voltage between the tap and ground should be limited to 6 kV . See figure 2 for details.TestingAs part of the manufacturing process, the bushing is sub-ject to a number of routine tests.Vacuum tightness is performed at nearly a full vacuum and a test is made with an oil overpressure of 41 psig for 8hours at ambient temperature. No evidence of a leak is per-mitted.Each bushing is subject to final electrical tests at ambient temperature with the lower end of the bushing submerged in transformer oil. The power-factor and capacitance are measured and the bushing is subjected to a one-minute power frequency test at a level of one half the BIL rating.During power frequency testing the level of partial discharge is carefully monitored. The power-factor and capacitance are also confirmed after the one-minute test.Bushing LoadingThe Ampere rating of a Type AB bushing indicates the maxi-mum continuous rating of the device without accelerated loss of life. These bushings are designed for overloading per IEEE Std C57.19.100-1995 with loss of life not to ex-ceed the calculations included in that standard.Draw rod applications have contacts with short circuit rat-ings of 20 times the continuous rating for not more than 2seconds and a dynamic peak not to exceed 2.5 times the rms value of the fault.For short circuit loss of life data relative to the bushing con-denser insulation, contact ABB.Recommended PositioningThe maximum stresses in the oil at the lower end of the bushing must be limited to those values normal for uninsulated conductors of similar components in the same transformer.The following recommendations are intended as guidelines only. See figure 3. Specific design calculations are recom-mended.Radius AEdge Radius BLower Insulator Large Flat SurfaceTable 1. Minimum Electrical ClearancesFigure 2. Bushing voltage tapVOLTAGE TAP COVERGASKETFILLER PLUGVOLTAGE TAPINSULATORGROUNDING SPRINGMOUNTING FLANGE6ABBOrdering DetailsWhen ordering please specify the following:1.Type, Style and Option Numbers 2.Current Rating3.Voltage Class and BIL4.Configurable Features or Option Number5.Special requirementsThe eighth through tenth characters, inclusive, indicate the maximum current rating of the bushing. The rating is the numerical value multiplied by100.Examples:•“ ...012 ...” indicates maximum 800 Amp. fordraw-lead and 1200 Amp. for bottom connected.• “...020 ...” indicates maximum 2000 Amp.The eleventh character is a hyphen.The twelth character indicates the ABB Inc. product designation; in this case, “A” for Type AB condenser bushing.The thirteenth and fourteenth characters are ABB designated letters for other characteristics such as CT pocket length, creepage and color of porcelain.The option number immediately follows the style number as characters fifteen through twenty.Characters fifteen and sixteen indicate the airside (or top end) bushing termination size and type. In most cases the termination should be selected to match IEEE Std C57.19.01-2000. But in some cases other selections can be made. See table 4 for options availableStyle and Option NumbersThe style number of a bushing provides information about the bushing it identifies. See page 9 for a graphical explanation of the functional style number discussed below.The first four characters of the style number are always 1ZUA.The fifth through seventh characters of the style number indicate the voltage class of the bushing in kV .Example:•“IZUA138 …” indicates 138 kV .Table 2. Voltage class designationsTable 4. Airside (top) terminationTable 3. Current rating designationsStud DescriptionTerminal TypeSize-Thread/Min. Useable ThreadApplication CommentDesignationThreaded Stud w/Silver Plating 1.5”-12UNF-2A/2.125”IEEE through 1200 Amp Ratings SE Threaded Stud w/Silver Plating 1.5”-12UNF-2A/2.5”IEEE 2000 Amp Ratings SG Threaded Stud w/Silver Plating 2.0”-12UNF-2A/3.0”IEEE 3000 Amp Ratings SMABB 7Characters nineteen and twenty define the draw-lead con-nector and extension to be supplied if the bushing has a draw-lead rating. If the bushing does not have a draw-lead rating or if a draw lead connector nor extension is not desired, these characters are “… XX…” See table 5 for the available draw-lead connectors in this technical guide.Airside extensions make it possible to apply a shorter bushing without cutting the draw lead or to accommodate other spe-cial circumstances. Contact ABB for further information.Special RequirementsAny nonstandard requirement, such as impulse tests or high temperature application, must be specified at the time of quotation.Characters seventeen and eighteen indicate the oil-side (or bottom end) bushing termination size and type. In most cases the termination should be selected to match IEEE Std C57.19.01-2000. But in some cases other selections can be made. Some options will affect cost and/or delivery.Table 6. Electrical DataTable 5. Draw-lead connector designations8ABBBottom Terminal ConnectionsThe Type AB bushing design allows for various oil end terminations.Draw Lead ConnectedSeveral specific connectors are available for draw lead ap-plication, as shown in figure 7. The standard industry con-nector is the flat blade type for welding or brazing. This is the connector historically provided with each draw lead ap-plicable bushing. This connector is designed for welding or brazing. Connectors for crimping are available. Draw leads are limited to 800 Ampere applications. See table 5 for connector designations. See table 7 for suggested draw lead cable ratings. Draw-lead bushings are always deliv-ered with a shield. (see figure 4)Bottom ConnectedType AB bushings in this Technical Guide generally have IEEE Std C57.19.01-2000 lower supports. Connection is made directly to the lower support of the bushing. The lower supports are shown in figure 5.Draw Rod ConnectedType AB bushings that are suitable for draw rod applica-tions have an opening through the main axis of the bushing conductor. See figure 11. The draw rod is drawn through this opening and secured at the top of the bushing. This makes it possible to remove/install bushings without drain-ing the apparatus on which it is applied. With this applica-tion the current is not carried by the rod but is transferred to the bushing conductor at the lower end of the bushing.Therefore, the draw rod rating of the bushing is the same as for bottom connected. However, the rating of the bushing does not affect the rating of the draw rod. The rating of the bushing/draw rod combination is never greater than the maximum rating of the lower rated component.Top Terminal ConnectionsThe Type AB bushings in this T echnical Guide generally have IEEE Std C57.19.01-2000 standard top terminals. The pur-chaser can order bushings with other terminals if desired.The choice of terminals may affect price and/or delivery.Table 7. Suggested Draw Lead Cable Ratings Suggested Draw Lead Cable RatingsSize Maximum Continuous Rating (MCM)(mm 2)(Amperes)450228440800405.46709004567501000506.7800Figure 4. Shield for draw-lead bushingsB. 1200, 2000, or 3000 A.Figure 5. Lower supportsOil-Side Terminal “EA”IEEE Std C57.19.01-2000 Fig. 3.4Oil-Side Terminal “EA”IEEE Std C57.19.01-2000 Fig. 3.5Oil-Side Terminal “WC”A. 800A.Figure 6. Graphical Explanation of Style and Option NumbersABB 9Figure 7. Sample Draw Lead Connectors10ABBABB 11Figure 8. Top end construction for Type AB bushingsTOP TERMINAL (not removable)SELF-LOCKING NUT LOCKPIN(2) 5/32” HOLESIN RODLOCK RETAINER CONDUCTOR EXTENSIONCONNECTORSTEEL WASHER INSULATING SPACER (note orientation)TOP TERMINAL (removable)TOP PLUG5/32” HOLE IN ROD STEEL WASHERDRAW RODINSULATING WASHERA. 800/1200 Amp DrawLead/Bottom ConnectedB. 1200 Amp Draw Rod ConnectedC. 2000 or 3000 Amp Bottom ConnectedD. 2000 or 3000 Amp DrawRod ConnectedTUBE EXTENSIONDimensional DataFig. 9 Dimensional Outline2) “EL” is the recommended minimum oil level. “W” is the absolute minimum oil level permitted under any condition.Table 8. Lower End Dimensions12ABBTable 9. Flange Dimensions1) The length given includes IEEE Std C57.19.01-2000 terminals3) “Lowest HV” is the shortest distance from the flange mounting surface to any “live parts” on the airside of the bushing.Table 10. Top End DimensionsABB1314ABBDimensional DataFigure 9. Dimensional OutlineFigure 10. Bottom TerminalsABB15T a b l e 11. T e r m i n a t i o n D i m e n s i o n s16ABBFigure 11. Configuration for draw-rod bushingTRANSFORMER LEADTRANSFER OF CURRENT TO BUSHINGJOINT IN DRAW RODSEE FIGURE 8B AND 8D FOR DETAILFLATS FOR WRENCH0.312” - 18 UN FEMALE THREAD 0.5” DEEPUPPER TERMINALTRANSFORMERCOVERFLANGESHIELDC.T.POCKET LENGTHABB1718ABBABB19DISCLAIMER OF WARRANTIESAND LIMITATION OF LIABILITYTHERE ARE NO UNDERSTANDINGS, AGREEMENTS, REP RESENTATIONS OR WARRANTIES, EXP RESSED OR IMP LIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A P ARTICULAR PURPOSE OTHER THAN THOSE SPECIFICALLY SET OUT BY AN EXISTING CONTRACT BETWEEN THE P ARTIES. ANY SUCH CONTRACT STATES THE ENTIRE OBLIGATION OF SELLER. THE CONTENTS OF THIS DOCUMENT SHALL NOT BECOME PART OF OR MODIFY ANY P RIOR OR EXISTING AGREEMENT, COMMITMENT OR RELATIONSHIP.THE INFORMATION, RECOMMENDATIONS, DESCRIP-TION AND SAFETY NOTATIONS IN THIS DOCUMENT ARE BASED ON OUR EXPERIENCE AND JUDGEMENT WITH RESPECT TO BUSHINGS. THIS INFORMATION SHOULD NOT BE CONSIDERED TO BE ALL INCLUSIVE OR COVERING ALL CONTINGENCIES. IF FURTHER INFORMATION IS REQUIRED, ABB INC. SHOULD BE CONSULTED.NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY, OR WARRANTIES ARISING FROM COURSE OF DEALING OR USAGE OF TRADE, ARE MADE REGARDING THE INFORMATION, RECOMMENDATIONS, DESCRIPTIONS, AND SAFETY NOTATIONS CONTAINED HEREIN. IN NO EVENT WILL ABB INC. BE RESPONSIBLE TO THE USER IN CON-TRACT, IN TORT (INCLUDING NEGLIGENCE), STRICT LI-ABILITY OR OTHERWISE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGE OR LOSS WHATSOEVER INCLUDING BUT NOT LIMITED TO DAM-AGE TO OR LOSS OR USE OF EQUIPMENT, PLANT OR POWER SYSTEM, COST OF CAPITAL, LOSS OF PROF-ITS OR REVENUES, COST OF REPLACEMENT POWER, ADDITIONAL EXPENSES IN THE USE OF EXISTING POWER FACILITIES, OR CLAIMS AGAINST THE USER BY ITS CUSTOMERS RESULTING FROM THE USE OF THE INFORMATION, RECOMMENDATIONS, DESCRIPTION, AND SAFETY NOTATIONS CONTAINED HEREIN.ABB Inc.1128 S. Cavalier Drive Alamo, TN 38001, USA Telephone: 731-696-5561 Fax: 731-696-5269 I Z U A 2 7 5 1 -2 1 2 e n , J u l y 2 0 0 3 N e w d o c u m e n t P r i n t e d i n U S A b y T e n n e s s e e I n d u s t r i a l P r i n t i n g S e r v i c e s , I n c.。