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2750 515-1 EN, REV. 14, 2020-06-26 Transformer bushing, type GOE 250 to 2550 Installation and commissioning guide...
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The information contained in this document may be subject to change without prior warning and should not be considered as binding on ABB AB’s behalf. ABB AB accepts no liability for any errors that may appear in this document. ABB AB is not liable for any damage resulting from the incorrect interpretation of this document.
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5 Commissioning 5.1 Waiting time before energization ..............................61 5.2 Recommended test before energization ............................. 62 5.2.1 Overview ................................... 62 5.2.2 Tightness test between transformer and bushing flange................... 62 5.2.3 Tightness test of bushing outer terminal........................62 5.2.4 ...
1 Safety 1.1 Levels of safety risks Throughout the manual, various types of safety risks are indicated. The most serious level on this scale provides a warning about serious personal injury or possible death, or major damage to a product, if the instructions are not observed.
1.2 Hazardous working situations Hazard Action Working close to high voltage. Disconnect all plant power. Ground all objects at the workplace. If work must be done close to live plant components, make sure that the safety distance is in compliance with the applicable safety regulations.
2 Product description 2.1 Design Overview The GOE is a capacitance graded oil impregnated paper bushing made for immersed oil/air service. For a detailed description, please refer to the Technical guide, 1ZSE 2750-105. General schematics Oil plug Sight glass, GOE 250 to 950 Oil-level gauge, GOE 1050 to 2550 Oil sampling valve ¼”...
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Terminal system The bushing can be configured with one of two terminal systems: the draw-lead system, or the draw-rod system. The draw-rod system can be configured with a small, or a large bottom contact. Terminal system Option Draw-lead system Draw-rod system Small bottom contact Large bottom contact Draw-lead system...
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Draw-rod system The draw rod can be configured with an optional joint (53) to fit transformers with short bushing turrets. The bottom-contact joint (56) is locked with threadlocking fluid as standard. Large bushings with long draw rods have one or two upper joints (52), they are always locked with threadlocking fluid.
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Horizontal installation CAUTION! Do not install bushings that does not have the oil passage (42) in the horizontal position. If the bushing will be installed in the horizontal position, then this must be specified in the order. Because horizontally installed bushings must be fully filled with oil (there is no expansion space for the oil), the oil must flow freely to and from the transformer tank through an oil passage (42).
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Test tap The bushing has a test tap that is connected to the outermost conductive layer of the condenser core. The test tap is used to measure the bushing insulation by capacitance and dissipation factor. The cover connects the outermost conductive layer to ground, and must always be installed when the bushing is energized. The maximum one minute test voltage for this test tap is 20 kV .
In the axial direction, the bushing can withstand a static load of 20 kN. NOTE! The loads described in this section are static loads, for dynamic loads such as earthquakes and extreme wheather conditions, please contact your ABB sales representative. Installation and commissioning guide 2750 515-1 EN, REV. 14, 2020-06-26...
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Maximum cantilever load at installation angle 0° Maximum cantilever load at installation angle 30° Maximum cantilever load at installation angle 60° Maximum axial static load Load applied at the midpoint Type Test load 1 Maximum cantilever load in operation at Maximum minute (N) installation angle (N)
3 Delivery 3.1 Incoming inspection • Make sure that all items have been delivered, refer to the packing list. • Carefully inspect the bushings for shipping damage. NOTE! The bushing has been routine tested in oil, and there can be small quantities of oil remaining on the oil-side of the bushing.
As an alternative: keep the bushing in the transport box and lift it to an inclined position, with the top end upwards and at an angle of at least 7°. The bushing is delivered from ABB in a transport box, and the bushing is held in place by support blocks and fiberboard in the box.
Procedure Make sure that the crane and the soft lifting slings are approved for the total weight of the transport box and bushing. Refer to the weight in the packing list. Attach soft lifting slings (8). Make sure that the angle of the soft lifting sling is not more than 20°. Carefully lift the transport box.
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NOTE! If the outer terminal is not installed, please contact ABB. Carefully lift the bushing. Make sure that the support blocks are in the same positions as the support blocks in the transport box.
For removal, and installation of the bottom contact. Draw-rod system. Tackle For installation of the bushing at a specific angle. 4.2 Consumables Item Brand ABB part Note number Oil based Vaseline Fuchs For treatment of contact surfases. Does not react with transformer oil. Mobilgrease 28...
4.3 Preparations 4.3.1 Lifting the bushing Overview Lifting tool Soft bedding, e.g. rubber mat or woodboard Shackle Procedure Make sure that the crane can lift the bushing. Refer to net weight in the packing list. Loosen the M8 bolts (24). NOTE! It is not necessary to remove the M8 bolts.
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Remove the M10 bolts (6) and washers (7), and then remove the outer terminal (5). NOTE! Keep the outer terminal (5), washers (7) and bolts (6), they will be used again. Install the lifting tool (1), the M10 bolts (6) and the washers (7).
For installation at a specific angle: attach soft lifting slings with a shackle (31) from the flange to the crane hook. Align the crane hook with the lifting tool on the bushing. Carefully lift the bushing. CAUTION! Make sure that the bushing does not rotate. Adjust the shackle (31) until the bushing flange has the same angle as the transformer flange.
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Procedure Install the lifting tool: Remove the bolts (6) and washers (7). Install the lifting tool (1), and align the side of the lifting tool with the oil-level glasses (25). Install the longer M10 bolts (6) and washers (7) if the lifting tool is mounted on the stud. Torque 40 ±4 Nm Lift the bushing to the vertical position.
4.4 Horizontal installation of the bushing on the transformer Overview The bushing is installed without removal of the bottom contact. Procedure Install the springs (15), the guiding sleeves (16), the pressing ring (17), and the hex screws (18) to the bottom contact. Remove the covering plate (27).
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Remove the lifting tool (1): Remove the long bolts (6), washers (7) and lifting tool (1). Install the original bolts (6) and washers (7). NOTE! The lifting tool uses longer bolts (6), use the original bolts (6) to attach the outer terminal (5).
4.5 Installation with draw lead 4.5.1 Calculation of the length of the draw lead Overview Because of the tolerances in the length of the porcelain, a nominal lenght for the draw lead can not be given. The actual distance between the inner terminal and the sealing surface of the flange must be calculated. Procedure Measure the length (L2).
4.5.2 Installation with draw lead Overview Draw lead Pull-through cord Inner terminal Bushing Procedure Remove the inner terminal (32) from the bushing. Remove the nut (19) and washers. Installation and commissioning guide 2750 515-1 EN, REV. 14, 2020-06-26...
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Braze the draw lead (2) from the transformer windings to the inner terminal (32). Carefully clean the bottom end of the bushing, and the inside of the center hole. Look for damage. Install the springs (15), the guiding sleeves (16), the pressing ring (17), and the hex screws (18) to the bottom end of the bushing.
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Put the washers and the nut (19) on the pull-through cord. CAUTION! Make sure that the washers are in the correct order. Plain washer Conical spring washer Contact washer Lower the pull-through cord (12) through the bushing. Apply Molykote Multilub to the pull-through cord (12), and attach it to the inner terminal (32).
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Hold the pull-through cord (12) in tension, while lowering the bushing onto the transformer. CAUTION! Do not damage the stud bolts on the transformer. There is a risk of metal falling into the transformer. CAUTION! Make sure that the draw lead is entering the bushing correctly.
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Install the nuts and washers. Tighten the nuts in a crosswise sequence. CAUTION! Make sure that the nuts are tightened evenly. First tighten all nuts to half the torque, then to the full torque. Torque Please refer to the transformer manufacturer.
4.6.1 Removal of the lower draw rod with bottom contact from the bushing Overview The bottom contact is usually installed in the bushing when it is delivered from ABB, the first step at the transformer factory is thus to remove it.
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Make sure that more than 10 mm of the threads on the upper draw rod (35) is used by the shaft (37). Put the hydraulic jack (38) on the shaft (37), and install the nut (44) and washer but do not tighten it.
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Loosen the nut (44). Turn the shaft (37) counter clockwise to remove the shaft-socket from the upper draw rod (35). Remove the hydraulic jack (38) from the bushing. Apply Molykote Multilub to the threads on the pull-through cord (12), then connect it to the upper draw rod.
Remove the draw rod nut (10). NOTE! The draw rod will fall out of the bushing if it is not in the horizontal position. Pull down the draw rod from the bottom end of the bushing, and disassemble it at the lower joint (39). NOTE! The upper thread (60) is locked with thread-locking fluid grade 42.
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Procedure Install the springs (15), the guiding sleeves (16), the pressing ring (17), and the hex screws M10 (18) to the bottom end of the bushing. Torque 40 Nm Put the winding cables through the end-shield. Install the winding cables to the bottom contact. CAUTION! Make sure that there is no tension in the winding cables.
Continue with Installation of the bushing on the transformer, page 39. End of instruction 4.6.3 Installation of the large bottom contact (N1=6) in the transformer Overview The end-shield can be installed to both the large bottom contact and the bottom nut of the bushing. This procedure describes installation on the bottom contact.
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Install the winding cables to the bottom contact. CAUTION! Make sure that there is no tension in the winding cables. Tension in the winding cables will cause damage to the bottom contact. Torque 68 ±6 Nm Install the end shield: Push the end shield carefully against the pressing ring (17), until the hex screw heads come through the holes in the end shield.
It is important to install the draw rod correctly, thus the ends of the draw rod parts must make contact at (67). CAUTION! Do not disassemble the joints (52), these are correctly assembled and locked with tread-locking fluid by ABB. Procedure Connect the upper draw rod (35) to the lower draw rod (4).
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Make sure that the joint is correctly threaded: Calculate the nominal distance: H = L - 25 mm (± 2 mm). Refer to the rating plate for the distance L. Measure the distance H and compare it to the nominal distance H. NOTE! When the joint is correctly threaded, 2 threads on the upper (60) and...
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If the bushing is installed in a non vertical position: • For GOE 250 to 950: the sight glasses (25) must be perpendicular to the angle of the bushing. • For GOE 1050 to 2600: the oil-guage (26) must point down. Install the washers and nuts.
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Tighten the draw-rod nut (10). NOTE! Make sure that more than 10 mm of the threads on the upper draw rod (35) is remaining. Torque 10 Nm Remove the pull-through cord (12). Remove the bolts (6), the washers (7) and the lifting tool (1).
4.7 Installation with draw rod at site 4.7.1 Preparations at site Overview This procedure is only applicable if the lower draw rod with the bottom contact (36) is installed in the transformer. Procedure Loosen the M8 bolts (24). Remove the M10 bolts (6), and then remove the outer terminal (5).
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Install the lifting tool (1), the M10 bolts (6) and the washers (7). • For GOE 250 to 950: align the side of the lifting tool with the oil-level sight glasses (25). • For GOE 1050 to 2550: align the side of the lifting tool with the oil-level guage (26).
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Remove the M16 nut (10), and washer. With a soft cloth, carefully clean the bottom end of the bushing, and the inside of the center hole. Look for damage. Pull down the upper draw rod (35) from the bottom end of the bushing. Remove the transport cover (45) from the transformer (46) and the lower draw rod (4).
4.7.2 Installation of the bushing on the transformer at site Procedure Apply locking fluid on the threads (39) on the lower draw rod (4). • If the bottom contact is removed from the lower draw rod (4): apply locking fluid on the threads (56).
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If the bushing has the small bottom contact, then install the end shield: Push the end shield carefully against the pressing ring (17), until the hex screw heads comes through the holes in the end shield. Turn the end shield approximately 20°, to its locked position.
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Install the washers and nuts. Tighten the nuts in a crosswise sequence. CAUTION! Make sure that the nuts are tightened evenly. First tighten all nuts to half the torque, then to the full torque. Torque Please refer to the transformer documentation.
Remove the bolts (6), washers (7) and lifting tool (1). Remove the pull-through cord (12). Tighten the draw-rod nut, refer to Hydraulic tightening of the draw-rod nut, page 49, or Manual tightening of the draw-rod nut, page 53. End of instruction 4.8 Hydraulic tightening of the draw-rod nut Overview Draw rod nut...
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Procedure Measure the distance (a). Measuring is performed when the draw rod nut is tightened with torque 10 Nm. NOTE! The bushing is delivered with an information sheet that specifies the draw-rod extension (b-a). These values are measured when the bushing is manufactured, and are unique to every unit.
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Put the hydraulic jack (38) on the shaft (37), and install the nut (44) but do not tighten it. Pull the draw rod with 40 kN. DANGER! Apply the hydraulic pressure carefully. Incorrectly used high pressure hydraulics can break with explosive force. NOTE! It is not necessary to compensate for variations in ambient temperature.
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Measure the distance (b). Calculate the extension of the draw rod: (b) minus (a). Compare the calculated value (b-a) with the dimension in the table. NOTE! Please contact ABB for special bushings. Type Extension GOE 250 - 210 3.5 mm ±1.0 GOE 380 - 300 3.5 mm ±1.0...
If possible, ABB recommends that the draw rod is hydraulically tightened, refer to Hydraulic tightening of the draw-rod nut, page 49.
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Turn the nut clockwise until you get the correct extension (b). Distance (b) = (a) + extension, refer to the table. CAUTION! Make sure that you do not overtighten the nut. Use a torque wrench set to 140 Nm. NOTE! One turn of the nut corresponds to a 2 mm extension of the draw rod.
4.10 Minimum oil-level in transformer Procedure Make sure that the transformer oil-level is maximum 30 mm from the lower side of the bushing flange. CAUTION! A lower oil-level will reduce the electrical insulation. End of instruction 4.11 Installation of the outer terminal Procedure Prepare the contact surface (47) and gasket surface (87):...
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Prepare the contact surface (47), gasket surface (87) and O-ring (3): Carefully clean the contact surface and gasket surface with a soft cloth. Apply Vaseline to the contact surface. Apply Mobilgrease 28 to the gasket surface and O-ring (3). CAUTION! Do not use a wire brush on the tin/zinc coating on aluminium outer-terminals.
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Apply Molykote Multilub to the M10 bolts (6). Install the M10 bolts (6) and plain washers (7). Tighten the M10 bolts (6) in a crosswise sequence. CAUTION! Make sure that the outer terminal moves straight down. Turn each bolt a little, and then the next bolt, until all bolts can be tightened to the correct torque.
4.12 Grounding of the bushing flange Overview The bushing flange must be grounded to the transformer tank. This prevents electrical discharge between the bushing flange and the transformer tank under normal service conditions. There are two alternatives. DANGER! Make sure that the grounding is correct. An unsatisfactory grounding can cause damage to equipment, or death to personnel.
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Put a flexible cable (64) between the grounding hole in the bushing flange and a grounding point on the transformer. Apply a large quantity of Mobilgrease 28 to the bolt (50). CAUTION! The quality of the bolt is important, stainless steel of A4-80 quality is recommended. NOTE! Or use a lubricant similar to Mobilgrease 28.
5 Commissioning 5.1 Waiting time before energization General requirements for the bushing • If the bushing has been stored in the vertical position with the top end upwards, then no waiting time is required. • If the bushing has been stored in an inclined position of 7°, required waiting time in the vertical position is 24 hours.
Water could enter directly into the transformer insulation. It is thus recommended to do a tightness test after installation of the bushing, both with vacuum and pressure. Different methods can be used, and ABB refers to the instructions given by the company responsible for the field erection of the bushing.
Find leaking gas with gas detector (sniffer) near the gasket. End of instruction 5.2.4 Measurement of capacitance and dissipation factor Overview After installation of the bushing, it is recommended to measure the capacitance values for future reference, such as repairs, service etc. This can be done on an installed bushing because it has an insulated test tap. Refer to 2750 515-142, “Bushing diagnostics and conditioning”.
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* Reference values from ABB Components. Dissipation factor, tan δ The dissipation factor varies with the temperature of the bushing core, and thus the measured dissipation factor must be multiplied with the correction factor given below. Bushing core temperature °C Correction factor to 20 °C (IEC)
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Connect the measuring equipment. Connect the low voltage cable to the stud (57). Connect the high voltage cable to the outer terminal. Connect the ground cable to the bushing flange (65). Measure the capacitance (C ) between the outer terminal and the stud (57). •...
5.2.5 Measurement of through-resistance Overview The method to use for measuring the through-resistance depends on the design of the transformer. In general, a current is applied from bushing to bushing. The voltage drop from the outer terminal to outer terminal is measured.
6 Maintenance 6.1 Recommended maintenance General The bushings are maintenance free, no regular maintenance is necessary. DANGER! Risk of electrocution! Do not go near the bushing while it is energized, or ungrounded. High voltages can kill you. Make sure that the bushing is de-energized, and grounded before you do work on it. Cleaning of the insulator surface If the insulator is exposed to very high pollution, it can be necessary to clean the surface.
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Make a visual inspection for oil leakage during regular station supervision. After repairs ABB recommends that the capacitance is measured after repairs have been done, after maintenance of connected equipment, or after work near the bushing is completed. It is important to compare the capacitance before energization with the capacitance that was measured at commisioning.
The oil-level at normal and high temperatures, must always be above the red area on the oil-level indicator. If the oil-level is in the red area, fill the bushing with clean and dry transformer oil. Please contact ABB for the correct oil-level. Oil-filling is only allowed when the temperature of the bushing is between +5 °C and +35 °C.
Remove the cover (58) and oil-plug (9). Fill the bushing with transformer oil to the correct oil-level. For more information, contact ABB. Install and tighten the oil-plug (9). Use a new gasket, article number: 1ZSC001591-AAC. Install the cover (58) and gasket (66).
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Procedure for bushings with oil valve Put a container under the oil valve (51) to collect oil-spills. CAUTION! If transformer oil spills, clean the are immediately. A wet surface is dangerous and can cause you to fall. Remove the cover (89). CAUTION! Make sure that the oil valve does not rotate.
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Check the oil-level. If the oil-level is low, refer to Checking the oil-level, page 69. CAUTION! The oil-level must be above the red area (29). NOTE! It is generally not necessary to fill the bushing with oil after an oil sample is taken.
NOTE! The terminal on the pull-through cord (12) has M8 threads. NOTE! ABB Components recommends that the hydraulic jack is used for the removal of the lower draw rod, refer to Removal of the lower draw rod with bottom contact from the bushing , page steps 1 through 8.
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Remove the M16 nut (10) on the draw rod with the box spanner (13). Remove the nuts and washers. Lift the bushing from the transformer. CAUTION! Do not damage the stud bolts, there is a risk of metal falling into the transformer.
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Disassemble the draw rod at the lower joint (39). Use the key grip on the lower draw rod. DANGER! Make sure that the upper draw rod does not fall down when the lower joint (39) is disassembled. CAUTION! Do not disassemble the joint (60), this increases the risk of incorrect assembly.
Pull out the upper draw rod (35) and support tubes (80) by hand. CAUTION! Be careful when pulling out the draw rod. The bushings inside can easily be damaged. Install the lower draw rod (4) in the transport cover (45). Install the transport cover (45) on the transformer turret (46).
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Install the covering plate (27) and the gasket over the oil-passage. Torque M12 50 ±5 Nm Put the bushing in the vertical position. Remove the cover for oil-plug and the oil-plug (9). Remove transformer oil until the oil-level is correct for storage. CAUTION! Make sure that the oil level is correct.
7.3 Re-packing of the bushing Overview Procedure Put plastic wrap on the draw rod, and fix it to the transport box. CAUTION! Do not put the draw rod into the bushing, the threads on the draw rod will scratch the inside of the center-tube.
8 Spare parts and special tools 8.1 Summary If the bushing is damaged, we recommend that it is returned to ABB for repairs and re-testing. Some parts that are damaged or lost during transportation or installation can be ordered from ABB.
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Oil-plug 2522 731-A Position Part Article number Note Oil-plug 2121 738-18 Gasket 1ZSC001591-AAC Cover for oil-plug 2522 731-A For new design of the top chamber. This cover gives protection to the oil-plug 2522 731-A. Position Part Article number Note Cover 2522 732-42 Gasket 2152 795-67...
8.3 Special tools Lifting tool Position Part Article number Note Lifting tool 9760 668-A Pull-through cord Position Part Article number Note Pull-through cord 9760 669-A With M8-terminal. Installation and commissioning guide 2750 515-1 EN, REV. 14, 2020-06-26...
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Hydraulic jack Position Part Article number Note Hydraulic jack 9769 897-A For removal, and installation of the bottom contact. Draw-rod system. Box-spanner Position Part Article number Note Box-spanner 9760 669-B Installation and commissioning guide 2750 515-1 EN, REV. 14, 2020-06-26...
9.2 Disposal and recycling ABB strives to minimize the product's impact on the environment throughout its entire life cycle. Technical and product development focuses on environmental aspects. The ecocycle approach is striven for, and consideration is taken to the materials' environmental impact and recycling alternatives.
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Many metal components of iron, steel and aluminum are large and easy to identify, e.g. support structures. ABB strives to reduce the use of precious metals and the release of environmentally hazardous metals.
11 Appendix 11.1 Measurement record Overview Record the final measurements of the draw rod. Record Serial number Date Operator H (mm) c (mm) X1 (mm) Ø (mm) a (mm) b (mm) Thread diameter. Draw-rod nut tightened with 10 Nm. After hydraulic tightening.