01 Installation of cold shrinkable cable accessories.
Cold shrinkable cable accessories are usually made of elastic rubber materials (commonly used silicone rubber and ethylene propylene rubber) in the factory to inject various cable accessories into parts and vulcanized molding, and then the inner diameter is expanded and lined with spiral plastic support strips to maintain the expanded inner diameter. For on-site installation, these pre-expanders are placed at the end of the treated cable (termination) or at the connector (intermediate joint), and the spiral plastic support strip is withdrawn, and the rubber part shrinks and presses against the cable insulation, thus forming a terminal or intermediate joint. Because it is elastically retracted at room temperature, unlike heat shrinkable cable accessories, which are heated and contracted by fire, it is called cold shrinkable cable accessories.
1.1 10 kV power cable cold shrink terminal fabrication
1) Main process flow.
Figure 1 shows the main process flow of cold shrink terminal production of 10 kV power cable.
Figure 1The main process of cold shrink terminal production of 10 kV power cable
2) Specific operation steps and requirements of 10 kV power cable cold shrinkable terminal.
1) Preparation for construction.
Clean up the work site, and check whether the tools and accessories used are complete and qualified before construction, such as crimping pliers, molds and cable specifications should be matched.
Open the package and take out the cable accessories, check whether the accessories are complete, and whether they are consistent with the size and specifications of the cable, as shown in Figure 2.
Figure 2Check the attachments
Before installing the cable accessories, check whether the cable ends are well sealed and whether there is moisture. For cross-linked cables, if they are wet, they should be treated before they are wet.
2) Cable pretreatment.
Fixed cable: The production and installation of the cable terminal head should be fixed vertically as far as possible, so as to avoid the dislocation of the wire core during hoisting after ground installation, and the length of the three-phase is different, so that the branch glove accessories are partially damaged. According to the installation position of the terminal head, the cable is fixed on the terminal head support clip, in order to prevent damage to the outer sheath, the liner should be added between the clip and the cable, and the excess cable is sawed off according to the actual measurement size plus the construction allowance.
Determine the stripping size: straighten and clean the cable, as shown in Figure 3, determine the stripping size of the cable, and strip the outer sheath, armor layer, inner sheath and filler in turn.
Figure 310 kV power cable cold shrink terminal stripping dimensions
Stripping the outer sheath: take A+B from the cable end (A is the actual size of the site, B is the depth of the terminal hole) and strip the cable outer sheath. Peel off the outer sheath, which should be done in two installments to avoid loosening of the steel strip of the cable armor layer. Peel down the outer sheath 25 mm to expose the steel armor, and scrub it with cleaning paper 50 mm down from the peeling place.
Sawing the armor layer: fastening the armor layer of the steel armor, measuring the steel armor 25 mm from the outer sheath port of the cable to see the armor layer, when sawing the steel armor, its circumferential saw marks should not exceed 2 3 of the thickness of the steel armor, and should not be sawed through, so as not to damage the inner sheath.
Strip the inner sheath and filler: wrap the three-phase copper shield end of the cable with insulating self-adhesive tape to prevent the copper shield from loosening. Keep the 10 mm inner sheath according to the size requirements, and remove the rest, and the copper shield shall not be damaged when peeling the inner sheath. Cut the filler along the edge of the inner sheath from the inside to the outside of the knife edge, and the copper shield must not be damaged when cutting. When separating the three-phase core, do not bend it hard to avoid the wrinkles and deformation of the copper shielding layer. Wrap the folded parts with insulating self-adhesive tape to prevent scratching the cold shrink tube.
Fixing the ground wire of the steel armor: Stuff the triangular cushion cone into the bifurcation of the cable, polish the paint and rust on the steel armor, and fix the ground wire of the steel armor on the steel armor with a constant force spring. In order to be firm, the ground wire should be left with a head of 10 20 mm, after the constant force spring wraps it around, the exposed head is folded back, and then wound with the constant force spring, as shown in Figure 4, the installation is finished with 23 No. 23 insulating tape wrapped in two layers to cover the constant force spring.
Figure 4Fixed steel armor ground wire
Fixing the copper shield ground wire: wrap the ground wire at the root of the three-core copper shield, lead it out downward (note that the position of the ground wire is contrary to the position of the steel armor ground wire), fix the ground wire on the copper shield with a constant force spring, and semi-overlap the second layer of No. 23 insulating tape, and clamp the ground wire in it to prevent water and gas from seeping into the ground wire gap.
Wrapping filler: wrap and enrich the grounding wire with filler, and wrap two layers with filler from 50 mm below the port to the entire constant force spring, steel armor and inner sheath, and wrap one more layer at the three-way junction, so that the cold shrinkable finger sleeve is full and full. A layer of black self-adhesive tape is wrapped around the filler and constant force spring to make it easy to extract the plastic strip in the cold shrinkable finger sleeve.
3) Install the cold shrink attachment.
Install the cold shrinkage branch gloves: first pull out the support tube inside the 3 finger tubes slightly (aligned with the finger roots from the inside), then put the branch gloves into the cable bifurcation and press down as much as possible, first pull out the lower plastic strip counterclockwise, and then pull out the plastic strip in the finger tube. The shrinkage should be even, and brute force should not be used to avoid damage to the attachment.
Install the cold shrinkable sheath: wrap the PVC tape within 100 mm of the finger tip of the finger sleeve, put the cold shrinkable tube to the root of the finger sleeve, and pull out the plastic strip counterclockwise, the speed should be uniform and slow, the two hands should cooperate and coordinate, hold the end of the cold shrink tube with your hand, release it after positioning, and do not hold the unshrunken cold shrink tube all the time, as shown in Figure 5.
Fig.5. Installing the cold shrink sheath
Cutting the sheath tube: according to the distance from the end of the cold shrinkable pipe to the terminal, cut or lengthen the cold shrinkable tube, when cutting the sheath pipe, it must be fixed with two layers of insulating self-adhesive tape, and after the circumferential circumference is cut, it can be cut longitudinally, and the copper shield shall not be damaged when stripping, and it is strictly forbidden to cut without bandaging.
4) Pressure treatment.
Stripping copper shielding layer: 30 mm copper shield is measured upwards from the port of the cold shrinkable sheath, and the rest is removed, in order to prevent the copper shielding tape from loosening, it can be tied tightly with insulating self-adhesive tape at the appropriate position of the cable core. The cutting place is tied tightly with insulating self-adhesive tape or fine copper wire, and when cutting, only one knife mark can be cut by the ring, about 2 3 depths, and it cannot be cut through, so as not to damage the semi-conductive layer. When stripping the copper shield, it should be torn off at the knife mark and stripped off to the end of the wire core after disconnection. The ports of the copper shield should be cut flat and free of tips and burrs.
Peel the outer semi-conductive shielding layer: take 10 mm of semi-conductive shielding from the copper shield port upwards, and peel off the rest. Peel off the outer semi-conductive layer, circumferential cutting and longitudinal cutting knife marks, can not be cut through, so as not to damage the main insulation. The outer semi-conductive layer should be peeled off clean, and no residue should be left, and the semi-conductive dust adsorbed on the insulating surface must be sanded with fine sandpaper and the surface of the insulating layer must be cleaned and clean.
Insulation end stress treatment: the outer semi-conductive layer and the end of the insulator are sanded with sandpaper or cut chamfered with a knife, and polished to be smooth and smooth, and the transition with the insulation is smooth. Two layers of semi-conductive tape are wrapped around to cover the steps between the copper shield and the outer semi-conductive layer. A layer of waterproof glue is wrapped 6 mm below the nozzle of the cold shrink sleeve.
5) Install the terminal.
Strip the insulation at the end of the core: clean the insulation surface of the cable with cleaning paper, and wipe it from the end of the core to the direction of the outer semi-conductive layer, and never wipe it back and forth. The length of the insulation at the end of the core is stripped to the hole depth of the terminal block plus 5 mm. When stripping the core insulation, the core conductor shall not be damaged, and the conductor shall be carried out in the direction of wire stranding, and the conductor shall not be loosely deformed.
Installation terminal: 25 mm below the mouth of the three-phase branch glove, wrap the insulating tape for identification, which is used as the terminal installation reference. Coat the surface of the core with silicone grease (multi-coating), insert it into the cold shrinkable terminal, insert the terminal forcefully, and slowly pull the support strip in the terminal until the lower port of the terminal is aligned with the logo, and the logo shall not be exceeded.
The cold shrink terminal shrinks from the root to the insulated end, and gently pulls the support strip counterclockwise to shrink the cold shrink tube (if the terminal and the logo are misaligned when the shrinkage begins, you can correct it by hand). The contraction should be even, and the force should not be too large, so as not to cause damage to the attachment. At the junction between the terminal and the cold shrinkable sheath, several layers of insulating self-adhesive tape must be wrapped to strengthen the seal.
6) Crimp the terminals.
When crimping, select the corresponding mold according to the specifications of the cable, insert the terminal block, and make close contact with the conductor, and crimp in the order of first down and then up.
After crimping, polish the burrs and flashes, wipe them clean, and fill the terminal according to the filler specified in the installation process manual.
The ground terminal must be firmly connected to the ground grid.
7) Install the cold shrinkable phase tube.
The cold shrinkable phase tubes are inserted into each phase according to the color of the phase, and the plastic spiral strip is withdrawn counterclockwise, as shown in Figure 6. The two ends of the same cable core should be the same in color and correspond to the phase sequence of the connecting busbar.
When fixing the three phases, the distance between the phases (between the terminals) should be ensured, not less than 200 mm outdoors and not less than 125 mm indoors.
Fig.6. Installing the cold shrinkable color tube
1.2 10 kV power cable cold shrinkable intermediate joint fabrication
1) Main process flow.
The main process flow of 10 kV power cable cold shrinkable intermediate joint production is shown in Figure 7.
Fig.7. The main process of making cold-shrinkable intermediate joints for 10 kV power cables
2) Specific operation steps and requirements of 10 kV power cable cold shrinkable intermediate joint.
1) Preparation for construction.
Before construction, it should be checked whether the tools and accessories used are complete and qualified, such as crimping pliers, molds and cable specifications should be matched.
Check whether the packing list of accessories is consistent with the accessories materials, and the specifications of the cable accessories should be consistent with the specifications of the installed cables.
Before installing the cable accessories, check whether the cable ends are well sealed and whether there is moisture. For cross-linked cables, if they are wet, they should be treated before they are wet.
2) Cable pretreatment.
Determine the center of the joint: Place the cable in its final position, scrub the cable sheath within 1 m of each end, and wipe off dust, oil and other dirt. Straighten the cable, straighten the two cables, overlap 200 300 mm, determine the center of the joint, and saw off the excess cable.
Determine the peeling size: Determine the peeling size as shown in Figure 8.
Fig.8. Stripping dimensions of cold shrinkable intermediate joints of 10 kV cables
Stripping the outer sheath: Measure the long end 800 mm and the short end 600 mm respectively from the center of the joint, and peel the outer sheath, and the stripping should be carried out in two times to avoid the loosening of the steel belt of the cable armor layer. The 100 mm section behind the port of the outer sheath was flipped with an abrasive cloth and scrubbed with cleaning paper.
Sawing the armor layer: keep a small section of the outer sheath at the port (to prevent the steel armor from spreading), first tighten the armor layer steel armor with a constant force spring, measure the steel armor 30 mm from the cable outer sheath port to see the armor layer, when sawing the steel armor, its circumferential saw mark should not exceed 2 3 of the thickness of the steel armor, and it should not be sawed through, so as not to damage the inner sheath, the incision should be neat, and there should be no sharp corner burrs. After removal, wrap the sharp edge of the port with insulating self-adhesive tape.
Strip the inner sheath and filler: wrap the three-phase copper shield end of the cable with insulating self-adhesive tape to prevent the copper shield from loosening. Peel off the inner sheath at a distance of 30 mm from the armor layer according to the size requirements, and the copper shield shall not be damaged when peeling the inner sheath. Cut the filler along the edge of the inner sheath from the inside to the outside of the knife edge, and the copper shield must not be damaged when cutting. When separating the three-phase core, do not bend it hard to avoid the wrinkles and deformation of the copper shielding layer.
Sawing off the excess cable core: tie the corresponding core according to the color requirements, and the core should not be bent too large to facilitate the operation, but it is necessary to ensure that the bending radius meets the specified requirements. Before sawing the core, the size of the center of the joint should be checked accurately as shown in Figure 8, and the excess core should be sawed off. When sawing, keep the cable core port straight.
3) Stress treatment.
Stripping the copper shield: Remove the copper shield at a distance of 300 mm from the end, and in order to prevent the copper shield from loosening, it can be tightened with insulating self-adhesive tape at the appropriate position of the cable core. When stripping the copper shield, the cutting place is tied tightly with insulating self-adhesive tape or fine copper wire, and when cutting, only one knife mark can be cut by the ring, about 2 3 depth, and it cannot be cut through, so as not to damage the semi-conductive layer. When stripping the copper shield, it should be torn off at the knife mark and stripped off to the end of the wire core after disconnection. The ports of the copper shield should be cut flat and free of tips and burrs.
Stripping the outer semi-conductive layer: Peel off the outer semi-conductive shield at a distance of 50 mm from the copper shield port. Peel off the outer semi-conductive layer, circumferential cutting and longitudinal cutting knife marks, can not be cut through, so as not to damage the main insulation. The outer semi-conductive layer should be peeled off clean, and no residue should be left, and the semi-conductive dust adsorbed on the insulating surface must be sanded and cleaned with fine sandpaper after peeling.
Stripping core end insulation: stripping core end insulation, the length of which is 1 2 connecting pipe length plus 5 mm. When stripping the core insulation, the core conductor shall not be injured, and the core conductor shall be carried out in the direction of the core twisting to prevent the loose deformation of the core conductor.
Stress treatment at the end of the insulation layer: 3 mm 45° chamfer is made at the end of the cable insulation at both ends.
4) Insert the intermediate joint.
The chamfer of the insulating layer port should be polished with an abrasive cloth or a small round file, and the sharp edge of the end of the core conductor should be filed, and the main insulating surface should be polished with an abrasive cloth (the main insulation cannot be polished with an abrasive cloth that polishes the semi-conductive layer), and wrapped with insulating self-adhesive tape after cleaning.
Insert the intermediate joint pipe: Insert the cold shrinkable insulating body from the long end of the stripping length, and insert the copper shielding braided mesh sleeve from the shorter end. The insulating layer, the outer semi-conductive layer, and the copper shielding layer must be cleaned with cleaning paper before inserting.
5) Crimp one after another.
Before crimping, check that the connecting pipe is consistent with the nominal cross-sectional area of the cable core, and select the corresponding mold. When crimping the connecting tube, the cores at both ends should be firmly held and not loosened, and the crimping should be carried out in the order of the middle first and then the two sides. After crimping, the tip of the surface of the connecting pipe and the burr are polished with a file and sandpaper, and the surface of the insulation layer, the surface of the connecting pipe and the intermediate joint near the end of the connecting pipe are cleaned with cleaning paper. Fill the conduit as required.
6) Install the intermediate joint.
Clean the insulating surface of the core and the surface of the copper cover once with cleaning paper, and apply a layer of insulating mixture on the insulating surface after the detergent volatilizes.
According to the requirements of the installation process, the positioning mark of the stress cone is made on the semi-conductive layer at the short end of the cable. After careful inspection, the intermediate joint is moved to the center with one end flush with the positioning mark. Then rotate the lining in the counterclockwise direction, as shown in Figure 9, the speed must be slow and uniform, so that the intermediate joint naturally shrinks, and immediately adjusts the position after the contraction is completed, and pinches it with both hands from the middle of the joint to the circumference of both ends, so that the inner wall structure of the intermediate joint is insulated from the cable, and the semi-conductive shielding layer has better interface contact.
Figure 9 Schematic diagram of installing the intermediate joint
1 copper shield; 2. Positioning markers; 3. Cold-shrinkable insulating body; 4 Pull liners.
The two ends of the shrinking insulating body are wound with water-blocking glue to form a slope of 45°. The top of the slope is flush with the end face of the intermediate joint. It is then wrapped on the surface with semi-conductive tape.
7) Restore the inner sheath.
Connect the copper shield: put a copper shielding braided mesh on the outside of the assembled joint body, tie the copper mesh sleeve to the joint body with insulating self-adhesive tape, and fix the copper mesh sleeve on the cable copper shield with a constant force spring. The two ends of the copper mesh sleeve are trimmed, 10 mm is kept in front of the constant force spring, and two layers of insulating self-adhesive tape are semi-overlapped to cover the constant force spring.
Restore the inner sheath: the gap between the three-phase joints of the cable must be filled with filler, and then the PVC tape is semi-overlapped and wrapped to tie the three-phase cable together to enhance the tightness and mechanical strength of the overall structure of the joint. On the inner sheath of 30 mm at both ends, it is sanded rough with insulating sandpaper and cleaned, and then from the inner sheath at one end, the waterproof tape is semi-overlapped and wrapped on the inner sheath at the other end, and the tape is stretched to 3 4 of the original width when wrapping, and after completion, squeeze the tape with both hands to make it adhere tightly.
8) Restore the outer sheath.
Connect the steel armor at both ends: first use a file and sandpaper to remove the anti-rust layer on the surface of the steel armor and polish it well. The braided wire is unfolded within the range of 80 mm at both ends of the copper braided belt, the unfolded part is attached to the waterproof belt and the steel armor and lapped with the outer sheath, clamped into and reversed into the constant force spring, tightened forcefully, and tightly fixed with insulating self-adhesive tape to increase the contact surface and stability of the copper braided belt and the steel armor. Use waterproof tape as a moisture-proof seal, start from the distance of 60 mm from one end of the sheath to the other end of the sheath 60 mm back and forth, stretch the tape to 3 4 of the original width when wrapping, after completion, squeeze the tape with both hands to make it tightly adherent.
Restore the outer sheath: Wrap the hot melt adhesive as required, first heat and shrink one end of the sheath, and after closing one end, continue to wrap the hot melt, heat and shrink the other end of the sheath. Water was poured into the armor belt package, kneaded for 1 min, and after the armor belt was removed, the armor belt was taken out from 100 mm of the cable outer sheath outside the heat sheath tube at one end, and the armor belt was semi-overlapped and wrapped around the other end. For best results, do not move the cable for 30 minutes.
*] Material Cloud "Power Cable Design and Procurement Manual".
Statement] This article is original content, the copyright belongs to "Material Cloud", please do not do it without authorization**.