Method for repairing damage of metal sheath of high-voltage single-core cable

Abstract

The invention relates to a damage repair method for a metal sheath of a high-voltage single-core cable. The method comprises the following steps: heating, straightening and pretreating the cable; removing an asphalt layer on the surface of the metal sheath; cutting off the damaged metal sheath; cable insulation shielding surface treatment and protection; installing a protective copper shell, sealing lead, and sealing with epoxy mud; and performing waterproof treatment inside and outside the copper shell to finally realize the damage repair method for the metal sheath of the high-voltage single-core cable. According to the invention, the electrical performance and the mechanical performance of the cable metal sheath can be rapidly and well recovered, the normal operation of the cable is ensured, and the method has potential engineering application value.

Description

Technical Field

[0001] The invention belongs to the technical field of cable operation, maintenance and repair, and in particular to a method for repairing damage to a metal sheath of a high-voltage single-core cable. Background Art

[0002] With the development of the power industry and the advancement of technology, high-voltage cables, as an important part of power transmission, have received more and more attention for their performance and safety. In the structure of high-voltage power cables, the main function of the metal sheath is to protect the cable insulation from damage and to play a certain sealing role. The metal sheath is mostly made of aluminum or lead, and its structure is mainly corrugated. As a barrier, the metal sheath can effectively prevent external moisture and humidity from invading the interior of the cable, thereby ensuring the dryness and safety of the cable insulation; when a short-circuit fault occurs in the cable, the metal sheath bears the short-circuit current and constitutes a channel for the short-circuit current discharge. It also serves as a ground potential reference for the cable insulation layer, which helps to ensure that the cable system can operate stably under different working conditions.

[0003] The metal sheath of the cable may be damaged when it is punctured by a sharp external object or hit by a heavy object, or when the cable is processed during the production of cable accessories. The damage is mostly in the form of perforation, deformation, scratches and other problems, which make the normal function of the metal sheath ineffective. Long-term operation will lead to local water corrosion, damage to the insulation of the cable body, and cause breakdown failures. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to propose a method for repairing damage to the metal sheath of a high-voltage single-core cable, which can quickly and well restore the electrical and mechanical properties of the cable metal sheath, ensure the normal operation of the cable, and has potential engineering application value.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A method for repairing damage to a metal sheath of a high-voltage single-core cable comprises the following steps:

[0007] Step 1: Cable heating, straightening and pretreatment;

[0008] Step 2: remove the asphalt layer on the surface of the metal sheath;

[0009] Step 3: Remove the damaged metal sheath;

[0010] Step 4: Surface treatment and protection of cable insulation shielding;

[0011] Step 5: Install the protective copper shell, seal with lead and epoxy mud;

[0012] Step 6: Waterproof the inside and outside of the copper shell.

[0013] Moreover, the specific implementation method of step 1 is: heat and straighten the cable in the section to be repaired, determine the metal sheath cutting range, and then measure a 200mm length range at both ends of the metal sheath cutting range as the starting and ending points for stripping the cable outer sheath, cut the starting and ending points of the cable outer sheath, and remove the cable outer sheath.

[0014] Moreover, the specific implementation method of step 2 is: use a spray gun to burn the asphalt within the exposed metal sheath range to a molten state, and then use a clean rag to wipe the melted asphalt clean. Stearic acid is used for auxiliary cleaning during the cleaning process. After cleaning, the metal sheath should be wiped again with a clean rag to ensure that there is no stearic acid residue in the lead sealing section. The cleaning should be done in one direction from one side to the other.

[0015] Moreover, the specific implementation method of step 3 is: circular cutting of the metal sheath removal range starts and ends, the cutting depth is controlled at 2 / 3 of the depth, the metal sheath cannot be cut through, and the cable insulation shielding layer must not be damaged during stripping, and then the metal sheath breaking tool is used to break the metal sheath longitudinally before removing it.

[0016] Moreover, the specific implementation method of step 4 is: clean the surface of the cable insulation shielding layer and blow dry it with a hot air blower, and then wrap the semi-conductive tape, lead tape, and copper mesh tape in sequence from the fracture of the metal sheath at one end to the fracture of the metal sheath at the other end, and use copper binding wire to tie the copper mesh tape tightly to the metal sheath. At the same time, wrap the waterproof tape outside the copper mesh tape, and require the waterproof tape to cover the copper mesh tape and the copper binding wire. Finally, wrap the PVC adhesive tape outside the waterproof tape, and require it to cover the waterproof tape. The cross-sectional area of ​​the wrapped lead tape and copper mesh tape is not less than the cross-sectional area of ​​the cable metal sheath.

[0017] Moreover, the specific implementation method of step 5 is: install the copper protective shell on the cable, bend the V-grooves at the tail of the copper protective shell at both ends downward to form a slope transition between the cable, and then perform lead sealing treatment on the circumferential direction of the tail of the copper protective shell and the metal sheath, and fill the copper protective shell flange step with epoxy mud and wrap the flange connection interface.

[0018] Moreover, the copper protective shell is composed of multiple sections, and O-shaped sealing strips are used to seal between the sections. Before the sealing strips are installed, a layer of sealing silicone needs to be evenly applied in the sealing groove.

[0019] Moreover, the specific implementation method of step 6 is: starting from the outer sheath break at one end of the cable to the outer sheath break at the other end, first wrap the insulating tape, then wrap the waterproof tape, and then wrap the PVC adhesive tape outside the waterproof tape, and finally shrink the zipper-type heat shrink tube on the outside, requiring the overlap with the cable outer sheath to be no less than 250mm, and then wrap the waterproof tape and PVC adhesive tape at the end of the heat shrink tube to strengthen the seal.

[0020] The advantages and positive effects of the present invention are:

[0021] The present invention achieves a method for repairing the damaged metal sheath of a high-voltage single-core cable by heating, straightening and pre-treating the cable; removing the asphalt layer on the surface of the metal sheath; removing the damaged metal sheath; treating and protecting the surface of the cable insulation shield; installing a protective copper shell, sealing with lead and epoxy mud; and waterproofing the inside and outside of the copper shell. The present invention can quickly and well restore the electrical and mechanical properties of the metal sheath of the cable, ensure the normal operation of the cable, and has potential engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the present invention;

[0023] Figure 2 It is a schematic diagram of the metal sheath repair structure of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings.

[0025] A method for repairing damage to a metal sheath of a high-voltage single-core cable, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0026] Step 1: Cable heating, straightening and pretreatment.

[0027] Heat and straighten the cable in the section that needs to be repaired, determine the metal sheath removal range, and then measure a 200mm length range at both ends of the metal sheath removal range as the starting and ending points for stripping the cable outer sheath. Use a hand saw (or a crescent knife or other tool) to cut the starting and ending points of the cable outer sheath to remove the cable outer sheath.

[0028] Step 2: Remove the asphalt layer on the surface of the metal sheath.

[0029] Use a spray gun to burn the asphalt in the exposed metal sheath until it melts. The overall temperature should be as consistent as possible. Then use a clean rag to wipe the melted asphalt clean. Use stearic acid to assist in the cleaning process. After cleaning, use a clean rag to wipe the metal sheath again to ensure that there is no stearic acid residue in the lead sealing section. Cleaning should not be done back and forth, but should be done in a one-way direction from one side to the other.

[0030] Step 3: Remove the damaged metal sheath.

[0031] Use a hand saw (or a crescent knife or other tool) to cut the metal sheath in a circular motion from the beginning to the end of the removal range. The cutting depth should be controlled at about 2 / 3 of the depth. The metal sheath cannot be cut through. The cable insulation shielding layer must not be damaged during stripping. Then use a metal sheath removal tool to break the metal sheath longitudinally before removing it.

[0032] After removing the metal sheath, remove the cable semi-conductive buffer tape, and retain part of the semi-conductive water-repellent buffer layer above the metal sheath fracture, and fix it with PVC adhesive tape.

[0033] Step 4: Surface treatment and protection of cable insulation and shielding.

[0034] Clean the surface of the cable insulation shielding layer with a cleaning towel (or anhydrous alcohol) and blow dry with a hot air blower. Then wrap the semi-conductive tape, lead tape, and copper mesh tape from the fracture of the metal sheath at one end to the fracture of the metal sheath at the other end in turn, and then use copper tie wire to tie the copper mesh tape tightly to the metal sheath. Then wrap the waterproof tape outside the copper mesh tape, requiring the waterproof tape to cover the copper mesh tape and copper tie wire, and finally wrap the PVC adhesive tape outside the waterproof tape, requiring it to cover the waterproof tape. The cross-sectional area of ​​the wrapped lead tape and copper mesh tape should not be less than the cross-sectional area of ​​the cable metal sheath.

[0035] Step 5: Install the protective copper shell, seal with lead and epoxy mud.

[0036] Install the copper protective shell (double semi-arc structure) on the cable. The copper protective shell can be composed of multiple sections, and O-type sealing strips are used to seal between the sections. Before installing the sealing strip, a layer of sealing silicone needs to be evenly applied in the sealing groove.

[0037] Bend the V-shaped grooves at the tail of the copper protective shell at both ends downward to form a slope transition between the cable, and then seal the copper protective shell tail and the metal sheath in the circumferential direction. Note that:

[0038] ①The lead welding at the lead sealing point is tight and can play a sealing role.

[0039] ② Appropriate cooling measures should be taken during the lead sealing process (such as applying stearic acid on the lead sealing surface to cool it down, etc.) to ensure that the inside of the cable is not damaged.

[0040] Fill the copper protective shell flange step with epoxy mud and wrap the flange connection interface.

[0041] Step 6: Waterproof the inside and outside of the copper shell.

[0042] After the sealing lead temperature cools to room temperature and the epoxy mud solidifies, use a funnel to pour the sealant into the copper protective shell until it is full. Starting from the outer sheath break at one end of the cable to the outer sheath break at the other end, first wrap the insulation tape (the overlap with the outer sheath is required to be no less than 50mm), then wrap the waterproof tape (the waterproof tape covers the insulation tape), and then wrap the PVC adhesive tape outside the waterproof tape (it is required to cover the waterproof tape). Finally, shrink the zipper heat shrink tube on the outside, requiring the overlap with the cable outer sheath to be no less than 250mm. Then wrap the waterproof tape and PVC adhesive tape at the end of the heat shrink tube to strengthen the seal.

[0043] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for repairing damage to a metal sheath of a high-voltage single-core cable, characterized in that: The following steps are involved: Step 1: Cable heating, straightening and pretreatment; Step 2: remove the asphalt layer on the surface of the metal sheath; Step 3: Remove the damaged metal sheath; Step 4: Surface treatment and protection of cable insulation shielding; Step 5: Install the protective copper shell, seal with lead and epoxy mud; Step 6: Waterproof the inside and outside of the copper shell.

2. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The specific implementation method of step 1 is: heat and straighten the cable in the section to be repaired, determine the metal sheath removal range, then measure a 200mm length range at both ends of the metal sheath removal range as the starting and ending points for stripping the cable outer sheath, cut the starting and ending points of the cable outer sheath, and remove the cable outer sheath.

3. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The specific implementation method of step 2 is: use a spray gun to burn the asphalt within the exposed metal sheath to a molten state, and then use a clean rag to wipe the melted asphalt clean. Use stearic acid to assist in cleaning during the cleaning process. After cleaning, use a clean rag to wipe the metal sheath again to ensure that there is no stearic acid residue in the lead sealing section. Cleaning should be done in one direction from one side to the other.

4. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The specific implementation method of step 3 is: circular cutting of the metal sheath removal range starts and ends, the cutting depth is controlled at 2 / 3 of the depth, the metal sheath cannot be cut through, and the cable insulation shielding layer must not be damaged during stripping, and then the metal sheath breaking tool is used to break the metal sheath longitudinally before removing it.

5. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The specific implementation method of step 4 is: clean the surface of the cable insulation shielding layer and blow dry it with a hot air blower, then wrap the semi-conductive tape, lead tape, and copper mesh tape in sequence from the fracture of the metal sheath at one end to the fracture of the metal sheath at the other end, use copper binding wire to tightly tie the copper mesh tape to the metal sheath, and at the same time wrap the waterproof tape around the copper mesh tape, requiring the waterproof tape to cover the copper mesh tape and the copper binding wire, and finally wrap the PVC adhesive tape around the waterproof tape, requiring it to cover the waterproof tape, and the cross-sectional area of ​​the wrapped lead tape and copper mesh tape should not be less than the cross-sectional area of ​​the cable metal sheath.

6. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The specific implementation method of step 5 is: install the copper protective shell on the cable, bend the V-grooves at the tail of the copper protective shell at both ends downward to form a slope transition between the cable, and then perform lead sealing treatment on the circumferential direction of the tail of the copper protective shell and the metal sheath, fill the copper protective shell flange step with epoxy mud, and wrap the flange connection interface.

7. A method for repairing damage to a metal sheath of a high-voltage single-core cable according to claim 1, characterized in that: The copper protective shell is composed of multiple sections, and O-shaped sealing strips are used to seal the sections. Before the sealing strips are installed, a layer of sealing silicone needs to be evenly applied in the sealing groove.

8. A method for repairing damage to a high-voltage single-core cable metal sheath according to claim 1, characterized in that: The specific implementation method of step 6 is: starting from the outer sheath break at one end of the cable to the outer sheath break at the other end, first wrap the insulating tape, then wrap the waterproof tape, and then wrap the PVC adhesive tape outside the waterproof tape, and finally shrink the zipper-type heat shrink tube on the outside, requiring the overlap with the cable outer sheath to be no less than 250mm, and then wrap the waterproof tape and PVC adhesive tape at the end of the heat shrink tube to strengthen the seal.

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