In-situ repair method for major insulation of high-voltage cable

Abstract

The invention provides a high-voltage cable main insulation in-situ repair method, which belongs to the technical field of high-voltage cable repair, and comprises the following specific steps: step 1, stripping a cable at a fault point; step 2, stripping a faulty phase metal shielding layer of the stripped cable, and taking off the faulty phase metal shielding layer; 3, girdling the main insulator at the fault point, separating the girdled insulator, and then chamfering and polishing the main insulators on the two sides; step 4, winding an insulation repair adhesive tape at the girdling position; and step 5, winding a fireproof tape outside the insulation repair adhesive tape in the step 4, and finally completing winding of the metal shielding layer. And 6, hot melting treatment is carried out, and after hot melting treatment is completed, main insulation repair is completed. According to the method, in-situ repair is directly carried out at the fault point, the cable of the fault section does not need to be intercepted, the use of a cable intermediate joint is avoided, the fault rate in the later operation process is reduced, and the whole operation process is more stable and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of high-voltage cables, and in particular relates to an in-situ repair method for main insulation of a high-voltage cable. Background Art

[0002] The use of cables is becoming more and more common. As the use of cables increases, the probability of cable failure increases.

[0003] Announcement No. CN114977022B discloses a repair device, a repair system and a repair method for the main insulation of a cable. A controller is connected to the repair device through a communication cable; one end of the driving mechanism is connected to the side of the hot melt extruder facing the moving mechanism, and the other end of the driving mechanism is connected to the moving mechanism, and the moving mechanism can slide along the extension direction of the driving mechanism; the main body is surrounded by a accommodating cavity, one end of the extrusion component is inserted in the accommodating cavity, and the other end of the extrusion component extends to the outside of the accommodating cavity, and the extrusion component is connected to the hot melt extruder through a telescopic component; the repair process is: install the cable to be repaired-repair the cable to be repaired; by setting the hot melt extruder to be connected to the extrusion component through the telescopic component, it is convenient to simultaneously injection mold and repair the three-layer insulation structure, so that the three-layer insulation structure can be formed in one time. Compared with the traditional cable single-layer injection molding repair device, the flatness and smoothness of the main insulation surface of the cable after repair are improved; at the same time, the scope of application is increased.

[0004] A high-voltage cable may experience a main insulation breakdown failure. When the fault point is located in the middle of the cable, using an intermediate joint to repair the cable will, on the one hand, increase the cable failure rate in the later period; on the other hand, the cost of repairing with an intermediate joint is relatively high.

[0005] In order to solve the above problems, a method for in-situ repair of main insulation of high-voltage cables was specially developed.

[0006] When an insulation breakdown fault occurs in a high-voltage cable (the conductor is not damaged), the in-situ repair method for the main insulation of the direct-buried high-voltage cable is used to repair the main insulation of the cable and restore the cable to its operating state. Summary of the invention

[0007] In order to overcome the problem that when the existing fault point is located in the middle part of the cable, when an intermediate joint is used to repair the cable for this fault, on the one hand, the intermediate joint will lead to an increase in the cable failure rate in the later period, and on the other hand, the cost of repairing with the intermediate joint is relatively high, the present invention provides an in-situ repair method for the main insulation of a high-voltage cable. The present invention directly performs in-situ repair at the fault point, does not need to cut off the cable of the faulty section, avoids the use of the cable intermediate joint, reduces the failure rate in the later operation process, and makes the entire operation process more stable and reliable.

[0008] The technical solution adopted by the present invention is: A method for in-situ repair of main insulation of a high-voltage cable, comprising the following specific steps: Step 1: Strip the cable at the fault point. Step 2: peel off the metal shielding layer of one phase of the cable stripped in step 1, and remove the metal shielding layer at the faulty position; Step 3: perform ring cutting on the main insulator at the fault point, separate the ring cut insulators, and then perform chamfering and grinding on the main insulators on both sides; Step 4: Then wrap the insulating repair tape around the ring cut position; Step 5, wrapping the fire-resistant tape around the outside of the insulation repair tape in step 4, and finally wrapping the metal shielding layer; Step six: After the winding in step five is completed, hot melt treatment is performed. After the hot melt treatment is completed, the main insulation repair is completed.

[0009] In the step 1, the cable stripping length is not less than two meters, one meter on each side of the fault point.

[0010] In the step three, a ring cut is performed at the fault point of the main insulator with a length of at least 10 mm.

[0011] In the step 3, after the insulators are separated after the ring cutting, the insulators at both ends of the ring cutting part are chamfered and polished at 30°; after the chamfering and polishing are completed, they are blown with a hair dryer and then wiped with alcohol paper.

[0012] The cable is a high voltage cable not exceeding 110Kv.

[0013] In the step 4, a cross-linked polyethylene hot-melt high-voltage cable insulation repair tape is wound.

[0014] In the step 4, the winding length of the insulation repair tape and the overlap length of the main insulation on both sides of the ring cutting position shall not be less than 2 cm.

[0015] In the step 5, the winding length of the refractory tape and the overlapping length of the main insulation are not less than 5 cm.

[0016] In the step six, after the main insulation repair is completed, the cable shielding layer, filling layer, inner sheath, steel armor layer and outer sheath are repaired in sequence after cooling.

[0017] The outer sheath is repaired by high voltage insulation repair tape.

[0018] Beneficial effects of the present invention: The present invention directly performs in-situ repair at the fault point, does not need to cut the cable of the fault section, avoids the use of cable intermediate joints, reduces the failure rate in the later operation process, and makes the entire operation process more stable and reliable.

[0019] The present invention can accurately locate the fault point, quickly repair the main insulator of the cable, reduce the power outage time of the equipment, and reduce the economic loss in terms of power generation.

[0020] Compared with the method of replacing the faulty cable with high repair cost and poor economy, the in-situ repair method of the main insulation of the high-voltage cable provided by the method has low repair cost, reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of ring cutting at the main insulation fault site of the high-voltage cable main insulation in-situ repair method of the present invention.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] In the figure, the reference numerals are: 1. Cable conductor; 2. Inclined surface; 3. Metal shielding layer. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0026] Embodiment 1: In order to overcome the problem that when the existing fault point is located in the middle part of the cable, when an intermediate joint is used to repair the cable for this fault, on the one hand, the intermediate joint will lead to an increase in the cable failure rate in the later period, and on the other hand, the cost of repairing with the intermediate joint is relatively high, the present invention provides an in-situ repair method for the main insulation of a high-voltage cable. The present invention directly performs in-situ repair at the fault point, does not need to cut off the cable of the faulty section, avoids the use of the cable intermediate joint, reduces the failure rate in the later operation process, and makes the entire operation process more stable and reliable.

[0027] A method for in-situ repair of main insulation of a high-voltage cable, comprising the following specific steps: Step 1: Strip the cable at the fault point. Step 2: peel off the metal shielding layer of one phase of the cable stripped in step 1, and remove the metal shielding layer at the faulty position; Step 3: perform ring cutting on the main insulator at the fault point, separate the ring cut insulators, and then perform chamfering and grinding on the main insulators on both sides; Step 4: Then wrap the insulating repair tape around the ring cut position; Step 5, wrapping the fire-resistant tape around the outside of the insulation repair tape in step 4, and finally wrapping the metal shielding layer; Step six: After the winding in step five is completed, hot melt treatment is performed. After the hot melt treatment is completed, the main insulation repair is completed.

[0028] The cable in the present invention is a high voltage cable not exceeding 110Kv. The high voltage cable is preferably 110Kv, 66Kv, 35kv. The specifications of the high voltage cable are existing mature technologies and are not further described in the present invention.

[0029] The present invention is applied to the in-situ repair of the main insulation of a high-voltage cable not exceeding 110KV directly buried, and the in-situ repair is performed on the fault point where the internal cable conductor 1 is not damaged, without replacing the cable.

[0030] In the present invention, Figure 1 As shown, after the metal shielding layer 3 is peeled off at the fault point, the main insulator at the corresponding position is removed without damaging the internal cable conductor 1, and the main insulator at the two fractures is chamfered and polished to form a trapezoidal inclined surface 2.

[0031] In the present invention, the fault point of the cable main insulation is first located and searched, and after the fault point is found, the cable fault part is stripped, and then the main insulation is repaired, and after the repair is completed, the corresponding cable shielding layer, filling layer, inner sheath, steel armor layer and outer sheath are repaired.

[0032] The invention provides an in-situ repair method for the main insulation of a high-voltage cable, which directly performs in-situ repair at the fault point without cutting the cable of the faulty section, thus avoiding the use of intermediate cable joints, reducing the failure rate in the later operation process, and making the entire operation process more stable and reliable.

[0033] The purpose of the present invention is to solve the problems of long construction period, low construction quality and high repair cost in the prior art. The present invention provides an in-situ repair method for the main insulation of a high-voltage cable, which can accurately locate the fault point, quickly repair the main insulation of the cable, reduce the power outage time of the equipment, and reduce the economic loss in terms of power generation.

[0034] The invention provides an in-situ repair method for the main insulation of a high-voltage cable, which is not restricted by terrain and avoids the problem that a method using a cable intermediate joint requires large-area excavation and the cable intermediate joint cannot be placed.

[0035] The invention provides an in-situ repair method for the main insulation of a high-voltage cable, which has low repair cost, is reliable and stable. The existing method of replacing a faulty cable has high repair cost and poor economic efficiency. Embodiment 2: Based on Example 1, in this embodiment, preferably, in the step 1, the cable stripping length is not less than two meters, one meter on each side of the fault point.

[0036] In the present invention, the cable needs to be stripped at the fault point, and the stripping length is not less than two meters, 1 meter on each side of the fault point, to facilitate the subsequent separation of the wire cores.

[0037] Preferably, in step three, a ring cut is performed at the fault point of the main insulator with a length of at least 10 mm.

[0038] Preferably, in the step three, after the insulators are separated after the ring cutting, the insulators at both ends of the ring cutting part are chamfered and polished at 30°; after the chamfering and polishing are completed, they are blown with a hair dryer and then wiped with alcohol paper.

[0039] Preferably, the cable is a high voltage cable not exceeding 110Kv.

[0040] In the present invention, in step three, a 10 mm ring cut is performed at the fault point of the main insulator, and after the insulator is separated, both ends are chamfered and polished at 30°, and after the polishing is completed, a hair dryer is used to blow, and then the insulator part is wiped with alcohol paper to effectively clean it.

[0041] Preferably, in the step 4, a cross-linked polyethylene hot-melt high-voltage cable insulation repair tape is wound.

[0042] In the present invention, the insulation repair tape is preferably a 35kV cross-linked polyethylene hot-melt high-voltage cable insulation repair tape.

[0043] Preferably, in step 4, the winding length of the insulation repair tape and the overlap length of the main insulation on both sides of the ring cutting position shall not be less than 2 cm.

[0044] In the present invention, the winding length of the insulation repair tape and the overlapping length of the main insulation on both sides shall not be less than 2 cm; this ensures the connection performance and does not cause leakage.

[0045] Preferably, in step five, the winding length of the refractory tape and the overlapping length of the main insulation are not less than 5 cm.

[0046] In the present invention, the winding length of the refractory tape and the overlapping length of the main insulation are not less than 5 cm, ensuring that the winding is tight, and then the copper tape (metal shielding layer) is wound to complete.

[0047] Preferably, in step six, after the main insulation repair is completed, the cable shielding layer, filling layer, inner sheath, steel armor layer and outer sheath are repaired in sequence after cooling.

[0048] Preferably, the outer sheath is repaired by means of a high voltage insulation repair tape.

[0049] In the present invention, the cable fault welding processing method is as follows: First, find the breakdown cable and analyze the breakdown cable. Second, peel off the outer sheath of the punctured cable, break the steel belt, and peel off the inner sheath to expose the high-voltage cable.

[0050] Third, remove the copper shield of the cable core, peel off the outer semi-conductive material, and clean up the waste at the main insulation breakdown.

[0051] Fourth, after cleaning and disinfecting with alcohol, repair the main insulation part, then repair the outer shielding semi-conductive material, copper belt connection, steel belt connection, waterproof the outer sheath, and repair it.

[0052] The purpose of the present invention is to solve the problems of long construction period, low construction quality and high repair cost in the prior art. The present invention directly performs in-situ repair at the fault point, does not need to cut the cable of the fault section, avoids the use of cable intermediate joints, reduces the failure rate in the later operation process, and makes the entire operation process more stable and reliable.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0055] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. Any design that is the same or similar to the present invention belongs to the protection scope of the present invention. The device structures and method steps not described in detail in the present invention are all prior art and will not be further described in the present invention.

Claims

1. A method for in-situ repair of main insulation of a high-voltage cable, characterized in that: The specific steps are: Step 1: Strip the cable at the fault point; Step 2: peel off the metal shielding layer of one phase of the cable stripped in step 1, and remove the metal shielding layer at the faulty position; Step 3: perform ring cutting on the main insulator at the fault point, separate the ring cut insulators, and then perform chamfering and grinding on the main insulators on both sides; Step 4: Then wrap the insulating repair tape around the ring cut position; Step 5, wrapping the fire-resistant tape around the outside of the insulation repair tape in step 4, and finally wrapping the metal shielding layer; Step six: After the winding in step five is completed, hot melt treatment is performed. After the hot melt treatment is completed, the main insulation repair is completed.

2. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step 1, the cable stripping length is not less than two meters, one meter on each side of the fault point.

3. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step three, a ring cut is performed at the fault point of the main insulator with a length of at least 10 mm.

4. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step 3, after the insulators are separated after the ring cutting, the insulators at both ends of the ring cutting part are chamfered and polished at 30°; after the chamfering and polishing are completed, they are blown with a hair dryer and then wiped with alcohol paper.

5. The method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: The cable is a high voltage cable not exceeding 110Kv.

6. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step 4, a cross-linked polyethylene hot-melt high-voltage cable insulation repair tape is wound.

7. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step 4, the winding length of the insulation repair tape and the overlap length of the main insulation on both sides of the ring cutting position shall not be less than 2 cm.

8. The method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step 5, the winding length of the refractory tape and the overlapping length of the main insulation are not less than 5 cm.

9. A method for in-situ repair of main insulation of a high-voltage cable according to claim 1, characterized in that: In the step six, after the main insulation repair is completed, the cable shielding layer, filling layer, inner sheath, steel armor layer and outer sheath are repaired in sequence after cooling.

10. A method for in-situ repair of main insulation of a high-voltage cable according to claim 9, characterized in that: The outer sheath is repaired by high voltage insulation repair tape.

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