CN111711129A - Construction method for searching and repairing fault of outer sheath of single-core high-voltage cable - Google Patents
Construction method for searching and repairing fault of outer sheath of single-core high-voltage cable Download PDFInfo
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- CN111711129A CN111711129A CN202010610678.7A CN202010610678A CN111711129A CN 111711129 A CN111711129 A CN 111711129A CN 202010610678 A CN202010610678 A CN 202010610678A CN 111711129 A CN111711129 A CN 111711129A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/16—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for repairing insulation or armouring of cables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/06—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for laying cables, e.g. laying apparatus on vehicle
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The embodiment of the invention provides a construction method for searching and repairing faults of an outer sheath of a single-core high-voltage cable, and relates to the field of cable construction. The construction method for searching and repairing the fault of the outer sheath of the single-core high-voltage cable comprises the following steps: connecting the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested to obtain a prepositioned fault point of a cable outer sheath of the cable to be tested; obtaining an accurate positioning fault point of the cable outer sheath on the cable metal protective sleeve near the pre-positioning fault point; detecting whether a cable metal protective sleeve or an insulating layer at a fault point accurately positioned on the cable outer sheath is damaged or not; if the damage exists, evaluating the damage degree of the cable to be tested; and if the cable sheath is not damaged, repairing the cable sheath at the accurately positioned fault point. The construction method can accurately find the fracture or scratch point of the cable outer sheath, avoids the condition of missed inspection, reduces the time consumption of manual observation and inspection, improves the labor productivity and reduces the cost consumption of engineering.
Description
Technical Field
The invention relates to the field of construction, in particular to a construction method for searching and repairing faults of an outer sheath of a single-core high-voltage cable.
Background
The crosslinked polyethylene cable is widely applied to power transformation and distribution lines of a power system due to the characteristics of convenience in laying, convenience in maintenance, heat resistance, good electrical insulation performance and the like, and the direct buried type laid cable is increasingly adopted in view of easiness in determining a path, low construction cost and no occupation of the ground space of a production device. However, sharp corners on the cable laying tool, brackets in the cable trench, sharp obstacles at the cable conduit entry, and the like are prone to scratching and scratching of the outer sheath during cable laying. The outer sheath is used as a first defense line for protecting the cable, once the outer sheath of the cable is damaged, the outer sheath forms a passage through the ground and is influenced by an alternating electric field of a cable loop conductor adjacent to a cable loop, the induced potential on the sheath is not equal to zero, and at the moment, circulating current loss is generated on the metal sheath of the cable, so that the current-carrying capacity of the cable is influenced. Moreover, the circulation current generated by grounding the metal sheath can cause the cable to generate heat, accelerate the aging of the cable and influence the insulation life of the cable. Therefore, the cable outer sheath damage fault can be timely detected and positioned very necessarily, the cable outer sheath fracture and scratch conditions can be judged by testing whether the cable metal sheath is grounded, and the use requirements can be met by repairing.
However, the existing construction specification detection requirements are that defects such as twisting, armor flattening, sheath fracture and surface scratch cannot exist in the cable laying process, and an inspection method of observation and inspection is adopted. The observation and inspection can only determine the fracture or scratch defects which are obvious and exposed at the non-buried part, but other defects of the cable which are not exposed can not be detected by adopting the observation and inspection method after direct burial, so that the condition of missing inspection is easy to occur, and the defects are hidden troubles in the later operation process of the cable.
Disclosure of Invention
The invention aims to provide a construction method for searching and repairing the fault of an outer sheath of a single-core high-voltage cable, which can accurately find the fracture or scratch point of the outer sheath of the cable, avoid the condition of missed detection, reduce the time consumption of manual observation and inspection, improve the labor productivity and reduce the cost consumption of engineering.
The embodiment of the invention is realized by the following steps:
in a first aspect, an embodiment of the present invention provides a construction method for troubleshooting and repairing a single-core high-voltage cable outer sheath, including:
connecting the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested to obtain a prepositioned fault point of a cable outer sheath of the cable to be tested;
feeding high-voltage pulses into the cable metal protective sleeve near the pre-positioning fault point to obtain a precisely positioned fault point of the cable outer sheath;
detecting whether the metal protective sleeve or the insulating layer of the cable at the accurate positioning fault point of the outer sheath of the cable is damaged or not;
if the cable metal protective sleeve or the insulating layer at the accurate positioning fault point is damaged, evaluating the damage degree of the cable to be tested;
and if the cable metal protective sleeve and the insulating layer at the accurate positioning fault point are not damaged, repairing the accurate positioning fault point.
In an optional embodiment, the step of connecting the auxiliary cable, the high-voltage dc generator, and the processed cable to be tested to obtain the pre-positioning fault point includes:
stripping cable outer sheaths at two ends of the cable to be tested by a preset length so as to expose the metal protective sleeves of the cable to be tested at the two ends of the cable to be tested;
the metal protective sleeve is connected with the auxiliary cable, the high-voltage direct-current generator and the cable to be tested;
starting the high-voltage direct current generator, performing a boosting test, and recording a test result of the boosting test;
and calculating to obtain the predetermined positioning fault point according to the test result.
In an optional embodiment, in the step of connecting the auxiliary cable, the high-voltage dc generator and the metal protective sheath of the cable to be tested, a connection relationship of a circuit is as follows:
one end of the high-voltage direct-current generator is electrically connected with one end of the auxiliary cable, the other end of the auxiliary cable is electrically connected with the metal protective sleeve at one end of the cable to be tested, the other end of the high-voltage direct-current generator is electrically connected with the other end of the cable to be tested, and one end of the ground resistor is electrically connected between the metal protective sleeve at the fault point of the cable to be tested and the ground.
In an optional embodiment, the high voltage direct current generator includes a high frequency high voltage constant current source, a high sensitivity galvanometer and an adjustable resistor, the high frequency high voltage constant current source with the adjustable resistor is electrically connected, the high sensitivity galvanometer with the adjustable resistor is parallelly connected, and respectively with the one end of the cable to be measured and the one end of the auxiliary cable are connected.
In an alternative embodiment, the step of feeding the high voltage pulse to the cable metal protective sheath near the prepositioned fault point to obtain the precisely located fault point includes:
connecting a pulse voltage generator at a position which is a preset distance from the front to the back of the pre-positioning fault point;
feeding the high-voltage pulse into the cable metal protective sleeve and the cable metal protective layer through the pulse voltage generator;
and measuring the discharge voltage of the cable metal protective sleeve, and obtaining the accurate positioning fault point through the discharge voltage.
In an alternative embodiment, the step of measuring a discharge voltage of the cable metal protective sheath and obtaining the accurate positioning fault point through the discharge voltage includes:
and if the voltage value of the voltage is within a preset voltage value range, judging that the measurement position is the accurate positioning fault point.
In an optional implementation manner, in the step of feeding the high-voltage pulse to the cable metal protective sheath near the pre-positioning fault point to obtain the precisely positioned fault point, a connection relationship of a circuit is as follows:
the pulse voltage generator is electrically connected with a measuring pen, and the measuring pen is electrically connected with the cable metal protective layer and used for feeding the high-voltage pulse into the cable metal protective sleeve and the cable metal protective layer;
probes of the CU modules are inserted into the buried sand above the fault point at intervals and used for measuring the discharge voltage of the cable metal protective sleeve.
In an optional embodiment, if the metal protective sheath or the insulating layer of the cable at the precisely positioned fault point is damaged, after the step of evaluating the damage degree of the cable to be tested, an intermediate joint is manufactured at the precisely positioned fault point.
In an optional embodiment, the step of repairing the precisely located fault point includes:
cleaning the precisely positioned fault point;
wrapping the precisely positioned fault point with a repair composite material, and fixing the repair composite material outside the precisely positioned fault point;
and heating the repairing combined material to ensure that the repairing combined material is fixed outside the accurate positioning fault point in a thermal shrinkage manner.
In an optional embodiment, after the step of repairing the precisely located fault point, the method further comprises:
inspecting the cable jacket with the high voltage direct current generator;
and if the leakage phenomenon does not occur after the pressure resistance value is reached, judging that the cable to be detected is qualified to repair.
The embodiment of the invention has the beneficial effects that: according to the construction method, the pre-positioning fault point is found firstly, and then the accurate positioning fault point is found according to the pre-positioning fault point, so that the positioning accuracy can be improved. Meanwhile, whether damage exists or not is detected according to the accurate positioning fault point, and the cable is repaired when the damage does not exist so as to ensure normal use of the cable. Specifically, firstly, the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested are connected, and a pre-positioning fault point of the cable outer sheath of the cable to be tested is obtained. And feeding high-voltage pulse on the cable metal protective sleeve near the prepositioned fault point to obtain the accurately positioned fault point of the cable outer sheath. And then, detecting whether the metal protective sleeve or the insulating layer of the cable at the accurately positioned fault point of the outer sheath of the cable is damaged or not. And if the cable metal protective sleeve and the insulating layer at the accurate positioning fault point are not damaged, repairing the accurate positioning fault point. The steps can accurately find the fracture or scratch point of the cable outer sheath, avoid the condition of missed inspection, reduce the time consumption of manual observation and inspection, improve the labor productivity and reduce the cost consumption of engineering.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic block diagram of a flow of a construction method for troubleshooting and repairing a cable outer sheath according to an embodiment of the present invention;
FIG. 2 is a block diagram schematic flow chart of a sub-step of step S10 in FIG. 1;
FIG. 3 is a schematic circuit diagram illustrating the step S10 in FIG. 1;
FIG. 4 is a block diagram schematic flow chart of a sub-step of step S20 in FIG. 1;
FIG. 5 is a schematic circuit diagram illustrating the step S20 in FIG. 1;
FIG. 6 is a block diagram schematic flow chart of a sub-step of step S50 in FIG. 1;
fig. 7 is a schematic block diagram of the flow of step S60 and step S70 according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to fig. 1, a construction method for searching and repairing a fault of an outer sheath of a single-core high-voltage cable provided by an embodiment of the invention is shown, and is used for searching a damaged position of the cable and repairing the damaged position, so as to be beneficial to reducing hidden dangers in a cable operation process. The construction method for searching and repairing the fault of the cable outer sheath provided by the embodiment of the invention can accurately find the fracture or scratch point of the cable outer sheath, thereby avoiding the condition of missed detection, reducing the time consumption of manual observation and inspection, improving the labor productivity and reducing the cost consumption of engineering.
The embodiment of the invention provides a construction method for searching and repairing faults of an outer sheath of a single-core high-voltage cable.
Step S10: and connecting the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested to obtain a prepositioned fault point of the cable outer sheath of the cable to be tested.
It should be noted that, when the step S10 is performed, it may be determined whether the cable is a cable to be tested, and a multimeter may perform cable calibration to determine that the cable is a root test cable; and respectively stripping the outer sheaths at two ends of the cable to be tested by about 30cm, so that the steel armor of the metal protective sleeve of the single-core cable is leaked out, and the test is convenient for wiring.
Referring to fig. 2, in an alternative embodiment, step S10: the method comprises the following steps of connecting an auxiliary cable, a high-voltage direct-current generator and a processed cable to be tested, and obtaining a prepositioned fault point:
substep S11: stripping cable outer sheaths at two ends of the cable to be tested by a preset length so as to expose the metal protective sleeves of the cable to be tested at the two ends of the cable to be tested;
substep S12: the metal protective sleeve is connected with the auxiliary cable, the high-voltage direct-current generator and the cable to be tested;
substep S13: starting a high-voltage direct current generator, performing a boosting test, and recording a test result of the boosting test;
substep S14: and calculating to obtain the prepositioned fault point according to the test result.
Referring to fig. 3, in an alternative embodiment, in the step S10 and the sub-steps S11 to S14, the connection relationship of the circuit may be:
one end of the high voltage DC generator (element in the dotted line frame in FIG. 3) and the auxiliary cable (R in FIG. 3)3) Is electrically connected with one end of the auxiliary cable, and the other end of the auxiliary cable is connected with the cable to be tested (R in figure 3)3b) The metal protective sleeve at one end is electrically connected, and the other end of the high-voltage direct-current generator is connected with a cable to be tested (R in figure 3)X) Is electrically connected to ground (R in FIG. 3)F) One end of the cable is electrically connected between the metal sheath of the fault point of the cable to be tested and the ground.
Optionally, the HVDC generator comprises a high frequency high voltage constant current source (elements within the dashed box in FIG. 3), a high sensitivity galvanometer (elements labeled "G" in FIG. 3), and an adjustable resistor (R in FIG. 3)1And R2) The high-frequency high-voltage constant current source is electrically connected with the adjustable resistor, and the high-sensitivity galvanometer is connected with the adjustable resistor in parallel and is respectively connected with one end of the cable to be tested and one end of the auxiliary cable.
It should be noted that, the bridge is formed by the core resistor of the cable metal protective layer on both sides of the fault point and the proportional resistor, the four-terminal method resistance measurement principle is adopted, the high-frequency high-voltage constant current source and the high-sensitivity galvanometer are contained in the bridge, and the power supply and the bridge are combined into a whole, so that the problem of the balance interference of the power supply to the bridge is solved. The measuring cable is a special high-voltage cable, the positioning precision is high, the electric bridge is arranged on the high-voltage side, and the operating button is grounded safely, so that the limitation of the bridge method for positioning the high resistance is thoroughly solved, the application of the bridge method is free of blind areas, and the measuring cable has the characteristics of accuracy and convenience. The auxiliary conductor has the same diameter and conductor material so that the resistance value does not affect the measurement. Tested cableThe metal protective sleeve of the fault phase is in short circuit with the metal protective sleeve of the non-fault phase, two arms of the bridge are respectively connected with the fault phase and the non-fault phase, and the measurement also comprises a loop bridging resistor at two ends of the cable, so the resistor must be very low. In this case, RX＝(R2/R1)*(R3+Rloop Bridge+R3b) Wherein R is3Is the resistance of the auxiliary line, RLoop BridgeIs the resistance of the loop bridge, R3bIs the resistance of the cable to loop bridge fault. By RXThe distance from the measuring point to the grounding fault point of the cable metal sheath can be calculated.
Alternatively, in step S10 described above, the preregistration fault point can be obtained. The method can adopt a concrete mode that a boosting test is started, three times of measurement are carried out, test results are recorded, an average value is counted and taken as a prepositioned fault point, the cable metal protection steel armor is discharged after the test is finished, and then an instrument power supply is turned off.
After the predetermined bit error point is obtained, step S20 is executed: and feeding high-voltage pulse to the cable metal protective sleeve near the prepositioned fault point to obtain the accurately positioned fault point of the cable outer sheath.
Referring to fig. 4, in an alternative embodiment, step S20: feeding high-voltage pulse to a cable metal protective sleeve near a prepositioned fault point to obtain a step of accurately positioning the fault point, which comprises the following steps:
substep S21: connecting a pulse voltage generator on a metal sheath of the cable to be tested;
alternatively, the front-rear preset distance may be at a position ten meters forward and rearward.
Substep S22: feeding high-voltage pulses into the cable metal protective sleeve and the cable metal protective layer through a pulse voltage generator;
substep S23: and measuring the discharge voltage of the cable metal protective sleeve, and obtaining an accurate positioning fault point through the discharge voltage.
In an alternative embodiment, sub-step S23: the step of measuring the discharge voltage of the cable metal protective sleeve and obtaining the accurate positioning fault point through the voltage comprises the following steps:
and if the voltage value of the discharge voltage is within the preset voltage value range, judging that the measurement position is a precise positioning fault point. The preset voltage value range may be set at about 5V.
Referring to fig. 5, in an alternative embodiment, in the step of feeding a high voltage pulse to the cable metal sheath near the predetermined location fault point to obtain the precisely located fault point, the connection relationship of the circuit is as follows:
the pulse voltage generator is electrically connected with the measuring pen, and the measuring pen is electrically connected with the cable metal protective layer and used for feeding high-voltage pulses into the cable metal protective sleeve and the cable metal protective layer;
probes of the CU modules are inserted into the buried sand above the fault point at intervals and used for measuring the discharge voltage of the metal protective sleeve of the cable.
Optionally, a precise positioning measurement method is adopted according to the low-impedance grounding condition of the pre-positioning measurement. And measuring and positioning by using a probe of an accurate positioning voltage method at each ten meters before and after the pre-positioning measurement result. The pulse voltage generator is connected on the cable metal protective sleeve, a series of high-voltage pulses are fed into the metal protective layer of the damaged cable, the voltage pulses are discharged through a damaged point, the damaged point is grounded, a voltage funnel is formed on the buried soil (buried sand), and the damaged position of the cable outer sheath is judged by measuring the voltage. When the probe measures a certain point, the pulse voltage with the rule of about 5V is displayed on the display screen of the CU module, and therefore the point is judged to be the accurate positioning fault point.
In an optional embodiment, if the metal protective sleeve or the insulating layer of the cable at the precisely positioned fault point is damaged, after the step of evaluating the damage degree of the cable to be tested, an intermediate joint is manufactured at the precisely positioned fault point.
Step S30: and detecting whether the metal protective sleeve or the insulating layer of the cable at the accurate positioning fault point of the outer sheath of the cable is damaged or not.
Optionally, before detecting whether the cable is damaged, the cable at the fault point can be excavated, the appearance sundries can be cleaned, and the cable fault point can be raised.
Step S40: and if the metal protective sleeve or the insulating layer of the cable at the accurately positioned fault point is damaged, evaluating the damage degree of the cable to be tested.
Step S50: and if the cable metal protective sleeve and the insulating layer at the accurate positioning fault point are not damaged, repairing the accurate positioning fault point.
Referring to fig. 6, in an alternative embodiment, step S50: the step of repairing the precisely positioned fault point comprises the following steps:
substep S51: cleaning the precisely positioned fault point; such as using acetone (or alcohol) to accurately locate the fault point (generally no less than 3 cm)2Range) is scrubbed clean around.
Substep S52: wrapping the precisely positioned fault point with a repairing combined material, and fixing the repairing combined material outside the precisely positioned fault point; the zipper type repairing composite material can be intercepted to wrap the fault point and the zipper is locked.
Substep S53: and heating the repairing combined material to ensure that the repairing combined material is fixed outside the precisely positioned fault point in a thermal shrinkage manner. The heat gun can be uniformly heated to be completely contracted in the damaged outer sheath, and the temperature of the heat gun is not too high easily.
It should be noted that, after the repair is completed, the cable is laid again, the cable is buried in soil (sand), the entire cable outer sheath is checked again by using the high-voltage direct-current generator, and no leakage phenomenon occurs after the voltage withstanding value is reached, so that the repair of the cable fault point is qualified, and no damage condition of other cable outer sheaths exists.
Referring to fig. 7, in an alternative embodiment, after the step of repairing the precisely located fault point, the method further includes:
step S60: inspecting the cable outer sheath by using the high-voltage direct-current generator;
step S70: and if the leakage phenomenon does not occur after the pressure resistance value is reached, judging that the cable to be detected is qualified for repairing.
It should be understood that, the above steps S60 and S70, the re-detection and measurement after the cable repair can detect that all damaged fault points of the whole high voltage cable are exposed and complete the repair, so as to ensure that the whole buried high voltage cable can operate safely.
Referring to fig. 1 to fig. 7, the beneficial effects of the embodiment of the present invention are as follows: according to the construction method, the pre-positioning fault point is found firstly, and then the accurate positioning fault point is found according to the pre-positioning fault point, so that the positioning accuracy can be improved. Meanwhile, whether damage exists or not is detected according to the accurate positioning fault point, and the cable is repaired when the damage does not exist so as to ensure normal use of the cable. Specifically, firstly, the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested are connected, and a pre-positioning fault point of the cable outer sheath of the cable to be tested is obtained. And feeding high-voltage pulse on the cable metal protective sleeve near the prepositioned fault point to obtain the accurately positioned fault point of the cable outer sheath. And then, detecting whether the metal protective sleeve or the insulating layer of the cable at the accurately positioned fault point of the outer sheath of the cable is damaged or not. And if the cable metal protective sleeve and the insulating layer at the accurate positioning fault point are not damaged, repairing the accurate positioning fault point. The steps can accurately find the fracture or scratch point of the cable outer sheath, avoid the condition of missed inspection, reduce the time consumption of manual observation and inspection, improve the labor productivity and reduce the cost consumption of engineering.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A construction method for searching and repairing the fault of an outer sheath of a single-core high-voltage cable is characterized by comprising the following steps:
connecting the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested to obtain a prepositioned fault point of a cable outer sheath of the cable to be tested;
feeding high-voltage pulses into the cable metal protective sleeve near the pre-positioning fault point to obtain a precisely positioned fault point of the cable outer sheath;
detecting whether the metal protective sleeve or the insulating layer of the cable at the accurate positioning fault point of the outer sheath of the cable is damaged or not;
if the cable metal protective sleeve or the insulating layer at the accurate positioning fault point is damaged, evaluating the damage degree of the cable to be tested;
and if the cable metal protective sleeve and the insulating layer at the accurate positioning fault point are not damaged, repairing the accurate positioning fault point.
2. The construction method for searching and repairing the fault of the outer sheath of the single-core high-voltage cable according to claim 1, wherein the step of connecting the auxiliary cable, the high-voltage direct-current generator and the processed cable to be tested to obtain the pre-positioning fault point comprises the following steps of:
stripping cable outer sheaths at two ends of the cable to be tested by a preset length so as to expose the metal protective sleeves of the cable to be tested at the two ends of the cable to be tested;
the metal protective sleeve is connected with the auxiliary cable, the high-voltage direct-current generator and the cable to be tested;
starting the high-voltage direct current generator, performing a boosting test, and recording a test result of the boosting test;
and calculating to obtain the predetermined positioning fault point according to the test result.
3. The construction method for troubleshooting and repairing the outer sheath of the single-core high-voltage cable as claimed in claim 2, wherein in the step of connecting the auxiliary cable, the high-voltage direct-current generator and the metal protective sheath of the cable to be tested, a connection relationship of circuits is as follows:
one end of the high-voltage direct-current generator is electrically connected with one end of the auxiliary cable, the other end of the auxiliary cable is electrically connected with the metal protective sleeve at one end of the cable to be tested, the other end of the high-voltage direct-current generator is electrically connected with the other end of the cable to be tested, and one end of the ground resistor is electrically connected between the metal protective sleeve of the cable to be tested and the ground.
4. The construction method for troubleshooting repair of the outer sheath of the single-core high-voltage cable as claimed in claim 3, wherein the high-voltage direct-current generator includes a high-frequency high-voltage constant-current source, a high-sensitivity galvanometer and an adjustable resistor, the high-frequency high-voltage constant-current source is electrically connected with the adjustable resistor, and the high-sensitivity galvanometer is connected in parallel with the adjustable resistor and is respectively connected with one end of the cable to be tested and one end of the auxiliary cable.
5. The construction method for searching and repairing the fault of the outer sheath of the single-core high-voltage cable according to claim 1, wherein the step of feeding the high-voltage pulse to the metal cable protective sheath near the pre-positioning fault point to obtain the precisely positioned fault point comprises the following steps of:
the metal sheath of the cable to be tested is connected with a pulse voltage generator;
feeding the high-voltage pulse into the cable metal protective sleeve and the cable metal protective layer through the pulse voltage generator;
and measuring the discharge voltage of the cable metal protective sleeve, and obtaining the accurate positioning fault point through the discharge voltage.
6. The construction method for searching and repairing the fault of the outer sheath of the single-core high-voltage cable according to claim 5, wherein the step of measuring the discharge voltage of the metal protective sheath of the cable and obtaining the accurate positioning fault point through the discharge voltage comprises the following steps of:
and if the voltage value of the voltage is within a preset voltage value range, judging that the measurement position is the accurate positioning fault point.
7. The construction method for searching and repairing the fault of the outer sheath of the single-core high-voltage cable according to claim 5, wherein in the step of feeding the high-voltage pulse to the metal sheath of the cable to obtain the accurate positioning fault point, the connection relationship of the circuit is as follows:
the pulse voltage generator is electrically connected with a measuring pen, and the measuring pen is electrically connected with the cable metal protective layer and used for feeding the high-voltage pulse into the cable metal protective sleeve and the cable metal protective layer;
and probes of the CU modules are inserted into the buried sand above the prepositioned fault point at intervals and used for measuring the discharge voltage of the cable metal protective sleeve of the prepositioned fault point.
8. The construction method for troubleshooting and repairing the outer sheath of the single-core high-voltage cable as claimed in claim 1, wherein if the metal protective sheath or the insulating layer of the cable at the accurate positioning fault point is damaged, an intermediate joint is manufactured at the accurate positioning fault point after the step of evaluating the damage degree of the cable to be tested.
9. The construction method for troubleshooting and repairing the outer sheath of the single-core high-voltage cable as claimed in any one of claims 1 to 8, wherein the step of repairing the precisely positioned fault point comprises the steps of:
cleaning the precisely positioned fault point;
wrapping the precisely positioned fault point with a repair composite material, and fixing the repair composite material outside the precisely positioned fault point;
and heating the repairing combined material to ensure that the repairing combined material is fixed outside the accurate positioning fault point in a thermal shrinkage manner.
10. The construction method for troubleshooting and repairing the outer sheath of the single-core high-voltage cable as claimed in any one of claims 1 to 8, wherein after the step of repairing the precisely positioned fault point, the method further comprises:
inspecting the cable jacket with the high voltage direct current generator;
and if the leakage phenomenon does not occur after the pressure resistance value is reached, judging that the cable to be detected is qualified to repair.
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