JP7409648B2 - Power cable inspection device and inspection method - Google Patents

Description

The present invention relates to a power cable inspection device and method.

In power cables installed underground, a structure is known in which a metal shielding layer such as copper tape is formed around the power transmission conductor via an insulator, and the metal shielding layer is covered with a sheath. ing. Patent Document 1 proposes a technique in which a coil unit is scanned along an electric wire, the output voltage of the coil unit is amplified by a differential amplifier, and an abnormality in a shield member is detected based on the difference in the amplified output voltages. There is.

JP2010-226934A

In the case of the technique described in Cited Document 1, the coil unit is scanned along the longitudinal direction of the power cable at the site where the power cable is installed. If the cross-sectional structure of the power cable along the longitudinal direction is uniform, scanning of the coil unit is easy. However, a terminal connection section provided at a location where the terminal end of the power cable is connected to other equipment, electric wires, etc. has a cross-sectional structure different from the cross-sectional structure of the power cable itself.

The terminal connection part has a structure in which the ends of the sheath, etc. are removed in stages, the connection between the conductor and metal shielding layer is secured, and then the surrounding electrical insulation is reinforced and waterproofed using insulating tape, etc. It has become. Furthermore, since the terminal portion of the power cable is cut at the terminal connection portion, shrinkback of the sheath (backward movement due to contraction) is likely to occur. For this reason, there is a strong need to understand the presence or absence of displacement, rupture, etc. of the metal shielding layer at the connection part, but there has been no proposal to solve the problems caused by the structure, shape, etc. of the connection part.

The present invention has been made in view of the above circumstances, and provides a power cable that allows the metal shielding layer of the power cable to be easily inspected even if the inspection point is the connection part of the power cable or the vicinity thereof. An object of the present invention is to provide an inspection device and an inspection method.

One aspect of the present invention includes a measurement probe that detects the metal shield layer, and a measurement probe that is set at a certain distance from the central axis of the power cable, with respect to an inspection location including a connection part of a power cable having a metal shield layer. and a guide jig that guides the measurement probe so that the measurement probe is scanned along the power cable at a position away from the outer peripheral surface of the connection portion of the power cable. This is a power cable inspection device featuring:

According to the inspection device of the above aspect, since the measurement probe is scanned at a position away from the outer circumferential surface of the connection portion of the power cable, even if the inspection location is the connection portion of the power cable or its vicinity, the power cable This makes it possible to easily inspect metal shielding layers in a non-destructive manner.

One aspect of the present invention is to maintain a measurement probe that detects the metal shielding layer at a certain distance from the central axis of the power cable with respect to an inspection location including a connection part of a power cable having a metal shielding layer. , a method for inspecting a power cable, characterized in that the measurement probe scans along the power cable at a position away from an outer circumferential surface of a connecting portion of the power cable.

According to the inspection method of the above aspect, since the measurement probe is scanned at a position away from the outer circumferential surface of the connection part of the power cable, even if the inspection point is the connection part of the power cable or its vicinity, the power cable This makes it possible to easily inspect metal shielding layers in a non-destructive manner.

In the inspection device and the inspection method, the measurement probe maintains a certain distance from the central axis of the power cable, and the measurement probe measures the power at a position away from the outer circumferential surface of the connection portion of the power cable. A guide jig may be used to guide the measurement probe so that it is scanned along the cable.
In this case, it is possible to easily scan the measurement probe at a position away from the outer circumferential surface of the connection portion of the power cable.

In the inspection device and the inspection method, the measurement probe may detect metal using a capacitive, eddy current, or inductive proximity sensor.
In this case, the metal shielding layer can be easily detected even when the measurement probe is scanned at a position remote from the outer circumferential surface of the connection part of the power cable.

In the inspection device and the inspection method, the metal shielding layer is wrapped in a spiral around the central axis of the power cable, and the measurement probe is arranged to cover the metal shielding layer along the power cable. A gap may also be detected.
In this case, a change in the metal shielding layer can be detected as an abnormality in the power cable due to shrink-back of the sheath or a symptom thereof.

According to the present invention, there is provided a power cable testing device and testing method that can easily test a metal shielding layer of a power cable even if the testing location is a power cable connection or its vicinity. be able to.

FIG. 1 is a partially cutaway sectional view showing the inspection device of the first embodiment. FIG. 2 is a perspective view of a guide jig in the first embodiment. It is a front view showing the inspection device of a 2nd embodiment. It is a perspective view showing an inspection device of a 3rd embodiment. FIG. 3 is an explanatory diagram of a power cable inspection method.

Hereinafter, the present invention will be described based on preferred embodiments and with reference to the drawings.

(First embodiment)
FIG. 1 shows an inspection device 20 according to the first embodiment. This inspection device 20 is an inspection device 20 for a power cable 10 having a metal shielding layer 11, and can inspect exposure of an insulator due to displacement, tearing, etc. of the metal shielding layer 11. The power cable 10 has a structure in which a metal shielding layer 11 such as a copper tape is formed around a power transmission conductor via an insulator, and the metal shielding layer 11 is covered with a sheath 12. The power cable 10 has a connection 13 to a connection device 14 with an external device 17 . The connection part 13 is not limited to a terminal connection part by which the power cable 10 is connected to another device, but may be an intermediate connection part by which the power cables 10 are connected to each other.

At the connection portion 13, the sheath 12 and the like are removed in stages from the end of the power cable 10, and an insulating coating 16 is formed using adhesive tape or the like. Therefore, the outer peripheral surface 15 of the connecting portion 13 has surface undulations. In the case of a structure in which a plurality of power cables 10 are twisted together, for example, a duplex type (twisted with two cables), a triplex type (twisted with three cables), a quadraplex type (twisted with four cables), etc., the end of the power cable 10 Separate connecting portions 13 may be constructed by untwisting the strands.

In the power cable 10 that uses a high voltage, a metal shielding layer 11 is provided around the insulator for the purpose of maintaining the performance of the power transmission conductor and the insulator (not shown) disposed around it. It will be done. Further, when the metal shielding layer 11 is grounded, a grounding wire (not shown) is pulled out from the connecting portion 13. The operating voltage of the power cable 10 is not particularly limited, but may be, for example, 6.6 kV to 35 kV.

The metal shielding layer 11 may be formed by substantially uniformly covering the periphery of the insulator with a conductive material, and may be formed of a thin wire, thin film, tube, braid, or the like made of a conductor such as metal. From the viewpoint of flexibility, productivity, etc. of the power cable 10, it is preferable to configure the metal shielding layer 11 by spirally winding a metal tape 11T such as a copper tape or an aluminum tape.

Examples of the insulator disposed inside the metal shielding layer 11 include crosslinked resin such as crosslinked polyethylene. Examples of the material for the sheath 12 include synthetic resins such as polyvinyl chloride, polyethylene, and fluororesins, and synthetic rubbers such as natural rubber, butyl rubber, and chloroprene rubber. Further, other layers, accessories, etc. may be added to the power cable 10 for the purpose of corrosion protection, identification, etc.

The outer diameter of the power cable 10 is not particularly limited, but examples include about 30 to 80 mm, and about 50 to 60 mm. The range in which the metal shielding layer 11 is inspected at or near the connection portion 13 of the power cable 10 at the inspection location is, for example, about 20 to 50 cm in the longitudinal direction of the power cable 10. The inspection location is not limited to areas such as on the outer circumferential surface 15 or the insulating coating 16 of the connecting portion 13, but may be a nearby portion in contact with the connecting portion 13.

The inspection device 20 of the first embodiment includes a measurement probe 21 that detects the metal shielding layer 11 and a guide jig 23 that guides the measurement probe 21. The measurement probe 21 is capable of detecting the metal constituting the metal shielding layer 11 in a non-contact manner by distinguishing it from electrical insulators such as the sheath 12 and the insulation coating 16 provided close to the metal shielding layer 11. It is preferable to employ a sensor. Examples of non-contact sensors include sensors that perform detection using electricity, magnetism, electromagnetic waves, and the like. For example, a two-wire proximity sensor (model: EV-30M) manufactured by Keyence Corporation can be used.

The measurement probe 21 may be connected to an external electric computer, control device, etc. (not shown) via an electric wire 22. It is also possible to carry out communication and information transmission between the measurement probe 21 and an external device wirelessly. The operation of the measurement probe 21 may be controlled using a programmable controller, computer, or the like. In order to present the output signal of the measurement probe 21 or its analysis result to the operator, a display, an alarm, a printing device, etc. may be used.

As a sensor constituting the measurement probe 21, for example, a proximity switch described in JIS C 8201-5-2 (Low voltage switchgear and control device - Part 5-2: Control circuit equipment and switchgear element - Proximity switch) is used as a proximity sensor. It may also be used as Examples of the proximity sensor include a capacitance type proximity sensor, an eddy current type proximity sensor, an inductive type proximity sensor, and the like. By using these proximity sensors, metal shielding layer 11 can be easily detected even when measurement probe 21 is located away from outer circumferential surface 15 of connection portion 13 of power cable 10 .

Capacitive proximity sensors can detect changes in the size, distance, etc. of the object to be detected by detecting changes in capacitance that occur between the sensor and the object to be detected, such as metal. . For example, if a sensor is equipped with a measurement electrode and a dielectric (electrical insulator) such as air is present between the measurement electrode and the detection target, the capacitance between the measurement electrode and the detection target changes. is detected by the detection circuit. Thereby, changes in the size, distance, etc. of the object to be detected can be detected.

An eddy current type proximity sensor (or displacement sensor) causes a high-frequency current to flow through a coil inside the sensor to generate a high-frequency magnetic field (alternating current magnetic field), and causes the magnetic field to act on a detection target made of metal. When the object to be detected includes a metal surface having a certain area, eddy currents are generated on the metal surface around the magnetic field received from the sensor due to the action of electromagnetic induction. Energy loss in the coil increases on the sensor side depending on the degree of eddy current generated in the object to be detected. Thereby, changes in the size, distance, etc. of the object to be detected can be detected.

Similar to eddy current type proximity sensors, inductive proximity sensors utilize the fact that eddy currents are generated on the surface of metal when the metal approaches a high frequency magnetic field emitted from a detection coil. Although a method that operates in the same way as the eddy current type described above is sometimes employed, sensors using other methods for detecting eddy current are also known. For example, there is a method that generates an output signal when the operation of an oscillation circuit for generating a high-frequency magnetic field in a detection coil is affected by energy loss due to the generation of eddy currents, and the oscillation attenuates or stops. Furthermore, the method of detecting changes in oscillation frequency and phase can be suitably used for objects to be detected that include non-magnetic metals such as aluminum. Alternatively, an inductance bridge may be used to detect changes in the inductance of the detection coil. These detection methods make it possible to detect changes in the size, distance, etc. of the object to be detected.

Generally, the output of a non-contact sensor such as a proximity sensor changes depending on the distance from the object to be detected. As described above, if the cross-sectional structure of the power cable 10 along the longitudinal direction is uniform, scanning with the measurement probe 21 is easy. However, if there are irregularities due to surface undulations in the connection portion 13 and its vicinity at the inspection location, the output of the measurement probe 21 changes due to a change in the distance between the measurement probe 21 and the metal shielding layer 11. For this reason, it becomes difficult to distinguish a change in the output due to the displacement of the measurement probe 21 from a change due to the presence or absence of displacement, rupture, etc. of the metal shielding layer 11.

When using the inspection device 20 of the first embodiment, the measurement probe 21 is placed at a position away from the outer circumferential surface 15 of the connection portion 13 of the power cable 10 . The measurement probe 21 is scanned along the power cable 10 such that the measurement probe 21 maintains a constant distance from the central axis 10A of the power cable 10. As a result, even if there are surface undulations in the connection part 13 of the power cable 10, the measurement probe 21 can be placed at a predetermined position without being affected by the surface undulation, so that the metal shielding layer 11 can be inspected. It becomes possible to do it easily. Moreover, since the measurement probe 21 can be maintained at a predetermined position for inspection, it is possible to easily detect displacements, cracks, breaks, etc. of the metal shielding layer 11. Thereby, a change in the metal shielding layer 11 can be detected as an abnormality in the power cable 10 or a predictive phenomenon thereof.

The inspection device 20 of the first embodiment includes a guide jig 23 that guides the measurement probe 21 so that the measurement probe 21 maintains a constant distance from the central axis 10A of the power cable 10. The guide jig 23 can be attached or detached near the connection portion 13 of the power cable 10 as required for inspection. Thereby, it becomes possible to easily carry out scanning of the measurement probe 21 at a position away from the outer peripheral surface 15 of the connection portion 13 of the power cable 10.

A cross-sectional view and a perspective view of the guide jig 23 in the first embodiment are shown in FIGS. 1 and 2, respectively. The guide jig 23 is composed of half-split cover members 23A and 23B that sandwich the power cable 10 therebetween. As a result, even if the connecting portion 13 of the power cable 10 is connected to the connecting device 14, the guide jig 23 can be attached to the outer periphery of the power cable 10 without separating the end of the power cable 10 from the connecting device 14. can be placed. The same applies when removing the guide jig 23 from the power cable 10 after the inspection is completed. Thereby, the power cable 10 can be inspected without changing the connection state between the connection part 13 of the power cable 10 and the connection device 14, which is excellent in workability.

As shown in FIG. 1, the holding portion 23C, in which the cover members 23A and 23B sandwich and hold the power cable 10, preferably contacts a portion of the power cable 10 whose cross-sectional structure is substantially uniform in the longitudinal direction. Thereby, the cover members 23A and 23B can be attached to the power cable 10 while avoiding surface coating on the outer periphery of the connecting portion 13. Furthermore, it becomes easier to align the center of the holding portion 23C with the central axis of the power cable 10. This makes it easy to adjust the attitude of the guide jig 23 so that the measurement probe 21 maintains a constant distance from the central axis 10A of the power cable 10.

The cover members 23A and 23B may have an accommodating portion 23D for accommodating the connecting portion 13 on at least one side of the holding portion 23C. The housing portion 23D is a hollow portion formed between the cover members 23A and 23B. The inside of the housing portion 23D may be a space into which outside air can flow, and a cushioning material made of a non-metallic material such as cotton or sponge may be arranged. The cover members 23A and 23B may be supported in a cantilevered manner in the holding portion 23C so that the inner surface of the housing portion 23D does not come into contact with the outer periphery of the power cable 10. When a cushioning material is provided in the housing portion 23D, the cushioning material may come into contact with the outer periphery of the power cable 10.

The position of the measurement probe 21 can be maintained at a constant distance from the central axis A of the power cable 10 by moving the measurement probe 21 along the outer periphery of the cover members 23A, 23B. That is, the cover members 23A and 23B have a guide function for guiding the position of the measurement probe 21, and a spacer function for suppressing the measurement probe 21 from approaching the power cable 10 beyond a predetermined distance.

The material constituting the cover members 23A, 23B is not particularly limited, but may be composed of a dielectric material (electrical insulator) such as synthetic resin or rubber. Since the cover members 23A, 23B are interposed between the power cable 10 and the measurement probe 21 at least in the housing portion 23D of the cover members 23A, 23B, the material, wall thickness, etc. of the cover members 23A, 23B surrounding the housing portion 23D are It is preferable to keep it constant.

Further, the cover members 23A, 23B may be transparent or opaque, but by coloring them differently from the power cable 10, it becomes easier for the operator to confirm the positions of the cover members 23A, 23B. A guide line, arrow, etc. indicating the direction of movement may be displayed at the position where the measurement probe 21 is moved along the guide jig 23.

Although the illustrated example of the guide jig 23 is composed of a pair of cover members 23A and 23B facing each other on both sides of the power cable 10, the guide jig 23 may be composed of one member or three or more members. It is possible. The guide jig may be integrated by connecting the structural members of the power cable 10 divided into a plurality of parts in the circumferential direction using a hinge or the like. The guide jig may be attached so as to be wrapped around the power cable 10. The guide jig may be prepared in different sizes depending on the dimensions and outer diameter of the power cable 10 or the connecting portion 13. The circumferential length of the guide jig may be made variable to allow attachment to power cables 10 of different sizes.

(Second embodiment)
Next, referring to FIG. 3, an inspection apparatus 20A according to a second embodiment will be described. The inspection device 20A of the second embodiment includes a guide jig 24 that guides the measurement probe 21 so that the measurement probe 21 maintains a constant distance from the central axis 10A of the power cable 10. Thereby, it becomes possible to easily carry out scanning of the measurement probe 21 at a position away from the outer peripheral surface 15 of the connection portion 13 of the power cable 10.

The guide jig 24 of the second embodiment can be attached to structures other than the power cable 10, such as surrounding walls, ceilings, mechanical devices, etc. The guide jig 23 attached to the power cable 10 and the guide jig 24 attached to a structure other than the power cable 10 may be used together. Further, instead of using the guide jig 24 attached to a structure other than the power cable 10, the guide jig 23 attached to the power cable 10 may be omitted. In addition, since the inspection apparatus 20A of the second embodiment can be implemented in the same manner as the inspection apparatus 20 of the first embodiment except for the guide jig 24, overlapping explanation may be omitted.

The guide jig 24 has a holder 25 that is driven along a track 24A that is arranged substantially parallel to the longitudinal direction of the power cable 10. The measurement probe 21 is held in the holder 25 . The measurement probe 21 is guided by driving the holder 25 holding the measurement probe 21 along the trajectory 24A of the guide jig 24. The track 24A can be composed of an actuator, a ball screw, a rail, a guide groove, a piston, a cylinder, a rope, a wire, a belt, a chain, a rack (linear gear), and the like. When the power cable 10 is straight, it is preferable that the track 24A is also straight. If the power cable 10 has a curved portion, the track 24A may be curved similarly to the power cable 10.

The driving method of the track 24A in the guide jig 24 is not particularly limited, and examples include electric, hydraulic, hydraulic, hydraulic, and mechanical methods. In the case of an electric type, the driving force of the rotary motor may be converted from a rotational direction to a linear direction using a ball screw or the like. Examples of the hydraulic drive system include a configuration in which a piston, cylinder, etc. are operated using hydraulic pressure, water pressure, or the like. Examples of the mechanical drive system include a configuration in which the measurement probe 21 is moved along the trajectory 24A using a spring, human power, or the like. It is preferable if the measurement probe 21 can be driven at a constant speed because this improves the reproducibility of the test.

The track 24A of the guide jig 24 is arranged along the longitudinal direction of the power cable 10. The holder 25 can move along the longitudinal direction of the guide jig 24 by being guided by the track 24A. When the holder 25 moves along the track 24A, the holder 25 may be configured to be displaced in the longitudinal direction without the track 24A being displaced in the longitudinal direction. Further, as the track 24A is displaced in the longitudinal direction, the holder 25 may be configured to follow the track 24A and displace. Wheels, rollers, bearings, gears, etc. may be provided on the holder 25 or the track 24A to facilitate movement.

The guide jig 24 can be configured not to be interposed between the measurement probe 21 and the power cable 10. Therefore, it is possible to use not only dielectric materials (electrical insulators) such as synthetic resins and rubber, but also materials containing conductors such as metals and carbon fiber reinforced plastics. The core material of the guide jig 24 may be made of metal or the like, and the periphery of the core material may be coated with resin or the like to provide electrical insulation.

The method of arranging the guide jig 24 at a predetermined position is not particularly limited, and the guide jig 24 may be fixed to a surrounding structure at a location where the power cable 10 is installed. A support device such as a movable trolley or stand may be prepared and the guide jig 24 may be held by the support device. An inspection worker or an assistant may support the guide jig 24 in their hands. It is also possible to support the guide jig 24 by burying one end of the guide jig 24 underground.

When using the inspection device 20A of the second embodiment, the guide jig 24 is placed at a position away from the outer peripheral surface 15 of the connection portion 13 of the power cable 10. By driving the measurement probe 21 along the guide jig 24, the measurement probe 21 is scanned along the power cable 10 such that the measurement probe 21 maintains a constant distance from the central axis 10A of the power cable 10. . Thereby, similarly to the inspection device 20 of the first embodiment, the measurement probe 21 can be placed at a predetermined position without being affected by the surface undulations of the power cable 10, and the metal shielding layer 11 can be easily inspected. becomes possible. In addition, it becomes easier to detect displacement, cracks, breaks, etc. of the metal shielding layer 11, and changes in the metal shielding layer 11 can be detected as an abnormality in the power cable 10 or a symptom of the abnormality.

By using the guide jig 24, if the correspondence between the position of the measurement probe 21 and the shape of the output signal is specified, it is possible to eliminate gaps caused by exposing the insulator due to displacement, cracks, rupture, etc. of the metal tape 11T. This is preferable because it makes it easier to identify locations where abnormalities or deterioration exist. For example, the moving speed of the measuring probe 21 may be kept constant, and the elapsed time after the start of movement may be associated with the position of the measuring probe 21. Further, when the members forming the track 24A are displaced together with the measurement probe 21, the position of the measurement probe 21 can also be specified using the distance by which the members forming the track 24A are displaced.

(Third embodiment)
Next, the guide jig 23 of the third embodiment will be described with reference to FIG. 4. The third embodiment can be implemented in the same manner as the inspection device 20 of the first embodiment, except that the guide jig 23 has the guide groove 26. The illustrated guide groove 26 is formed along the longitudinal direction of the power cable 10 on the outer periphery of the cover members 23A, 23B. It is preferable to match the groove width of the guide groove 26 to the dimensions of the measurement probe 21 because the displacement of the measurement probe 21 along the circumferential direction of the power cable 10 can be regulated by the guide groove 26.

A plurality of guide grooves 26 may be formed in parallel in the circumferential direction of the power cable 10. For example, it is also possible to form one or more guide grooves 26 in each of the cover members 23A and 23B of the guide jig 23. Further, the direction in which the guide groove 26 extends, that is, the direction in which the measurement probe 21 moves is not limited to the longitudinal direction of the power cable 10, but may also be in a direction inclined to the longitudinal direction, or in a spiral manner around the power cable 10. It may be in the direction of the power cable 10, in the circumferential direction of the power cable 10, or the like. The guide groove 26 may directly guide the measurement probe 21 or may guide the holder 25 of the second embodiment or the like.

(Inspection method)
Next, an example of a method for inspecting the power cable 10 will be described with reference to FIG. 5. The graph shown in FIG. 5 is a schematic diagram showing the concept. The metal shielding layer 11 of the power cable 10 has a metal tape 11T that is spirally wrapped around the central axis 10A. Since the end of the sheath 12 is cut at the connection portion 13, there is a possibility that the metal tape 11T may be displaced, cracked, or torn due to changes in the sheath 12 over time, such as shrink-back. Further, the insulator may be exposed due to displacement, cracking, rupture, etc. of the metal tape 11T, and a gap 11G may occur.

When a gap 11G exists in the metal tape 11T, the measurement probe 21 in the above-mentioned inspection apparatuses 20 and 20A uses a detection section such as a detection coil to give a different output from the location where the metal tape 11T exists. For example, for a position L in the longitudinal direction, the output signal S gives a peak Q that can be distinguished from the output P at a location where the metal tape 11T is uniformly formed. This allows the measurement probe 21 to detect the gap 11G in the metal shielding layer 11 along the power cable 10. In addition, in the graph shown in FIG. 5, the position L on the horizontal axis of the graph is aligned with the position in the longitudinal direction of the power cable 10 in order to correspond the positional relationship between the peak Q and the gap 11G. When displaying the output of the measurement probe 21, the position L shown on the display can be enlarged, reduced, or deformed with respect to the actual length of the power cable 10 in the longitudinal direction. The peak Q may be emphasized with respect to the output P.

When the detection sensor is arranged so as to be in contact with the outer surface of the power cable 10, a difference may occur in the output signal between a location where the metal tapes 11T overlap and a location where the metal tapes 11T do not overlap. When wrapping the metal tape 11T, areas where the metal tape 11T overlaps and areas where the metal tape 11T does not overlap are alternately formed along the longitudinal direction of the power cable 10, but both are normal. This is a part included in the power cable 10. If the signal changes periodically depending on whether or not the metal tapes 11T overlap, it may become difficult to confirm the signal at a location where an abnormality or deterioration exists, such as the gap 11G. Therefore, it is preferable that a change in the signal at a location where an abnormality or deterioration exists, such as the gap 11G, is distinguished from a change in the signal due to the presence or absence of overlapping of the metal tapes 11T.

According to the inspection devices 20 and 20A of the embodiments described above, the measurement probe 21 is scanned at a position away from the outer peripheral surface of the power cable 10. Therefore, the difference between the output at a location where the metal tapes 11T overlap and the output at a location where the metal tapes 11T do not overlap tends to become small. Since it is easy to distinguish between outputs depending on locations where an abnormality or deterioration exists, such as the gap 11G, it becomes easier to discover problematic locations. For example, even if the measurement probe 21 is placed at a distance of, for example, about 10 mm to 15 mm from the outer surface of the sheath 12 in the radial direction of the power cable 10, it will not work properly at a location where there is an abnormality or deterioration such as the gap 11G. It is possible to obtain a different output from the power cable 10.

The installation location of the power cable 10 is not particularly limited, and examples include underground, overhead, and within a premises. The use of the power cable 10 is not particularly limited, and examples thereof include power generation, power transmission, power distribution, railway use, and industrial use. The guide jigs 23 and 24 may be assembled, attached, etc. on site each time an inspection is required. Further, depending on the situation at the site, the frequency of inspection, etc., the guide jigs 23 and 24 may be permanently installed at the site.

Furthermore, the inspection apparatus and inspection method of the above-described embodiments can be used to inspect a power cable in which an internal semiconducting layer is formed between a conductor and an insulator, and an external semiconducting layer is formed between an insulator and a metal shielding layer. It is also possible to use In this case as well, by facilitating the detection of shifts, cracks, breaks, etc. in the metal shielding layer, it is possible to detect changes in the metal shielding layer as an abnormality in the power cable or a symptom thereof. Furthermore, exposure of the external semiconducting layer due to displacement, tearing, etc. of the metal shielding layer can be inspected.

Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. Modifications include additions, substitutions, omissions, and other changes to components in each embodiment. It is also possible to appropriately combine the components used in two or more embodiments.

The inspection apparatus and inspection method of the above-described embodiments are not limited to the inspection of the connection part of the power cable, but also the inspection of the power cable in parts other than the connection part, the inspection of the power cable before laying it on the site, and the inspection of the power cable during manufacture. It can also be used to inspect semi-finished products and various cables such as communication cables and composite cables.

DESCRIPTION OF SYMBOLS 10...Power cable, 10A...Central axis, 11...Metal shielding layer, 11G...Gap, 11T...Metal tape, 12...Sheath, 13...Connection part, 14...Connection device, 15...Outer peripheral surface, 16...Insulating coating, 20 , 20A... Inspection device, 21... Measurement probe, 23, 24... Guide jig.

Claims (6)

a measurement probe that detects a metal shielding layer for a test location including a connection part of a power cable having a metal shielding layer;
the measurement probe maintains a constant distance from the central axis of the power cable, such that the measurement probe is scanned along the power cable at a position remote from the outer circumferential surface of the connection part of the power cable; a guide jig that guides the measurement probe;
Equipped with
The guide jig includes a cover member attached to the power cable,
The power cable inspection device characterized in that the cover member has a holding part that holds and holds the power cable, and a housing part that houses the connection part on at least one side of the holding part . The power cable inspection device according to claim 1, wherein the measurement probe detects metal using a capacitance type, eddy current type, or inductive type proximity sensor. the metal shielding layer is spirally wrapped around a central axis of the power cable;
3. The power cable inspection apparatus according to claim 1, wherein the measurement probe detects a gap in the metal shielding layer along the power cable. For an inspection point including a connection part of a power cable having a metal shielding layer, a measurement probe that detects the metal shielding layer is placed at a constant distance from the central axis of the power cable, and the measurement probe detects the power cable. scanning along the power cable using a guide jig that guides the measurement probe at a position away from the outer peripheral surface of the connection portion of the cable ;
The guide jig includes a cover member attached to the power cable,
The method for inspecting a power cable, wherein the cover member has a holding part that holds the power cable by sandwiching it therein, and a housing part that houses the connection part on at least one side of the holding part . 5. The power cable inspection method according to claim 4 , wherein the measurement probe detects metal using a capacitance type, eddy current type, or inductive type proximity sensor. the metal shielding layer is spirally wrapped around a central axis of the power cable;
6. The power cable inspection method according to claim 4, wherein the measurement probe detects a gap in the metal shielding layer along the power cable.

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