Cable detection tool

Abstract

The utility model discloses a cable detection tool which comprises a magnetic conductor and a detector connected with the magnetic conductor. The detector is used for detecting the magnitude of the magnetic field force borne by the magnetic conductor when the magnetic conductor is located on the outer side of the detected cable connected with the direct current so as to determine whether the detected cable is broken or not according to the magnitude of the magnetic field force. According to the cable detection tool, the magnetic field intensity of the periphery of the detected cable can be indirectly measured only by placing the magnetic conductor in the magnetic field on the outer side of the detected cable and measuring the magnitude of the magnetic field force borne by the magnetic conductor through the detector, and then whether the problem of cable core breakage exists in the detected cable or not is determined; the whole detection tool is simple in structure and low in cost, and can be widely applied to fracture detection of other cable cores on the basis of reducing the difficulty of fracture detection of the two water-cooled cables which are connected in parallel.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit component detection, in particular to a cable detection tool. Background Art

[0002] Symmetrical water-cooling cables are generally used to power a constant current source in vacuum consumable furnaces. In the constant current source DC power supply circuit of the vacuum consumable furnace, two water-cooling cables with the same material, diameter and length need to be set in parallel. If the number of broken conductive copper cores in one of the water-cooling cables exceeds the limit, the normal operation of the vacuum consumable furnace will be directly affected.

[0003] The best way to detect whether the conductive core in the cable is broken is to perform magnetic field detection. The most commonly used sensor for magnetic field detection is the Hall sensor, and the conductive core needs to be passed through the coil of the Hall sensor. Since the two water-cooling cables arranged in parallel are continuous and uninterrupted, it is impossible to pass one of the two water-cooling cables through the coil of the Hall sensor, and thus it is impossible to detect the breakage of the two water-cooling cables arranged in parallel. Utility Model Content

[0004] The purpose of the utility model is to provide a cable detection tool, which can simply realize the fracture detection of parallel water-cooled cables and other similar cables, and reduce the difficulty of cable broken strand detection.

[0005] In order to solve the above technical problems, the utility model provides a cable detection tool, comprising a magnetic conductor and a detector connected to the magnetic conductor;

[0006] The detector is used to detect the magnitude of the magnetic field force exerted on the magnetic conductor when the magnetic conductor is located outside the tested cable connected to direct current, so as to determine whether the tested cable is broken based on the magnitude of the magnetic field force.

[0007] In an optional embodiment of the present application, the magnetic conductor is a metal iron sheet;

[0008] Alternatively, the magnetic conductor includes an electrode plate, and the electrode plate is connected to a power supply via a control switch.

[0009] In an optional embodiment of the present application, the detector is a pressure sensor; and the magnetic conductor is arranged on a pressure sensing surface of the pressure sensor.

[0010] In an optional embodiment of the present application, the pressure sensor is a planar bellows pressure sensor; the magnetic conductor is arranged on the force-bearing surface of the pressure sensor by means of screws.

[0011] In an optional embodiment of the present application, a clamping structure is further connected to one side of the pressure sensor for detachable clamping connection with the cable under test.

[0012] In an optional embodiment of the present application, the clamping structure is a spring clip, and the spring clip is an insulating clip.

[0013] In an optional embodiment of the present application, a temperature sensor is further provided on the surface of the spring clip for contacting the cable under test.

[0014] In an optional embodiment of the present application, the pressure sensor is further connected to a display or a pressure transmitter for displaying the pressure data measured by the pressure sensor.

[0015] In an optional embodiment of the present application, two groups of the interconnected magnetic conductors and detectors are provided; and each of the detectors is commonly connected to the same comparator for comparing the magnitudes of the magnetic field forces respectively measured by the two detectors.

[0016] In an optional embodiment of the present application, the comparator is further connected to an alarm.

[0017] The cable detection tool provided by the utility model includes a magnetic conductor and a detector connected to the magnetic conductor; the detector is used to detect the magnitude of the magnetic field force exerted on the magnetic conductor when the magnetic conductor is located outside the cable being tested that is connected to direct current, so as to determine whether the cable being tested is broken based on the magnitude of the magnetic field force.

[0018] The cable detection tool of the present application includes a magnetic conductor, so that when the magnetic conductor is placed in a magnetic field, it can be affected by the magnetic field force exerted by the magnetic field. On this basis, the cable detection tool further includes a detector that can detect the magnetic field force exerted on the magnetic conductor. Therefore, in actual application, it is only necessary to place the magnetic conductor in the cable detection tool in the magnetic field outside the cable to be tested. The magnitude of the magnetic field force exerted on the magnetic conductor measured by the detector can be used to indirectly measure the magnetic field strength of the periphery of the cable to be tested, and then determine whether there is a core break problem inside the cable to be tested. The entire detection tool has a simple structure and low cost. On the basis of reducing the difficulty of detecting the break of two water-cooled cables connected in parallel, it can also be widely used for detecting the break of other cable cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Schematic diagram of the magnetic field on the cross section of two parallel water-cooled cables when there is no broken strand;

[0021] Figure 2 Schematic diagram of the magnetic field on the cross section of two parallel water-cooling cables when one of the water-cooling cables is broken;

[0022] Figure 3 A schematic diagram of the structure of a cable detection tool provided in an embodiment of the present application;

[0023] Figure 4 A schematic diagram of a clamping structure provided in an embodiment of the present application;

[0024] In the accompanying drawings: 10 is a water-cooled cable, 11 is a core, 1 is a cable to be tested, 2 is a detector, 3 is a magnetic conductor, 4 is a clamping structure, 41 is an S-shaped structure, 411 is a clamping part, 412 is a ring part, 42 is a rotating shaft, and 5 is a temperature sensor. DETAILED DESCRIPTION

[0025] To help those skilled in the art better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a portion of the present invention, not all of the embodiments. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0026] Reference Figure 1 and Figure 2 , Figure 1 and Figure 2 1 and 2 show schematic cross-sectional views of two water-cooled cables 10 connected in parallel, wherein the circle with a dot at the center is the cross-sectional view of the core 11 in the water-cooled cable 10, and the dot at the center of the circle indicates that the direction of the current in the core 11 is perpendicular to the paper and outward; Figure 2 There are several circles in which there is no point indicating the direction of the current at the center, which means that there are broken strands in the cores 11 and no current flows through them; Figure 1 and Figure 2 The dotted lines in the figure represent the magnetic field lines of the two water-cooled cables 10. The arrows on the magnetic field lines are the directions of the magnetic field. Figure 1 The figure shows the magnetic field when there is no broken strand in the two water-cooled cables 10. Figure 2 FIG. 2 shows the magnetic field when one of the water-cooling cables 10 is partially broken.

[0027] based on Figure 1 It can be seen that when the copper core wires of the parallel water-cooling cables 10 are not broken, the currents flowing through the two water-cooling cables 10 are the same, and the magnetic fields generated are symmetrical to each other; Figure 2 As shown, when one of the two water-cooling cables 10 connected in parallel is broken, its resistance increases, the current carrying capacity decreases, and the intensity of the magnetic field generated also decreases accordingly; at the same time, the current of the other water-cooling cable 10 also increases accordingly, and the intensity of the magnetic field generated also increases accordingly, so that the magnetic fields of the two water-cooling cables 10 are no longer symmetrical.

[0028] In practice, if a few strands of one of the two parallel water-cooling cables 10 break and gradually deteriorate, reducing its current carrying capacity, if not discovered and replaced promptly, the current in the other water-cooling cable 10 will increase, causing a chain reaction. Because the broken strands increase resistance, the broken copper core wires, under the impact of the water flow, appear to be disconnected, causing the resistance to fluctuate, causing the voltage drop in the cables to fluctuate, directly affecting the stability of the vacuum consumable furnace smelting arc.

[0029] Based on the above discussion, this application provides a cable detection tool based on the different magnetic fields generated when the two water-cooled cables are broken and when they are not broken, which can be used to detect whether two parallel cables have broken strands.

[0030] like Figure 3 As shown, Figure 3 A schematic diagram of the structure of a cable detection tool provided in an embodiment of the present application.

[0031] In an optional embodiment of the present application, the cable detection tool may include:

[0032] A magnetic conductor 3, and a detector 2 connected to the magnetic conductor 3;

[0033] The detector 2 is used to detect the magnitude of the magnetic field force exerted on the magnetic conductor 3 when the magnetic conductor 3 is located outside the tested cable 100 connected to direct current, so as to determine whether the tested cable is broken based on the magnitude of the magnetic field force.

[0034] like Figure 3 As shown, the cable detection tool of this embodiment includes a magnetic conductor 3; the magnetic conductor 3, as the name suggests, is an object with relatively large magnetic permeability. The magnetic conductor 3 in this embodiment can be a metal iron sheet, a magnet sheet or an electrode plate.

[0035] Taking the magnetic conductor 3 as a metal iron sheet as an example, when the metal iron sheet is placed on the outside of the cable under test 1, the cable under test 1 that can generate a magnetic field at the periphery is equivalent to a magnet that has a magnetic field adsorption force on the metal iron sheet. Therefore, the magnetic field force exerted by the magnetic field of the cable under test 1 on the metal iron sheet is also the driving force that drives the metal iron sheet to move closer to the cable under test 1. The detector 2 can determine the magnetic field force exerted on the metal iron sheet by detecting the magnitude of this driving force.

[0036] For example, consider a magnet as the magnetic conductor 3. Unlike a metal iron sheet, this magnet is inherently magnetic and can be a bar magnet with one end facing south and the other north, similar to a compass needle. During actual testing, the magnet can be positioned on the side of the cable under test 1 with the north pole pointing in the direction of the magnetic field lines. This magnet will then be subject to a magnetic field force that drives it to rotate, causing its north and south poles to swap positions. Detector 2 can then determine the magnitude of this magnetic force by detecting the torque generated by the magnet's rotational motion.

[0037] Taking the magnetic conductor 3 as an electrode plate as an example, the electrode plate can be electrically connected to the positive pole or positive pole of the power supply through a control switch. Based on the principle that a charged object will move in a direction perpendicular to the magnetic field lines in a magnetic field, the positively charged electrode plate is driven to move toward the side of the cable 1 under test by the magnetic field force. At this time, by detecting the size of the driving force that drives the electrode plate to move toward the side of the cable 1 under test, the magnetic field force exerted on the electrode plate by the cable 1 under test can be detected.

[0038] It should be noted that although in actual applications, metal iron sheets that are neither charged nor magnetic can be directly used as magnetic conductors 3, the use of magnetic magnet sheets or charged electrode plates can to a certain extent enhance the magnetic field force exerted by the magnetic field on the magnetic conductor 3, thereby enhancing the sensitivity of the cable detection tool.

[0039] Based on the above discussion, when the magnetic conductor 3 is disposed outside the cable 1 under test, that is, within the magnetic field of the cable 1 under test, it is clear that this magnetic field will generate a magnetic force on the magnetic conductor 3. Furthermore, the greater the magnetic field strength of the cable 1 under test, the greater the magnetic force generated by this magnetic field on the magnetic conductor 3. Conversely, the smaller the magnetic field strength of the cable 1 under test, the smaller the magnetic force generated by this magnetic field on the magnetic conductor 3. Therefore, based on this, the present embodiment further provides a detector 2 capable of detecting the magnitude of the magnetic force exerted on the magnetic conductor 3.

[0040] Taking the example of two water-cooled cables connected in parallel and arranged in parallel as the cable under test 1, the magnetic conductor 3 can be first placed on the side of the first water-cooled cable facing away from the second water-cooled cable, so that the magnetic conductor 3 is only affected by the magnetic field force generated by the first water-cooled cable. At this time, the first magnetic field force on the magnetic conductor 3 measured by the detector 2 is also the magnetic field force exerted on the magnetic conductor 3 by the magnetic field of the first water-cooled cable. Then, the magnetic conductor 3 is placed on the side of the second water-cooled cable facing away from the first water-cooled cable. At this time, the second magnetic field force on the magnetic conductor 3 measured by the detector 2 is also the magnetic field force exerted on the magnetic conductor 3 by the magnetic field of the second water-cooled cable. If neither the first water-cooled cable nor the second water-cooled cable has broken strands, the magnitude of the first magnetic field force and the magnitude of the second magnetic field force should be completely equal. Therefore, it is only necessary to compare the magnitudes of the first magnetic field force and the second magnetic field force. If the difference between the two is too large, it can be clearly determined that the water-cooled cable corresponding to the smaller of the first and second magnetic field forces has broken strands.

[0041] It is understandable that the cable detection tool in this embodiment is obviously not limited to the detection of water-cooled cables. In actual applications, for cables with good appearance and uninterrupted structure, a magnetic field will be generated around them, and the strength of the magnetic field is proportional to the current flowing in the cable. Therefore, in actual applications, in order to detect whether a tested cable 1 with good appearance is broken, the magnetic conductor 3 of the cable detection tool in this application can also be set on the side of the tested cable 1 when both ends of the tested cable 1 are energized. Based on the fact that the tested cable 1 is normally energized and the current is known, the corresponding magnetic field strength should be determined. Therefore, based on the magnitude of the magnetic field force exerted on the magnetic conductor 3 directly measured by the detector 2, it can also be determined whether the tested cable 1 has a break. It can be seen that the cable detection tool in the present application can not only detect whether two water-cooled cables (can also be non-water-cooled cables, the principle is the same) that are arranged in parallel are broken, but can also be used for the detection of single cables in various other application scenarios. For example, when a circuit breaker occurs in the equipment circuit, the cable detection tool in the present application can be used to check the location of the circuit breaker, or it can be used for troubleshooting of daily maintenance of equipment cables, etc., to facilitate the detection of cable breaks.

[0042] On this basis, the detector 2 for detecting the magnitude of the magnetic field force exerted on the magnetic conductor 3 in the present application can include multiple implementations. In an optional embodiment of the present application, the detector 2 can be a pressure sensor, and the magnetic conductor 3 is arranged on the pressure sensing surface of the pressure sensor.

[0043] It can be understood that in actual applications, the pressure sensing surface of the pressure sensor should be located on the side of the movement trend generated by the magnetic conductor 3 driven by the magnetic field force, and should be perpendicular to the movement trend direction of the magnetic conductor 3. Therefore, when the magnetic conductor 3 is driven by the magnetic field force and tends to move in a specific direction (for example, in the direction close to the cable 1 under test), an extrusion pressure can be generated on the pressure sensing surface of the pressure sensor. The greater the magnetic field force exerted on the magnetic conductor 3, the greater the extrusion pressure exerted on the pressure sensor. Therefore, based on the extrusion pressure measured by the pressure sensor, the magnitude of the magnetic field force exerted on the magnetic conductor 3 can be indirectly determined.

[0044] In an optional embodiment of the present application, the pressure sensor may be a planar bellows pressure sensor; the magnetic conductor 3 is arranged on the force-bearing surface of the pressure sensor by means of screws.

[0045] like Figure 3 As shown, when the cable 1 under test is actually tested, the magnetic conductor 3 should be set on the side of the planar diaphragm box pressure sensor away from the cable 1 under test; taking the magnetic conductor 3 as a metal iron sheet of 100mm×30mm×1.5mm as an example, the magnetic conductor 3 and the planar diaphragm box pressure sensor are arranged as a whole on the side of the cable 1 under test, and the planar diaphragm box pressure sensor is located between the magnetic conductor 3 and the cable 1 under test; when the current is connected to the cable 1 under test, a magnetic adsorption force can be generated on the magnetic conductor 3, and then the magnetic conductor 3 generates an extrusion force on the pressure sensing surface of the planar diaphragm box pressure sensor, and the planar diaphragm box pressure sensor can measure a pressure data at this time; the magnetic conductor 3 and the planar diaphragm box pressure sensor are used to detect the magnetic field of another parallel cable 1 under test, and the measured pressure data is compared with the previously measured pressure data, thereby determining whether there is a broken cable in the two parallel and parallel cables 1 under test.

[0046] It is understood that in practical applications, the detector 2 for detecting the magnitude of the magnetic field force of the magnetic conductor 3 is not limited to a pressure sensor. As described above, when the magnetic conductor 3 is a bar magnet with one end having an N pole and the other end having an S pole, the cable 1 under test can generate a torque on the magnetic conductor 3 that drives the magnetic conductor 3 to rotate. Therefore, the detector 2 in this case can adopt a torque sensor capable of measuring the magnitude of the torque of the bar magnet. The detector 2 in this application also has other implementation methods, which are not listed here.

[0047] In addition, in order to more intuitively display the pressure data measured by the pressure sensor, the pressure sensor may be connected to a display or a pressure transmitter for displaying the pressure data measured by the pressure sensor.

[0048] Based on any of the above embodiments, in order to further improve the convenience of using the cable detection tool, the present application Figure 3 and Figure 4 As shown, in another optional embodiment of the present application, the cable detection tool may further include:

[0049] The pressure sensor is also connected to a clamping structure 4 for detachably clamping the measured cable 1 .

[0050] like Figure 4 As shown, in the present application, a clamping structure 4 is provided on the pressure sensor. Thus, in actual application, the pressure sensor and the magnetic conductor 3 can be fixed together on the side of the cable 1 under test through the clamping structure 4 without the need for manual support and fixation by the staff. On the one hand, the hands of the staff can be freed during the detection process, and on the other hand, the problem of inaccurate measurement results caused by the shaking of the pressure sensor and the magnetic conductor 3 can be avoided.

[0051] The clamping structure 4 can specifically be a spring clip or a rubber belt with a buckle, etc. Figure 3 and Figure 4 The clamping structure shown in the figure takes a spring clip as an example, which includes two S-shaped structures 41. The middle parts of the two S-shaped structures 41 are connected to form an X-shaped structure through a rotating shaft 42, wherein the two S-shaped structures 41 have a clamping portion 411 at one end and a ring portion 422 at the other end. The clamping portions 411 of the two S-shaped structures 41 are located at the same end of the X-shaped structure, and a spring is provided on the rotating shaft 42 to resist the two S-shaped structures 41. Therefore, the staff can manually control the relative distance between the two ring portions 412 to realize the opening or closing of the two clamping portions 411 on the X-shaped structure, thereby realizing the clamping or removal of the spring clip on the cable 1 under test.

[0052] On this basis, the rotating shaft 42 on the spring clip further extends to one side to be fixedly connected to the pressure sensor. Therefore, when the spring clip is clamped on the cable under test 1, the pressure sensor can also be fixedly set on the outside of the cable under test 1.

[0053] In addition, the spring clip may preferably be an insulating clip to prevent the skin of the tested cable 1 from being accidentally damaged and conducting electricity, thereby threatening the safety of the workers.

[0054] It is further considered that when the cable 1 under test is a water-cooled cable, if some of the conductive cores in the water-cooled cable are broken, resulting in an increase in the resistance of the entire cable, it will inevitably increase the heat generated by the cable during the power-on process, thereby causing the temperature of the cable to rise. Even if the water-cooled cable has a cooling effect, the temperature between the two water-cooled cables in parallel will be different. For this reason, in this embodiment, a temperature sensor 5 can also be set on the surface of the spring clip on which the user adheres to the cable under test 1. Therefore, when actually testing the two water-cooled cables in parallel, in addition to detecting the magnetic fields generated by the two water-cooled cables respectively, the temperatures of the two water-cooled cables can be further detected. The measured magnetic field force and temperature data can be used to verify each other, thereby determining a more accurate measurement result.

[0055] Of course, for a completely disconnected cable, since there is no current connected, there is no heat generated by the power supply. Therefore, compared with a cable with a normal circuit, its temperature will be lower than that of a normal cable. Therefore, the temperature measured by the temperature sensor 5 can further verify the detection result of whether the cable is broken.

[0056] As described above, when testing two parallel water-cooled cables, it is necessary to compare the two sets of data that can represent the magnetic field strength measured by the detector 2. In other words, it is necessary to use the detector 2 to perform a test operation on each water-cooled cable. To this end, in another optional embodiment of the present application, the cable testing tool may further include:

[0057] Two groups of magnetic conductors 3 and detectors 2 connected to each other are provided; and each detector 2 is connected to the same comparator for comparing the magnitudes of the magnetic field forces respectively measured by the two detectors 2 .

[0058] It should be noted that the comparator in this embodiment can specifically be a processor, which is used to compare the magnitudes of the magnetic field forces measured by the two detectors 2 respectively, which eliminates the process of data comparison and can synchronously detect the magnetic fields of the two parallel water-cooled cables, thereby improving the accuracy and reliability of the detection results.

[0059] Of course, if the two detectors 2 are pressure sensors and the output pressure data are electrical signals, the comparator can also use a differential comparator circuit device to output the detection results by comparing the sizes of the pressure electrical signals output by the two pressure sensors, which can also realize the technical solution of this application.

[0060] In addition, the comparator in this embodiment can be further connected to an alarm. Once the comparator obtains a relatively large difference between the results measured by the two detectors 2, the alarm can issue an alarm prompt. The alarm can be an indicator light or a buzzer alarm, etc., which is not specifically limited in this application.

[0061] To sum up, the cable detection tool of the present application includes a magnetic conductor, so that when the magnetic conductor is placed in a magnetic field, it can be affected by the magnetic field force exerted by the magnetic field. On this basis, the cable detection tool further includes a detector that can detect the magnetic field force exerted on the magnetic conductor. Therefore, in actual application, it is only necessary to place the magnetic conductor in the cable detection tool in the magnetic field outside the cable to be tested. The magnitude of the magnetic field force exerted on the magnetic conductor measured by the detector can be used to indirectly measure the magnetic field strength on the periphery of the cable to be tested, and then determine whether there is a wire core break problem inside the cable to be tested. The entire detection tool has a simple structure and low cost. On the basis of reducing the difficulty of detecting the break of two water-cooled cables arranged in parallel, it can also be widely used for the detection of breakage of other cable cores.

[0062] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements are inherent to the elements. In the absence of further restrictions, the elements limited by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are not described in detail in accordance with the corresponding technical solutions in the prior art to achieve the same principle, so as to avoid excessive elaboration.

[0063] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A cable detection tool, characterized in that: It includes a magnetic conductor and a detector connected to the magnetic conductor; The detector is used to detect the magnitude of the magnetic field force exerted on the magnetic conductor when the magnetic conductor is located outside the tested cable connected to direct current, so as to determine whether the tested cable is broken based on the magnitude of the magnetic field force.

2. The cable detection tool according to claim 1, wherein: The magnetic conductor is a metal iron sheet; Alternatively, the magnetic conductor includes an electrode plate, and the electrode plate is connected to a power supply via a control switch.

3. The cable detection tool according to claim 1, wherein: The detector is a pressure sensor; the magnetic conductor is arranged on the pressure sensing surface of the pressure sensor.

4. The cable detection tool according to claim 3, wherein: The pressure sensor is a planar bellows type pressure sensor; the magnetic conductor is arranged on the force-bearing surface of the pressure sensor by means of screws.

5. The cable detection tool according to claim 3, wherein: A clamping structure is also connected to one side of the pressure sensor for detachable clamping connection with the tested cable.

6. The cable detection tool according to claim 5, characterized in that: The clamping structure is a spring clip, and the spring clip is an insulating clip.

7. The cable detection tool according to claim 6, wherein: A temperature sensor is also provided on the surface of the spring clip used for contacting the cable to be tested.

8. The cable detection tool according to claim 3, wherein: The pressure sensor is also connected to a display or a pressure transmitter for displaying the pressure data measured by the pressure sensor.

9. The cable detection tool according to any one of claims 1 to 8, characterized in that: Two groups of the magnetic conductors and the detectors connected to each other are provided; and each of the detectors is connected to the same comparator for comparing the magnitudes of the magnetic field forces respectively measured by the two detectors.

10. The cable detection tool according to claim 9, characterized in that: The comparator is also connected to an alarm.

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