Improved cable detector

Abstract

The embodiment of the present invention relates to the technical field of hanging cable detection, and specifically to an improved cable detector, which includes a transmitter and a receiver. In the electric field detection mode: the transmitter is configured to apply voltage to the hanging cable; the receiver includes an electric field sensor, an electric field detection circuit and a main control device, and the electric field detection circuit is configured to output the detection result of the hanging cable based on the potential difference at two different positions around the hanging cable. The beneficial effect of the embodiment of the present invention is that the cable detector usually uses the electromagnetic field induction method to detect the cable. However, when detecting the hanging cable, if the target cable is not effectively grounded, a current loop to the ground cannot be formed, and an electromagnetic field cannot be formed around the target cable, and this method is completely ineffective. On the basis of adopting the electromagnetic field induction method, the present invention simultaneously senses the electrostatic field of the target cable, effectively solving the problem of detecting ungrounded hanging optical cables.

Description

Technical Field

[0001] The invention relates to the technical field of hanging cable detection, and in particular to an improved cable detector. Background Art

[0002] The cable detector consists of a set of signal transmitters and receivers. It is usually used for routing positioning of metal pipelines such as cables, optical cables (optical cables with metal reinforcement cores), long-distance tracking, and depth measurement of underground metal pipelines. The transmitter sends a low-frequency (usually less than 200kHz) AC signal on the cable, and the receiver obtains information such as the route and depth of the cable by detecting the direction and strength of the electromagnetic field radiated by the target cable.

[0003] Cable detector receivers usually use electromagnetic field induction to detect metal pipelines:

[0004] According to the electromagnetic field theory revealed by Maxwell's equations, low-frequency alternating current will generate an electromagnetic field coaxial with the target pipeline around the target metal pipeline when passing through it. The strength of the electromagnetic field is proportional to the current passing through the pipeline and inversely proportional to the vertical distance from the pipeline. The cable detector receiver can sense the strength and direction of the magnetic field through multiple built-in magnetic field induction coils, thereby calculating the direction of the pipeline and the depth of burial underground, and completing the detection of the pipeline. High-end cable detectors usually use this method, and their receivers are equipped with several magnetic field induction coils, see Figure 7.

[0005] As long as an alternating current of a specific frequency can be applied to the target pipeline, this method can theoretically detect all cables, including underground pipelines and hanging cables.

[0006] However, the disadvantage of this method is that a circuit loop must be formed to generate current in the target pipeline, and only with current can a magnetic field around the target pipeline be generated to complete the detection of the target pipeline. In actual use, due to various reasons such as poor pipeline grounding, the target pipeline often fails to form a loop, so that an alternating current of a specific frequency cannot be applied to the target pipeline, and the target pipeline cannot be detected.

[0007] Therefore, an improved cable detector is needed to overcome the above problems. Summary of the invention

[0008] In order to solve the above problem, that is, to solve the problem of being unable to detect hanging cables, an embodiment of the present invention provides an improved cable detector, which includes a transmitter and a receiver. In the electric field detection mode:

[0009] The transmitter is configured to apply voltage to the hanging cable;

[0010] The receiver includes an electric field sensor, a potential difference judgment circuit between two points and a main control device, wherein:

[0011] At least one of the electric field sensors is configured to detect an induced electromotive force at a first position around the hanging cable, which is referred to as a first induced electromotive force;

[0012] At least another electric field sensor is configured to detect an induced electromotive force at a second position around the hanging cable, which is referred to as a second induced electromotive force;

[0013] The two-point potential difference determination circuit is configured to determine a potential difference of the hanging cable based on the first induced electromotive force and the second induced electromotive force.

[0014] Furthermore, the voltage is a low-frequency alternating current voltage.

[0015] Furthermore, the electric field sensor at the first position is a telescopic antenna.

[0016] Furthermore, in the electromagnetic field detection mode:

[0017] The transmitter is configured to apply a low-frequency AC voltage to the hanging cable;

[0018] The receiver includes a magnetic field sensor and a magnetic field detection circuit, wherein:

[0019] The magnetic field sensor is configured to detect the electromagnetic field around the hanging cable based on Maxwell's equations;

[0020] The magnetic field detection circuit is configured to output a detection result of an unhung cable based on the detected electromagnetic field.

[0021] Furthermore, the detection result of the hanging cable includes whether the hanging cable is grounded and the route of the hanging cable.

[0022] The beneficial effects of the embodiments of the present invention are:

[0023] Cable detectors usually use electromagnetic field induction to detect cables. However, when detecting hanging cables, if the target cable is not effectively grounded, a current loop to the ground cannot be formed, and an electromagnetic field cannot be formed around the target cable, so this method is completely ineffective. The present invention uses the electromagnetic field induction method and simultaneously senses the electrostatic field of the target cable, effectively solving the problem of detecting ungrounded hanging optical cables. You can choose to use the electric field detection mode or the electromagnetic field detection mode according to actual needs, thereby avoiding the situation where the single electric field detection mode cannot be applied to cables that are shielded (such as cables in walls, cables buried underground), and also avoiding the situation where the single electromagnetic field detection mode cannot be applied to cable breaks. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a working principle diagram of an embodiment of a cable detector in an electric field detection mode;

[0025] FIG2 is a flowchart of an embodiment of a cable detector in an electric field detection mode;

[0026] FIG3 is a flowchart of the working process of another embodiment of the cable detector in the electric field detection mode and the magnetic field detection mode;

[0027] Figure 4 is an electric field image obtained by simulating the electric field distribution between the hanging cable and the ground using MATLAB;

[0028] Figure 5 shows the relationship between the horizontal distance x and the electric field strength when the vertical distance y in Figure 4 is a certain value (3m);

[0029] Figure 6 is a specific embodiment of this patent;

[0030] FIG. 7 is a working principle diagram of an existing cable detector. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0032] 1 to 6 , an embodiment of the present invention discloses an improved cable detector, which includes a transmitter and a receiver. In the electric field detection mode:

[0033] The transmitter is configured to apply voltage to the hanging cable;

[0034] The receiver includes an electric field sensor, a potential difference judgment circuit between two points, and a main control device, wherein: at least one of the electric field sensors is configured to detect an induced electromotive force at a first position around the hanging cable, which is set as a first induced electromotive force;

[0035] At least another electric field sensor is configured to detect an induced electromotive force at a second position around the hanging cable, which is referred to as a second induced electromotive force;

[0036] The two-point potential difference determination circuit is configured to determine a potential difference of the hanging cable based on the first induced electromotive force and the second induced electromotive force.

[0037] Furthermore, the voltage is a low-frequency (usually less than 200 KHz) alternating current voltage.

[0038] Furthermore, the electric field sensor is a telescopic antenna.

[0039] Furthermore, in the electromagnetic field detection mode:

[0040] The transmitter is configured to apply a low-frequency AC voltage to the hanging cable; The receiver includes a magnetic field sensor and a magnetic field detection circuit, wherein:

[0041] The magnetic field sensor is configured to detect the electromagnetic field around the hanging cable based on Maxwell's equations;

[0042] The magnetic field detection circuit is configured to output a detection result of an unhung cable based on the detected electromagnetic field.

[0043] It should be noted that the detection result of the hanging cable includes whether the hanging cable is grounded and the route of the hanging cable.

[0044] The present invention simultaneously senses the electromagnetic field and the electrostatic field of the target cable in one cable detector receiver to make up for the deficiency of only using the electromagnetic field induction method (see FIG. 7 ).

[0045] For hanging cables (not buried underground), the method of detecting the electrostatic field of the target cable can be used to detect the cable. The principle is as follows:

[0046] ① According to physics theory, there is an electrostatic field around any effective charge. When the transmitter sends a low-frequency AC signal on the cable, there must be an electric field around the hanging cable. Even if the empty cable is not grounded and cannot form a current with the earth, the electrostatic field around it always exists. See Figure 1 for a schematic diagram of the electrostatic field.

[0047] ② According to the definition of electric field strength, its magnitude E=f / q (where E is the electric field, f is the amount of charge in the cable, and q is the distance from the electric field detection point to the cable), it can be seen that the magnitude of the electric field is proportional to the amount of charge in the cable, and its strength decreases rapidly as the distance from the cable increases. Therefore, there must be a potential difference between two locations at different distances from the target cable.

[0048] ③The receiver can form an induced current in the receiver by using an antenna to detect the potential difference between two different positions in the electric field.

[0049] ④ Since the transmitter applies low-frequency alternating current excitation to the target cable, the electrostatic field around the target cable changes in an alternating manner, and the potential difference between its two different positions also changes in an alternating manner. Therefore, the detection result of the receiver also changes in an alternating manner, and its frequency is exactly the same as that of the target cable.

[0050] ⑤This type of equipment is usually equipped with a telescopic antenna to obtain the electric field induction result at another location. See Figure 2 for the telescopic antenna and electrostatic field potential induction method.

[0051] The receiver can detect electromagnetic fields and electrostatic fields at the same time, and the customer can select one of them as the result output, as shown in Figure 3.

[0052] When the loaded voltage is assumed to be U = 10sin(1000·2π·t), the electric field image obtained by simulating the electric field distribution using MATLAB is shown in FIG4 .

[0053] From the simulation results, it can be seen that the electric field weakens as the distance from the cable increases, but due to the influence of the ground, the electric field strength has changed. The influence of the ground on the electric field is quantitatively analyzed from the horizontal distance and vertical distance. When the vertical distance y is a certain value (3m is shown), the relationship between the horizontal distance x and the electric field strength is shown in Figure 5.

[0054] Finally, according to actual measurements, the transmitter applied a 1kHz5V AC signal excitation to a 1km section of ungrounded optical cable. The receiver used the electromagnetic field induction method. Since no induced current was generated in the optical cable, no induced magnetic field could be generated. When magnetic field induction was used for reception, the received signal strength was 0.0mV. However, using the electrostatic field potential induction method, with a 1.4-meter pull-rod antenna 2 meters below the optical cable, the received signal strength was about 1.6mV.

[0055] In addition, the circuit design of the present invention is shown in FIG6 , and each circuit module thereof is a mature design. If the solution of the present invention is to be implemented, it is only necessary to purchase matching models and then connect the respective communication interfaces.

[0056] In addition, it should be noted that the hardware and software of the above-mentioned cable detector that only senses electric fields are both mature technologies that have been applied (there are many products that only sense electrostatic fields, such as the electric pens we usually use, and this type of network cable detector, all of which use the electrostatic field induction method), and have been disclosed in a large number of documents.

[0057] Likewise, the hardware and software of the cable detector in the electromagnetic field detection mode described above are both mature technologies that have been applied.

[0058] It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0059] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.

[0061] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An improved cable detector, characterized in that: Includes transmitter and receiver, in electric field detection mode: The transmitter is configured to apply a voltage to the hanging cable, wherein the voltage is a low-frequency AC voltage; The receiver includes an electric field sensor, a potential difference judgment circuit between two points, and a main control device, wherein: at least one of the electric field sensors is configured to detect an induced electromotive force at a first position around the hanging cable, which is set as a first induced electromotive force; At least another electric field sensor is configured to detect an induced electromotive force at a second position around the hanging cable, which is referred to as a second induced electromotive force; The two-point potential difference judgment circuit is configured to judge the potential difference of the hanging cable based on the first induced electromotive force and the second induced electromotive force; the electric field sensor at the first position is a telescopic antenna; In electromagnetic field detection mode: The transmitter is configured to apply a low-frequency AC voltage to the hanging cable; The receiver includes a magnetic field sensor and a magnetic field detection circuit, wherein: The magnetic field sensor is configured to detect the electromagnetic field around the hanging cable based on Maxwell's equations; The magnetic field detection circuit is configured to output a detection result of an unhung cable based on the detected electromagnetic field.

2. The improved cable detector according to claim 1, characterized in that: Also includes a main control device, wherein: The two-point potential difference judgment circuit is configured to judge the potential difference of the hanging cable based on the first induced electromotive force and the second induced electromotive force; The magnetic field detection circuit is configured to output a magnetic field detection result based on the detected electromagnetic field; The main control device is configured to output a detection result of the hanging cable according to either the potential difference or the magnetic field induction detection result.

3. The improved cable detector according to claim 2, characterized in that: The detection result of the hanging cable includes whether the hanging cable is grounded and the route of the hanging cable.

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