A coupling coil and current detection integrated device for non-invasive cable detection

Abstract

This utility model discloses a non-invasive cable testing device integrating a coupling coil and current detection, relating to the field of power cable testing technology. It includes: a split-type ferrite core coupling coil, a Rogowski coil, and a fixing assembly. The split-type ferrite core coupling coil and the Rogowski coil are fixedly connected by the fixing assembly. The split-type ferrite core coupling coil includes a U-shaped ferrite core, an insulating shell, and a coupling coil winding. The coupling coil winding is wound around the U-shaped ferrite core, which is embedded within the insulating shell. This utility model features integration, high precision, and adaptability to high-voltage environments. It solves problems such as low efficiency of split installation, high difficulty in core closure processing, and insufficient high-voltage insulation in existing technologies, and is convenient for field personnel to use.

Description

Technical Field

[0001] This utility model relates to the field of power cable testing technology, specifically a non-invasive cable testing device integrating a coupling coil and current detection. Background Technology

[0002] Currently, power cables are widely used in power transmission, distribution, and industrial power applications, and their operating status directly affects the safety and reliability of the power grid. During long-term operation, cables may fail due to insulation aging, mechanical damage, or partial discharge, therefore, it is necessary to regularly inspect their insulation condition and current parameters.

[0003] Traditional cable testing methods mainly include pulse current method (for partial discharge detection) and current measurement method (for load current or fault current monitoring), but existing technologies have some problems.

[0004] In existing technologies, partial discharge detection typically employs high-frequency current transformers (HFCTs) or coupled coils, while current measurement relies on Rogowski coils or current clamps. These two types of sensors require separate installation, which not only occupies space but also increases the complexity of on-site operations. For example, during high-voltage cable inspection, operators need to repeatedly disassemble and reassemble the sensors, which is not only time-consuming and labor-intensive but may also introduce measurement errors due to improper operation.

[0005] Some split-type magnetic core coupling coils employ an openable / closeable structure. However, due to insufficient manufacturing precision or structural design defects, a significant gap (typically >0.5mm) remains even after the magnetic core is closed. This leads to increased magnetic reluctance and decreased permeability, consequently affecting the coupling efficiency of pulse signals. Experimental data shows that when the magnetic core gap increases from 0.1mm to 0.5mm, the transmission loss of high-frequency signals (>1MHz) can increase by more than 20%, severely impacting the sensitivity of partial discharge detection. This device balances the magnetic flux of the coupling coil and the Rogowski coil, designing a magnetic core gap of approximately 1cm after closure. This significantly reduces manufacturing difficulty, and the combination of the two devices has little impact on measurement accuracy. Therefore, a non-invasive cable testing device integrating a coupling coil and current detection is needed to solve the aforementioned technical problems. Utility Model Content

[0006] In view of this, the present invention provides a non-invasive cable testing device that integrates a coupling coil and a current detection unit, which solves the problems of low efficiency of separate installation, high difficulty in magnetic core closure processing, and insufficient high-voltage insulation in the prior art. It is convenient for field personnel to use, and features integration, high precision, and adaptability to high-voltage environments. It is suitable for scenarios such as cable metal sheath fault location and insulation status assessment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A non-invasive cable testing device integrating a coupling coil and current detection includes: a split ferrite core coupling coil, a Rogowski coil, and a fixing assembly, wherein the split ferrite core coupling coil and the Rogowski coil are fixedly connected by the fixing assembly;

[0009] The split ferrite core coupling coil includes a U-shaped ferrite core, an insulating shell, and a coupling coil winding. The coupling coil winding is wound around the U-shaped ferrite core, and the U-shaped ferrite core is embedded in the insulating shell.

[0010] Furthermore, the inner diameter of the split ferrite core coupling coil is the same as that of the Rogowski coil, and the inner diameter is 1.2-1.5 times the diameter of the cable to be tested.

[0011] Furthermore, the Rogowski coil and the split ferrite core coupling coil are coaxially arranged with an axial distance ≤5mm, and a flexible Rogowski coil with a range of 0.1A-10kA is used.

[0012] Furthermore, the U-shaped ferrite core is broken in the middle, divided into two half-piece U-shaped ferrite cores. After the cross-sectional gap is closed, the core gap is 1cm. The cross-sectional area of ​​the U-shaped ferrite core is 8mm×12mm to 15mm×20mm, and the surface is covered with an epoxy insulation layer of 0.1mm-0.3mm. The Curie temperature is ≥200℃.

[0013] Furthermore, a pivot is provided on one side of the insulating shell, and the insulating shell is hinged to form an openable structure via the pivot. A buckle is provided on the other side. The thickness of the insulating shell is 2mm-8mm, the gap of the insulating shell is <0.1mm, and it is injection molded from high-temperature resistant and flame-retardant PC material.

[0014] Furthermore, the fixing component includes two weather-resistant nylon plastic cable ties, which are fixed to both sides of the rotating shaft, with an operating temperature range of -40°C to 85°C.

[0015] Furthermore, the side wall of the insulating housing is also provided with a wire outlet for leading out the wires of the coupling coil winding.

[0016] Furthermore, the coupling coil winding uses high-voltage resistant enameled wire with a wire diameter of 0.5mm-1.0mm and an inductance of 0.5mH-2mH.

[0017] The beneficial effects of this utility model are as follows:

[0018] This utility model features quick installation, simple operation, strong adaptability, and suitability for on-site application needs. The design of a 1cm gap between the two half-piece U-shaped ferrite core sections after closure greatly reduces the processing difficulty. The integrated design of the split ferrite core coupling coil and Rogowski coil reduces installation time by 50% and makes operation more convenient. The modular size design can adapt to the testing needs of cables of different specifications. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of a split-type ferrite core coupled coil.

[0022] Figure 3 This is a schematic diagram of the structure of the coupling coil winding;

[0023] In the figure:

[0024] 1-Split ferrite core coupled coil; 2-Rogowski coil; 3-Fixing assembly; 4-U-shaped ferrite core; 5-Insulating shell; 6-Coupled coil winding; 7-Shaft; 8-Snap-on; 9-Outlet. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Please see the appendix Figure 1-3 This utility model provides a non-invasive cable testing device integrating coupling coil and current detection, including: a split ferrite core coupling coil 1, a Rogowski coil 2 and a fixing component 3, wherein the split ferrite core coupling coil 1 and the Rogowski coil 2 are fixedly connected by the fixing component 3;

[0027] The split ferrite core coupling coil 1 includes a U-shaped ferrite core 4, an insulating shell 5, and a coupling coil winding 6. The coupling coil winding 6 is wound around the U-shaped ferrite core 4, and the U-shaped ferrite core 4 is embedded in the insulating shell 5.

[0028] The split-type ferrite core coupling coil 1 mainly realizes the injection of non-invasive pulse signals into the cable's metallic sheath, while the Rogowski coil 2 mainly realizes the monitoring of current in the cable's metallic sheath. The monitoring data is used to determine whether there is a fault in the cable. Therefore, through the integrated design of the split-type ferrite core coupling coil 1 and the coaxial Rogowski coil 2, the pulse injection and current detection functions are completed simultaneously.

[0029] Preferably, the inner diameters of the split-type ferrite core coupling coil 1 and the Rogowski coil 2 are the same, and the inner diameter is 1.2-1.5 times the diameter of the cable to be measured. For 220kV cables, the inner diameter is designed to be 10cm (suitable for 80mm diameter cables); for 10kV cables, the inner diameter can be reduced to 3cm. This ratio has been verified by a large number of experiments, which can achieve the best signal detection sensitivity while ensuring installation convenience. The axial distance between the split-type ferrite core coupling coil 1 and the Rogowski coil 2 is strictly controlled within the range of ≤5mm. The Rogowski coil 2 is made of a flexible PCB substrate, with a measurement range covering 0.1A to 10kA and three switchable measurement ranges.

[0030] Preferably, the Rogowski coil 2 and the split ferrite core coupling coil 1 are coaxially arranged with an axial distance ≤ 5 mm, and a flexible Rogowski coil with a range of 0.1A-10kA is used.

[0031] Preferably, the U-shaped ferrite core 4 is broken in the middle, divided into two half-pieces of U-shaped ferrite core 4. After the cross-sectional gap is closed, the core gap is 1cm. The cross-sectional area of ​​the U-shaped ferrite core 4 is 8mm×12mm to 15mm×20mm, and the surface is covered with an epoxy insulation layer of 0.1mm-0.3mm. The Curie temperature is ≥200℃. The size range of this application has been verified by multiple experiments. It can control the volume of the overall device while ensuring sufficient magnetic permeability. The epoxy insulation layer adopts a special formula, which not only ensures good insulation performance, but also does not significantly increase the magnetic resistance of the magnetic circuit.

[0032] Preferably, a rotating shaft 7 is provided on one side of the insulating shell 5, and the insulating shell 5 is hinged to the rotating shaft 7 to form an openable structure. A buckle 8 is provided on the other side. The thickness of the insulating shell 5 is 2mm-8mm, the gap of the insulating shell 5 is <0.1mm, and it is injection molded from high temperature resistant and flame retardant PC material. The buckle 8 is a self-locking buckle 8. This thickness range ensures sufficient mechanical strength without excessively increasing the weight of the device.

[0033] Preferably, the fixing component 3 includes two weather-resistant nylon plastic cable ties, which are fixed on both sides of the rotating shaft 7. The working temperature range is -40℃ to 85℃, which can adapt to various harsh environments. It adopts a ratchet locking mechanism, which can withstand a maximum tensile force of 500N, ensuring that it will not loosen under long-term vibration environment.

[0034] Preferably, the side wall of the insulating housing 5 is also provided with a wire outlet 9 for leading out the wires of the coupling coil winding 6. All wires are led out through the wire outlet 9, and the wire outlet 9 is also equipped with a waterproof sealing structure.

[0035] Preferably, the coupling coil winding 6 uses high-voltage resistant enameled wire with a wire diameter of 0.5mm-1.0mm and an inductance of 0.5mH-2mH, which can well match the output impedance of common pulse signal sources. The coupling coil winding 6 adopts a layered close winding process, with an insulation layer between each layer, which effectively reduces the inter-turn capacitance and improves the high-frequency response characteristics.

[0036] The specific method of using this utility model is as follows:

[0037] Step 1: Select a suitable integrated device according to the voltage level (thickness) of the cable to be tested. For example, for a 220KV cable, a device with an inner diameter of 10cm can be selected.

[0038] Step 2: Unlock the bayonet of the split ferrite core coupling coil 1 and the Rogowski coil 2 respectively, secure the instrument to the cable, and then close the bayonet.

[0039] Step 3: Perform pulse injection using a split-type magnetic core coupling coil as required, and use Rogowski coil 2 to monitor the current in the cable's metallic sheath.

[0040] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A non-invasive cable testing device integrating a coupling coil and current detection, characterized in that, include: A split ferrite core coupling coil (1), a Rogowski coil (2), and a fixing assembly (3) are provided, wherein the split ferrite core coupling coil (1) and the Rogowski coil (2) are fixedly connected by the fixing assembly (3); The split ferrite core coupling coil (1) includes a U-shaped ferrite core (4), an insulating shell (5), and a coupling coil winding (6). The coupling coil winding (6) is wound around the U-shaped ferrite core (4), and the U-shaped ferrite core (4) is embedded in the insulating shell (5).

2. The non-invasive cable testing device integrating coupling coil and current detection according to claim 1, characterized in that, The inner diameter of the split ferrite core coupling coil (1) is the same as that of the Rogowski coil (2), and the inner diameter is 1.2-1.5 times the diameter of the cable to be tested.

3. The non-invasive cable testing device integrating coupling coil and current detection according to claim 1, characterized in that, The Rogowski coil (2) is coaxially arranged with the split ferrite core coupling coil (1) and the axial distance is ≤5mm. It adopts a flexible Rogowski coil with a range of 0.1A-10kA.

4. The non-invasive cable testing device integrating coupling coil and current detection according to claim 1, characterized in that, The U-shaped ferrite core (4) is broken in the middle and divided into two half U-shaped ferrite cores (4). After the cross-sectional gap is closed, the core gap is 1cm. The cross-sectional area of ​​the U-shaped ferrite core (4) is 8mm×12mm to 15mm×20mm. The surface is covered with an epoxy insulation layer of 0.1mm-0.3mm and the Curie temperature is ≥200℃.

5. The non-invasive cable testing device integrating coupling coil and current detection according to claim 1, characterized in that, The insulating shell (5) has a rotating shaft (7) on one side, and the insulating shell (5) is hinged to the rotating shaft (7) to form an open and close structure. The other side is provided with a buckle (8). The thickness of the insulating shell (5) is 2mm-8mm, and the gap of the insulating shell (5) is <0.1mm. It is injection molded from high temperature resistant and flame retardant PC material.

6. The non-invasive cable testing device integrating coupling coil and current detection according to claim 5, characterized in that, The fixing component (3) includes two weather-resistant nylon plastic cable ties, which are fixed on both sides of the rotating shaft (7) and have an operating temperature range of -40°C to 85°C.

7. The non-invasive cable testing device integrating coupling coil and current detection according to claim 5, characterized in that, The side wall of the insulating housing (5) is also provided with a wire outlet (9) for leading out the wires of the coupling coil winding (6).

8. The non-invasive cable testing device integrating coupling coil and current detection according to claim 1, characterized in that, The coupling coil winding (6) uses high-voltage resistant enameled wire with a wire diameter of 0.5mm-1.0mm and an inductance of 0.5mH-2mH.

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