A novel adjustable opening and closing type power equipment leakage current detection device

Abstract

The application relates to the technical field of weak current measurement, and provides a novel adjustable opening and closing type power equipment leakage current detection device which comprises a base assembly for opening and closing clamping of a to-be-measured cable, a magnetic gathering ring for gathering a magnetic field generated by leakage current of the to-be-measured cable, a sensing assembly for detecting the magnetic field intensity, a controller, a cable shielding member for shielding external electromagnetic interference, and a circuit shielding member. The leakage current detection device provided by the application can clamp the to-be-measured cable into the magnetic gathering ring without affecting the original circuit operation, and can shield external electromagnetic fields through the cable shielding member and the circuit shielding member, so that the detection environment at the to-be-measured cable is kept free from external interference, and more accurate leakage current results are obtained.

Description

Technical Field

[0001] This invention relates to the field of weak current measurement technology, specifically to a novel adjustable openable leakage current detection device for power equipment. Background Technology

[0002] In recent years, with the rapid development of the number and types of power equipment, online monitoring of the insulation performance and real-time inspection of the operational performance of insulated power equipment such as surge arresters, insulators, and sensor bushings have become particularly important for the stable and reliable operation of the power system. The magnitude of leakage current is an important indicator of the insulation condition of equipment. Leakage current is often in the milliampere or microampere range. However, the high voltage and high current operating environment of power grids contains strong power frequency electromagnetic fields, making leakage current detection susceptible to interference and leading to inaccurate results. This is because while there are methods that use magnetic rings to collect and amplify the magnetic field signal generated by the leakage current to measure its magnitude, the electromagnetic field generated by the testing device itself and interference from external electromagnetic fields can affect the measured current value, resulting in inaccurate results.

[0003] Meanwhile, existing leakage current detection requires disconnecting the original circuit, connecting the cable under test to the detection device, and then reconnecting the circuit. This is cumbersome and complicated, making it difficult to achieve non-invasive operation and hindering rapid leakage current detection.

[0004] Therefore, it is necessary to propose a more reasonable technical solution to solve the technical problems existing in the current technology. Summary of the Invention

[0005] To overcome at least one of the aforementioned defects, this invention proposes a novel adjustable opening and closing power equipment leakage current detection device. Through the opening and closing detection structure, it achieves non-invasive cooperation with the cable under test, improving the efficiency of leakage current detection; and it can shield the electromagnetic field outside the cable under test, avoiding the influence of weak current detection, thereby improving the detection accuracy.

[0006] To achieve the above objectives, the leakage current detection device disclosed in this invention can adopt the following technical solution:

[0007] A novel adjustable on / off leakage current detection device for power equipment includes:

[0008] The base assembly includes a fixed seat and a movable seat that open and close relative to each other, the opening and closing surfaces of the fixed seat and the movable seat forming a clamping structure for clamping the cable under test;

[0009] The magnetic ring connected to the fixed base is made of magnetic material. The magnetic ring is aligned with the clamping structure so that the cable under test passes through the middle of the magnetic ring. The magnetic ring is also provided with an air gap for the cable under test to be inserted.

[0010] The sensing component is connected to the fixed base and flips to enter or leave the air gap. The sensing component is used to detect the magnetic field signal generated by the interaction between the cable under test and the magnetic ring when the cable under test passes through the middle of the magnetic ring.

[0011] The controller is electrically connected to the sensing component and is used to receive and process the magnetic field signal detected by the sensing component.

[0012] The cable shield includes two shielding parts that are movably mounted on a fixed base and open and close relative to each other. When the two shielding parts are open, the air gap of the magnetic ring is exposed. When the two shielding parts are closed, the magnetic ring and the test section of the cable under test are sealed. The non-test section of the cable under test passes through the cable shield.

[0013] The circuit shield covers the controller and moves relative to the fixed base. When the circuit shield moves upward, it drives the controller and the sensing component to move and exposes the air gap of the magnetic ring. When the circuit shield moves downward to fit the base assembly, it places the sensing component into the air gap.

[0014] The aforementioned leakage current detection device, through its fixed and movable seats that are designed to open and close, allows the air gap of the magnetic ring to allow the cable under test to be placed into and pass through the center of the magnetic ring without interfering with the original power supply system. The magnetic ring collects the magnetic field generated by the cable under test, while electromagnetic shielding is provided by the cable shielding and circuit shielding to ensure no environmental interference during the detection process. By placing the sensing component inside the air gap and the controller outside the magnetic ring, the electromagnetic field generated by the leakage current can be detected, while avoiding interference from the electromagnetic field generated by the controller's circuit.

[0015] Furthermore, in this invention, the clamping structure is not limited to a single solution; multiple feasible solutions can be adopted. Here, we optimize and illustrate one feasible option: the clamping structure includes clamping grooves respectively disposed on the fixed base and the movable base. With this solution, the clamping grooves can clamp cables of different sizes, keeping them in a centered detection position. The magnetic field collected by the magnetic ring from the leakage current of the cable under test will be more accurate, thereby improving detection accuracy.

[0016] Furthermore, in this invention, considering that the distance between the clamping surfaces of the fixed seat and the movable seat will change when clamping different cables, if the diameter of the cable under test is too small, the clamping surfaces may come into contact, which would affect the stable clamping of the cable under test. Therefore, the structure of the fixed seat and the movable seat is optimized and improved. One feasible option is as follows: the clamping surfaces of the clamping grooves of the fixed seat and / or the movable seat are convex surfaces. When the movable seat approaches the fixed seat and the clamping grooves move closer together to clamp the cable under test, the two clamping surfaces of the movable seat and the fixed seat maintain a gap. With this solution, the clamping surfaces of the fixed seat and the movable seat will not come into contact or interfere. No matter how small the size of the cable under test is, after being clamped by the clamping grooves, a gap remains between the clamping surfaces.

[0017] Furthermore, when the fixed seat and the movable seat open and close relative to each other to clamp the cable under test, a certain amount of damping is provided to protect the cable. The damping method is not limited to a single approach; for example, in some solutions, a torsion spring structure can be installed at the hinge point between the fixed seat and the movable seat. Here, we optimize the design and provide one feasible option: an elastic blocking element is provided between the fixed seat and the movable seat. In some feasible solutions, the elastic blocking element is connected to either the fixed seat or the movable seat. When the elastic blocking element simultaneously contacts both the fixed seat and the movable seat, it applies an elastic force to prevent them from moving closer together. With this approach, the elastic blocking element only intervenes when simultaneously contacting both the fixed seat and the movable seat, and does not intervene at other times, thus improving the ease of operation of the movable seat.

[0018] Furthermore, in this invention, the structure of the elastic blocking element is not uniquely limited. Here, we offer an optimized and feasible option: the elastic blocking element is one of a spring, an elastic telescopic rod, an elastic abutment arm, or an elastic abutment block. With this approach, the elastic blocking element can be mounted on a movable or fixed base and provides sufficient elastic contact to protect the cable under test.

[0019] Furthermore, in this invention, the cable shielding component is openable and closable, aiming to allow the cable under test to be inserted into the magnetic ring without intervention, while maintaining the shielding effect. The structure of the cable shielding component is not uniquely limited; optimization is proposed here, and one feasible option is given: one shielding part of the cable shielding component is connected to a fixed base or a movable base, and is hinged to the other shielding part for relative flipping and opening / closing. Both shielding parts are provided with grooves for the cable under test to pass through. When the two shielding parts are closed, the grooves are joined to form a wire hole. With this solution, the mating surfaces of the two shielding parts can adopt a corresponding slot structure. The bent mating surfaces reduce magnetic leakage and improve the shielding effect against external electromagnetic fields.

[0020] Furthermore, in this invention, to maintain stability and reliability during shielding, the structure of the cable shielding component is optimized. One feasible option is to provide corresponding fastening structures for the two shielding parts, which lock together when the two shielding parts are closed. When using this approach, the fastening structure can be a snap fastener, a locking mechanism, or similar structure.

[0021] Furthermore, to better operate the fixed seat and the movable seat, an optimization and improvement are proposed, and one feasible option is given: the fixed seat and the movable seat are respectively connected to handle structures for operation of opening and closing. When adopting this solution, the handle structure can be integrally formed with the fixed seat and the movable seat, or it can be a separate structure.

[0022] Furthermore, the handle structure itself is not limited to a single solution. Here, we optimize and give one feasible option: the handle structure includes a handle arm with a handle hole.

[0023] Furthermore, the opening and closing structure of the fixed seat and the movable seat is not limited to a single one. Here, we optimize and give one feasible option: the fixed seat and the movable seat are respectively provided with hinge arms, and the two hinge arms cooperate with each other to open and close the fixed seat and the movable seat relative to each other. When this solution is adopted, the hinge arms are integrally formed with the fixed seat and the movable seat.

[0024] Compared with the prior art, some of the beneficial effects of the technical solution disclosed in this invention include:

[0025] The leakage current detection device provided by this invention, without affecting the operation of the original circuit, opens the cable shield by opening the fixed base and the movable base, and at the same time causes the sensing component to flip away from the air gap, so that the cable under test can be inserted into the magnetic ring. After resetting the base component, cable shield and circuit shield, leakage current detection can be performed. The cable shield and circuit shield shield the external electromagnetic field, keeping the detection environment at the cable under test free from external interference, thereby obtaining more accurate leakage current results. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the testing device. In this state, the base assembly is open, the cable shield and circuit shield are flipped up, and the movable seat and the fixed seat are closed.

[0028] Figure 2 This is a schematic diagram of the overall structure of the testing device. In this state, the base assembly is open, and the cable shield and circuit shield are flipped up. In this state, the movable seat and the fixed seat are separated.

[0029] Figure 3 A schematic diagram of the structure of the detection device during operation.

[0030] Figure 4 A simulation diagram of the magnetic field generated by the magnetic ring to collect leakage current of the cable under test.

[0031] Figure 5 This is a schematic diagram of the magnetic ring structure.

[0032] Figure 6 This is a schematic diagram showing the effect of trace current on the induced magnetic field strength of the TMR chip.

[0033] Figure 7 This is a schematic diagram of the shielding provided by the cable shielding component at the magnetic ring.

[0034] Figure 8 This is a schematic diagram of the shielding provided by the circuit shielding component at the controller.

[0035] Figure 9 This is a schematic diagram of the magnetic field simulation results of a shielding structure composed of cable shielding and circuit shielding.

[0036] Figure 10 This is a schematic diagram of LoRa communication transmission.

[0037] In the above attached figures, the meanings of each label are as follows:

[0038] 1. Fixed base; 2. Movable base; 3. Cable shielding component; 4. Circuit shielding component; 5. Handle arm; 6. Handle hole; 7. Magnetic ring; 8. Sensing component; 9. Hinge arm; 10. Elastic blocking component; 11. Clamping groove; 12. Clamping surface. Detailed Implementation

[0039] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0040] Existing leakage current detection methods, especially for weak leakage currents, suffer from external electromagnetic interference, affecting detection accuracy and leading to errors in leakage current assessment. Furthermore, current leakage current detection devices cannot achieve non-invasive detection; they require dismantling the original circuit for installation and reconnection, resulting in cumbersome operation. The following embodiments are optimized to overcome these shortcomings.

[0041] Example

[0042] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides a novel adjustable opening and closing power equipment leakage current detection device, which aims to collect and detect the magnetic field generated by the cable under test through the magnetic ring 7, and isolate the electromagnetic field around the cable under test through the cable shield 3 and the circuit shield 4, thereby improving the accuracy of leakage current detection.

[0043] As one of the structures of the detection device provided in this embodiment, it includes:

[0044] The base assembly includes a fixed base 1 and a movable base 2 that open and close relative to each other. The opening and closing surfaces of the fixed base 1 and the movable base 2 form a clamping structure for clamping the cable under test.

[0045] In this embodiment, the clamping structure is not limited to a single option; multiple feasible solutions can be adopted. This embodiment optimizes and adopts one feasible option: the clamping structure includes clamping grooves 11 respectively disposed on the fixed base 1 and the movable base 2. When this solution is adopted, the clamping grooves 11 can clamp the test cables of different sizes, keeping the test cables in a centered detection position. The magnetic field collected by the magnetic ring 7 from the leakage current of the test cable will be more accurate, thereby improving the detection accuracy.

[0046] In this embodiment, considering that the distance between the clamping surfaces 12 of the fixed seat 1 and the movable seat 2 will change when clamping different cables, if the diameter of the cable under test is too small, the clamping surfaces 12 may come into contact, which will affect the stable clamping of the cable under test. Therefore, the structure of the fixed seat 1 and the movable seat 2 is optimized and improved, and the following feasible option is adopted: the clamping surface 12 where the clamping groove 11 of the fixed seat 1 and / or the movable seat 2 is located is an outwardly convex surface. When the movable seat 2 approaches the fixed seat 1 and the clamping groove 11 moves closer to each other to clamp the cable under test, the two clamping surfaces 12 of the movable seat 2 and the fixed seat 1 maintain a gap. With this solution, the clamping surfaces 12 of the fixed seat 1 and the movable seat will not come into contact or interfere. No matter how small the size of the cable under test is, after being clamped by the clamping groove 11, a gap is left between the clamping surfaces 12.

[0047] Preferably, in this embodiment, both the fixed base 1 and the movable base 2 are made of epoxy resin material.

[0048] When the fixed seat 1 and the movable seat 2 open and close relative to each other to clamp the cable under test, a certain amount of damping is provided to protect the cable under test. The damping method is not limited to one specific method. For example, in some methods, a torsion spring structure can be set at the hinge of the fixed seat 1 and the movable seat. This embodiment optimizes and adopts one feasible option: an elastic blocking member 10 is provided between the fixed seat 1 and the movable seat 2. The elastic blocking member 10 is connected to the fixed seat 1 or the movable seat 2. When the elastic blocking member 10 contacts the fixed seat 1 and the movable seat 2 at the same time, the elastic blocking member 10 applies an elastic force to the fixed seat 1 and the movable seat 2 to prevent the fixed seat 1 and the movable seat 2 from moving closer together. With this solution, the elastic blocking member 10 only intervenes when it contacts the fixed seat 1 and the movable seat 2 at the same time, and does not intervene at other times, which improves the ease of operation of the movable seat 2.

[0049] Preferably, in this embodiment, the clamping surface 12 of the fixed seat is a concave surface, and the clamping surface 12 of the movable seat is a convex surface, and the concave angle formed by the concave surface is larger than the convex angle formed by the convex surface. This arrangement can make the clamping effect between the fixed seat and the movable seat better.

[0050] Preferably, when the elastic blocking member 10 is provided, a mounting hole can be provided on the movable seat 2 or the fixed seat 1, and the elastic blocking member 10 is partially hidden in the mounting hole.

[0051] In this embodiment, the structure of the elastic blocking member 10 is not limited to a single type. This embodiment optimizes and adopts one feasible option: the elastic blocking member 10 includes a spring, an elastic telescopic rod, an elastic abutment arm, or an elastic abutment block. When such a solution is adopted, the elastic blocking member 10 can be installed on the movable seat 2 or the fixed seat 1, and provides sufficient elastic contact to protect the cable under test.

[0052] Preferably, to better operate the fixed base 1 and the movable base 2, this embodiment is optimized and improved by adopting one feasible option: the fixed base 1 and the movable base 2 are respectively connected to handle structures for operation of opening and closing. When this solution is adopted, the handle structure can be integrally formed with the fixed base 1 and the movable base 2, or it can be a separate structure.

[0053] Preferably, the handle structure itself is not limited to a single solution. Here, we optimize and give one feasible option: the handle structure includes a handle arm 5, and the handle arm 5 is provided with a handle hole 6.

[0054] In this embodiment, the opening and closing structure of the fixed seat 1 and the movable seat 2 is not uniquely limited. This embodiment optimizes and adopts one feasible option: the fixed seat 1 and the movable seat 2 are respectively provided with hinge arms 9, and the two hinge arms 9 cooperate with each other to open and close the fixed seat 1 and the movable seat 2 relative to each other. When this solution is adopted, the hinge arms 9 are integrally formed with the fixed seat 1 and the movable seat 2.

[0055] As the detection device provided in this embodiment, its second structure includes:

[0056] The magnetic ring 7 is fixedly connected to the mounting base 1. The magnetic ring 7 is made of magnetic material. The magnetic ring 7 is aligned with the clamping structure so that the cable under test passes through the middle of the magnetic ring 7. The magnetic ring 7 is also provided with an air gap for the cable under test to be inserted.

[0057] Preferably, in this embodiment, the magnetic ring 7 is made of permalloy, with a relative permeability of approximately 1,000,000.

[0058] As the detection device provided in this embodiment, its third structure includes:

[0059] The sensing component 8, used to detect the magnetic field strength collected on the magnetic ring 7, is connected to the fixed base 1 and flips to enter or leave the air gap.

[0060] Preferably, in this embodiment, the sensing component 8 includes a TMR sensor for detecting magnetic field strength.

[0061] As the detection device provided in this embodiment, its fourth structure includes:

[0062] The controller is electrically connected to the sensing component 8 and rotates synchronously.

[0063] Preferably, in this embodiment, the controller can be a PLC or a microcontroller. Other feasible solutions may also use controllers such as Raspberry Pi.

[0064] Preferably, in this embodiment, the controller includes a PCB board, and the PCB board is spaced apart from the sensing component 8. When the PCB board is electrically connected to the sensor, the wiring cable does not overlap with the sensing component 8 vertically, so as to avoid the magnetic field generated by the wiring cable interfering with the detection of the sensing component 8.

[0065] As the detection device provided in this embodiment, its fifth structure includes:

[0066] The cable shield 3 used to shield the external magnetic field of the magnetic ring 7 includes two shielding parts that are flipped and set on the fixed base and open and close relative to each other. When the two shielding parts are open, the air gap of the magnetic ring 7 is exposed. When the two shielding parts are closed, the magnetic ring 7 and the test section of the cable under test are sealed. The non-test section of the cable under test passes through the cable shield 3.

[0067] Preferably, in this embodiment, the cable shield 3 is openable and closable, aiming to allow the cable under test to be inserted into the magnetic ring 7 without intervention, while maintaining the shielding effect. The structure of the cable shield 3 is not limited to a single type. This embodiment optimizes and adopts one feasible option: one shielding part of the cable shield 3 is connected to the fixed base 1 or the movable base 2, and is hinged to the other shielding part to open and close relative to each other. Both shielding parts are provided with grooves for the cable under test to pass through. When the two shielding parts are closed, the grooves are joined together to form a wire hole. When this solution is adopted, the contact surfaces of the two shielding parts can adopt a corresponding slot structure. The bending of the contact surface reduces magnetic leakage and also improves the shielding effect against external electromagnetic fields.

[0068] In this embodiment, to maintain stability and reliability during shielding, the structure of the cable shield 3 is optimized. One feasible option is to provide corresponding fastening structures for the two shielding parts, which lock together when the two shielding parts are closed. When using this approach, the fastening structure can be a snap fastener, a locking mechanism, or similar structure.

[0069] Preferably, in this embodiment, the cable shield 3 is made of aluminum.

[0070] As the detection component provided in this embodiment, its sixth structure includes:

[0071] The circuit shield 4, used to isolate and shield the electromagnetic field generated by the controller, covers the controller and flips relative to the fixed base 1. When the circuit shield 4 flips upward, it causes the controller and the sensing component 8 to flip and expose the air gap of the magnetic ring 7. When the circuit shield 4 flips downward to fit the base assembly, it places the sensing component 8 into the air gap.

[0072] Preferably, in this embodiment, the circuit shielding component 4 adopts a double-layer shielding structure, with the inner layer made of permalloy with high magnetic permeability and the outer layer made of aluminum.

[0073] The aforementioned leakage current detection device, through its fixed and movable seats that are designed to open and close, allows the air gap of the magnetic ring to allow the cable under test to be placed into and pass through the center of the magnetic ring without interfering with the original power supply system. The magnetic ring collects the magnetic field generated by the cable under test, while electromagnetic shielding is provided by the cable shielding and circuit shielding to ensure no environmental interference during the detection process. By placing the sensing component inside the air gap and the controller outside the magnetic ring, the electromagnetic field generated by the leakage current can be detected, while avoiding interference from the electromagnetic field generated by the controller's circuit.

[0074] The above-disclosed solution explains the structural composition of the detection device provided in this embodiment, and its working principle will now be explained.

[0075] I. According to the Biot-Savart law, the magnetic field generated by a current-carrying conductor at a point P in space is:

[0076]

[0077] Where r is the distance between point P and the current-carrying wire, μ0 is the permeability in vacuum, I is the current flowing through the wire, and B is the magnetic induction intensity.

[0078] The current flowing through the long straight current-carrying conductor AB is I, and the distance between a point P in space and the conductor AB is r0. Therefore, the magnetic field generated by the conductor AB at point P can be calculated as follows:

[0079]

[0080] Where θ1 is the angle between the line connecting point P and point A and the conductor, and θ2 is the angle between the line connecting point P and point B and the conductor.

[0081] When the length of conductor AB is constant and the position of conductor AB relative to point P remains relatively fixed, the magnitude B of the magnetic field generated by conductor AB at point P is proportional to the value of the current inside the conductor.

[0082] Within a certain magnetic field strength range, the output voltage of a TMR chip is linearly related to the magnitude of the magnetic field along the induced magnetic axis. Therefore, by monitoring the magnitude of the magnetic field generated by the current using a TMR chip, and then using its output voltage for current inversion calculation, the purpose of current measurement can be achieved.

[0083] II. About Current Sensors

[0084] 2.1) Supplementary explanation of the magnetic ring structure

[0085] Because the measured current is very weak, the magnetic field sensed by the TMR chip is also very weak, resulting in a very small output voltage, making it impossible to process and calculate subsequent signals to achieve current inversion. This embodiment employs a slit-type magnetic ring structure, placing the TMR chip within the air gap to amplify the magnetic field strength sensed by the TMR chip. Figure 4 As shown. The magnetic focusing ring mainly serves to concentrate the magnetic field generated by the conductor; therefore, the magnetic focusing ring is made of soft magnetic material.

[0086] According to Ampère's circuital law:

[0087]

[0088] Where H is the magnetic field strength, l is the length of the path through which the magnetic field passes, and I is the magnitude of the current in the conductor.

[0089] Will Figure 3 Substituting the parameters into the given information, we can obtain:

[0090]

[0091] Among them, H C H represents the magnetic field strength inside the magnetic ring. A r0 represents the magnetic field strength in the air gap, and r0 represents the average radius of the magnetic ring. D1 is the inner diameter of the magnetic ring, D2 is the outer diameter of the magnetic ring, and d is the air gap of the magnetic ring.

[0092] B = μ0H A =μH C Substituting into the equation, we get:

[0093]

[0094] μ represents the relative permeability of permalloy.

[0095] therefore:

[0096]

[0097] B represents the magnetic induction intensity in the air gap after the addition of the magnetic ring.

[0098] Since the permeability μ of permalloy is much greater than the permeability μ0 of air, it can be simplified to:

[0099]

[0100] When no magnetic ring is used, the magnetic flux density B0 at the center of the air gap is:

[0101]

[0102] The ratio of the magnetic induction intensity at the center of the air gap before and after using the magnetic ring is:

[0103]

[0104] Based on the above derivation, it can be seen that the gap size of this patent is designed according to the actual size of the TMR chip, and the overall size of the magnetic ring is determined comprehensively based on the radius of the weak current conductor and the gap size on site.

[0105] 2.2) Supplementary sensor specifications

[0106] The sensor's main circuit consists of a sensing chip, a power supply module, an instrumentation amplifier module, a zeroing and output module, and a hardware filtering module. The sensing chip is a low-noise, high-sensitivity TMR chip for X-axis direction sensing. The power supply module provides operating power to the TMR chip, instrumentation chip, operational amplifier chip, and filter chip. The main circuit amplification module employs a two-stage amplification method, with an instrumentation amplifier in the front stage and an operational amplifier in the rear stage, and a subtraction circuit is added to achieve the main circuit zeroing function. The hardware filtering uses a fourth-order Biotworth filter for low-pass filtering. Since noise has a significant impact on measurement accuracy when monitoring weak currents, low-noise selection was prioritized when choosing chips.

[0107] In the circuit board design, this patent appropriately incorporates bypass and decoupling capacitors at all power interfaces, placing them as close as possible to the chip pins to filter out high-frequency electromagnetic interference signals from the power supply. Circuit routing follows the minimum loop rule, minimizing the area enclosed by signal lines and ground loops during routing. This reduces interference from external electromagnetic fields and also reduces electromagnetic radiation emitted by the circuit board to the outside world. Isolation design is implemented between different electrical networks to reduce crosstalk; a certain distance is maintained between sensitive components and devices prone to interference; when routing parallel lines, the spacing between signal lines is greater than twice the line width, and chamfers are applied to avoid signal reflection and electromagnetic radiation; traces on adjacent layers are orthogonal.

[0108] Meanwhile, when the measured current is less than a certain value, the PCB trace current near the TMR chip will interfere with the magnetic field strength induced by the TMR. For example... Figure 5 As shown, we simplified the sensor structure, arbitrarily drew the current lines inside the housing surrounding the TMR sensor on the PCB board, and implemented a common ground. The TMR sensor was placed in the gap of the magnetic ring. Keeping the current magnitude inside the PCB board housing constant (10mA), we changed the current magnitude in the wires and performed simulations. Since the TMR chip used in the sensor fabrication is sensitive along the X-axis, we plotted a comparison of the magnification factor in the X-axis magnetic field direction before and after sensor placement, as shown in the figure. Figure 6 As shown in the comparison diagram, when the current flowing through the conductor is less than the internal current (10mA), the amplification factor increases non-linearly. Only when the current is larger does the influence of the internal current on the magnetic field measured by the sensor become qualitative, indicating that PCB traces have a significant impact on the accuracy of weak current measurements. Therefore, this patent designs the PCB traces around the TMR chip to prevent them from passing under the TMR chip. Most traces are parallel to the X-axis, while traces perpendicular to the X-axis are kept as far away from the TMR chip as possible.

[0109] 2.3) Explanation of circuit shielding components

[0110] like Figure 7 , Figure 8 and Figure 9 As shown, stable electromagnetic interference shielding is achieved for the TMR sensor chip and main circuit. The inner shield uses permalloy with high magnetic permeability, while the outer layer uses aluminum. Electromagnetic interference waves passing through the aluminum shield can effectively suppress electric field interference and filter out some magnetic field interference. Further, the permalloy shielding layer can effectively suppress the remaining magnetic field interference, thus achieving electromagnetic interference shielding.

[0111] The effectiveness of shielding is represented by the shielding performance SE, as shown in the formula:

[0112]

[0113]

[0114] Where H0 represents the magnetic field strength without a shielding layer, H s E represents the magnetic field strength with a shielding layer; E0 represents the electric field strength without a shielding layer. s This represents the electric field strength when a shielding layer is present.

[0115] With two external sources of interference from wires, the shielding structure designed in this patent can achieve a magnetic field SE of 33.1 dB and an electric field SE of 77 dB. Simulation results are as follows. Figure 9 As shown.

[0116] The sensor's main circuit board is designed with double-layer shielding, which can suppress electric fields while shielding magnetic fields, thereby reducing external electromagnetic interference.

[0117] 2.4) LoRa communication transmission and cloud processing

[0118] like Figure 10 As shown, the leakage current detection communication transmission process includes a power supply unit, a core processing unit, a LoRa wireless transmission module, and a leakage current detection unit. The power supply unit draws power from the input terminal, rectifies and filters the AC power, and then performs AC / DC conversion to provide stable low-voltage DC power to the core processing unit, leakage current detection unit, and LoRa wireless transmission module. The leakage current detection unit converts the detected leakage current into a signal recognizable by the core processing unit, collects it, calculates the current leakage current value, and then transmits the leakage current value to the LoRa wireless transmission module in real time. The LoRa wireless transmission module uses a customized protocol to transmit the leakage current data to a base station within a certain range. The base station then uploads the data to a cloud server via a 4G network. The cloud server provides an interface that can be accessed via a mobile app and PC to view the data and status of each node switch, achieving real-time monitoring.

[0119] The wireless communication method based on LoRa technology has the advantages of long transmission distance, low power consumption, multiple nodes that can be attached, strong anti-interference ability and low cost. It can transmit the measured leakage current data to the host computer in real time, which helps users to keep track of changes in leakage current.

[0120] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments under the guidance of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be defined in the claims.

Claims

1. A novel adjustable on / off type leakage current detection device for power equipment, characterized in that, include: The base assembly includes a fixed seat (1) and a movable seat (2) that open and close relative to each other. The opening and closing surfaces of the fixed seat (1) and the movable seat (2) form a clamping structure for clamping the cable to be tested. The magnetic ring (7) connected to the fixed base (1) is made of magnetic material. The magnetic ring (7) is aligned with the clamping structure so that the cable under test passes through the middle of the magnetic ring (7). The magnetic ring (7) is also provided with an air gap for the cable under test to be inserted. The sensing component (8) is connected to the fixed base (1) and flipped to enter the air gap or flipped to leave the air gap. The sensing component (8) is used to detect the magnetic field signal generated by the interaction between the cable under test and the magnetic ring (7) when the cable under test passes through the middle of the magnetic ring (7). The controller is electrically connected to the sensing component (8) and is used to receive and process the magnetic field signal detected by the sensing component (8); The cable shield (3) includes two shielding parts that are movably mounted on the fixed base and are movably fitted together. When the two shielding parts are open, the air gap of the magnetic ring (7) is exposed. When the two shielding parts are closed, the magnetic ring (7) and the test section of the cable under test are sealed. The non-test section of the cable under test passes through the cable shield (3). The circuit shield (4) covers the controller and moves relative to the fixed base (1). When the circuit shield (4) moves upward, it drives the controller and the sensing component (8) to move and exposes the air gap of the magnetic ring (7). When the circuit shield (4) moves downward to fit the base assembly, it places the sensing component (8) into the air gap.

2. The novel adjustable opening and closing power equipment leakage current detection device according to claim 1, characterized in that: The clamping structure includes clamping grooves (11) respectively provided on the fixed seat (1) and the movable seat (2).

3. The novel adjustable opening and closing power equipment leakage current detection device according to claim 1 or 2, characterized in that: The clamping surface (12) where the clamping groove (11) of the fixed seat (1) and / or movable seat (2) is located is an outwardly convex surface. When the movable seat (2) approaches the fixed seat (1) and the clamping groove (11) approaches each other, the cable to be tested is clamped.

4. The novel adjustable opening and closing power equipment leakage current detection device according to claim 1, characterized in that: An elastic blocking element (10) is provided between the fixed seat (1) and the movable seat (2).

5. The novel adjustable opening and closing power equipment leakage current detection device according to claim 4, characterized in that: The elastic blocking element (10) is one of the following: spring, elastic telescopic rod, elastic abutment arm, and elastic abutment block.

6. The novel adjustable opening and closing power equipment leakage current detection device according to claim 1, characterized in that: One of the shielding parts of the cable shield (3) is connected to the fixed seat (1) or the movable seat (2) and is hinged to the other shielding part to open and close relative to each other. Both shielding parts are provided with grooves for the cable to be tested to pass through. When the two shielding parts are closed, the grooves are spliced ​​together to form a wire hole.

7. The novel adjustable opening and closing power equipment leakage current detection device according to claim 6, characterized in that: The two shielding parts are provided with corresponding fastening structures, which lock the two shielding parts together when they are closed.

8. The novel adjustable opening and closing power equipment leakage current detection device according to any one of claims 1, 2, 4 to 7, characterized in that: The fixed seat (1) and the movable seat (2) are respectively connected to handle structures for operation of opening and closing.

9. The novel adjustable opening and closing power equipment leakage current detection device according to claim 8, characterized in that: The handle structure includes a handle arm (5) and a handle hole (6) is provided on the handle arm (5).

10. The novel adjustable opening and closing power equipment leakage current detection device according to claim 1, characterized in that: The fixed seat (1) and the movable seat (2) are respectively provided with hinge arms (9), and the two hinge arms (9) are hinged to each other to make the fixed seat (1) and the movable seat (2) open and close relative to each other.

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