Variable-caliber leakage current measurement clamp-shaped meter head based on non-return-to-zero principle

Abstract

The invention discloses a non-return-to-zero principle-based variable-caliber leakage current measurement clamp-shaped meter head, and particularly relates to the technical field of leakage detection. The meter head comprises a base, and the base is provided with a clamping detection assembly and a current measurement assembly; the clamping detection assembly comprises a supporting plate fixedly arranged on the base, a traction frame adjustable in the vertical direction, a first deflection plate, a second deflection plate and two clamping plates, and the two clamping plates are correspondingly installed at the free end of the first deflection plate and the free end of the second deflection plate respectively. The opposite sides of the two clamping plates are respectively provided with a clamping groove used for accommodating a circuit. The adjusting plate with the long-strip-shaped adjusting hole is arranged at the end of the clamping plate, the bolt fixing structure is matched, the installation height of the clamping plate on the deflection plate can be accurately adjusted, and the clamping plate can be accurately adjusted by combining the design of the clamping groove with the arc-shaped cross section and flexible adaptation of lines with different diameters. And diversified measurement requirements of industrial large-diameter cables, civil thin wires and the like can be met without replacing the clamp head.

Description

Technical Field

[0001] This invention relates to the field of leakage current detection technology, and more specifically, to a clamp meter for measuring variable-diameter leakage current based on the principle of non-zero return. Background Technology

[0002] Leakage current, as a core evaluation indicator of the insulation performance and electrical safety of electrical systems, is directly related to the safe operation of various fields such as industrial production, building power distribution, and household appliances. This current is the residual current in an electrical circuit that leaks abnormally into the ground, equipment casing, or other unexpected paths due to problems such as insulation damage, aging, moisture, equipment failure, or abnormal wiring connections, breaking away from the closed circuit between the phase and neutral wires. If operators fail to detect and handle it in time, it can easily cause safety accidents such as electric shock, equipment burnout, or even fire, resulting in significant losses to production and daily life.

[0003] The core requirement of leakage current measurement is to achieve real-time monitoring of leakage current without damaging the circuit structure or interrupting power supply. This allows for assessment of the insulation status of the circuit / equipment, troubleshooting of leakage faults, and verification of the effectiveness of leakage current protection devices (RCD / ELCB), ensuring electrical safety. Currently, mainstream measuring tools include clamp-on leakage current meters and leakage current testers, whose measurement principles mainly fall into two categories: One type is the traditional zeroing / reference zeroing principle. This type of instrument requires manual or automatic zeroing before measurement to eliminate the influence of residual magnetism in the clamp, stray magnetic fields in the environment, and the instrument's own zero-point drift on the measurement results. The zeroed value is then used as a fixed measurement reference, and the reading directly reflects the current instantaneous current value. However, leakage current is often a weak signal at the microampere level. Forced zeroing can easily filter out real-time slow fluctuations and steady-state residual leakage, leading to lower measurement readings and even missing potential chronic leakage hazards. Furthermore, once the reference is fixed, it cannot dynamically adapt to real-time operating conditions such as changes in the environmental magnetic field and the relative position of the clamp and the line, resulting in significant measurement errors. It can only acquire instantaneous single-point values ​​and cannot record current change trends, making it unsuitable for scenarios such as intermittent leakage troubleshooting and long-term operational status monitoring. Finally, it has weak discrimination capabilities against external interference such as power frequency interference and magnetic fields from nearby lines, easily generating false readings or false alarms, affecting the operator's judgment efficiency.

[0004] Another type is the non-return-to-zero principle, whose core feature is that no operator needs to perform forced zero-point calibration during the measurement process. Instead, it retains and continuously records the offset of the measurement reference, the difference between historical fluctuation values ​​and the real-time signal. Through advantages such as dynamic tracking of reference offset, high-fidelity small signal, trend-based measurement, and anti-interference correction, it makes up for many shortcomings of the zero-return principle. However, current clamp meters based on the non-return-to-zero principle still have significant technical shortcomings: most products have a fixed diameter, which can only be adapted to specific sizes of circuits. When operators encounter circuits of different diameters, they need to change to special clamp heads, which seriously affects work efficiency; a few products with diameter adjustment functions have problems such as complex adjustment structure, cumbersome operation, and insufficient clamping stability, resulting in low circuit positioning accuracy, which in turn affects the accuracy of leakage current detection; at the same time, the relative position design of the current sensor and the clamping area of ​​some products is unreasonable, which further aggravates the measurement error and cannot meet the diverse measurement needs of circuits of different diameters and complex environments. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a variable diameter leakage current measuring clamp meter based on the non-zero principle, which aims to solve the problems mentioned in the background art.

[0006] The present invention provides the following technical solution: a variable diameter leakage current measuring clamp meter head based on the non-zero principle, including a base, wherein a clamping detection component and a current measuring component are provided on the base; The clamping detection assembly includes a support plate fixedly mounted on the base, a traction frame adjustable in the vertical direction, a first deflection plate, a second deflection plate, and two clamping plates. The two clamping plates are respectively installed on the free ends of the first deflection plate and the second deflection plate, and each of the two clamping plates has a clamping groove for accommodating the line on its opposite side. The cross-section of the clamping groove is arc-shaped. The current measurement component includes a deflection rod, a current sensor, and a current display meter; The deflection rod is fixedly installed in the middle of the base, with one end extending to the outside of the base and connected to the current display meter. The current sensor is fixedly installed on the deflection rod and electrically connected to the current display meter. The current sensor is plugged into and fixed on the base, with its detection end corresponding to the clamping area of ​​the two clamping plates. The base has an installation cavity, and a drive assembly is provided in the installation cavity. The drive assembly is used to drive the traction frame to move up and down in the vertical direction, thereby causing the first deflection plate and the second deflection plate to deflect around the limiting axis, so that the two clamping plates move closer or further apart, thereby achieving clamping and positioning of lines of different sizes.

[0007] Furthermore, the drive assembly includes an inner liner block embedded in the mounting cavity and two symmetrically arranged electric push rods; The inner liner block fits tightly against the inner wall of the mounting cavity. The two electric push rods are fixed at both ends of the liner block, and the output shaft of the electric push rod extends vertically upward, passes through the top wall of the base, and is fixedly connected to the bottom of the traction frame. The top of the support plate is fixedly embedded with a limiting shaft. One end of the first deflection plate and the second deflection plate is provided with a hollow block. The hollow block is sleeved on the limiting shaft and rotatably connected to the limiting shaft. The traction frame is located in the middle of the support plate. Its two side walls are respectively engaged with the ends of the first deflection plate and the second deflection plate away from the hollow block through a sliding connection structure. The two hollow blocks are fixedly embedded with inner bushings. The inner bushings are made of wear-resistant insulating material and are tightly sleeved on the limiting shaft, rotatably engaging with the limiting shaft. Furthermore, each of the two clamping plates is provided with an adjusting plate at the end away from the clamping groove. The adjusting plate has an elongated adjusting hole. The clamping plates are detachably fixed to the free ends of the first deflection plate and the second deflection plate respectively by bolts passing through the adjusting holes. By adjusting the position of the bolt in the adjusting hole, the installation height of the clamping plate can be changed, thereby adjusting the clamping range between the two clamping plates. The axis of the limiting shaft intersects perpendicularly with the symmetrical center line of the two clamping plates. The detection center of the current sensor and the center of the clamping groove are in the same vertical plane. The sliding connection structure includes sliding grooves opened on both sides of the traction frame and shaft pins fixed to the ends of the first deflection plate and the second deflection plate. The chute extends along the height of the traction frame, and the pin slides into the chute with a clearance fit between the pin and the inner wall of the chute.

[0008] The technical effects and advantages of this invention are as follows: 1. This invention provides an adjustment plate with elongated adjustment holes at the end of the clamping plate, which, together with a bolt fixing structure, allows for precise adjustment of the installation height of the clamping plate on the deflection plate. Combined with the design of the clamping groove with an arc cross-section, it allows for flexible adaptation to wires of different diameters. It can meet the diverse measurement needs of industrial large-diameter cables, civilian fine wires, etc., without the need for personnel to frequently change the clamping head. 2. This invention uses an electric push rod to drive the lifting and lowering of the traction frame. Through the sliding cooperation between the traction frame slide groove and the deflection plate shaft pin, the first and second deflection plates are driven to deflect synchronously around the limiting shaft, so that the clamping plate forms a uniform and adjustable clamping force. The arc-shaped clamping groove has a higher degree of contact with the circuit surface, effectively preventing the circuit from loosening or damaging the insulation layer. It solves the technical defects of existing products such as fixed diameter, cumbersome adjustment or unstable clamping, and greatly improves the convenience and reliability of on-site measurement. 3. The detection center of the current sensor of this invention is on the same vertical plane as the center of the clamping groove, ensuring that the leakage current signal can be accurately captured after the line is clamped. The application of the non-zero principle eliminates the drawbacks of forced zero-point calibration. By dynamically tracking the baseline offset caused by the environmental magnetic field, clamp state, and line position, and incorporating the offset as an inherent parameter into the calculation instead of directly discarding it, the slow fluctuations and steady-state residual leakage in the microampere-level weak signal are effectively preserved. This avoids the problems of missed detection of chronic leakage and underestimation of readings, and significantly reduces the probability of false readings and false alarms caused by power frequency interference and magnetic fields of adjacent lines, allowing operators to obtain reliable detection results in diverse scenarios. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0010] Figure 1 This is a front view of the overall structure of the present invention.

[0011] Figure 2 This is a side view of the overall structure of the present invention.

[0012] Figure 3 This is a schematic diagram of the base, support plate, second deflection plate, and mounting cavity of the present invention.

[0013] Figure 4 This is a schematic diagram of the deflection rod, current display meter, inner lining block, electric push rod, traction frame, first deflection plate, second deflection plate and clamping plate of the present invention.

[0014] Figure 5 This is a schematic diagram of the traction frame, slide, first deflection plate, second deflection plate, clamping plate, clamping groove and hollow block of the present invention.

[0015] Figure 6 This is a schematic diagram of the base, mounting cavity, limiting shaft, inner bushing, and support plate of the present invention.

[0016] The attached figures are labeled as follows: 1. Base; 2. Support plate; 3. Traction frame; 4. First deflection plate; 5. Second deflection plate; 6. Clamping plate; 7. Clamping groove; 8. Limiting shaft; 9. Hollow block; 10. Mounting cavity; 11. Inner liner block; 12. Electric push rod; 13. Deflection rod; 14. Current display meter; 15. Current sensor; 16. Inner bushing; 17. Adjusting plate; 18. Slide groove. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0018] Example 1 like Figure 1 , Figure 2 As shown, the variable-diameter leakage current measuring clamp meter head based on the non-zero principle in this embodiment includes a base 1, a clamping detection component, and a current measuring component. The base 1 is made of high-strength insulating plastic and has an overall rectangular structure, providing stable support for the entire device. The clamping detection component is installed on the upper part of the base 1 to achieve clamping and positioning of lines of different sizes. The current measurement component is integrated in the middle of the base 1 and works with the clamping detection component to achieve leakage current detection and display.

[0019] like Figure 1 , Figure 3 , Figure 5 As shown, the clamping detection assembly includes a support plate 2, a traction frame 3, a first deflection plate 4, a second deflection plate 5, a clamping plate 6, and a drive assembly. The support plate 2 is made of metal alloy material and is vertically arranged. Its bottom is fixed to the top wall of the base 1 by bolts. The top of the support plate 2 has a mounting hole, and the limiting shaft 8 is fixedly embedded in the mounting hole. The axis of the limiting shaft 8 is arranged in the horizontal direction, and both ends of it extend out of the sides of the support plate 2. The first deflecting plate 4 and the second deflecting plate 5 have the same structure, both being long strip-shaped metal plates, symmetrically arranged on both sides of the support plate 2; a hollow block 9 is welded and fixed to one end of both the first deflecting plate 4 and the second deflecting plate 5, and an inner bushing 16 is fixedly embedded inside the hollow block 9. Figure 6 As shown, the inner bushing 16 is made of polytetrafluoroethylene wear-resistant insulating material. The hollow block 9 is sleeved on the limiting shaft 8 through the inner bushing 16 to achieve a rotatable connection with the limiting shaft 8. The friction is small and the stability is strong during the rotation. Furthermore, the free end faces of the first deflection plate 4 and the second deflection plate 5 are provided with threaded holes that match the bolts. The side of the adjusting plate 17 that contacts the deflection plate is provided with anti-slip teeth, and positioning protrusions are also provided on both sides of the adjusting plate 17. The deflection plate is provided with corresponding positioning grooves to prevent the adjusting plate 17 from sliding laterally after the height is adjusted.

[0020] The traction frame 3 has a U-shaped frame structure and is located in the middle of the support plate 2. Both its side walls are provided with sliding grooves 18. Figure 5As shown; the ends of the first deflection plate 4 and the second deflection plate 5 away from the hollow block 9 are both welded and fixed with shaft pins. The shaft pins slide into the corresponding slide grooves 18, and the shaft pins are clearance-fitted with the inner wall of the slide grooves 18 to form a sliding connection structure, so that when the traction frame 3 is raised and lowered, it can drive the first deflection plate 4 and the second deflection plate 5 to deflect around the limiting shaft 8. Two clamping plates 6 are respectively installed at the free ends of the first deflection plate 4 and the second deflection plate 5. An adjusting plate 17 is provided at the end of the clamping plate 6 away from the clamping groove 7. The adjusting plate 17 is integrally formed with the clamping plate 6, and an elongated adjusting hole is provided on the adjusting plate 17. Figure 5 As shown, the clamping plate 6 is detachably fixed to the free ends of the first deflection plate 4 and the second deflection plate 5 by bolts passing through the adjustment holes. By loosening the bolts and adjusting their vertical position in the adjustment holes, the installation height of the clamping plate 6 can be changed, thereby adjusting the clamping range between the two clamping plates 6 to accommodate different sizes of circuits with diameters of 0.5-50mm. Each of the two clamping plates 6 has a clamping groove 7 on one side opposite to the other. The cross-section of the clamping groove 7 is arc-shaped, and the arc-shaped surface is provided with an insulating rubber pad, which can increase the fit with the circuit, improve the clamping stability, and avoid damage to the circuit insulation layer. Example 2 Based on Example 1, the driving component is as follows: Figure 3 , Figure 4 As shown, the base 1 has a mounting cavity 10, which is a rectangular hollow structure. The top of the mounting cavity has a through hole through which the output shaft of the electric push rod 12 passes. An inner liner 11 is embedded in the mounting cavity 10. The inner liner 11 is made of rubber buffer material and fits tightly against the inner wall of the mounting cavity 10, which plays a role in shock absorption and fixation. Two electric push rods 12 are respectively fixed to the two ends of the liner 11 by bolts. The output shaft of the electric push rod 12 extends vertically upward, passes through the top wall of the base 1, and is welded to the bottom of the traction frame 3. The extension and retraction of the electric push rod 12 drives the traction frame 3 to rise and fall vertically.

[0021] like Figure 1 , Figure 4 As shown, the current measuring assembly includes a deflection rod 13, a current sensor 15, and a current display meter 14. The deflection rod 13 is made of a metal bracket, and its bottom is fixed to the middle of the base 1 by bolts. The axis of the deflection rod 13 is set in the horizontal direction, and one end extends to the outside of the base 1. The current display meter 14 is a digital display screen, which is fixedly installed on the extended end of the deflection rod 13 to display the measured leakage current value and its change curve in real time. The current sensor 15 is a high-precision Hall current sensor, which is fixed to the base 1 by plugging. Its detection end corresponds to the clamping area of ​​the two clamping plates 6, and the detection center of the current sensor 15 and the center of the clamping groove 7 are in the same vertical plane. Figure 2As shown, this ensures the accuracy of the detection signal; the current sensor 15 is electrically connected to the current display meter 14 via wires, and transmits the detected leakage current signal to the current display meter 14 for processing and display.

[0022] Furthermore, the current display meter 14 has a built-in microcontroller that stores a signal processing program for real-time acquisition of the raw signal output by the current sensor 15, establishing a baseline drift model, separating environmental interference from the real leakage current signal through sliding window filtering or adaptive algorithm, and superimposing the baseline offset as a compensation parameter onto the final display value. The microcontroller is also equipped with non-volatile memory for recording historical baseline data and leakage current trend curves. A matching plug can also be integrated at the bottom of the current sensor 15. After plugging in, it is locked by an elastic buckle. The wire is a double-shielded wire. One end is soldered to the output end of the current sensor 15, and the other end is connected to the signal input port of the current display meter 14 through a waterproof connector to suppress power frequency and electromagnetic interference from nearby lines.

[0023] The clamp meter in this embodiment is based on the non-return-to-zero measurement principle. Its core is to not perform forced zero-point calibration, but to retain and continuously record the offset of the measurement reference, the difference between historical fluctuation values ​​and the real-time signal, thereby achieving continuous reference tracking, small signal fidelity, trend-based measurement and anti-interference correction. The specific working process is as follows: According to the diameter of the circuit to be measured, adjust the height of the clamping plate 6: loosen the bolts on the adjusting plate 17, adjust the clamping plate 6 to the appropriate height, and then tighten the bolts to fix it; ensure that the circuit can be smoothly placed between the two clamping slots 7, and that the center of the circuit is aligned with the detection center of the current sensor 15 after clamping. When the electric push rod 12 is activated, its output shaft extends, pushing the traction frame 3 to move downwards in the vertical direction. Since the traction frame 3 slides with the first deflection plate 4 and the second deflection plate 5 through the sliding groove 18, the traction frame 3 exerts a downward force on the first deflection plate 4 and the second deflection plate 5 when it descends, causing them to deflect inwards around the limiting shaft 8. As the deflection angle increases, the two clamping plates 6 move closer to each other until the clamping groove 7 is tightly attached to the surface of the circuit, completing the clamping and positioning of the circuit. At this time, the electric push rod 12 stops working and remains in the clamping state. The current sensor 15 is activated, detecting leakage current in the circuit based on the principle of electromagnetic induction. Because it employs a non-return-to-zero measurement principle, the current sensor 15 does not perform forced zero-point calibration. Instead, it dynamically captures baseline offsets caused by the ambient magnetic field, clamp status, and circuit position, incorporating these offsets as inherent parameters into the calculation. Simultaneously, it continuously samples the leakage current signal, distinguishing between fixed interference baselines and genuine abrupt leakage signals, avoiding false readings and false alarms caused by power frequency interference and magnetic fields from nearby circuits. For weak leakage current signals at the microampere level, it can retain genuine slow fluctuations and steady-state residual leakage, preventing signal loss. The current sensor 15 transmits the detected leakage current signal to the current display meter 14. After processing the signal, the current display meter 14 displays the instantaneous value of the leakage current in real time and records the continuous change curve and baseline drift law, which makes it easy for operators to observe the trend change of the leakage current and is suitable for long-term monitoring and intermittent leakage troubleshooting. After the measurement is completed, the output shaft of the electric push rod 12 retracts, the traction frame 3 returns to its original position, and the first deflection plate 4 and the second deflection plate 5 deflect outward. The two clamping plates 6 move away from each other, the circuit is released, and the clamp meter head can be removed.

[0024] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A clamp meter head for measuring variable-diameter leakage current based on the principle of non-return-to-zero, comprising a base (1), characterized in that: The base (1) is provided with a clamping detection component and a current measurement component; The clamping detection assembly includes a support plate (2) fixedly mounted on the base (1), a traction frame (3) adjustable in the vertical direction, a first deflection plate (4), a second deflection plate (5), and two clamping plates (6). The two clamping plates (6) are respectively installed on the free ends of the first deflection plate (4) and the second deflection plate (5), and each of the two clamping plates (6) has a clamping groove (7) for accommodating the line on its opposite side. The cross-section of the clamping groove (7) is arc-shaped. The current measurement assembly includes a deflection rod (13), a current sensor (15), and a current display meter (14). The deflection rod (13) is fixedly installed in the middle of the base (1), with one end extending to the outside of the base (1) and connected to the current display meter (14). The current sensor (15) is fixedly installed on the deflection rod (13) and electrically connected to the current display meter (14). The current sensor (15) is plugged into and fixed on the base (1), with its detection end corresponding to the clamping area of ​​the two clamping plates (6). The base (1) has an installation cavity (10) and a drive assembly is provided in the installation cavity (10). The drive assembly is used to drive the traction frame (3) to rise and fall in the vertical direction, thereby driving the first deflection plate (4) and the second deflection plate (5) to deflect around the limiting shaft (8), so that the two clamping plates (6) move closer or further away from each other, thereby achieving clamping and positioning of lines of different sizes.

2. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 1, characterized in that: The drive assembly includes an inner liner (11) embedded in the mounting cavity (10) and two symmetrically arranged electric push rods (12). The inner liner (11) fits tightly against the inner wall of the mounting cavity (10). The two electric push rods (12) are fixed at both ends of the liner (11), and the output shaft of the electric push rod (12) extends vertically upward, passes through the top wall of the base (1), and is fixedly connected to the bottom of the traction frame (3).

3. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 1, characterized in that: The top of the support plate (2) is fixedly embedded with a limiting shaft (8). One end of the first deflection plate (4) and the second deflection plate (5) is provided with a hollow block (9). The hollow block (9) is sleeved on the limiting shaft (8) and rotatably connected to the limiting shaft (8). The traction frame (3) is located in the middle of the support plate (2). Its two side walls are respectively connected to the ends of the first deflection plate (4) and the second deflection plate (5) away from the hollow block (9) through a sliding connection structure.

4. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 1, characterized in that: Both hollow blocks (9) have an inner sleeve (16) fixedly embedded inside. The inner sleeve (16) is made of wear-resistant insulating material and is tightly fitted on the limiting shaft (8) and rotates with the limiting shaft (8).

5. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 1, characterized in that: Each of the two clamping plates (6) is provided with an adjusting plate (17) at the end away from the clamping groove (7). The adjusting plate (17) has an elongated adjusting hole. The clamping plates (6) are detachably fixed to the free ends of the first deflection plate (4) and the second deflection plate (5) respectively by bolts passing through the adjusting holes. By adjusting the position of the bolts in the adjustment holes, the installation height of the clamping plate (6) can be changed, thereby adjusting the clamping range between the two clamping plates (6).

6. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 1, characterized in that: The axis of the limiting shaft (8) intersects perpendicularly with the center line of the symmetry of the two clamping plates (6), and the detection center of the current sensor (15) and the center of the clamping groove (7) are in the same vertical plane.

7. The variable-diameter leakage current measuring clamp meter head based on the non-return-to-zero principle according to claim 3, characterized in that: The sliding connection structure includes sliding grooves (18) formed on both sides of the traction frame (3) and shaft pins fixed to the ends of the first deflection plate (4) and the second deflection plate (5); The groove (18) extends along the height direction of the traction frame (3), and the pin slides into the groove (18), with the pin and the inner wall of the groove (18) having a clearance fit.

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