An up-opening fiber optic clamp meter and current measurement method

Abstract

This application discloses an up-opening fiber optic clamp meter and a current measurement method. The up-opening fiber optic clamp meter includes a measuring head, a sensing fiber, an optical path docking assembly, a driving mechanism, and a signal processing host. The measuring head includes a base and at least one movable clamp arm, one end of which is rotatably mounted on the base. In the open position, the measuring head forms an upward-opening receiving opening for the conductor to be measured to be inserted from above. In the closed position, the sensing fiber forms a closed loop around the conductor to be measured in space. The optical signal is reflected by a mirror in the optical path docking assembly and propagates back and forth along the sensing fiber. The signal processing host is connected to the sensing fiber through a transmission fiber and determines the current value based on the change in polarization state of the returned optical signal. This application solves the problem of current measurement of rigid, thick conductors in confined spaces through its up-opening structure. The closed loop formed by the sensing fiber in space satisfies Ampere's circuital law, thus improving measurement accuracy.

Description

Technical Field

[0001] This application relates to the field of current measurement technology, specifically to an up-opening fiber optic current clamp meter and a current measurement method. Background Technology

[0002] In the field of current measurement technology, especially in power, non-ferrous metal smelting, and electrochemistry, rapid, non-contact measurement of large DC and AC currents is crucial. Taking the aluminum electrolysis industry as an example, as a vital pillar of non-ferrous metal smelting, its production process consumes enormous amounts of energy. The current distribution in the electrolytic cell directly affects current efficiency, energy consumption, and cell lifespan. Furthermore, the anode and cathode current distributions are key parameters for assessing the electrolytic cell's operating status, diagnosing faults, and optimizing processes. Therefore, accurate measurement of these currents is of great significance for ensuring efficient and stable production. With the continuous development of industry, the requirements for the accuracy, adaptability, and convenience of current measurement are also increasing.

[0003] Currently, there are numerous mainstream current measurement devices, including electromagnetic ammeters, shunts, electromagnetic current transformers, Hall effect sensors, Rogowski coils, and fiber optic current sensors. Among them, fiber optic current sensors, based on the Faraday magneto-optical effect, can measure AC / DC currents and complex waveforms. They feature a large dynamic range and high accuracy, making them an important development direction for high-precision current measurement. In practical applications, some clamp meters use a semi-circular clamp-on structure, forming a lateral notch when opened, requiring the conductor to be inserted from the side. Other clamp meters use a non-closed sensing structure, which allows the conductor to be inserted from above, but its measurement accuracy is limited by the structure, making it difficult to meet the requirements of high-precision measurement.

[0004] However, existing fiber optic clamp meters have significant drawbacks. The semi-circular clamp-on structure makes it difficult to measure the cathode steel rod in an electrolytic cell because the rod is a rigid, thick conductor that cannot be bent to fit through the lateral notch, and the limited space in the cathode area of ​​the electrolytic cell prevents operation from being performed on both sides. While the U-shaped clamp meter can clamp the conductor from above, its open optical path prevents the formation of a complete closed loop around the conductor being measured. According to Ampere's circuital law, an open optical path can only sense a portion of the magnetic field, resulting in low measurement accuracy. Furthermore, existing devices generally do not consider device protection and temperature compensation in high-temperature measurement scenarios. Fiber optic interfaces are often exposed, making them susceptible to dust and corrosive gas contamination. Additionally, the main unit and frame are often integrated, requiring complete replacement of the frame when damaged, leading to high maintenance costs. Summary of the Invention

[0005] To address the technical problems in the prior art, this application provides an up-opening fiber optic current clamp meter and a current measurement method.

[0006] The technical solution provided in this application for an up-opening fiber optic current clamp meter and current measurement method is as follows:

[0007] An up-opening fiber optic current clamp meter includes:

[0008] A measuring head, the measuring head including a base and at least one movable clamp arm, one end of the movable clamp arm being rotatably mounted on the base;

[0009] A sensing fiber is disposed inside the measuring head, and the sensing fiber is an optical fiber with Faraday magneto-optical effect;

[0010] An optical path docking assembly is disposed at the docking point between the movable clamp arm and the fixed part of the measuring head;

[0011] A drive mechanism, connected to the movable clamp arm, is used to drive the movable clamp arm to rotate between an open position and a closed position; wherein, in the open position, the measuring head forms an upward-opening receiving opening for the conductor to be measured to be inserted from above; in the closed position, the movable clamp arm and the fixed part of the measuring head close and mate, the sensing optical fiber forms a closed loop around the conductor to be measured in space, and the optical path docking assembly reflects the optical signal emitted from the end of the sensing optical fiber back to the sensing optical fiber, so that the optical signal propagates back and forth along the sensing optical fiber;

[0012] The signal processing host is optically connected to the sensing fiber optic via a transmission fiber. When the movable clamp arm is in the closed position, it injects a polarized light signal into the sensing fiber and receives the light signal returned by the sensing fiber. Based on the change in polarization state of the returned light signal, it determines the current value in the conductor under test.

[0013] This application also provides a current measurement method, which uses the aforementioned up-opening fiber optic current clamp meter and includes the following steps:

[0014] S1. Drive the movable clamp arm to rotate to the open position, so that the measuring head forms an upward-open receiving opening;

[0015] S2. Insert the conductor to be tested into the receiving opening from above;

[0016] S3. Drive the movable clamp arm to rotate to the closed position, so that the sensing optical fiber forms a closed loop around the conductor under test in space.

[0017] S4. Inject a polarized light signal into the sensing fiber. The polarized light signal propagates along the sensing fiber and undergoes Faraday polarization rotation under the action of the magnetic field generated by the current in the conductor being measured. After the polarized light signal reaches the end of the sensing fiber, it is reflected by the optical path docking component and returns along the original path of the sensing fiber.

[0018] S5. Receive the optical signal returned through the sensing optical fiber, and determine the current value in the conductor under test based on the change in polarization state of the optical signal.

[0019] In summary, this application includes at least one of the following beneficial technical effects:

[0020] 1. By adopting an upward-opening structural design, the movable clamp arm opens upward in the open state, forming an upward-opening U-shaped receiving opening for the measuring head. The conductor to be measured can be directly inserted from above without needing to pass through from the side or requiring operating space on both sides. At the same time, when the movable clamp arm is closed, the sensing fiber forms a closed loop around the conductor to be measured in space, satisfying the requirements of Ampere's circuital law. The collimating lens, quarter-wave plate and reflector in the optical path docking assembly are misaligned and coaxially aligned to achieve efficient reflection and coupling of the optical signal, allowing the optical signal to propagate back and forth along the sensing fiber. The Faraday polarization rotation angle is multiplied, thus solving the problem that the existing semi-circular clamp structure cannot measure rigid thick conductors in narrow spaces such as electrolytic cells. At the same time, it improves the measurement accuracy compared with the existing U-shaped open optical path structure.

[0021] 2. By setting a heat insulation layer on the inner surface of the measuring head facing the conductor being measured for passive thermal protection, setting a temperature sensor inside or on the inner surface of the measuring head in conjunction with an alarm unit for active temperature monitoring and over-temperature alarm, and using a pre-trained BP neural network model or least squares fitting polynomial model through a temperature compensation unit to intelligently correct the current measurement value according to the real-time temperature, the measurement error after compensation in a high-temperature environment of 200-300°C is reduced from ±2.8% to within ±0.5%, thus solving the problems of device protection and measurement accuracy in high-temperature environments.

[0022] 3. The connecting shaft in the drive mechanism is slidably inserted into the guide sleeve of the base and hinged to the movable clamp arm. The elastic reset element is sleeved on the connecting shaft to form a restoring force that tends to close the position. The handle in the control component is connected to the connecting shaft through a flexible cable passing through the inside of the support rod. This realizes the convenient operation of opening the movable clamp arm by pulling the handle with one hand and automatically returning the movable clamp arm to the closed position by releasing the handle. In the implementation of the double movable clamp arm, the two ends of the synchronous connecting rod are fixedly connected to the two connecting shafts respectively, ensuring the synchronous opening and closing movement of the two movable clamp arms. The synchronous connecting rod also has an upward upper limit function to ensure the accurate alignment of the quarter-wave plate and the reflector and the stability of the optical path after closure, so that the entire opening and closing operation is simple and quick and can be completed with one hand. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the top-opening fiber optic current clamp meter provided in Embodiment 2 of this application;

[0024] Figure 2 yes Figure 1 A schematic diagram of the top-opening fiber optic current clamp meter, omitting part of the protective housing;

[0025] Figure 3 yes Figure 1 A schematic diagram of the structure of the measuring head and the drive mechanism;

[0026] Figure 4 yes Figure 1 A schematic diagram of the assembly structure of the sensing fiber, optical path docking assembly and transmission fiber;

[0027] Figure 5 This is a schematic diagram of the overall structure of the top-opening fiber optic current clamp meter provided in Embodiment 3 of this application;

[0028] Figure 6 yes Figure 5 A schematic diagram of the measuring head.

[0029] Explanation of reference numerals in the attached drawings: 1. Measuring head; 11. Base; 111. Guide sleeve; 112. Fixed frame; 1121. Bottom section; 1122. First side section; 1123. Second side section; 12. Movable clamp arm; 13. Heat insulation layer; 2. Sensing fiber; 3. Optical path docking assembly; 31. Quarter-wave plate; 32. Reflector; 33. Collimating lens; 4. Drive mechanism; 41. Connecting shaft; 411. Protrusion; 42. Elastic reset component; 43. Synchronous linkage; 44. Locking pin; 45. Control assembly; 451. Support rod; 452. Handle; 453. Pull handle; 454. Flexible cable; 5. Signal processing host; 6. Transmission fiber; 7. Temperature sensor; 8. Quick-connect structure; 9. Pull ring release mechanism. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of the present invention, but are not limited thereto. Other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are also within the protection scope of the present invention.

[0031] This application mainly adopts an open-ended structure, which enables the sensing optical fiber to form a closed loop around the conductor under test in space, and realizes the round-trip propagation of optical signals through the optical path docking component, thus achieving the effect of adapting to narrow spaces and measuring current with high precision. The following is a further detailed description of this application.

[0032] In this application, "the sensing fiber forming a closed loop around the conductor under test in space" means that the routing path of the sensing fiber forms a closed geometric loop around the conductor under test in space, satisfying the requirement of a closed path in Ampere's circuital law. It should be noted that the optical signal does not propagate unidirectionally within this closed loop. Instead, it enters from the input end of the sensing fiber, propagates along the fiber to the end, is reflected by a mirror in the optical path assembly, and returns to the input end along the same path. The optical signal passes through the sensing fiber surrounding the conductor under test twice during its round trip; the superposition of the Faraday polarization rotation angles produces a multiplication effect, thereby improving the measurement sensitivity.

[0033] Example 1

[0034] Please refer to Figures 1 to 4 The top-opening fiber optic current clamp meter provided in this application includes a measuring head 1, a sensing fiber 2, an optical path docking assembly 3, a driving mechanism 4, and a signal processing host 5. The movable clamp arm 12 of the measuring head 1 is rotatably mounted on the base 11. The driving mechanism 4 drives the movable clamp arm 12 to rotate between open and closed positions. The sensing fiber 2 is placed inside the measuring head 1. When the movable clamp arm 12 is closed, it forms a closed loop around the conductor being measured in space. The optical signal is reflected by the optical path docking assembly 3 and propagates back and forth along the sensing fiber 2. The signal processing host 5 is connected to the sensing fiber 2 through the transmission fiber 6, realizing the measurement of the current of the conductor being measured. This meets the need for measuring the current of rigid, thick conductors in confined spaces such as electrolytic cells, and improves the accuracy and convenience of the measurement.

[0035] Specifically, the measuring head 1 includes a base 11 and at least one movable clamp arm 12. The base 11 is typically made of metal or high-strength plastic, possessing sufficient strength and stability to support the entire measuring head 1. The movable clamp arm 12 is generally made of a metal material, such as aluminum alloy, which is lightweight and high-strength. One end of the movable clamp arm 12 can be hinged to the base 11. A pin can be used at the hinge point, and the surface of the pin is smoothed to reduce friction during the rotation of the movable clamp arm 12. The shape of the movable clamp arm 12 can be arc-shaped or straight, and the specific shape can be determined according to the actual application scenario and design requirements.

[0036] In this embodiment, the measuring head 1 adopts an upward-opening structure design. "Upward-opening" means that the movable clamp arm 12 opens upwards in the open state, forming an upward-opening U-shaped receiving opening on the measuring head 1. The conductor being measured (such as a rigid, thick conductor like a cathode steel rod or anode rod in an aluminum electrolytic cell) can be directly inserted into this U-shaped opening from above, without needing to be inserted from the side or requiring operating space on both sides. This upward-opening structure adapts to the special working conditions of a small cathode space in an electrolytic cell and a rigid, thick conductor that cannot be bent, solving the problem that existing semi-circular clamp-type opening and closing structures cannot measure cathode steel rods due to the need for side operating space.

[0037] The sensing fiber 2 is an optical fiber exhibiting the Faraday magneto-optical effect, capable of sensing changes in magnetic fields. This type of fiber is typically made of a special glass material, possessing excellent optical performance and magneto-optical properties. The sensing fiber 2 is continuously deployed inside the measuring head 1. At the hinge point between the movable clamp arm 12 and the base 11, the sensing fiber 2 has a reserved bending allowance. The bending radius of this allowance is not less than the minimum permissible bending radius of the sensing fiber 2, ensuring optical path continuity when the movable clamp arm 12 rotates. This can be achieved by selecting a flexible optical fiber material or employing a special optical fiber bending structure. One end of the transmission fiber 6 extends from inside the base 11, passes through the support rod 451 connecting the base 11 and the signal processing host 5, and reaches the signal processing host 5. The transmission fiber 6 is used to transmit optical signals, and its outer sheath is typically made of a wear-resistant and corrosion-resistant material to protect the internal optical fiber.

[0038] When the movable clamp arm 12 is in the closed position, the sensing fiber 2 forms a closed loop around the conductor under test in space. It should be noted that the two ends of the sensing fiber 2 are not physically connected, and the optical signal does not propagate unidirectionally within this closed loop. The actual optical signal propagation is as follows: the polarized light signal enters from the input end of the sensing fiber 2, propagates along the sensing fiber 2 within the measurement head 1, reaches the end of the sensing fiber 2, is reflected by the reflector 32 in the optical path docking assembly 3, and returns to the input end along the original path of the sensing fiber 2. Because the sensing fiber 2 forms a closed loop around the conductor under test in space, the optical signal propagates along this closed loop twice during the round trip. The induced Faraday polarization rotation angle is proportional to the line integral of the magnetic field along the closed path. According to Ampere's circuital law, the line integral of the magnetic field along the closed path is equal to the sum of the currents around the closed path, i.e. , among which, among which Magnetic flux density For line elements along a closed path, The permeability of free space, The measured current is represented by the sensing fiber 2. After the fiber 2's routing forms a complete closed loop, the Faraday polarization rotation angle induced by the optical signal during propagation is proportional to the magnetic field line integral along the closed path, thus accurately reflecting the current value in the conductor being measured. Compared to existing U-shaped structures, which can only sense a portion of the magnetic field and have lower measurement accuracy due to the incomplete optical path, the closed-loop design of this application improves measurement accuracy. Furthermore, the optical signal travels through the sensing fiber 2 twice, and the superposition of the Faraday polarization rotation angles produces a multiplication effect, further enhancing measurement sensitivity.

[0039] Please refer to Figure 3 and Figure 4 The optical path docking assembly 3 is located at the docking point between the movable clamp arm 12 and the fixed part of the measuring head 1. When the movable clamp arm 12 is in the closed position, the optical path docking assembly 3 reflects the optical signal emitted from the end of the sensing fiber 2 back to the sensing fiber 2, realizing the round-trip propagation of the optical signal. The optical path docking assembly 3 may include a collimating lens 33, a quarter-wave plate 31 located at the docking point of one of the movable clamp arms 12, and a reflector 32 located at the docking point of the other movable clamp arm 12. The collimating lens 33 is located between the end of the sensing fiber 2 and the quarter-wave plate 31 to collimate the diverging beam emitted from the end of the sensing fiber 2 into a parallel beam, and to focus and couple the reflected parallel beam back to the core of the sensing fiber 2, thereby reducing the optical coupling loss at the optical path docking point. The collimating lens 33 may be a self-focusing lens (GRIN lens) or a miniature aspherical lens, with its focal length and numerical aperture matched to the parameters of the sensing fiber 2. The quarter-wave plate 31 is generally made of a birefringent crystal material, such as quartz crystal, which can change the polarization state of light. The reflector 32 typically uses a high-reflectivity coated lens to ensure the reflection of the optical signal. In the closed position, the mating points of the movable clamp arm 12 are misaligned, so that the collimating lens 33, the quarter-wave plate 31, and the reflector 32 are coaxially aligned, which can improve the transmission quality of the optical signal and the measurement accuracy.

[0040] Specifically, the optical path docking assembly 3 operates as follows: The polarized light signal emitted by the signal processing host 5 enters the sensing fiber 2 via the transmission fiber 6 and propagates within the measurement head 1 along the sensing fiber 2. Under the influence of the magnetic field generated by the current in the measured conductor, Faraday polarization rotation occurs. When the light signal reaches the end of the sensing fiber 2, it exits from the end face. Due to the numerical aperture (NA≈0.1-0.2) of the fiber, the outgoing beam diverges. The collimating lens 33 collimates this divergent beam into a parallel beam. The parallel beam enters the quarter-wave plate 31, which converts the linearly polarized light into circularly polarized light (or vice versa). The light signal continues to propagate to the reflecting mirror 32 and is reflected, returning along the original path to pass through the quarter-wave plate 31 again, completing a further conversion of the polarization state. The reflected parallel beam is then focused again by the collimating lens 33 and efficiently coupled back to the core of the sensing fiber 2. During the two round trips through the sensing fiber 2, the Faraday polarization rotation angles are superimposed, producing a multiplication effect, thereby improving the measurement sensitivity. The collimating lens 33 ensures efficient coupling of the optical signal at the optical path junction, avoiding severe optical loss caused by beam divergence. Precise coaxial alignment of the quarter-wave plate 31 and the reflector 32 is crucial for ensuring optical path quality. This application utilizes a height difference design at the junction of the movable clamp arm 12, allowing the two to naturally misalign vertically when closed, achieving precise alignment and avoiding optical path loss and measurement errors caused by alignment deviations.

[0041] It should be noted that in the optical path docking assembly 3, the collimating lens 33 and the quarter-wave plate 31 are located on one side of the end of the sensing fiber 2 (i.e., the second end of the movable clamp arm 12 or the end of the second side section 1123 of the fixed frame 112 where the end of the sensing fiber 2 is located), and the reflector 32 is located on the other side of the docking point. In the closed position, a free space optical path is formed between the collimating lens 33, the quarter-wave plate 31, and the reflector 32. The optical signal propagates in this free space in the form of a parallel beam and returns along the original path after being reflected by the reflector 32. Since the collimating lens 33 converts the diverging beam into a parallel beam, even if there is a gap of several millimeters between the collimating lens 33 and the reflector 32, the beam can still maintain good collimation. The reflected beam can be efficiently focused by the collimating lens 33 and coupled back to the core of the sensing fiber 2, and the optical coupling loss can be controlled within 1 dB.

[0042] It should also be noted that the quarter-wave plate 31 serves to eliminate linear birefringence errors in the reflective optical path of this application. Actual sensing fiber 2 inevitably exhibits linear birefringence (caused by factors such as fiber bending, internal stress, and temperature changes). Linear birefringence alters the polarization state of light. If left untreated, this polarization state change will overlap with the polarization rotation caused by the Faraday effect, leading to severe measurement errors. The combination of the quarter-wave plate 31 and the reflector 32 utilizes the fundamental physical difference between the Faraday effect and linear birefringence to solve this problem: the Faraday effect is a non-reciprocal effect, and its polarization rotation direction is determined by the direction of the magnetic field, independent of the light propagation direction. Therefore, when the light signal passes through the sensing fiber 2 twice, the Faraday polarization rotation angles are superimposed in the same direction, producing a multiplication effect; while linear birefringence is a reciprocal effect, and its effect on the polarization state depends on the light propagation direction. On the outward journey, after the optical signal reaches the quarter-wave plate 31, the quarter-wave plate 31 applies a 90° phase delay to the polarization state, converting the linearly polarized light into circularly polarized light. The circularly polarized light, after being reflected by the mirror 32, undergoes a rotational reversal and, after passing through the quarter-wave plate 31 again, is converted back into linearly polarized light. Through this polarization transformation process, the linear birefringence effect experienced by the optical signal on the return journey exactly cancels out the linear birefringence effect on the outward journey, while the Faraday rotation angle is multiplied. Therefore, the combination of the quarter-wave plate 31 and the mirror 32 achieves the effect of "preserving the Faraday rotation signal and eliminating linear birefringence interference," ensuring that the current measurement only reflects the magnetic field generated by the measured conductor and is unaffected by factors such as the bending state of the optical fiber and temperature changes.

[0043] Please refer to Figures 1 to 3The drive mechanism 4 is connected to the movable clamp arm 12 and is used to drive the movable clamp arm 12 to rotate between the open and closed positions. In the open position, the measuring head 1 forms an upward-opening receiving opening for the conductor to be measured to be inserted from above; in the closed position, the movable clamp arm 12 and the fixed part of the measuring head 1 close and engage. The drive mechanism 4 can take various forms, such as electric drive, hydraulic drive, or manual drive. In the manual drive mode, the drive mechanism 4 may include a connecting shaft 41, an elastic reset member 42, and a control component 45. The connecting shaft 41 is generally made of metal, such as stainless steel, and it is slidably inserted into a guide sleeve 111 formed on the base 11. The inner wall of the guide sleeve 111 is smoothed to reduce the friction when the connecting shaft 41 slides. One end of the connecting shaft 41 is hinged to one end of the movable clamp arm 12, and a pin can also be used at the hinge. The elastic reset element 42 can be a spring, which is sleeved on the connecting shaft 41. One end of the spring abuts against the guide sleeve 111, and the other end abuts against the protrusion 411 on the connecting shaft 41 to form a restoring force that tends the movable clamp arm 12 to reach the closed position. The control assembly 45 includes a support rod 451, a handle 452, a lever 453, and a flexible cable 454. The two ends of the support rod 451 are fixedly connected to the base 11 and the handle 452, respectively. The support rod 451 serves as a connection and support, and it can be made of metal tubing. The length of the support rod 451 can be customized according to the space requirements of the electrolytic cell, making it easy to reach into narrow spaces such as the bottom of the electrolytic cell for measurement. The lever 453 is slidably mounted on the handle 452, and a guide groove can be provided on the handle 452 to guide the sliding of the lever 453. The flexible cable 454 passes through the inside of the support rod 451 and is used to connect the handle 453 to the other end of the connecting shaft 41. When the handle 453 is pulled, the flexible cable 454 drives the connecting shaft 41 to move along the guide sleeve 111, causing the movable clamp arm 12 to rotate around the hinge point to the open position; when the handle 453 is released, the elastic reset member 42 drives the connecting shaft 41 to reset, causing the movable clamp arm 12 to return to the closed position.

[0044] When the operator pulls handle 453, handle 453 moves downward along the guide groove in handle 452, driving connecting shaft 41 to move outward along guide sleeve 111 via flexible cable 454 (such as steel wire). The movement of connecting shaft 41 causes movable clamp arm 12 to rotate upward around the hinge point, forming an upward-opening U-shaped receiving opening in measuring head 1. At the same time, elastic reset element 42 (spring) is compressed to complete energy storage. When the operator releases handle 453, the spring releases the stored elastic potential energy, driving connecting shaft 41 to reset. Connecting shaft 41 drives movable clamp arm 12 to close from above to the closed position. Collimating lens 33, quarter-wave plate 31 and reflector 32 in optical path docking assembly 3 are precisely aligned. Sensing fiber 2 forms a closed loop around the conductor under test in space. The optical signal is reflected by reflector 32 and propagates back and forth along sensing fiber 2, forming a stable optical path. The design of elastic reset element 42 ensures the stability of movable clamp arm 12 in the closed position and avoids optical path interruption caused by external force disturbance. The entire opening and closing operation can be completed with just one hand, making it simple and quick to operate and suitable for the needs of rapid multi-point measurement in electrolytic cells.

[0045] The signal processing host 5 is optically connected to the sensing fiber 2 via the transmission fiber 6. When the movable clamp arm 12 is in the closed position, it injects a polarized light signal into the sensing fiber 2 and receives the light signal returned via the sensing fiber 2. The current value in the conductor under test is determined based on the change in polarization state of the returned light signal. The signal processing host 5 internally includes an optical signal transmitting module, an optical signal receiving module, and a signal processing module. The optical signal transmitting module can use a laser light source to emit a stable polarized light signal. The optical signal receiving module receives the returned light signal and converts it into an electrical signal. The signal processing module processes the electrical signal and calculates the current value in the conductor under test according to a preset algorithm.

[0046] The specific working process of the signal processing host 5 is as follows: The optical signal transmitting module generates a stable polarized light signal, which is transmitted to the sensing optical fiber 2 via the transmission optical fiber 6. The layout path of the sensing optical fiber 2 forms a closed loop around the conductor under test in space. During the propagation of the polarized light signal along the sensing optical fiber 2, it is subjected to the magnetic field generated by the current in the conductor under test, resulting in Faraday polarization rotation. The rotation angle is proportional to the measured current. After the light signal propagates to the end of the sensing optical fiber 2, it is collimated by the collimating lens 33, passes through the quarter-wave plate 31, and is reflected by the reflecting mirror 32. It returns along the original path and is coupled back to the sensing optical fiber 2 again through the quarter-wave plate 31 and the collimating lens 33. During the return process, the Faraday polarization rotation angle is further superimposed. The returned light signal is transmitted back to the signal processing host 5 via the transmission optical fiber 6. The optical signal receiving module decomposes the returned light signal into two orthogonal polarization components through a polarization beam splitter, and detects their light intensity and polarization respectively. The signal processing module calculates the normalized signal value based on the light intensity of the two orthogonal polarization components. Then calculate the total angle of Faraday polarization rotation. Ultimately based on The measured current is calculated ,in Let be the Verdet constant of sensing fiber 2. is the vacuum permeability, and coefficient 2 is the multiplication factor generated when the optical signal passes through the sensing fiber 2 twice after being reflected by the reflector 32.

[0047] The implementation principle of this embodiment is as follows: This top-opening fiber optic current clamp meter, through its unique top-opening structural design, allows the conductor under test to be directly inserted into the receiving opening of the measuring head 1 from above, eliminating the need for side operation space. This makes it ideal for measuring the current of rigid, thick conductors in confined spaces such as electrolytic cells. When the movable clamp arm 12 is closed, the sensing fiber 2 forms a closed loop around the conductor under test in space, satisfying the requirements of Ampere's circuital law. The optical signal, after being reflected by the reflector 32 in the optical path docking assembly 3, propagates back and forth along the sensing fiber 2. The two round trips through the closed loop multiply the Faraday polarization rotation angle, greatly improving the measurement accuracy and sensitivity. Simultaneously, the collimating lens 33 in the optical path docking assembly 3 ensures efficient coupling of the optical signal at the docking point, reducing optical loss. The design of the drive mechanism 4 simplifies the opening and closing operation of the movable clamp arm 12, and the elastic reset component 42 ensures the stability of the movable clamp arm 12 in the closed position. The signal processing host 5 can accurately process the optical signal, thereby precisely measuring the current value in the conductor under test. Compared with existing technologies, this represents an improvement in measurement accuracy and adaptability.

[0048] Example 2

[0049] Please refer to Figures 1 to 4 The difference between this embodiment and the previous embodiment is that there are two movable clamp arms 12, and the first ends of the two movable clamp arms 12 are rotatably mounted on both ends of the base 11. This design of double movable clamp arms 12 can increase the opening and closing range of the measuring head 1, making it easier to insert the conductor being tested.

[0050] Specifically, two movable clamp arms 12 can be symmetrically installed at both ends of the base 11, and their structure and materials are similar to those of a single movable clamp arm 12. The sensing fiber 2 starts from one end of the base 11, extends along the interior of one of the movable clamp arms 12 (hereinafter referred to as the first movable clamp arm) to the second end (terminal end) of the first movable clamp arm, folds back at the second end, returns along the interior of the first movable clamp arm to the base 11, passes through the interior of the base 11 to the other end of the base 11, and then extends along the interior of the other movable clamp arm 12 (hereinafter referred to as the second movable clamp arm) to the second end (terminal end) of the second movable clamp arm. Thus, the sensing fiber 2 is continuously deployed inside the base 11 and inside the two movable clamp arms 12, and its deployment path forms a closed loop around the conductor being measured in space. The input end of the sensing fiber 2 (the end connected to the transmission fiber 6) is located inside the base 11, and the end of the sensing fiber 2 is located at the second end of the second movable clamp arm. A bending allowance is provided at the hinge point between the first end of the movable clamp arm 12 and the base 11. The bending radius of the bending allowance is not less than the minimum allowable bending radius of the sensing optical fiber 2, so as to maintain the continuity of the optical path when the movable clamp arm 12 rotates. One end of the transmission optical fiber 6 is led out from the inside of the base 11, passes through the support rod 451 connecting the base 11 and the signal processing host 5, and extends to the signal processing host 5.

[0051] The relationship between the deployment path of the sensing fiber 2 and the propagation mode of the optical signal needs further explanation: The sensing fiber 2 starts from the base 11, passes sequentially through the interior of the first movable clamp arm (outbound), the foldback at the second end of the first movable clamp arm, the interior of the first movable clamp arm (return), the interior of the base 11, and the interior of the second movable clamp arm, reaching the second end of the second movable clamp arm. After the two movable clamp arms 12 are closed, the second ends of the first movable clamp arm and the second ends of the second movable clamp arm are connected, and the deployment path of the sensing fiber 2 forms a closed loop around the conductor under test in space. The optical signal enters from the input end of the sensing fiber 2, propagates along the above deployment path to the end of the sensing fiber 2 (located at the second end of the second movable clamp arm), is collimated by the collimating lens 33 in the optical path docking assembly 3, undergoes polarization conversion by the quarter-wave plate 31, and is reflected by the reflector 32, before returning to the input end along the original path of the sensing fiber 2.

[0052] Please refer to Figure 3The drive mechanism 4 is used to drive the two movable clamp arms 12 to rotate synchronously. Two sets of guide sleeves 111 are formed at both ends of the base 11. The drive mechanism 4 includes two connecting shafts 41, two elastic reset members 42, a synchronous connecting rod 43, and a control assembly 45. The two connecting shafts 41 are slidably inserted into the two sets of guide sleeves 111, and one end of each connecting shaft 41 is hinged to the first end of each of the two movable clamp arms 12. The two elastic reset members 42 are respectively sleeved on the two connecting shafts 41, one end of each elastic reset member abutting against the two guide sleeves 111, and the other end abutting against the protrusions 411 on the two connecting shafts 41, to generate a restoring force that tends the two movable clamp arms 12 to reach the closed position. The two ends of the synchronous connecting rod 43 are fixedly connected to the other ends of the two connecting shafts 41, and are used to move the two connecting shafts 41 synchronously to drive the two movable clamp arms 12 to rotate synchronously. The synchronizing link 43 can be made of metal and its function is to ensure the synchronous movement of the two movable clamp arms 12 and prevent misalignment. The control component 45 is similar to the control component 45 for a single movable clamp arm 12, including a support rod 451, a handle 452, a pull handle 453, and a flexible cable 454. When the pull handle 453 is pulled, the flexible cable 454 drives the synchronizing link 43 and the two connecting shafts 41 to move outward along the guide sleeve 111, causing the first ends of the two movable clamp arms 12 to rotate around the hinge point to the open position; when the pull handle 453 is released, the two elastic reset members 42 drive the two connecting shafts 41 to reset, causing the two movable clamp arms 12 to return to the closed position.

[0053] In this embodiment, the synchronizing link 43 also has an upward upper limit function. That is, after the two movable clamp arms 12 are closed, the synchronizing link 43 restricts the two connecting shafts 41 from continuing to move upward, ensuring that the relative positions of the left and right movable clamp arms 12 remain unchanged after closing, thereby ensuring the accurate alignment of the quarter-wave plate 31 and the reflector 32 and the stability of the optical path.

[0054] Please refer to Figure 4 In the closed position, the second ends of the two movable clamp arms 12 synchronously close and align. The optical path alignment assembly 3 is located at the alignment point of the second ends of the two movable clamp arms 12, reflecting the optical signal emitted from the end of the sensing fiber 2 back to the sensing fiber 2. The optical path alignment assembly 3 includes a collimating lens 33 and a quarter-wave plate 31 located at the second end of one of the movable clamp arms 12, and a reflector 32 located at the second end of the other movable clamp arm 12. The collimating lens 33 and the quarter-wave plate 31 are located at the second end of the movable clamp arm 12 where the end of the sensing fiber 2 is located, with the collimating lens 33 positioned between the end face of the sensing fiber 2 and the quarter-wave plate 31. In the closed position, the second ends of the two movable clamp arms 12 are misaligned and aligned, forming a preset height difference, ensuring that the collimating lens 33, the quarter-wave plate 31, and the reflector 32 are coaxially aligned, guaranteeing the coaxiality of the optical path and the transmission quality of the optical signal.

[0055] The specific working process of the optical path docking assembly 3 is as follows: The diverging beam emitted from the end of the sensing fiber 2 is first collimated into a parallel beam by the collimating lens 33. After passing through the quarter-wave plate 31, the polarization state of the parallel beam is converted, and then it reaches the reflecting mirror 32 and is reflected. The reflected parallel beam passes through the quarter-wave plate 31 again to complete the further polarization state conversion, and finally is focused and coupled back to the core of the sensing fiber 2 by the collimating lens 33. The setting of the collimating lens 33 enables the optical signal to propagate in the form of a parallel beam between the collimating lens 33 and the reflecting mirror 32. Even if there is a gap of several millimeters between the two (determined by the spacing when the two movable clamp arms 12 are docked), the beam can still maintain good collimation. The reflected beam can be efficiently coupled back to the sensing fiber 2, and the optical coupling loss can be controlled within 1dB.

[0056] Please refer to Figure 2 When the operator pulls the handle 453, the handle 453 moves downward along the guide groove inside the handle 452, driving the synchronous connecting rod 43 downward through the flexible cable 454 (steel wire). The synchronous connecting rod 43, through its fixed connections at both ends, simultaneously drives the two connecting shafts 41 to move outward along their respective guide sleeves 111. The synchronous movement of the two connecting shafts 41 drives the first ends of the two movable clamp arms 12 to rotate upward synchronously around their respective hinge points, and the second ends of the two movable clamp arms 12 to open outward synchronously, forming a U-shaped receiving opening. Simultaneously, the two elastic reset elements 42 (springs) are compressed and have stored energy. When the operator releases the handle 453, the two springs simultaneously release their stored elastic potential energy, driving the two connecting shafts 41 to reset synchronously, and the two movable clamp arms 12 synchronously close from above to the closed position. The synchronous connecting rod 43 ensures the synchronicity and consistency of the movement of the two movable clamp arms 12, avoiding alignment deviations caused by one side closing first. After closing, the upward upper limit action of the synchronous link 43 ensures the stability of the relative position of the two movable clamp arms 12, ensuring the precise coaxial alignment of the collimating lens 33, quarter-wave plate 31, and reflector 32. This allows the sensing fiber 2 to form a stable closed loop around the conductor under test in space. After being reflected by the reflector 32, the optical signal propagates efficiently back and forth along the sensing fiber 2, forming a stable and reliable optical path. This design of synchronous opening and closing of the dual movable clamp arms 12 allows the conductor to be inserted and the optical path to be established in a single operation. The operation is simple and efficient, and it is particularly suitable for the rapid batch measurement of dozens of anodes and cathodes in an electrolytic cell.

[0057] The implementation principle of this embodiment is as follows: The design of the double movable clamping arms 12 makes the opening and closing of the measuring head 1 more flexible, and the conductor insertion and optical path establishment can be completed in one operation, improving the measurement efficiency. The synchronous connecting rod 43 ensures the synchronicity and consistency of the movement of the two movable clamping arms 12, avoiding optical path loss and measurement errors caused by alignment deviation. Through the staggered docking of the two movable clamping arms 12, the collimating lens 33, quarter-wave plate 31 and reflector 32 are precisely coaxially aligned, further improving the measurement accuracy, which is suitable for the needs of rapid multi-point measurement in electrolytic cells. In addition, the symmetrical arrangement of the double movable clamping arms 12 keeps the overall center of gravity of the equipment in the center and the weight distribution is balanced. When the operator holds the equipment, the posture of the equipment is stable, reducing the operation deviation caused by the center of gravity shift, which is conducive to maintaining the consistency of the equipment posture and reducing the measurement deviation caused by posture shift.

[0058] Example 3

[0059] Please refer to Figure 5 and Figure 6 The difference between this embodiment and the previous embodiment is that there is only one movable clamp arm 12, and a fixed frame 112 is integrally formed on the upper part of the base 11. This structure, in which a single movable clamp arm 12 cooperates with a fixed frame 112, is simpler, reduces the number of moving parts, and improves structural reliability.

[0060] Specifically, the fixed frame 112 has a bottom section 1121 and a first side section 1122 and a second side section 1123 extending upward from both ends of the bottom section 1121, which can be integrally formed with the base 11 by casting or welding. One end of the movable clamp arm 12 is hinged to the end of the first side section 1122. In the closed position, the other end of the movable clamp arm 12 is connected to the end of the second side section 1123. The movable clamp arm 12 and the fixed frame 112 together form a closed frame surrounding the conductor being tested.

[0061] The fiber optic cable 2 is laid out as follows: Starting from the bottom section 1121 of the fixed frame 112, the fiber optic cable 2 extends upwards along the interior of the first side section 1122 to its end. It then enters the interior of the movable clamp arm 12 through the hinge, extends along the movable clamp arm 12 to its free end, then folds back, returns along the movable clamp arm 12 to the hinge, then returns to the bottom section 1121 via the first side section 1122, and finally extends upwards along the interior of the second side section 1123 to its end. Thus, one section of the fiber optic cable 2 is continuously laid out along the interior of the fixed frame 112, and the other section is laid out along the interior of the movable clamp arm 12. The laying path of the fiber optic cable 2 forms a closed loop around the conductor being measured in space. The input end of the fiber optic cable 2 (the end connected to the transmission fiber optic cable 6) is located at the bottom section 1121, and the end of the fiber optic cable 2 is located at the end of the second side section 1123. The sensing optical fiber 2 has a pre-reserved bending allowance at the hinge point between the movable clamp arm 12 and the first side section 1122. The bending radius of the bending allowance is not less than the minimum allowable bending radius of the sensing optical fiber 2, so as to maintain the continuity of the optical path when the movable clamp arm 12 rotates. The transmission optical fiber 6 is led out from the bottom section 1121 of the fixed frame 112 and optically connected to the signal processing host 5. In this embodiment, the fixed frame 112 has a pre-set optical fiber channel (such as a hollow pipe), and the sensing optical fiber 2 is inserted into the optical fiber channel after the fixed frame 112 is formed.

[0062] The optical path docking assembly 3 is located at the docking point between the free end of the movable clamp arm 12 and the end of the second side section 1123. The end of the second side section 1123 is equipped with a collimating lens 33 and a quarter-wave plate 31, while the free end of the movable clamp arm 12 is equipped with a reflector 32. The collimating lens 33 is located between the end face of the sensing fiber 2 and the quarter-wave plate 31, and is used to collimate the diverging beam emitted from the end of the sensing fiber 2 into a parallel beam, and to focus and couple the reflected parallel beam back to the core of the sensing fiber 2. In the closed position, the free end of the movable clamp arm 12 and the end of the second side section 1123 are misaligned, forming a preset height difference, so that the collimating lens 33, the quarter-wave plate 31, and the reflector 32 are coaxially aligned.

[0063] The propagation process of the optical signal is as follows: The polarized optical signal enters from the input end of the sensing fiber 2 and propagates along the deployment path of the sensing fiber 2 (passing sequentially through the bottom section 1121, the first side section 1122, the outward path of the movable clamp arm 12, the free end return path of the movable clamp arm 12, the return path of the movable clamp arm 12, the first side section 1122, the bottom section 1121, and the second side section 1123), reaching the end of the sensing fiber 2 (located at the end of the second side section 1123). After the optical signal exits from the end of the sensing fiber 2, it is collimated into a parallel beam by the collimating lens 33, polarized by the quarter-wave plate 31, and reflected by the reflecting mirror 32. The reflected parallel beam passes through the quarter-wave plate 31 again, is focused and coupled back to the core of the sensing fiber 2 by the collimating lens 33, and returns to the input end along the original path of the sensing fiber 2.

[0064] Please refer to Figure 6 A guide sleeve 111 is formed on the base 11. The drive mechanism 4 includes a connecting shaft 41, an elastic reset member 42, and a control assembly 45. The connecting shaft 41 is slidably inserted into the guide sleeve 111, and one end of the connecting shaft 41 is hinged to one end of the movable clamp arm 12. The elastic reset member 42 is sleeved on the connecting shaft 41, and one end of the elastic reset member 42 abuts against the guide sleeve 111, while the other end abuts against the protrusion 411 on the connecting shaft 41, so as to form a restoring force that tends the movable clamp arm 12 and the second side section 1123 to reach the closed position. The control assembly 45 includes a support rod 451, a handle 452, a pull handle 453, and a flexible cable 454. The two ends of the support rod 451 are fixedly connected to the base 11 and the handle 452, respectively. The handle 453 is slidably disposed on the handle 452. The flexible cable 454 passes through the interior of the support rod 451 and is used to connect the handle 453 to the other end of the connecting shaft 41. When the handle 453 is pulled, the flexible cable 454 drives the connecting shaft 41 to move along the guide sleeve 111, causing the movable clamp arm 12 to rotate around the hinge point to the open position; when the handle 453 is released, the elastic reset member 42 drives the connecting shaft 41 to reset, causing the movable clamp arm 12 to return to the closed position.

[0065] When the operator pulls the handle 453, the flexible cable 454 drives the connecting shaft 41 to move along the guide sleeve 111. The movement of the connecting shaft 41 drives the movable clamp arm 12 to rotate upward around the hinge point with the end of the first side section 1122 to the open position. The free end of the movable clamp arm 12 separates from the end of the second side section 1123, and the measuring head 1 forms an upwardly open receiving opening. At the same time, the elastic reset member 42 is compressed and stores energy. After the conductor under test is inserted into the receiving opening from above, the operator releases the handle 453. The elastic reset component 42 releases its elastic potential energy to drive the connecting shaft 41 to reset. The movable clamp arm 12 rotates downward around the hinge point to the closed position. The free end of the movable clamp arm 12 is misaligned with the end of the second side section 1123. The collimating lens 33, the quarter-wave plate 31, and the reflector 32 are precisely coaxially aligned. The movable clamp arm 12 and the fixed frame 112 together form a closed frame surrounding the conductor under test. The sensing fiber 2 forms a complete closed loop around the conductor under test in space. Since the fixed frame 112 and the base 11 are integrally formed, they have good structural rigidity and can provide a stable reference for optical path docking in the closed state, further improving the accuracy and reliability of optical path docking.

[0066] The implementation principle of this embodiment is as follows: the structure of the single movable clamp arm 12 cooperating with the fixed frame 112 is simple and compact, reducing the number of moving parts, lowering the probability of failure, and improving the reliability of the structure. The fixed frame 112 is integrally formed with the base 11, providing good structural rigidity and stability. The movable clamp arm 12 and the fixed frame 112 form a closed frame in the closed position. Through staggered docking, the collimating lens 33, quarter-wave plate 31, and reflector 32 are precisely coaxially aligned, ensuring the optical quality of the round-trip propagation of the optical signal. This is suitable for applications with high requirements for structural compactness.

[0067] Example 4

[0068] Please refer to Figures 1 to 4 This embodiment, based on the above embodiment, adds a heat insulation layer 13 and a temperature sensor 7. The heat insulation layer 13 is disposed on the inner surface of the measuring head 1 facing the conductor being measured. The thermal conductivity of the heat insulation layer 13 is not greater than a certain value, and it can be made of high-temperature resistant materials such as fiberglass tubing, with a thickness of 1-3 mm. The function of the heat insulation layer 13 is to block the heat from the high-temperature conductor being measured from being conducted to the optical components inside the measuring head 1, such as the sensing fiber 2, quarter-wave plate 31, reflector 32, and collimating lens 33, protecting the optical components from the effects of thermal expansion deformation and refractive index changes, ensuring optical path stability and measurement accuracy, and extending the service life of the equipment.

[0069] In this embodiment, when the measuring head 1 is inserted into a high-temperature conductor being measured (such as a cathode steel rod in an electrolytic cell with a temperature reaching 200℃~300℃), the heat insulation layer 13 acts as a thermal barrier between the conductor being measured and the internal optical elements of the measuring head 1. Its extremely low thermal conductivity (not greater than 0.05 W / (m·K)) reduces the heat transfer rate. For example, when a 1mm thick glass fiber flexible tube with a thermal conductivity of 0.05 W / (m·K) is used as the heat insulation layer 13, even if the surface temperature of the conductor being measured reaches 250℃, the heat insulation layer 13 can control the heat conducted to the internal optical elements within a safe range. This avoids changes in the optical parameters of the quarter-wave plate 31, collimating lens 33, and reflector 32 due to thermal expansion deformation, and also avoids drift in the Verdet constant of the sensing fiber 2 due to changes in refractive index, thereby ensuring the stability of measurement accuracy. The heat insulation layer 13 is a passive protection measure, requiring no additional energy consumption, and has a simple and reliable structure, serving as the first layer of protection for high-temperature adaptability design.

[0070] Temperature sensor 7 is located inside or on the inner surface of the measuring head 1, and can be a PT100 platinum resistance thermometer or a thin-film thermocouple, etc. Temperature sensor 7 is used to detect the operating temperature of the measuring head 1 in real time.

[0071] The signal processing host 5 includes a temperature monitoring unit, an alarm unit, and a temperature compensation unit. The temperature monitoring unit receives the detection signal from the temperature sensor 7 and monitors the temperature of the measuring head 1 in real time. The alarm unit issues a warning signal when the detected temperature by the temperature sensor 7 exceeds a preset first threshold, and issues a danger alarm signal when it exceeds a second threshold higher than the first threshold, reminding the operator to pay attention to the operating temperature of the equipment and prevent damage to the device due to high temperature. In one specific embodiment, the first threshold... Set to 120℃ (warning), second threshold Set to 150℃ (hazard alarm). When the temperature exceeds the second threshold... When the temperature is high, the alarm unit emits an audible and visual alarm and can automatically control the movable clamp arm 12 to open, disengaging the measuring head 1 from the high-temperature conductor. This prevents continuous contact with the high-temperature conductor from damaging the device, protecting the equipment and alerting operators to safety. The temperature compensation unit is used to correct the current measurement value based on the detection signal from the temperature sensor 7. This correction is achieved using a pre-trained neural network model based on the correspondence between temperature and measurement error, or a pre-fitted least-squares fitting model stored in the signal processing host 5. This eliminates the influence of temperature changes on parameters such as the Verdet constant and waveplate birefringence characteristics of the sensing fiber 2, ensuring measurement accuracy over a wide temperature range.

[0072] The specific working process of the temperature compensation unit is as follows: Temperature sensor 7 detects and measures the working temperature of head 1 in real time. The temperature signal is then transmitted to the temperature monitoring unit of the signal processing host 5. The temperature compensation unit adjusts the temperature compensation based on the received temperature signal. The temperature compensation coefficient is calculated using a pre-established and stored temperature compensation model. The temperature compensation model can be one of the following two:

[0073] (a) A BP neural network model trained based on the correspondence between temperature and measurement error, wherein the model uses temperature... As input, with compensation coefficient For the output, the BP neural network can be configured with one node in the input layer (temperature), five nodes in the hidden layer, and one node in the output layer (compensation coefficient); or

[0074] (b) The polynomial model obtained by least squares fitting based on the correspondence between temperature and measurement error: ,in , , … These are the fitting coefficients. The order is a polynomial. The compensation coefficients are calculated. Then, the current measurement value After correction, the compensated current value is obtained. Experiments show that, within the temperature range of 200℃ to 300℃, the uncompensated measurement error is [missing value]. The compensated measurement error is less than This improves measurement accuracy in high-temperature environments.

[0075] The synergistic effect of the triple design of the insulation layer 13, temperature monitoring alarm, and temperature compensation is as follows: The insulation layer 13, as the first layer of protection, passively reduces heat conduction, lowering the rate and magnitude of temperature rise in optical components; the temperature sensor 7 and alarm unit, as the second layer of protection, actively sense and monitor the temperature status in real time, promptly alarming and automatically disconnecting when the temperature exceeds the limit, protecting equipment safety; the temperature compensation unit, as the third layer of protection, intelligently corrects residual temperature errors, ensuring measurement accuracy. The insulation layer provides passive thermal protection, the temperature sensor works with the alarm unit for temperature monitoring and over-temperature alarms, and the temperature compensation unit corrects the current measurement value based on the real-time temperature, solving the problems of measurement accuracy and device protection in high-temperature environments of 200℃~300℃.

[0076] The implementation principle of this embodiment is as follows: the heat insulation layer 13, temperature monitoring alarm, and temperature compensation work together to solve the measurement problems in high-temperature environments from three levels: passive protection, active sensing, and intelligent correction. The heat insulation layer 13 reduces heat conduction and protects the optical components; the temperature sensor 7 monitors the temperature in real time, and the alarm unit issues an alarm in a timely manner to remind the operator to take measures; the temperature compensation unit corrects the measured value according to temperature changes, reducing the measurement error caused by temperature changes, enabling the top-opening fiber optic clamp meter to work in high-temperature environments.

[0077] Example 5

[0078] Please refer to Figure 1 and Figure 2 This embodiment adds a sealing structure and a quick-connect structure 8 to the above embodiments to improve adaptability to industrial site environments.

[0079] Specifically, a sealing structure is installed at the joint of the cavity to provide a sealed protection for the fiber optic connector. The fiber optic connector is integrated and housed inside the cavity, and a fluororubber O-ring sealing structure is installed at the cavity joint to provide a fully enclosed seal and protection for the flexible optical fiber. The fluororubber O-ring has excellent high-temperature resistance and chemical corrosion resistance, and can withstand the high temperatures, dust (alumina, fluorides, etc.), and highly corrosive gases (HF, etc.) at the electrolytic cell site. It maintains a sealing effect over a long period of time in environments such as (etc.).

[0080] Under normal operating conditions, the fiber optic connector is completely housed within the cavity. Fluoropolymer O-rings form a reliable sealing barrier at the cavity joint, preventing external dust, moisture, and corrosive gases from entering the cavity and avoiding contamination of the fiber optic connector that could degrade connection reliability. Compared to the exposed fiber optic connector design of existing devices, the internally sealed design of this application improves the reliability and environmental adaptability of the fiber optic connection, meets the protection requirements of harsh operating conditions in the electrolytic cell, and ensures the long-term stable operation of the equipment.

[0081] A quick-connect structure 8 is installed between the transmission fiber optic cable 6 and the signal processing host 5, enabling rapid connection and disconnection of the transmission fiber optic cable 6 and the host. The quick-connect structure 8 can use a snap-fit ​​or rotary locking fiber optic connector, allowing operators to quickly connect and disconnect the fiber optic cable on-site without the need for specialized tools.

[0082] In field use, operators insert the connector of the transmission fiber optic cable 6 into the quick-connect interface of the signal processing host 5, and quickly connect the fiber optic cable to the host by snapping or rotating it in place. The entire process takes only a few seconds, requires no special tools, and improves the efficiency of multi-point measurements. During transportation or storage, operators can quickly detach the transmission fiber optic cable 6 from the host and store it separately, preventing damage to the fiber optic cable due to bending during transport. The quick-connect structure 8 is designed to balance ease of use in the field with the safety of equipment transportation and storage.

[0083] The implementation principle of this embodiment is as follows: The sealed structure and quick-connect structure 8 are specifically optimized for the harsh environment of the electrolytic cell site, including dust and corrosive gases. The sealed structure, by embedding the fiber optic interface within the cavity and sealing it with a fluororubber O-ring, achieves comprehensive protection for the fiber optic interface, preventing the external environment from affecting the fiber optic connection. The quick-connect structure 8 enables rapid docking and disconnection of the transmission fiber optic cable 6 with the host, improving on-site operation efficiency and equipment transportation safety. The combination of these two features enhances the adaptability and reliability of the top-opening fiber optic clamp meter in harsh industrial environments.

[0084] Example 6

[0085] Please refer to Figure 2 This embodiment adds a modular design and a pull-ring release mechanism 9 to the above embodiment to reduce maintenance costs.

[0086] Specifically, the signal processing host 5 and the frame (including the base 11 of the measuring head 1, the movable clamp arm 12, the support rod 451, and other mechanical structural parts) are detachably connected and equipped with a pull-ring type release mechanism 9. During normal use, the signal processing host 5 and the frame are locked together by a locking mechanism, forming a stable integrated structure. When separation is required, the operator pulls the pull ring in a preset direction (such as to the right) to the limit point to release the lock, and the signal processing host 5 detaches from the frame.

[0087] After prolonged use in the harsh environment of an electrolytic cell, the frame (especially the opening and closing structure such as the movable clamp arm 12) may deform or be damaged due to high temperature, corrosion, mechanical wear, etc., requiring replacement. In this case, the operator simply pulls the pull ring to the right to the limit point, the locking mechanism disengages, and the signal processing host 5 can quickly detach from the frame. The signal processing host 5 is then installed onto a new frame, completing the replacement. The entire process requires no special tools and is simple and quick. Since the signal processing host 5 is the most expensive core component of the entire clamp meter (containing the optical signal transmitting module, optical signal receiving module, signal processing module, temperature monitoring unit, alarm unit, temperature compensation unit, etc.), while the frame is a relatively low-cost mechanical structure component, the modular design allows for the separation and replacement of the host and frame. This enables the expensive host to be reused, requiring only the replacement of the easily damaged mechanical frame, reducing usage and maintenance costs. Simultaneously, the modular design facilitates product upgrades and iterations. When the host's signal processing algorithm or hardware is upgraded, the host can be directly replaced while retaining the frame, and vice versa. Damaged frame parts can also be recycled or repaired at low cost for reuse, further reducing maintenance costs.

[0088] The implementation principle of this embodiment is as follows: the modular design divides the top-opening fiber optic current clamp meter into two independent modules: a signal processing host 5 and a mechanical frame. A pull-ring release mechanism 9 enables rapid connection and separation of the two modules. This design addresses the issues of frame damage and high maintenance costs in the harsh environment of electrolytic cells, enabling modular and rapid replacement of key components, improving assembly and maintenance efficiency, reducing usage and repair costs, and facilitating product upgrades and iterations.

[0089] Example 7

[0090] Please refer to Figures 1 to 6 The current measurement method provided in this application uses the top-opening fiber optic current clamp meter described in any one of Embodiments 1 to 6 above, and includes the following steps:

[0091] S1, drive the movable clamp arm 12 to rotate to the open position, so that the measuring head 1 forms an upward-open receiving opening. The operator can pull the handle 453, using the flexible cable 454 to drive the connecting shaft 41 to move, thereby causing the movable clamp arm 12 to rotate around the hinge point to the open position. During this process, the elastic reset member 42 is compressed, storing elastic potential energy.

[0092] S2, Insert the conductor to be tested into the receiving opening from above. Because the measuring head 1 adopts an upward-opening structure, the conductor to be tested can be easily inserted directly from above without requiring side operating space, making it suitable for measurements in confined spaces such as electrolytic cells. The conductor to be tested can be the cathode steel rod of an aluminum electrolytic cell (cross-section as shown in the image). Temperatures can reach 200℃~300℃) or anode guide rods (cross-section such as...) Rigid, thick conductors (temperatures above approximately 120°C). When the conductor being measured is a high-temperature conductor, the heat insulation layer 13 on the inner surface of the measuring head 1 blocks heat from being conducted inward, protecting the optical components.

[0093] S3, drive the movable clamp arm 12 to rotate to the closed position, so that the sensing fiber 2 forms a closed loop around the conductor under test in space. After releasing the handle 453, the elastic reset member 42 releases elastic potential energy, driving the connecting shaft 41 to reset, so that the movable clamp arm 12 returns to the closed position. In the closed position, the movable clamp arm 12 and the fixed part of the measuring head 1 close and align, and the collimating lens 33, quarter-wave plate 31 and reflector 32 in the optical path docking assembly 3 are precisely aligned, establishing the optical path conditions for the round-trip propagation of the optical signal. In the implementation of the double movable clamp arm 12, the synchronous link 43 ensures that the two movable clamp arms 12 close synchronously from top to bottom. The upward upper limit action of the synchronous link 43 ensures that the relative positions of the left and right movable clamp arms 12 remain unchanged after closure, and the collimating lens 33, quarter-wave plate 31 and reflector 32 are precisely aligned, forming a stable optical path.

[0094] S4. A polarized light signal is injected into the sensing fiber 2. The polarized light signal propagates along the sensing fiber 2 and undergoes Faraday polarization rotation under the influence of the magnetic field generated by the current in the measured conductor. The optical signal transmitting module in the signal processing host 5 injects a stable polarized light signal into the sensing fiber 2. When this signal propagates along the sensing fiber 2, it undergoes Faraday polarization rotation due to the influence of the magnetic field generated by the current in the measured conductor. After the polarized light signal reaches the end of the sensing fiber 2, it is collimated by the collimating lens 33, polarized by the quarter-wave plate 31, and reflected by the reflector 32 in the optical path docking assembly 3, and returns along the original path of the sensing fiber 2. During the return process, the Faraday polarization rotation angle is further superimposed.

[0095] S5: Receive the optical signal returned via sensing fiber optic cable 2, and determine the current value in the conductor under test based on the change in the polarization state of the optical signal. The optical signal receiving module in the signal processing host 5 receives the returned optical signal and converts it into an electrical signal. The signal processing module processes the electrical signal and calculates the current value in the conductor under test according to a preset algorithm. The specific calculation process is as follows:

[0096] S51, Detect the intensity of the two orthogonal polarization components of the returned optical signal. and The optical signal receiving module can use a polarization beam splitter to decompose the returned optical signal into two orthogonal polarization components and detect their intensity.

[0097] S52, Calculate the normalized signal value based on the light intensity of the two orthogonal polarization components. : ,in, This represents the total Faraday polarization rotation angle. By calculating the normalized signal value, the effects of light source power fluctuations and optical path loss variations can be eliminated, improving measurement stability.

[0098] S53, based on the normalized signal value Calculate the total angle of Faraday polarization rotation : .

[0099] S54, based on the total angle of Faraday polarization rotation Verdet constant of sensing fiber 2 Calculate the measured current : ,in, is the vacuum permeability, and coefficient 2 is the multiplication factor generated when the optical signal passes through the sensing fiber 2 twice after being reflected by the reflector 32.

[0100] In addition, the method also includes a temperature compensation step:

[0101] S55, real-time temperature is obtained by a temperature sensor 7 located inside or on the inner surface of the measuring head 1. Temperature sensor 7 monitors the operating temperature of head 1 in real time and transmits the temperature signal to signal processing host 5.

[0102] S56, Determine real-time temperature Does it exceed the preset first threshold? Second threshold ,like and If so, a warning signal will be issued; if If the temperature exceeds the threshold, a danger alarm signal will be issued. The alarm unit in the signal processing host 5 determines whether the temperature exceeds the threshold based on the detection signal from the temperature sensor 7 and issues a corresponding alarm in a timely manner. In one specific embodiment, = 120℃ (Warning) = 150℃ (Danger Alarm). When In addition to issuing an audible and visual alarm, the device can also automatically control the movable clamp arm 12 to open, so that the measuring head 1 is separated from the high-temperature conductor, thus avoiding damage to the device due to continuous contact with the high-temperature conductor.

[0103] S57, based on real-time temperature The temperature compensation coefficient is calculated using a pre-established and stored temperature compensation model. The measured current calculated in step S54 After correction, the compensated current value is obtained. : The temperature compensation model can be a BP neural network model trained based on the correspondence between temperature and measurement error, using temperature... As input, with compensation coefficient The output can be either a polynomial model obtained by fitting the relationship between temperature and measurement error using the least squares method, or a model that can be used as the output. ,in , , … These are the fitting coefficients. Let be the order of the polynomial.

[0104] S6. After the measurement is completed, pull the handle 453 again to drive the movable clamp arm 12 to rotate to the open position, remove the clamp meter from the conductor being measured, move it to the next measurement point, and repeat steps S1 to S57 to complete the rapid measurement of multiple points.

[0105] The implementation principle of this embodiment is as follows: This current measurement method utilizes the structural characteristics of an open-type fiber optic clamp meter to achieve rapid, non-contact current measurement of rigid conductors. By forming a closed loop around the conductor being measured in space using the sensing fiber, the requirements of Ampere's circuital law are met. Utilizing the Faraday magneto-optical effect, the optical signal propagates back and forth along the sensing fiber after being reflected by a mirror. The current value is accurately determined by detecting the change in the polarization state of the optical signal. Simultaneously, the temperature compensation step is combined with the current calculation step to correct the measured value based on temperature changes, improving the measurement accuracy in high-temperature environments and ensuring the accuracy and reliability of the measurement results.

[0106] Example 8

[0107] This embodiment provides a specific application of an open-type fiber optic current clamp meter in measuring the current distribution of cathode steel rods in aluminum electrolysis cells.

[0108] The object being measured is the cathode steel rod of an electrolytic cell, with a cross-sectional dimension of [dimension value missing], and a temperature of approximately 250℃. The measurement environment is the side of the bottom of the electrolytic cell, with limited space, making bilateral operation impossible.

[0109] Measurements were performed using an up-opening fiber optic clamp meter with the dual movable clamp arm 12 structure described in Example 2. The insulation layer 13 is made of flexible glass fiber tubing with a thickness of [thickness missing] and a thermal conductivity of 0.05 W / (m·K). The temperature sensor 7 is a thin-film thermocouple with a response time of less than [time missing]. The alarm thresholds were set as follows: first threshold = 120℃ (early warning), second threshold = 150℃ (danger alarm). The temperature compensation algorithm uses a BP neural network with one node in the input layer (temperature), five nodes in the hidden layer, and one node in the output layer (compensation coefficient).

[0110] The measurement process is as follows: The operator holds a clamp meter and inserts the measuring head 1 into the narrow space of the cathode in the electrolytic cell via the support rod 451. Pulling the handle 453 causes the two movable clamp arms 12 to open upwards simultaneously, forming a U-shaped opening. The cathode steel rod is then inserted directly into the U-shaped opening from above. Releasing the handle 453 releases the stored energy from the spring, and the two movable clamp arms 12 close downwards simultaneously. The collimating lens 33, quarter-wave plate 31, and reflector 32 are precisely aligned, and the sensing fiber 2 forms a closed loop around the conductor under test in space. The signal processing host 5 emits a polarized light signal, which is transmitted to the sensing fiber 2 via the transmission fiber 6. The sensing fiber 2 senses the change in the magnetic field around the conductor under test. After the light signal propagates to the end of the sensing fiber 2, it is collimated by the collimating lens 33 and polarized by the quarter-wave plate 31. After being reflected by the reflector 32, it returns along the original path of the sensing fiber 2. This process of returning twice through the closed loop doubles the Faraday polarization rotation angle. Temperature sensor 7 detects the operating temperature of the sensing ring in real time. The temperature compensation unit uses a BP neural network algorithm to correct the current measurement value based on the temperature signal and outputs the accurate current value after compensation.

[0111] Measurement results show that the error without compensation is [value], and the error after compensation is less than [value], which meets the high-precision requirements for current distribution analysis in electrolytic cells.

[0112] Example 9

[0113] This embodiment provides a specific application of an open-type fiber optic current clamp meter in measuring the current distribution of the anode conductor in an aluminum electrolytic cell.

[0114] The object being measured is the anode guide rod of the electrolytic cell, with a cross-sectional dimension of [missing information]. The temperature was approximately 120℃. The measurement environment was an area with densely packed guide rods, with the distance between adjacent guide rods being only... .

[0115] Measurements were performed using an up-opening fiber optic clamp meter with the dual movable clamp arm 12 structure described in Example 2. Since the anode conductor temperature is relatively low (approximately 120°C), the thermal insulation layer 13 is optional. The temperature sensor 7 remains active to monitor the influence of ambient temperature. A temperature compensation algorithm is enabled to eliminate the effects of ambient temperature fluctuations.

[0116] The measurement process is similar to that in Example 8: The operator inserts the measuring head 1 into the narrow space between the guide rods, pulls the handle 453 to open the movable clamp arm 12, inserts the anode guide rod into the U-shaped opening from above, releases the handle 453 to close the movable clamp arm 12, and the signal processing host 5 completes the current measurement and temperature compensation.

[0117] Measurement results show that the error is less than In terms of measurement efficiency, the single-point measurement time is less than 10 seconds, and a single electrolytic cell (36 anodes) can complete all measurements within 10 minutes, meeting the needs of rapid multi-point measurement of electrolytic cells.

[0118] Example 10

[0119] Please refer to Figures 1 to 6 This embodiment describes the complete working process of the entire top-opening fiber optic current clamp meter device.

[0120] The entire working process of the device includes the following stages:

[0121] I. Preparation Stage

[0122] The operator first uses the quick-connect structure 8 to quickly connect the tail of the transmission optical fiber 6 to the signal processing host 5. The quick-connect structure 8 uses a snap-fit ​​or rotary-locking optical fiber connector, allowing connection without specialized tools. After connection, the fluororubber O-ring seal at the cavity joint provides a protective seal for the optical fiber connector, preventing dust and corrosive gases from entering. The operator then turns on the signal processing host 5, which performs a self-test, including functional checks of the optical signal transmitting module, optical signal receiving module, signal processing module, temperature monitoring unit, alarm unit, and temperature compensation unit. After passing the self-test, the device enters the measurement-ready state.

[0123] II. Opening the Measurement Head Stage

[0124] The operator holds the handle 452 and extends the measuring head 1 into the space where the conductor being measured is located (such as the narrow space of the cathode in an electrolytic cell or the area where the anode conductors are densely arranged) via the support rod 451. The operator pulls the handle 453, which moves downward along the guide groove inside the handle 452. In the embodiment of the double movable clamp arm 12, the handle 453 drives the synchronous connecting rod 43 downward via the flexible cable 454 (steel wire). The synchronous connecting rod 43 simultaneously drives the left connecting shaft 41 and the right connecting shaft 41 outward along their respective guide sleeves 111 via the locking pin 44, and the two elastic reset elements 42 (springs) are compressed to complete energy storage. During the outward movement of the left connecting shaft 41 and the right connecting shaft 41, the first ends of the left movable clamp arm 12 and the right movable clamp arm 12 rotate synchronously upward around their respective hinge points, and the second ends of the two movable clamp arms 12 open outward simultaneously, forming an upward-opening U-shaped receiving opening for the measuring head 1. In the embodiment of the single movable clamp arm 12, the handle 453 drives the connecting shaft 41 to move along the guide sleeve 111 via the flexible cable 454, the elastic reset member 42 is compressed and stored energy, the movable clamp arm 12 rotates upward around the hinge point to the open position, and the measuring head 1 forms an upwardly open receiving opening.

[0125] III. Stage of Inserting the Conductor Under Test

[0126] The operator inserts the conductor to be tested (such as a cathode steel rod or anode rod) directly into the U-shaped receiving opening from above. Due to the top-opening structure, the conductor does not need to be inserted from the side or bent; rigid, thick conductors can be directly inserted from above, adapting to the confined space of the electrolytic cell and the special working conditions of rigid conductors. When the conductor to be tested is a high-temperature conductor (such as a cathode steel rod with a temperature reaching 200℃~300℃), the heat insulation layer 13 on the inner surface of the measuring head 1 (such as a fiberglass flexible tube, thickness...) With a thermal conductivity of ≤0.05 W / (m·K), it blocks heat from being conducted to the internal optical components, protecting optical components such as the sensing fiber 2, quarter-wave plate 31, reflector 32, and collimating lens 33.

[0127] IV. Closed Measurement Head Stage

[0128] The operator releases handle 453. In the implementation of the double movable clamp arm 12, the two springs simultaneously release their stored elastic potential energy, driving the two movable clamp arms 12 to synchronously close from top to bottom via the left connecting shaft 41, right connecting shaft 41, synchronous connecting rod 43, and locking pin 44. The synchronous connecting rod 43 ensures the synchronicity and consistency of the movement of the two movable clamp arms 12, and the upward upper limit action of the synchronous connecting rod 43 ensures that the relative positions of the left and right movable clamp arms 12 remain unchanged after closing. The second ends of the two movable clamp arms 12 are misaligned and connected to form a preset height difference, so that the collimating lens 33, quarter-wave plate 31, and reflector 32 are precisely coaxially aligned, and the sensing fiber 2 forms a closed loop around the conductor under test in space, establishing stable optical path conditions for the round-trip propagation of the optical signal. The layout path of the sensing fiber 2 surrounds the conductor under test in space, forming a complete closed loop, satisfying the requirements of Ampere's circuital law. In the embodiment of the single movable clamp arm 12, the elastic reset member 42 releases elastic potential energy to drive the connecting shaft 41 to reset, and the movable clamp arm 12 rotates downward around the hinge point to the closed position. The free end of the movable clamp arm 12 is misaligned with the end of the second side section 1123 of the fixed frame 112. The collimating lens 33, the quarter-wave plate 31 and the reflector 32 are precisely coaxially aligned. The movable clamp arm 12 and the fixed frame 112 together form a closed frame surrounding the conductor under test.

[0129] V. Current Measurement and Signal Processing Stage

[0130] After the sensing fiber 2 forms a closed loop around the conductor under test in space, the optical signal transmitting module of the signal processing host 5 generates a stable polarized light signal, which is transmitted to the sensing fiber 2 via the transmission fiber 6. The layout path of the sensing fiber 2 forms a closed loop around the conductor under test in space. During propagation along the sensing fiber 2, the polarized light signal is subjected to the magnetic field generated by the current in the conductor under test, resulting in Faraday polarization rotation. After propagating to the end of the sensing fiber 2, the light signal exits from the end face of the sensing fiber 2, is collimated into a parallel beam by the collimating lens 33, and undergoes polarization state conversion after passing through the quarter-wave plate 31. The parallel beam continues to propagate to the reflecting mirror 32 and is reflected, returning along the original path. It then passes through the quarter-wave plate 31 again to complete a further polarization state conversion, is focused by the collimating lens 33, and couples back to the core of the sensing fiber 2. The light signal returns along the original path of the sensing fiber 2, and the superposition of the Faraday polarization rotation angles produces a multiplication effect. The returned light signal is transmitted back to the signal processing host 5 via the transmission fiber 6.

[0131] The optical signal receiving module uses a polarization beam splitter to decompose the returned optical signal into two orthogonal polarization components, and then detects the intensity of each component. and The signal processing module calculates the normalized signal value based on the light intensity of the two orthogonal polarization components:

[0132]

[0133] in, Let be the total angle of Faraday polarization rotation. Then calculate the total angle of Faraday polarization rotation:

[0134]

[0135] Finally, based on the total Faraday polarization rotation angle and the Verdet constant of sensing fiber 2... Calculate the measured current:

[0136]

[0137] in, is the vacuum permeability, and coefficient 2 is the multiplication factor generated when the optical signal passes through the sensing fiber 2 twice after being reflected by the reflector 32.

[0138] VI. Temperature Monitoring and Compensation Phase

[0139] Simultaneously with current measurement, a temperature sensor 7 (such as a PT100 platinum resistance thermometer or a thin-film thermocouple) located inside or on the inner surface of the measuring head 1 detects the operating temperature of the measuring head 1 in real time. The temperature signal is then transmitted to the temperature monitoring unit of the signal processing host 5.

[0140] The alarm unit determines whether the temperature signal exceeds a preset threshold: if... (e.g., 120℃) and (e.g., 150℃) will trigger a warning signal to alert operators; if If the device is not in contact with the high-temperature conductor, it will issue an audible and visual hazard alarm signal and automatically control the movable clamp arm 12 to open, so that the measuring head 1 is separated from the high-temperature conductor, thus avoiding continuous contact with the high-temperature conductor and causing damage to the device.

[0141] The temperature compensation unit calculates based on the temperature signal. The temperature compensation coefficient is calculated using a pre-established and stored temperature compensation model. For current measurement values After correction, the compensated current value is obtained:

[0142]

[0143] The temperature compensation model can be a BP neural network model (based on temperature). As input, with compensation coefficient (For output) or a polynomial model obtained by least squares fitting. The signal processing host 5 outputs the compensated, precise current value. .

[0144] VII. Retrieval and Transfer Stage

[0145] After the measurement is completed, the operator pulls handle 453 again, driving the movable clamp arm 12 to rotate to the open position, removing the clamp meter from the conductor being measured. Then, the measuring head 1 is moved to the next measuring point, and the above process of opening, clamping, closing, measuring, and removing is repeated to complete rapid multi-point measurements. For example, in the measurement of anode current distribution in an aluminum electrolytic cell, the measurement time at a single point is less than 10 seconds, and all measurements can be completed within 10 minutes for a single electrolytic cell (36 anodes).

[0146] VIII. Maintenance Phase

[0147] When the frame (including the movable clamp arm 12, base 11, support rod 451, and other mechanical structural parts) deforms or is damaged due to long-term use in high-temperature and corrosive environments, the operator pulls the pull ring of the pull-ring release mechanism 9 to the right to the limit point to release the lock, thus detaching the signal processing host 5 from the frame. The signal processing host 5 is then installed onto a new frame, completing the replacement. The expensive signal processing host 5 can be reused, requiring only the replacement of the low-cost mechanical frame, reducing maintenance costs.

[0148] IX. Collection and Transportation Stage

[0149] After the measurement task is completed, the operator quickly disconnects the transmission optical fiber 6 from the signal processing host 5 using the quick-connect structure 8 and stores them separately to prevent damage to the optical fiber due to bending during transportation. The sealing structure at the cavity joint continues to protect the optical fiber interface from dust and moisture during storage.

[0150] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Any other corresponding changes and modifications made based on the technical concept of this application should be included within the scope of protection of this application.

Claims

1. A top-opening fiber optic current clamp meter, characterized in that, include: The measuring head (1) includes a base (11) and at least one movable clamp arm (12), one end of which is rotatably mounted on the base (11). A sensing fiber (2) is disposed inside the measuring head (1), and the sensing fiber (2) is an optical fiber with Faraday magneto-optical effect; The optical path docking assembly (3) is disposed at the docking point between the movable clamp arm (12) and the fixed part of the measuring head (1); The driving mechanism (4) is connected to the movable clamp arm (12) for driving the movable clamp arm (12) to rotate between the open position and the closed position; wherein, in the open position, the measuring head (1) forms an upward-opening receiving opening for the conductor to be measured to be placed from above; in the closed position, the movable clamp arm (12) and the fixed part of the measuring head (1) are joined together, the sensing optical fiber (2) forms a closed loop around the conductor to be measured in space, and the optical path docking assembly (3) reflects the light signal emitted from the end of the sensing optical fiber (2) back to the sensing optical fiber (2), so that the light signal propagates back and forth along the sensing optical fiber (2); The signal processing host (5) is optically connected to the sensing fiber (2) via the transmission fiber (6) and is used to inject polarized light signals into the sensing fiber (2) and receive the light signals returned by the sensing fiber (2) when the movable clamp arm (12) is in the closed position, and determine the current value in the conductor under test based on the polarization state change of the returned light signals.

2. The top-opening fiber optic current clamp meter according to claim 1, characterized in that, The number of movable clamp arms (12) is two, and the first ends of the two movable clamp arms (12) are rotatably mounted on the two ends of the base (11); The sensing fiber (2) starts from one end of the base (11), extends along the inside of one of the movable clamp arms (12) to the second end of the movable clamp arm (12), then folds back into the base (11), and then extends along the inside of the other movable clamp arm (12) to the second end of the movable clamp arm (12), thus being continuously arranged inside the base (11) and inside the two movable clamp arms (12). The sensing fiber (2) has a bending allowance section reserved at the hinge, and the bending radius of the bending allowance section is not less than the minimum allowable bending radius of the sensing fiber (2) to maintain the continuity of the optical path when the movable clamp arm (12) rotates; one end of the transmission fiber (6) is led out from the inside of the base (11) and extends to the signal processing host (5); The driving mechanism (4) is used to drive the two movable clamp arms (12) to rotate synchronously; in the open position, the second ends of the two movable clamp arms (12) open outward to form the receiving opening; in the closed position, the second ends of the two movable clamp arms (12) close and dock synchronously, and the optical path docking assembly (3) is disposed at the docking point of the second ends of the two movable clamp arms (12). The optical path docking assembly (3) includes a collimating lens (33) and a quarter-wave plate (31) disposed at the second end of one of the movable clamp arms (12), and a collimating lens (33) and a quarter-wave plate (31) disposed at the second end of the other movable clamp arm (12). The end of the sensing fiber (2) is located at the second end of the movable clamp (12) on which the collimating lens (33) and the quarter-wave plate (31) are provided; in the closed position, the second ends of the two movable clamps (12) are misaligned and connected, so that the collimating lens (33), the quarter-wave plate (31) and the reflector (32) are coaxially aligned; the light signal emitted from the end of the sensing fiber (2) is collimated by the collimating lens (33), and then reflected by the quarter-wave plate (31) and the reflector (32) in sequence, and returns along the original path to couple back to the sensing fiber (2).

3. The top-opening fiber optic current clamp meter according to claim 2, characterized in that, Two sets of guide sleeves (111) are formed at both ends of the base (11); The drive mechanism (4) includes two connecting shafts (41), two elastic reset members (42), a synchronous link (43), and a control component (45); The two connecting shafts (41) are slidably inserted into the two sets of guide sleeves (111), and one end of the two connecting shafts (41) is hinged to the first end of the two movable clamp arms (12); The two elastic reset members (42) are respectively sleeved on the two connecting shafts (41). One end of the two elastic reset members (42) abuts against the two guide sleeves (111) respectively, and the other end abuts against the protrusions (411) on the two connecting shafts (41) respectively, so as to form a restoring force that tends to the two movable clamp arms (12) to reach the closed position; The two ends of the synchronous link (43) are respectively fixedly connected to the other ends of the two connecting shafts (41) to enable the two connecting shafts (41) to move synchronously to drive the two movable clamp arms (12) to rotate synchronously. The control assembly (45) includes a support rod (451), a handle (452), a lever (453), and a flexible cable (454). The two ends of the support rod (451) are fixedly connected to the base (11) and the handle (452), respectively. The lever (453) is slidably mounted on the handle (452). The flexible cable (454) passes through the interior of the support rod (451) and is used to connect the lever (453) and the synchronous linkage (…). 43); When the handle (453) is pulled, the flexible cable (454) drives the synchronous connecting rod (43) and the two connecting shafts (41) to move outward along the guide sleeve (111), so that the first ends of the two movable clamp arms (12) rotate around the hinge point to the open position; when the handle (453) is released, the two elastic reset members (42) drive the two connecting shafts (41) to reset, so that the two movable clamp arms (12) return to the closed position.

4. The top-opening fiber optic current clamp meter according to claim 1, characterized in that, The number of movable clamp arms (12) is one, and a fixed frame (112) is integrally formed on the upper part of the base (11); the fixed frame (112) has a bottom section (1121) and a first side section (1122) and a second side section (1123) extending upward from both ends of the bottom section (1121); One end of the movable clamp arm (12) is hinged to the end of the first side section (1122); in the closed position, the other end of the movable clamp arm (12) is connected to the end of the second side section (1123), and the movable clamp arm (12) and the fixed frame (112) together form a closed frame surrounding the conductor under test. One end of the sensing optical fiber (2) is continuously laid inside the fixed frame (112), and the other end is laid inside the movable clamp arm (12). The sensing optical fiber (2) starts from the bottom section (1121) of the fixed frame (112), extends upward along the inside of the first side section (1122), enters the inside of the movable clamp arm (12) through the hinge, extends along the movable clamp arm (12) to its free end and then turns back, returns to the hinge along the movable clamp arm (12), and then returns to the bottom section (1121) through the first side section (1122). Then, it extends upward along the interior of the second side section (1123) to the end of the second side section (1123). The sensing fiber (2) has a bending allowance section reserved at the hinge of the movable clamp arm (12) and the first side section (1122). The bending radius of the bending allowance section is not less than the minimum allowable bending radius of the sensing fiber (2) so as to keep the optical path continuous when the movable clamp arm (12) rotates. The transmission fiber (6) is led out from the bottom section (1121) of the fixed frame (112) and optically connected to the signal processing host (5). The optical path docking assembly (3) is located at the docking point between the free end of the movable clamp arm (12) and the end of the second side section (1123); wherein, the end of the second side section (1123) is provided with a collimating lens (33) and a quarter-wave plate (31), and the free end of the movable clamp arm (12) is provided with a reflector (32); the end of the sensing fiber (2) is located at the end of the second side section (1123); in the closed position, the free end of the movable clamp arm (12) and the end of the second side section (1123) are misaligned and docked, so that the collimating lens (33), the quarter-wave plate (31) and the reflector (32) are coaxially aligned; the light signal emitted from the end of the sensing fiber (2) is collimated by the collimating lens (33), and then reflected by the quarter-wave plate (31) and the reflector (32) in sequence, and returns along the original path to couple back to the sensing fiber (2).

5. The top-opening fiber optic current clamp meter according to claim 4, characterized in that, A guide sleeve (111) is formed on the base (11); The drive mechanism (4) includes a connecting shaft (41), an elastic reset member (42), and a control assembly (45); the connecting shaft (41) is slidably inserted into the guide sleeve (111), and one end of the connecting shaft (41) is hinged to one end of the movable clamp arm (12); the elastic reset member (42) is sleeved on the connecting shaft (41), one end of the elastic reset member (42) abuts against the guide sleeve (111), and the other end abuts against the protrusion (411) on the connecting shaft (41) to form a restoring force that tends to bring the movable clamp arm (12) and the second side section (1123) to the closed position; the control assembly (45) includes a support rod (451), a handle (452), a lever (453), and a flexible cable (454). The two ends of the support rod (451) are fixedly connected to the base (11) and the handle (452) respectively. The handle (453) is slidably disposed on the handle (452). The flexible cable (454) passes through the inside of the support rod (451) and is used to connect the handle (453) and the other end of the connecting shaft (41). When the handle (453) is pulled, the flexible cable (454) drives the connecting shaft (41) to move along the guide sleeve (111), so that the movable clamp arm (12) rotates around the hinge point to the open position. When the handle (453) is released, the elastic reset member (42) drives the connecting shaft (41) to reset, so that the movable clamp arm (12) returns to the closed position.

6. The top-opening fiber optic current clamp meter according to claim 1, characterized in that, The inner surface of the measuring head (1) facing the conductor being measured is provided with a heat insulation layer (13), and the thermal conductivity of the heat insulation layer (13) is not greater than 0.05 W / (m·K).

7. The top-opening fiber optic current clamp meter according to claim 1, characterized in that, It also includes a temperature sensor (7), which is disposed inside or on the inner surface of the measuring head (1); The signal processing host (5) includes: A temperature monitoring unit is used to receive the detection signal from the temperature sensor (7); An alarm unit is used to issue a warning signal when the temperature detected by the temperature sensor (7) exceeds a preset first threshold, and to issue a danger alarm signal when the temperature exceeds a second threshold higher than the first threshold. The temperature compensation unit is used to correct the current measurement value based on the detection signal of the temperature sensor (7) by using a neural network model based on the correspondence between temperature and measurement error, which is pre-trained and stored in the signal processing host (5), or a least squares fitting model that is pre-fitted and stored in the signal processing host (5).

8. A current measurement method, characterized in that, The method employs an up-opening fiber optic current clamp meter as described in any one of claims 1 to 7, and includes the following steps: S1. Drive the movable clamp arm (12) to rotate to the open position, so that the measuring head (1) forms an upward-open receiving opening; S2. Insert the conductor to be tested into the receiving opening from above; S3. Drive the movable clamp arm (12) to rotate to the closed position, so that the sensing fiber (2) forms a closed loop around the conductor under test in space; S4. Inject a polarized light signal into the sensing fiber (2). The polarized light signal propagates along the sensing fiber (2) and undergoes Faraday polarization rotation under the action of the magnetic field generated by the current of the conductor being measured. After the polarized light signal reaches the end of the sensing fiber (2), it is reflected by the optical path docking component (3) and returns along the original path of the sensing fiber (2). S5. Receive the optical signal returned through the sensing optical fiber (2) and determine the current value in the conductor under test based on the change in polarization state of the optical signal.

9. The current measurement method according to claim 8, characterized in that, The sensing optical fiber (2) wraps around the conductor under test once. In step S5, the current value in the conductor under test is determined based on the polarization state change of the optical signal, specifically including: S51. Detect the light intensity of the two orthogonal polarization components of the returned optical signal. and ; S52. Calculate the normalized signal value based on the light intensity of the two orthogonal polarization components. : ， in, This represents the total angle of Faraday polarization rotation; S53, Based on the normalized signal value Calculate the total angle of Faraday polarization rotation : ； S54. Based on the total angle of Faraday polarization rotation Verdet constant of sensing fiber (2) Calculate the measured current : ， in, is the vacuum permeability, and coefficient 2 is the multiplication factor generated by the optical signal passing through the sensing fiber (2) twice after being reflected by the mirror (32).

10. The current measurement method according to claim 9, characterized in that, It also includes a temperature compensation step: S55. The real-time temperature is obtained by a temperature sensor (7) located inside or on the inner surface of the measuring head (1). ; S56. Determine the real-time temperature. Does it exceed the preset first threshold? Second threshold ,like and If so, a warning signal will be issued; if If so, a danger alarm signal will be issued; S57. Based on the real-time temperature The temperature compensation coefficient is calculated using a pre-established and stored temperature compensation model. The measured current calculated in step S54 After correction, the compensated current value is obtained. : ， The temperature compensation model is one of the following: (a) A BP neural network model trained based on the correspondence between temperature and measurement error, wherein the BP neural network model uses temperature as the basis for measurement error. As input, with compensation coefficient For output; or (b) The polynomial model obtained by least squares fitting based on the correspondence between temperature and measurement error: in , , … These are the fitting coefficients. Let be the order of the polynomial.

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