A three-phase four-wire electric energy meter calibration device with a current transformer

Abstract

This utility model discloses a three-phase four-wire energy meter calibration device with a current transformer, comprising a housing, a quick-installation structure, and a clamping structure. The housing integrates a voltage interface, a current interface, and a current transformer interface. The quick-installation structure consists of a symmetrical mounting frame, which includes a mounting plate, a vertical plate, and a support plate. The mounting plate is quickly fixed to the calibration platform via mounting holes and bolts. The clamping structure includes a folded plate integrally formed with the support plate. The folded plate contains a bearing and a rotating rod. The rotating rod drives a push block to move along a slide groove and a sliding plate via an external thread. The push block is connected to the clamping plate via an extension rod. A rubber pad on the clamping plate protects the surface of the housing. A frustum-shaped support foot is provided at the lower end of the housing, which cooperates with the positioning holes and positioning sleeves on the support plate to achieve precise positioning. This device is easy to install, provides stable clamping, and offers accurate positioning. Furthermore, it eliminates the need for manual modification of the wiring, directly achieving physical matching between the energy meter / transformer interface and the calibration platform, thus solving the problem of connection incompatibility.

Description

Technical Field

[0001] This utility model relates to a calibration device for a three-phase four-wire energy meter with a current transformer, belonging to the field of power metering equipment. Background Technology

[0002] In the field of electricity metering, electricity meters are developing towards intelligence, digitalization, and multi-functionality, with electricity meters equipped with current transformer interfaces being widely used. Traditional electricity meter calibration mainly relies on the electricity meter's voltage terminals and current wiring holes to achieve a physical connection with the calibration bench. However, some current three-phase four-wire electricity meters with current transformers, such as embedded and compact electricity meters, are only equipped with voltage terminals, with the current transformer directly connected to the electricity meter terminals or interface. This means that such electricity meters cannot be directly calibrated using a calibration bench.

[0003] Problems with existing technology:

[0004] Firstly, the connection methods are incompatible; the output interfaces of the calibration bench, such as banana plugs and alligator clips, are not compatible with the interfaces of the current transformers, such as bolt-type and welded type. In actual operation, it is necessary to manually modify the wires or use transition connectors, which can easily introduce contact resistance errors and thus affect the accuracy of calibration.

[0005] Secondly, there are high safety risks. When the secondary side of the current transformer is open, high voltage will be generated, and the traditional manual wiring method is prone to misoperation, which poses a threat to the safety of operators and the stable operation of equipment.

[0006] Third, the calibration efficiency is low; traditional methods require manual connection phase by phase and lack anti-misinsertion design. In a three-phase four-wire system, phase adjustment is required frequently, which consumes a lot of time and is difficult to meet the needs of efficient calibration.

[0007] Fourth, the installation is cumbersome; it requires drilling holes or welding corner plates onto the calibration device.

[0008] Currently, although some improved calibration schemes exist for electricity meters, there is still no comprehensive and effective calibration device and method to address the issues of connection incompatibility, high safety risks, and low efficiency for electricity meters equipped only with current transformer interfaces. Therefore, a new technical solution is urgently needed to overcome these shortcomings. Utility Model Content

[0009] The purpose of this invention is to provide a calibration device for a three-phase four-wire energy meter with a current transformer, which can effectively solve the above-mentioned problems.

[0010] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution:

[0011] The calibration device integrates a voltage interface, a current interface, and a current transformer interface. The voltage interface connects the voltage input terminal of the energy meter to the voltage output terminal of the calibration platform. The current interface connects the current input terminal of the energy meter to the current output terminal of the calibration platform. The current transformer terminals connect to the current terminals or interfaces of the energy meter, supporting various transformer wiring methods such as bolt-on and plug-in types. It supports three-phase four-wire or three-phase three-wire wiring. The calibration device features a mis-insertion prevention design, including color markings, a TTB open-circuit protection terminal, and an aviation plug, to ensure correct wiring. The calibration device also has a quick-connect connector for rapid connection to the calibration platform.

[0012] Furthermore: the current transformer interface includes at least one of bolt-type interface, terminal-type interface, and plug-in interface; the bolt-type interface is compatible with M4-M6 bolts and has a built-in elastic copper sheet to ensure reliable contact; the terminal-type interface uses dedicated terminals for TTB current transformers and adopts an operating handle mechanism with "make-before-break" contacts, which can short-circuit the current transformer and prevent high voltage from being generated in the secondary winding; the plug-in interface uses a standard plug and supports quick replacement.

[0013] Furthermore: when the voltage interface is a three-phase four-wire interface, it includes voltage terminals and a 4-pin aviation plug, which are used to connect the UA, UB, UC and neutral terminals of the test bench, respectively; when it is a three-phase three-wire interface, it is used to connect the UA, UB and UC terminals of the test bench.

[0014] Furthermore: the calibration device includes a housing and a quick-installation structure disposed at the lower end of the housing; the quick-installation structure includes two symmetrically arranged mounting brackets, each mounting bracket consisting of two mounting plates, a vertical plate disposed at the upper end of the mounting plates, and a support plate disposed at the upper end of the vertical plates; the mounting plates are provided with mounting holes, and bolts are threaded through the mounting holes for installation; the housing is disposed on the support plate by a clamping structure.

[0015] Furthermore: the clamping structure includes a folding plate integrally formed with the bearing plate, the folding plate is provided with a through hole, a bearing is provided in the through hole, a rotating rod is provided in the bearing, an external thread is provided on the outer periphery of one end of the rotating rod, a pushing block is threadedly connected to the external thread, and the pushing block moves toward the housing under the interference of the external thread.

[0016] Furthermore, the support plate is also provided with a sliding groove, and a sliding plate is provided in the sliding groove, with the upper end of the sliding plate fixed to the push block.

[0017] Furthermore: an extension rod is provided at the end of the push block near the housing, a clamping plate is provided at the end of the extension rod, and a rubber pad is provided on the end face of the clamping plate.

[0018] Furthermore: the lower end of the housing is provided with a support foot, and the support plate is provided with a positioning hole for the support foot to pass through.

[0019] Furthermore: the support foot is shaped like a frustum, with the minor diameter of the frustum facing downwards; a positioning sleeve is provided on the positioning hole, and the inner surface of the positioning sleeve is in contact with the outer surface of the support foot.

[0020] The beneficial effects are:

[0021] 1. No manual modification of wiring is required; physical matching between the energy meter / current transformer interface and the calibration bench is achieved directly, resolving connection incompatibility issues. Safety protection measures such as anti-misinsertion design and TTB anti-open-circuit terminals reduce operational risks and prevent high voltage generation from open circuits on the secondary side of the current transformer, complying with relevant safety standards. Support for multiple transformer output methods and calibration bench interfaces improves compatibility, reduces calibration time by more than 50%, and greatly enhances calibration efficiency. Calibration results meet the accuracy requirements of relevant regulations, ensuring safety and reliability, and are suitable for fields such as power metering and industrial automation.

[0022] 2. Easy and efficient installation: The quick-installation structure includes symmetrical mounting brackets, mounting plates, vertical plates, support plates, mounting holes, and bolts, which can quickly fix the device on the calibration platform. The installation is simple, saves time, and is suitable for batch calibration.

[0023] 3. Stable clamping and simple operation: The clamping structure consists of a folding plate, bearing, rotating rod, external thread, pushing block, slide groove and sliding plate. The rotating rod drives the pushing block to move smoothly, making the clamping shell stable and labor-saving, and easy to operate.

[0024] 4. Protective housing and high durability: The push block is connected to the clamping plate through the extension rod. The rubber pad on the clamping plate flexibly contacts the housing to avoid scratches or damage, protect the electricity meter and extend its service life.

[0025] 5. Precise positioning and good adaptability: The frustum-shaped support feet at the bottom of the housing cooperate with the positioning holes and positioning sleeves on the bearing plate to ensure precise positioning of the housing, stability and reliability, and adaptability to various models of electricity meters.

[0026] 6. Simple structure and easy maintenance: The device adopts a modular design, and the components such as the mounting bracket, clamping structure and positioning sleeve are easy to process and replace. The materials are durable, maintenance is convenient, and the operating cost is reduced. Attached Figure Description

[0027] For ease of explanation, this utility model is described in detail below with reference to the specific embodiments and accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the structure of this utility model;

[0029] Figure 2for Figure 1 Enlarged view of a portion of the image;

[0030] Figure 3 This is a schematic diagram of the quick-installation interface of this utility model;

[0031] Figure 4 for Figure 3 Enlarged view of a portion of the image;

[0032] Figure 5 This is the front view of the present utility model;

[0033] Figure 6 This is the left view of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Housing; 2. Quick-installation structure; 3. Mounting bracket; 31. Mounting plate; 32. Vertical plate; 33. Bearing plate; 34. Mounting hole; 35. Bolt; 4. Clamping structure; 41. Folding plate; 42. Bearing; 43. Rotating rod; 44. External thread; 45. Push block; 46. Slide groove; 47. Slide plate; 48. Extension rod; 49. Clamping plate; 5. Rubber pad; 6. Support foot; 7. Positioning hole; 8. Positioning sleeve; 9. Voltage interface; 10. Current interface; 11. Current transformer interface. Detailed Implementation

[0036] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] It should be noted that, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0038] Furthermore, the terms “first,” “second,” “third,” etc., are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance.

[0039] See Figure 1-6 This is an embodiment of a calibration device for a three-phase four-wire energy meter with a current transformer, which is mainly used to calibrate the metering accuracy of a three-phase four-wire energy meter and is suitable for the energy meter calibration needs of industrial, commercial and civil power systems.

[0040] See Figure 1 As shown in the document, the three-phase four-wire energy meter calibration device with current transformer integrated in this application integrates a voltage interface 9, a current interface 10, and a transformer interface. The voltage interface 9 of the calibration device is used to connect the voltage input terminal of the energy meter and the voltage output terminal of the calibration platform. The current interface 10 connects the current input terminal of the energy meter and the current output terminal of the calibration platform. The current transformer terminal is used to connect the current terminal or interface of the energy meter, supporting various transformer output methods such as bolt type and plug-in type. It supports three-phase four-wire or three-phase three-wire wiring. The calibration device has a design to prevent mis-insertion, including color markings, TTB anti-open circuit terminals, and aviation plugs to ensure correct wiring. The calibration device also has a quick-connect connector for quick connection with the calibration platform.

[0041] The current interface 10 includes at least one of bolt-type interface, terminal-type interface, and plug-in interface; the bolt-type interface is compatible with M4-M6 bolts and has a built-in elastic copper sheet to ensure reliable contact; the terminal-type interface uses dedicated terminals for TTB current transformers and adopts an operating handle mechanism with "close first, then disconnect" contacts, which can short-circuit the current transformer and prevent high voltage from being generated in the secondary winding; the plug-in interface uses a standard plug and supports quick replacement.

[0042] When voltage interface 9 is a three-phase four-wire interface, it includes voltage terminals and a 4-pin aviation plug, which are used to connect the UA, UB, UC and neutral terminals of the test bench, respectively; when it is a three-phase three-wire interface, it is used to connect the UA, UB and UC terminals of the test bench.

[0043] The calibration method for the above-mentioned calibration device includes the following steps:

[0044] Parameter settings: Input the rated parameters of the energy meter on the calibration bench, including voltage level, current ratio, wiring method, and verification constant;

[0045] Connect the calibration device: Connect the current interface 10S1 / S2 of the calibration device to the current interface 10 of the energy meter, and the voltage interface 9 to the voltage terminal of the energy meter; at the same time, connect the other end of the calibration device to the calibration stand.

[0046] Calibration testing: Perform creep test, startup test and basic error test;

[0047] Data logging: The calibration bench automatically stores test data and generates calibration reports.

[0048] Among them, the creep test is to test the output unit pulse under the condition of applying a reference voltage of 115% and cosφ (sinφ) = 1; the start-up test is to test the start-up current IQ under the condition of applying a reference voltage Un and cosφ (sinφ) = 1; the basic error test is to measure the basic error in the order of decreasing load current under different power factors.

[0049] The calibration device also includes a housing 1 and a quick-installation structure 2 located at the lower end of the housing 1. The housing 1 houses the core components required for electricity meter calibration, such as circuit modules, current transformers, multiple interface units, signal processing units, and display modules. It is made of high-strength engineering plastic with an anti-static coating, providing excellent insulation and corrosion resistance. The quick-installation structure 2 allows for rapid mounting of the device onto the calibration platform or workbench, ensuring a simple and stable installation process.

[0050] Detailed design of the quick-installation structure:

[0051] like Figure 1 As shown, the quick-installation structure 2 includes two symmetrically arranged mounting brackets 3. Each mounting bracket 3 consists of two mounting plates 31, a vertical plate 32 disposed on the upper end of the mounting plate 31, and a support plate 33 disposed on the upper end of the two vertical plates 32 and fixed together. The entire mounting bracket 3 is made of high-strength aluminum alloy and is integrally formed by bending process, which has good rigidity and corrosion resistance, ensuring structural stability under long-term use.

[0052] like Figure 2 As shown, each mounting plate 31 is a rectangular plate structure with an anodized surface to enhance wear resistance. The mounting plate 31 has two elongated mounting holes 34 for standard bolts 35. The bolts 35 are made of stainless steel and equipped with flat washers and spring washers. They are threaded into the pre-drilled holes of the mounting platform through the mounting holes 34, ensuring a secure connection between the mounting frame 3 and the platform. A vertical plate 32 is fixed to the upper end of the mounting plate 31, supporting the load-bearing plate 33. The load-bearing plate 33 is a horizontally positioned rectangular plate with a flat upper surface, used to support the housing 1.

[0053] In existing technologies, the housing 1 is typically secured by adding external mounting angles and fixing them to the support plate 33 with bolts. This device incorporates a clamping structure to facilitate the assembly and disassembly of the housing 1. The housing 1 is fixed to the support plate 33 via the clamping structure 4. The clamping structure 4 is ingeniously designed, enabling rapid clamping and release of the housing 1 while ensuring protection of the housing 1 during the clamping process. The specific components of the clamping structure 4 are as follows:

[0054] Folding plate 41: Folding plate 41 is integrally formed with bearing plate 33 and is manufactured using a bending process with a bending angle of 90°. A through hole is provided on folding plate 41, and a bearing 42 is installed in the through hole via an interference fit. The bearing 42 is a deep groove ball bearing, which has low friction and wear resistance characteristics, ensuring smooth rotation of the rotating rod 43.

[0055] Rotating rod 43: The rotating rod 43 is made of stainless steel with a polished surface to reduce friction. One end is machined with external threads 44, and the other end is equipped with a knob for easy manual rotation. The rotating rod 43 passes through the bearing 42, and the knob end protrudes from the outside of the folding plate 41 for easy application of force by the operator.

[0056] Push block 45: Push block 45 is a rectangular block structure made of high-strength engineering plastic, which is lightweight and wear-resistant. The push block 45 has an internal threaded hole that matches the external thread 44, and it engages with the rotating rod 43 via a threaded connection. When the rotating rod 43 is rotated, the push block 45 moves axially along the rotating rod 43 under the interference of the external thread 44, moving closer to or away from the housing 1, thus achieving the clamping or releasing function.

[0057] like Figure 3 , Figure 4 As shown, the slide 46 and slide plate 47: The slide 46 is machined on the support plate 33 and is arranged axially along the rotating rod 43. The slide plate 47 is embedded in the slide 46 and is fixedly connected to the push block 45 by screws. The inner wall of the slide 46 is coated with grease (such as lithium-based grease) to reduce the sliding resistance of the slide plate 47 and ensure that the push block 45 moves smoothly.

[0058] Extension rod 48 and clamping plate 49: An extension rod 48 is fixed to one end of the push block 45 near the housing 1. The extension rod 48 is a round steel rod, and a clamping plate 49 is fixed to its end by a threaded connection. The clamping plate 49 is a rectangular steel plate with a rubber pad 5 attached to its surface. The rubber pad 5 is made of natural rubber, which has good elasticity and wear resistance, and can flexibly contact the surface of the housing 1 to avoid scratches or deformation during clamping.

[0059] Before clamping the housing 1, it is necessary to position the housing 1 to facilitate its movement during clamping. The positioning is achieved using a positioning structure; the detailed design of this positioning structure is as follows:

[0060] like Figure 4 As shown, a support foot 6 is provided at the lower end of the housing 1. The support foot 6 is truncated cone-shaped with its small diameter facing downwards to improve positioning accuracy. A positioning hole 7 is correspondingly provided on the bearing plate 33, and a positioning sleeve 8 is installed inside the positioning hole 7. The positioning sleeve 8 is made of wear-resistant engineering plastic, and its inner surface fits against the outer surface of the support foot 6 to ensure precise alignment of the housing 1 during installation. After the support foot 6 is inserted into the positioning hole 7, the positioning sleeve 8 restricts the horizontal movement of the housing 1, thereby enhancing installation stability.

[0061] Assembly and usage methods of the device

[0062] 1. Fix the mounting plates 31 of the two mounting brackets 3 to the calibration platform with bolts 35, ensuring that the mounting plates 31 are in close contact with the platform surface and that the bolts 35 are tightened without loosening.

[0063] 2. Place the housing 1 on the support plate 33, align the support foot 6 at the lower end of the housing 1 with the positioning hole 7 on the support plate 33, and slowly press down until the support foot 6 is fully inserted into the positioning sleeve 8 to achieve initial positioning.

[0064] 3. Rotate the rotating rod 43, which drives the pushing block 45 to move along the slide groove 46 through the external thread 44, so that the rubber pad 5 on the clamping plate 49 gradually approaches and contacts the side of the housing 1. Continue to rotate the rotating rod 43 until the clamping plate 49 applies sufficient clamping force to the housing 1 through the rubber pad 5 to ensure that the housing 1 is firmly fixed.

[0065] After securing housing 1, connect the power and signal lines of the calibration device and start the internal calibration circuit. Install the three-phase four-wire energy meter to be calibrated in the test slot inside housing 1, and connect the current transformer and voltage sampling module. Set the calibration parameters (such as voltage, current, power factor, etc.) through the display module on housing 1, start the calibration program, record the meter's measurement data, and compare it with the standard values.

[0066] This device achieves rapid connection to the calibration platform via the quick-installation structure 2, while the cooperation of the mounting plate 31 and bolts 35 ensures the overall stability of the device. The clamping structure 4 provides a smooth and controllable clamping force through the coordinated operation of the rotating rod 43, the pushing block 45, and the sliding plate 47. The rubber pad 5 effectively protects the surface of the housing 1, preventing scratches or deformation. The frustum-shaped design of the support feet 6 and the positioning sleeve 8 ensures precise positioning of the housing 1, adapting to various models of three-phase four-wire energy meters. The device is easy to operate, has high calibration efficiency, and is suitable for batch calibration scenarios.

[0067] The TTB open-circuit protection current transformer terminal is a product of the Klippon® Connect series developed by Weidmüller, used for safe wiring of current and voltage transformers in power transmission and distribution. Under normal operation, the TTB terminal keeps the secondary circuit of the current transformer closed. When it is necessary to disconnect the measurement circuit or perform maintenance operations, the operating handle should first short-circuit the secondary side of the current transformer, and then disconnect it from other equipment. After the operation is completed, the connection should be restored first, and then the short circuit should be released, following the principle of "close before disconnect" to prevent the secondary circuit from opening.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A calibration device for a three-phase four-wire energy meter with a current transformer, characterized in that: The device includes a housing (1) and a quick-installation structure (2) disposed at the lower end of the housing (1); the quick-installation structure (2) includes two symmetrically arranged mounting brackets (3), each mounting bracket (3) consisting of two mounting plates (31), a vertical plate (32) disposed at the upper end of the mounting plate (31), and a support plate (33) disposed at the upper end of the vertical plate (32); the mounting plate (31) is provided with mounting holes (34), and bolts (35) are threaded through the mounting holes (34) for installation; the housing (1) is disposed on the support plate (33) by a clamping structure (4).

2. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 1, characterized in that: The clamping structure (4) includes a folding plate (41) integrally formed with the bearing plate (33). The folding plate (41) is provided with a through hole, and a bearing (42) is provided in the through hole. A rotating rod (43) is provided in the bearing (42). An external thread (44) is provided on the outer periphery of one end of the rotating rod (43). A push block (45) is threadedly connected to the external thread (44). The push block (45) moves toward the housing (1) under the interference of the external thread (44).

3. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 2, characterized in that: The support plate (33) is also provided with a slide groove (46), and a slide plate (47) is provided in the slide groove (46). The upper end of the slide plate (47) is fixed to the push block (45).

4. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 3, characterized in that: An extension rod (48) is provided at the end of the push block (45) near the housing (1), and a clamping plate (49) is provided at the end of the extension rod (48), with a rubber pad (5) provided on the end face of the clamping plate (49).

5. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 4, characterized in that: The lower end of the housing (1) is provided with a support foot (6), and the bearing plate (33) is provided with a positioning hole (7) for the support foot (6) to pass through.

6. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 5, characterized in that: The support foot (6) is shaped like a frustum, with the minor diameter of the frustum facing downwards; a positioning sleeve (8) is provided on the positioning hole (7), and the inner surface of the positioning sleeve (8) is in contact with the outer surface of the support foot (6).

7. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 1, characterized in that: The housing (1) integrates a voltage interface (9), a current interface (10), and a current transformer interface (11), and supports three-phase four-wire or three-phase three-wire wiring.

8. The calibration device for a three-phase four-wire energy meter with a current transformer according to claim 7, characterized in that: The voltage interface (9) is used to connect the voltage input terminal of the energy meter and the voltage output terminal of the test bench; the current interface (10) is used to connect the current input terminal of the energy meter and the current output terminal of the test bench; the current transformer interface (11) is used to connect the current terminal or interface of the energy meter, and supports various transformer output methods such as bolt type and plug-in type.

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