Three-phase electric energy meter and three-phase electric energy metering circuit

Abstract

The utility model relates to a three-phase electric energy meter, a metering register is arranged in the three-phase electric energy meter, the metering register is provided with an A-phase interface, a B-phase interface, a C-phase interface and an N-phase interface, the A-phase interface is used for connecting an A-phase wire, the B-phase interface is used for connecting a B-phase wire, the C-phase interface is used for connecting a C-phase wire, and the N-phase interface is used for connecting an N-phase wire. And the N-phase interface is not connected with the electric wire. The application scenarios of three-phase four-wire and three-phase four-wire wiring modes can be compatible through one electric energy meter, equipment does not need to be replaced when the wiring modes are converted, the same electric energy meter is adopted to carry out simple wiring change, the conversion of the wiring modes can be completed, the complexity of the whole process of the product and the operation management cost are reduced, and the production efficiency is improved. In the use and installation process, the labor cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of electricity meters, and more particularly to a three-phase electricity meter and a three-phase electricity metering circuit. Background Technology

[0002] Currently, the three-phase electricity meters used in the power grid mainly have two wiring methods: three-phase three-wire and three-phase four-wire. However, three-phase three-wire electricity meters and three-phase four-wire electricity meters are two independent products with different characteristics in terms of hardware, structure, and firmware functions. Moreover, the use and wiring of three-phase three-wire electricity meters and three-phase four-wire electricity meters are completely different.

[0003] Three-phase three-wire energy meters and three-phase four-wire energy meters need to be designed, developed, and tested independently, which greatly increases the complexity of the entire product process and the cost of operation and management. In addition, in the procurement and installation stages, it is necessary to strictly distinguish the application and wiring scenarios of the two types of energy meters, which increases labor costs. Utility Model Content

[0004] This utility model provides a three-phase energy meter and a three-phase energy metering circuit to solve the problems of high complexity of the entire product process, high operation and management costs, and high labor costs of three-phase energy meters.

[0005] To achieve the above objectives, in one embodiment, a three-phase electricity meter is provided, wherein the three-phase electricity meter is provided with a metering register, the metering register having an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface.

[0006] The A-phase interface is used to connect the A-phase wire, the B-phase interface is used to connect the B-phase wire, the C-phase interface is used to connect the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

[0007] In one embodiment, the metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

[0008] In one embodiment, the N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

[0009] In one embodiment, the metering chip is model RN8302B-V3.

[0010] In one embodiment, the metering chip may also be of model HT7136L.

[0011] In one embodiment, a three-phase power metering circuit is provided, wherein the three-phase power metering circuit is provided with a metering register, the metering register having an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface.

[0012] The A-phase interface is used to connect the A-phase wire, the B-phase interface is used to connect the B-phase wire, the C-phase interface is used to connect the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

[0013] In one embodiment, the metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

[0014] In one embodiment, the N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

[0015] In one embodiment, the metering chip is model RN8302B-V3.

[0016] In one embodiment, the metering chip may also be of model HT7136L.

[0017] The aforementioned three-phase energy meter and three-phase energy metering circuit are compatible with both three-phase three-wire and three-phase four-wire wiring methods. One product can be used for application scenarios with both wiring methods. In three-phase four-wire wiring, the A, B, C, and N phase interfaces of the energy meter are connected to the corresponding A, B, C, and N lines of the power grid. The collected current and voltage of phases A, B, C, and N are input to the metering chip in the metering register for calculation, obtaining the energy in three-phase four-wire metering mode. In three-phase three-wire wiring, the A, B, and C phase interfaces of the energy meter are connected to the corresponding A, B, and C lines of the power grid. The collected current and voltage of phases A, B, and C are input to the metering unit in the metering register for calculation, obtaining the energy in three-phase four-wire metering mode. A single electricity meter can be used in both three-phase four-wire and three-phase four-wire wiring scenarios. When changing the wiring method, there is no need to replace the equipment. The wiring method can be changed simply by using the same electricity meter, which reduces the complexity of the entire product process and the cost of operation and management. It also reduces labor costs during use and installation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a three-phase energy meter according to one embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram showing the connection between the metering chip and the current and voltage sampling units of each phase in one embodiment of the present invention;

[0021] Figure 3 This is a wiring diagram of a three-phase three-wire power supply scenario in one embodiment of this utility model;

[0022] Figure 4 This is a wiring diagram of a three-phase four-wire power supply scenario in one embodiment of this utility model.

[0023] Explanation of reference numerals in the attached diagram: 1. Three-phase energy meter; 2. Metering register; 3. Phase A current and voltage sampling unit; 4. Phase B current and voltage sampling unit; 5. Phase C current and voltage sampling unit; 6. N-phase interface; 7. Metering chip. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0026] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0027] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0029] To fully understand this invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0030] In one embodiment, a three-phase energy meter is provided, wherein the three-phase energy meter is provided with a metering register, the metering register having an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface, wherein the A-phase interface is used to connect to the A-phase wire, the B-phase interface is used to connect to the B-phase wire, the C-phase interface is used to connect to the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

[0031] Among them, such as Figure 1 As shown, the three-phase energy meter 1 has an internal metering register 2. The metering register has an A-phase interface, a B-phase interface, and a C-phase interface, all of which are used to connect to the external power grid. The A-phase interface is connected to the A-phase wire, the B-phase interface is connected to the B-phase wire, the C-phase interface is connected to the C-phase wire, and the N-phase interface is not connected to the N-phase wire of the external power grid. In this case, the energy meter is connected in a three-phase three-wire configuration.

[0032] For an already installed three-phase energy meter, when the wiring method of the three-phase energy meter is changed from three-phase four-wire to three-phase three-wire, it is only necessary to disconnect the connection between the N-phase interface and the N-phase wire and switch the metering mode from three-phase four-wire to three-phase three-wire.

[0033] The three-phase energy meter provided in this embodiment is designed and manufactured according to the standard three-phase four-wire energy meter in terms of both hardware and structure. This reduces the product range of the manufacturing company, decreases the number of structural types, and reduces the number of molds. A single energy meter can be compatible with both three-phase four-wire and three-phase four-wire wiring application scenarios. When changing the wiring method, it is not necessary to change the equipment. The wiring method can be changed by simply modifying the wiring using the same energy meter. This reduces the complexity of the entire product process and the cost of operation and management. When the demand for electricity changes, the three-phase energy meter of this embodiment can be directly used for corresponding wiring or installation to meet the usage requirements. At the same time, it improves installation efficiency, reduces installation errors, and reduces labor costs.

[0034] In one embodiment, the metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

[0035] Among them, such as Figure 2 and Figure 3 As shown, the metering algorithm of the metering chip 7 is three-phase three-wire. The A-phase current and voltage sampling unit 3 inside the metering register collects the current Ia and voltage Ua of the A-phase wire, the B-phase current and voltage sampling unit 4 collects the voltage Ub of the B-phase wire, and the C-phase current and voltage sampling unit 5 collects the current Ic and voltage Uc of the C-phase wire. The A-phase, B-phase, and C-phase current and voltage sampling units send the collected data to the metering chip for calculation, so as to obtain the electrical energy of the three-phase three-wire power consumption scenario.

[0036] The energy meter is configured to have the A-phase, B-phase, and C-phase current and voltage sampling units permanently enabled. Since the hardware and structure of this three-phase energy meter are set as a standard three-phase four-wire energy meter, the default configuration is three-phase four-wire. The three-phase energy meter is calibrated in three-phase four-wire mode to ensure that the metering accuracy reaches the preset target. When the power consumption mode is three-phase three-wire, the energy meter metering algorithm is switched to three-phase three-wire mode.

[0037] This embodiment of the three-phase energy meter connects the A-phase, B-phase, and C-phase interfaces of the energy meter to the A-phase, B-phase, and C-phase wires of the power grid, respectively. Data collected by the current and voltage sampling units of each phase is input into the metering chip for calculation to obtain the electrical energy in the three-phase, three-wire power consumption mode. Before using the three-phase energy meter, it must be calibrated in three-phase, four-wire mode to ensure the accuracy of the metering results, avoid economic losses due to metering errors, effectively reduce line loss rates, improve the operating efficiency of the power system, and achieve the expected metering accuracy. Using a single energy meter to accommodate both three-phase three-wire and three-phase four-wire wiring scenarios reduces the variety of products available to the manufacturing company, decreases structural types and molds, lowers the complexity of the entire product process, and reduces operational and management costs. When changing wiring methods, no equipment replacement is required; a simple wiring change using the same energy meter is sufficient to switch between three-phase three-wire and three-phase four-wire. When the power usage scenario changes, the three-phase energy meter of this embodiment can be directly used for correct wiring or installation to meet usage requirements, improving installation efficiency, reducing installation errors, and lowering labor costs.

[0038] In one embodiment, the N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

[0039] In a three-phase four-wire wiring configuration, the A-phase interface of the energy meter is connected to the A-phase wire, the B-phase interface to the B-phase wire, the C-phase interface to the C-phase wire, and the N-phase interface to the N-phase wire. At this time, the metering chip's metering algorithm switches to three-phase four-wire mode. Figure 4 As shown, phase A current and voltage sampling unit 3 collects the current Ia and voltage Ua of phase A wire, phase B current and voltage sampling unit 4 collects the current Ib and voltage Ub of phase B wire, and phase C current and voltage sampling unit 5 collects the current Ic and voltage Uc of phase C wire. The phase A, phase B, and phase C current and voltage sampling units transmit the collected data to the metering chip for calculation, so as to obtain the electrical energy of the three-phase four-wire power consumption scenario.

[0040] For an already installed three-phase energy meter, when the wiring method of the three-phase energy meter is changed from three-phase three-wire to three-phase four-wire, it is only necessary to connect the N-phase interface to the N-phase wire to switch the three-phase three-wire metering mode to three-phase four-wire.

[0041] In this embodiment, when the three-phase energy meter is used to implement the three-phase four-wire power consumption mode, the metering algorithm of the metering chip switches to the three-phase four-wire mode, and the collected data is sent to the metering chip for calculation to obtain the power in the three-phase four-wire mode. When the power consumption scenario changes, there is no need to replace the equipment. The wiring method can be converted by simply changing the wiring of the energy meter. This reduces labor costs during use and installation.

[0042] In one embodiment, the metering chip is model RN8302B-V3 or HT7136L.

[0043] Among these, the metering chip should be selected with voltage vector subtraction calculation function. In essence, whether it is a three-phase three-wire energy meter or a three-phase four-wire energy meter, it is to realize the actual power consumption of the three-phase power grid load. Taking active power metering as an example, the principle of reactive power metering is similar to that of active power. The calculation of reactive power metering requires phase shifting of the sampled waveform.

[0044] Analysis of the metering principle in three-phase three-wire mode (active power metering): The formula for calculating the instantaneous power P consumed by the load is:

[0045] , (1)

[0046] Where Ua is the phase A voltage, Ia is the phase A current, Ub is the phase B voltage, Ib is the phase B current, Uc is the phase C voltage, and Ic is the phase C current. This represents the dot product, where U and I are both vectors, containing magnitude and direction. This represents the vector dot product operation.

[0047] According to Kirchhoff's current law (node ​​current law):

[0048] , (2)

[0049] Transforming (2), we get:

[0050] , (3)

[0051] Substituting (3) into the formula (1) for calculating instantaneous power P, we get:

[0052] , (4)

[0053] Among them, vector subtraction The potential difference between phase A and phase B voltages is the line voltage Uab, and the vector subtraction method... Let Ucb be the potential difference between phase C voltage and phase B voltage, which is the line voltage. Then, the above formula (4) is:

[0054] (5)

[0055] In the three-phase three-wire mode, the voltages of phase A (Ua), phase B (Ub), phase C (Uc), phase A (Ia), and phase C (Ic) are sampled and vector subtraction is performed in the metering chip to obtain the line voltages Uab and Ucb. These are then substituted into formula (5) to calculate the instantaneous power P, and finally integrated over time to obtain the load energy consumption.

[0056] Analysis of the metering principle in three-phase four-wire mode (active power metering): The formula for calculating the instantaneous power P consumed by the load is:

[0057] , (6)

[0058] Where Ua is the phase A voltage, Ia is the phase A current, Ub is the phase B voltage, Ib is the phase B current, Uc is the phase C voltage, and Ic is the phase C current. This represents the dot product, where U and I are both vectors, containing magnitude and direction. This represents the vector dot product operation.

[0059] In the three-phase four-wire mode, the voltages of phase A (Ua), phase B (Ub), phase C (Uc), phase A (Ia), phase B (Ib), and phase C (Ic) are sampled and substituted into formula (6) to calculate the instantaneous power P. Then, the load energy consumption is obtained by integrating over time.

[0060] In this embodiment, the metering chip can provide calculations for active energy, active power, reactive energy, and reactive power. It has small nonlinear errors, meeting the accuracy requirements of 0.5S and 0.2S class active energy meters. It adopts a low-power design, which helps to extend the battery life of the device and reduce energy consumption. The metering chip is a chip that supports vector subtraction, which can simultaneously meet the energy calculation needs of both three-phase three-wire and three-phase four-wire power consumption scenarios. Compared with the traditional two completely independent energy meter systems, it simplifies the product types for manufacturing companies, reduces the complexity of the entire product process, and saves operating and management costs.

[0061] In one embodiment, a three-phase power metering circuit is provided, wherein the three-phase power metering circuit is provided with a metering register, the metering register having an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface.

[0062] The A-phase interface is used to connect the A-phase wire, the B-phase interface is used to connect the B-phase wire, the C-phase interface is used to connect the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

[0063] The metering circuit of this embodiment can be applied not only to electricity meters but also to other products with electricity metering functions. This allows other products to perform electricity metering functions while fulfilling their original functions. It can adopt advanced metering technology to ensure high accuracy of electricity metering, reduce metering errors, and also has multiple functions such as data analysis and event logging. It can realize remote data communication through communication interfaces such as infrared and GPRS, which facilitates remote monitoring and management, improves the operating efficiency of the power system, and reduces product complexity and operation and management costs when applied to other products. In use, if you want to realize the conversion between three-phase four-wire and three-phase three-wire, you do not need to replace the product. You only need to make a simple wiring change to realize the conversion, which reduces labor costs.

[0064] In one embodiment, the metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

[0065] Among them, such as Figure 2 and Figure 3 As shown, at this time, the A-phase current and voltage sampling unit 3, the B-phase current and voltage sampling unit 4, and the C-phase current and voltage sampling unit 5 are connected to the corresponding A-phase, B-phase, and C-phase wires, respectively, and transmit the collected current and voltage data to the metering chip 7. The metering chip 7 calculates the data according to the three-phase three-wire mode set by the program to obtain the power consumption under the three-phase three-wire power consumption scenario.

[0066] The metering circuit in this embodiment can calculate the consumed electrical energy through a metering chip. Applying the metering circuit to other instruments not only reduces the number of molds used in production and lowers production costs, but also provides users with a more convenient and efficient electricity management experience. It helps users understand electricity usage information at any time, make reasonable plans, improve energy utilization, and realize remote acquisition of electricity data through communication technology, thereby reducing labor costs and achieving intelligent management.

[0067] In one embodiment, the N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

[0068] Among them, such as Figure 3 and Figure 4As shown, at this time, the A-phase current and voltage sampling unit 3, the B-phase current and voltage sampling unit 4, and the C-phase current and voltage sampling unit 5 are connected to the corresponding A-phase, B-phase, and C-phase wires, respectively, and the N-phase interface 6 is connected to the N-phase wire. The collected current and voltage data are transmitted to the metering chip 7. At this time, the metering chip 7 is in three-phase four-wire mode, and the power consumption under the three-phase four-wire power consumption scenario is calculated and output.

[0069] In this embodiment, the metering circuit inputs the collected voltage and current data from each phase current and voltage sampling unit into the metering chip. The metering chip uses a three-phase four-wire metering algorithm to calculate the energy consumption under the three-phase four-wire connection mode. Applying the metering circuit to other products enables the products to be compatible with energy calculation functions, providing more comprehensive energy metering and management functions, and reducing the complexity of the entire product process and operation and management costs.

[0070] In one embodiment, the metering chip is model RN8302B-V3 or HT7136L.

[0071] The metering chip is a chip that supports voltage vector subtraction. The formulas obtained in the above embodiments for different metering modes are input into the metering chip for calculation to obtain the energy consumption under different power consumption scenarios.

[0072] In this embodiment, a metering chip of model RN8302B-V3 or HT7136L is used, which enables the metering circuit to accurately measure electrical energy, improve the accuracy and reliability of metering, adapt the metering circuit to different current loads, simplify design and maintenance, reduce the complexity of the whole process, and the metering chip is designed with a high-voltage area to ensure the stable operation of the metering circuit in various environments, reduce the failure rate, extend the service life of the metering circuit, and save costs.

[0073] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A three-phase electricity meter, characterized in that, The three-phase energy meter is equipped with a metering register, which has an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface. The A-phase interface is used to connect the A-phase wire, the B-phase interface is used to connect the B-phase wire, the C-phase interface is used to connect the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

2. The three-phase energy meter as described in claim 1, characterized in that, The metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

3. The three-phase energy meter as described in claim 1, characterized in that, The N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

4. The three-phase energy meter as described in claim 2, characterized in that, The metering chip is model RN8302B-V3.

5. The three-phase energy meter as described in claim 2, characterized in that, The metering chip can also be of model HT7136L.

6. A three-phase power metering circuit, characterized in that, The three-phase power metering circuit is equipped with a metering register, which has an A-phase interface, a B-phase interface, a C-phase interface, and an N-phase interface. The A-phase interface is used to connect the A-phase wire, the B-phase interface is used to connect the B-phase wire, the C-phase interface is used to connect the C-phase wire, and the N-phase interface is not connected to the wire in the three-phase three-wire connection method.

7. The three-phase power metering circuit as described in claim 6, characterized in that, The metering register includes: a metering chip, an A-phase current and voltage sampling unit, a B-phase current and voltage sampling unit, and a C-phase current and voltage sampling unit. The input terminal of the A-phase current and voltage sampling unit is connected to the A-phase interface, and the output terminal of the A-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the B-phase current and voltage sampling unit is connected to the B-phase interface, and the output terminal of the B-phase current and voltage sampling unit is connected to the metering chip. The input terminal of the C-phase current and voltage sampling unit is connected to the C-phase interface, and the output terminal of the C-phase current and voltage sampling unit is connected to the metering chip.

8. The three-phase power metering circuit as described in claim 6, characterized in that, The N-phase interface is connected to the N-phase wire in a three-phase four-wire connection method.

9. The three-phase power metering circuit as described in claim 7, characterized in that, The metering chip is model RN8302B-V3.

10. The three-phase power metering circuit as described in claim 7, characterized in that, The metering chip can also be of model HT7136L.

Images