Three-phase current transformer eddy current reducing method, three-phase current transformer and automatic calibrating device

Abstract

The invention provides a three-phase current transformer eddy current reduction method, a three-phase current transformer and an automatic calibration device, and belongs to the field of electric energy meter calibration. The method for reducing the eddy current of the three-phase current transformer comprises the following steps that a first wiring hole and a second wiring hole are formed in a shell of the three-phase current transformer; the first wiring hole is used for installing a positive terminal, and the second wiring hole is used for installing a negative terminal. An isolation groove is formed between the first wiring hole and the second wiring hole; the isolation groove is communicated with at least one of the first wiring hole and the second wiring hole. According to the three-phase current transformer eddy current reducing method, the three-phase current transformer and the automatic calibrating device in the embodiment of the invention, the eddy current generated by the shell can be reduced, the heat productivity of the shell can be reduced, the overall heat productivity of the three-phase current transformer can be further reduced, and the working period of the three-phase current transformer and the working period of the automatic calibrating device can be prolonged.

Description

Technical Field

[0001] The invention relates to the field of electric energy meter verification, and in particular to a three-phase current transformer eddy current reduction method, a three-phase current transformer and an automatic verification device. Background Art

[0002] In the related art, the automated verification line of three-phase smart energy meters can automatically perform verification operations through an automatic verification device. The automatic verification device includes a three-phase current transformer, which is used to isolate the current and voltage of the three-phase energy meter.

[0003] The existing three-phase current transformer comprises a housing and a transformer assembly, wherein the housing is used to accommodate and protect the transformer assembly; the transformer assembly is electrically connected to the three-phase electric energy meter through wires.

[0004] In order to prevent the three-phase current transformer from overheating, the staff needs to shut down the three-phase current transformer for cooling every working cycle. However, the existing technology lacks technical means to effectively reduce the heat generation of the three-phase current transformer, resulting in high heat generation and low working efficiency. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for reducing eddy current of a three-phase current transformer, which can reduce the eddy current generated by the shell, reduce the heat generated by the shell, and further reduce the overall heat generated by the three-phase current transformer, thereby extending the working cycle of the three-phase current transformer.

[0006] The present invention also provides a three-phase current transformer manufactured by adopting the above-mentioned three-phase current transformer eddy current reduction method and an automatic testing device including the above-mentioned three-phase current transformer.

[0007] According to the first aspect of the present invention, a method for reducing eddy current of a three-phase current transformer comprises the following steps:

[0008] A first wiring hole and a second wiring hole are provided on the housing of the three-phase current transformer; wherein the first wiring hole is used to install the positive electrode terminal, and the second wiring hole is used to install the negative electrode terminal;

[0009] An isolation groove is provided between the first wiring hole and the second wiring hole; wherein the isolation groove is connected to at least one of the first wiring hole and the second wiring hole.

[0010] The three-phase current transformer according to the embodiment of the present invention has at least the following beneficial effects: since an isolation groove is provided between the first wiring hole and the second wiring hole, the magnetic resistance in the isolation groove is relatively large, and the isolation groove is at least connected to the first wiring hole or the second wiring hole, the magnetic field generated by the current passing through the first wiring hole or the second wiring hole will avoid the isolation groove, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, the electromotive force of the induced magnetic field also decreases, the size of the eddy current is reduced, the heat generated by the shell is also reduced, and the working cycle of the three-phase current transformer is also prolonged.

[0011] According to some embodiments of the present invention, the average path of the magnetic flux lines on the shell is a circle with a diameter of D, the distance the magnetic flux lines on the shell pass through in the isolation slot is H, and the relative magnetic permeability of the material of the shell is μ r ;

[0012] The magnetic induction intensity of the magnetic field generated by the current passing through the first wiring hole or the second wiring hole in the housing provided with the isolation slot is B1, and the magnetic induction intensity of the magnetic field generated by the housing without the isolation slot is B2, and B1 and B2 satisfy

[0013] The three-phase current transformer according to the second aspect of the present invention is manufactured by using the three-phase current transformer eddy current reduction method described in any one of the above embodiments, and the three-phase current transformer includes:

[0014] A transformer assembly including a first terminal;

[0015] The shell is made of ferromagnetic material and has an installation cavity inside, and the transformer assembly is accommodated in the installation cavity; the shell is provided with a first wiring hole, and the first terminal is passed through the first wiring hole;

[0016] Wherein, the housing is further provided with a first isolation groove connected with the first wiring hole.

[0017] According to the three-phase current transformer of the embodiment of the present invention, at least the following beneficial effects are achieved: when the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal, the current passing through the first terminal will generate a changing magnetic field, resulting in eddy currents on the housing. Due to the large air magnetic resistance in the first isolation slot, the magnetic flux lines of the magnetic field generated by the current passing through the first terminal will avoid the first isolation slot, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, and the electromotive force of the induced magnetic field also decreases. On the other hand, the resistance on the housing will not decrease due to the opening of the first isolation slot. Therefore, according to Joule's law, the heat generated by the eddy current on the housing per unit time will decrease due to the decrease in the electromotive force of the induced magnetic field, the operating temperature rise rate of the three-phase current transformer will also decrease, the working cycle of the three-phase current transformer will also become longer, and the production efficiency of the automated verification assembly line of the three-phase intelligent electric energy meter will be higher. According to some embodiments of the present invention, the transformer assembly also includes a second terminal; the housing is also provided with a second wiring hole, the second terminal is penetrated through the second wiring hole, and the first isolation slot extends toward the second wiring hole.

[0018] According to some embodiments of the present invention, the transformer assembly also includes a first power frequency transformer, the positive pole of the first power frequency transformer is connected to the first terminal, the negative pole of the first power frequency transformer is connected to the second terminal, and the first isolation slot is connected to the second terminal hole.

[0019] According to some embodiments of the present invention, the transformer assembly further includes a third terminal, a fourth terminal, a fifth terminal, a sixth terminal, a second power frequency transformer and a third power frequency transformer; the housing is further provided with a third wiring hole, a fourth wiring hole, a fifth wiring hole and a sixth wiring hole, the third terminal is passed through the third wiring hole, the fourth terminal is passed through the fourth wiring hole, the fifth terminal is passed through the fifth wiring hole, the sixth terminal is passed through the sixth wiring hole, the positive pole of the second power frequency transformer is connected to the third terminal, the negative pole of the second power frequency transformer is connected to the fourth terminal, the positive pole of the third power frequency transformer is connected to the fifth terminal, and the negative pole of the third power frequency transformer is connected to the sixth terminal;

[0020] Wherein, the housing is further provided with a second isolation groove and a third isolation groove, the second isolation groove is connected to the third wiring hole and the fourth wiring hole, and the third isolation groove is connected to the fifth wiring hole and the sixth wiring hole.

[0021] According to some embodiments of the present invention, the housing includes a first connecting plate, and the first wiring hole, the second wiring hole, the third wiring hole, the fourth wiring hole, the fifth wiring hole and the sixth wiring hole are all arranged on the first connecting plate.

[0022] According to some embodiments of the present invention, the first isolation groove, the second isolation groove and the third isolation groove are all arranged on the first connecting plate.

[0023] According to some embodiments of the present invention, the first connecting plate includes a first edge and a second edge that are arranged opposite to each other, the first wiring hole, the third wiring hole and the fifth wiring hole are arranged on a side close to the first edge, and the second wiring hole, the fourth wiring hole and the sixth wiring hole are arranged on a side close to the second edge.

[0024] According to some embodiments of the present invention, along the extension direction of the first edge, the first wiring hole, the third wiring hole and the fifth wiring hole are arranged in sequence, and the second wiring hole, the fourth wiring hole and the sixth wiring hole are arranged in sequence.

[0025] According to some embodiments of the present invention, the housing is further provided with a fourth isolation groove communicating with the second wiring hole.

[0026] According to some embodiments of the present invention, the housing is further provided with a fifth isolation groove communicating with the first wiring hole.

[0027] According to some embodiments of the present invention, the three-phase current transformer further includes a filling piece, which is made of a non-ferromagnetic material and at least partially fills the first isolation slot.

[0028] According to some embodiments of the present invention, the first isolation trench extends along a straight line.

[0029] According to some embodiments of the present invention, a spacing between the first isolation grooves is greater than or equal to 2 mm.

[0030] According to some embodiments of the present invention, the first terminal is made of non-ferromagnetic material.

[0031] The automatic verification device according to the third aspect of the present invention comprises:

[0032] Three-phase energy meter;

[0033] As in any one of the three-phase current transformers in the above embodiments, the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal.

[0034] The automatic calibration device according to the embodiment of the present invention has at least the following beneficial effects: due to the large air magnetic resistance in the first isolation slot, when the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal, the magnetic flux lines of the magnetic field generated by the current passing through the first terminal will avoid the first isolation slot, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, and the electromotive force of the induced magnetic field also decreases. On the other hand, the resistance on the shell will not decrease due to the first isolation slot. Therefore, according to Joule's law, the heat generated by the eddy current on the shell per unit time will decrease due to the decrease in the electromotive force of the induced magnetic field, the rate of increase of the operating temperature of the three-phase current transformer will also decrease, and the working cycle of the three-phase current transformer will also be longer, thereby making the working cycle of the automatic calibration device longer, and the production efficiency of the automated calibration line of the three-phase smart electric energy meter is higher.

[0035] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0037] Figure 1 Schematic diagram of a method for reducing eddy current of a three-phase current transformer according to some embodiments of the present invention;

[0038] Figure 2 It is an overall schematic diagram of a three-phase current transformer according to some embodiments of the present invention;

[0039] Figure 3 for Figure 2 Explosion diagram of the three-phase current transformer;

[0040] Figure 4 for Figure 3 An exploded diagram showing the transformer components removed;

[0041] Figure 5 for Figure 2 A schematic diagram of a first connecting plate;

[0042] Figure 6 Schematic diagram of a first connecting plate according to some embodiments of the present invention;

[0043] Figure 7 Schematic diagram of the first connecting plate according to some embodiments of the present invention.

[0044] Reference numerals:

[0045] Three-phase current transformer 10;

[0046] A first terminal 110a, a second terminal 110b, a third terminal 110c, a fourth terminal 110d, a fifth terminal 110e, a sixth terminal 110f, a first power frequency transformer 120a, a second power frequency transformer 120b, and a third power frequency transformer 120c;

[0047] The housing 200, the mounting cavity 210, the first wiring hole 220a, the second wiring hole 220b, the third wiring hole 220c, the fourth wiring hole 220d, the fifth wiring hole 220e, the sixth wiring hole 220f, the first isolation groove 230a, the second isolation groove 230b, the third isolation groove 230c, the fourth isolation groove 230d, the fifth isolation groove 230e, the first connecting plate 240a, the first edge 241a, the second edge 241b, the second connecting plate 240b, the third connecting plate 240c, the fourth connecting plate 240d, the fifth connecting plate 240e, and the sixth connecting plate 240f. DETAILED DESCRIPTION

[0048] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0049] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0050] In the description of the present invention, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0051] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0052] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0053] In the related art, the automated calibration line of the three-phase intelligent electric energy meter can automatically perform the calibration operation through the automatic calibration device, and then automatically detect the accuracy of the electric energy meter. The automatic calibration device includes a three-phase current transformer 10, a three-phase electric energy meter and a plurality of functional modules. The three-phase electric energy meter can be used as a standard for calibrating other electric energy meters that need to be detected. The three-phase current transformer 10 is used to isolate the current and voltage of the three-phase electric energy meter, so that the functional modules of the automatic calibration device can be adjusted according to the current and voltage of the three-phase electric energy meter. The types of functional modules include correction modules, control modules and acquisition modules. The correction module can correct the electric energy meter that needs to be detected according to the current and voltage isolated by the three-phase current transformer 10. The control module can adjust the parameters, execution actions, etc. of the automatic calibration device according to the current and voltage isolated by the three-phase current transformer 10. The communication module can collect the current and voltage isolated by the three-phase current transformer 10 and exchange data with other control terminals.

[0054] In order to isolate the current and voltage of the three-phase electric energy meter by the three-phase current transformer 10, the three-phase current transformer 10 is electrically connected to the three-phase electric energy meter through its own transformer assembly. In order to protect the transformer assembly, the three-phase current transformer 10 also includes a housing 200 for accommodating the transformer assembly.

[0055] During operation, the three-phase current transformer 10 gradually accumulates heat, and after a working cycle, the operating temperature of the three-phase current transformer 10 reaches a critical value, and the staff needs to shut down the three-phase current transformer 10 for cooling to avoid overheating of the three-phase current transformer 10.

[0056] In order to extend the working cycle of the three-phase current transformer 10 and improve the working efficiency of the three-phase current transformer 10, the prior art believes that it is necessary to reduce the heat generated inside the transformer component, or to improve the heat dissipation efficiency of the three-phase current transformer 10. Therefore, the prior art provides a plurality of heat dissipation holes on the housing 200 to dissipate the heat generated by the transformer component faster, or reduces the heat generated by the three-phase current transformer 10 by changing the manufacturing material of the transformer component.

[0057] After many experiments, the inventors of the present invention found that since the shell 200 of the three-phase current transformer 10 is made of ferromagnetic material, the current passing through the shell 200 will induce eddy currents on the shell 200, causing the shell 200 to heat up, thereby causing the three-phase current transformer 10 to generate additional heat, and the operating temperature of the three-phase current transformer 10 reaches the critical value faster, thereby shortening the working cycle, increasing the maintenance frequency of the three-phase current transformer 10 by the staff, and reducing production efficiency.

[0058] In view of this, please refer to Figure 1 As shown, the present invention proposes a method for reducing eddy current of a three-phase current transformer, comprising the following steps:

[0059] S101: A first wiring hole 220a and a second wiring hole 220b are set on the housing 200 of the three-phase current transformer 10; wherein the first wiring hole 220a is used to install the positive electrode terminal, and the second wiring hole 220b is used to install the negative electrode terminal.

[0060] S102: An isolation groove is provided between the first wiring hole 220a and the second wiring hole 220b; wherein the isolation groove is connected to at least one of the first wiring hole 220a and the second wiring hole 220b.

[0061] Since an isolation groove is provided between the first wiring hole 220a and the second wiring hole 220b, the magnetic resistance in the isolation groove is relatively large, and the isolation groove is at least connected to the first wiring hole 220a or the second wiring hole 220b, the magnetic field generated by the current passing through the first wiring hole 220a or the second wiring hole 220b will avoid the isolation groove, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, the electromotive force of the induced magnetic field will also decrease, the size of the eddy current is reduced, the heat generated by the housing 200 is also reduced, and the working cycle of the three-phase current transformer 10 will also be prolonged.

[0062] It should be understood that when the first wiring hole 220a and the second wiring hole 220b are both connected to the isolation groove, the isolation groove can simultaneously reduce the eddy current generated by the current passing through the first wiring hole 220a and the second wiring hole 220b.

[0063] Furthermore, in some embodiments, the average path of the magnetic flux lines on the housing 200 is a circle with a diameter of D, the distance that the magnetic flux lines on the housing 200 pass through in the isolation slot is H, and the relative magnetic permeability of the material of the housing is μ r The current passing through the first wiring hole 220a or the second wiring hole 220b generates a magnetic field with a magnetic induction intensity of B1 in the housing 200 provided with the isolation groove, and generates a magnetic field with a magnetic induction intensity of B2 in the housing 200 without the isolation groove. B1 and B2 satisfy

[0064] Since B1 and B2 satisfy the above relationship, on the premise of determining the size of the magnetic induction intensity B1 that needs to be reduced, the staff can adjust the specifications of the first wiring hole, the second wiring hole and the isolation slot according to the above relationship to change the diameter D of the average path through which the magnetic flux lines pass, and the distance H that the magnetic flux lines pass in the isolation slot, and then adjust the specifications of the shell of the three-phase current transformer 10, thereby simplifying the shell design of the three-phase current transformer 10 while reducing eddy currents.

[0065] Please refer to Figure 2-5 As shown, the present invention further proposes a three-phase current transformer 10 , which is manufactured by using the three-phase current transformer eddy current reduction method in any of the above embodiments, and includes a transformer assembly and a housing 200 .

[0066] The transformer assembly of the present invention includes a first terminal 110a, and the first terminal 110a is used to connect to the circuit inside the transformer assembly. Exemplarily, the transformer assembly includes a plurality of power frequency transformers for isolating voltages and currents of different phases, and the first terminal 110a can be electrically connected to the positive or negative pole of one of the power frequency transformers, so that the positive or negative pole of one of the power frequency transformers can be electrically connected to the external circuit through the first terminal 110a.

[0067] The housing 200 of the present invention is made of ferromagnetic material. The ferromagnetic material in the present invention is iron, cobalt, nickel and their alloys, as well as manganese-containing compounds. Compared with the housing 200 made of non-ferromagnetic materials in the prior art, the housing 200 of the present invention has lower material cost and is easier to manufacture.

[0068] The housing 200 of the present invention has an installation cavity 210 inside, and the transformer assembly is accommodated in the installation cavity 210. The transformer assembly accommodated in the installation cavity 210 can be protected by the housing 200, reducing the possibility of dust in the external environment directly contacting the transformer assembly, and reducing the damage to the transformer assembly when the three-phase current transformer 10 is subjected to external impact. The housing 200 is also provided with a first wiring hole 220a, and the first terminal 110a is penetrated through the first wiring hole 220a, so that the power frequency transformer can be electrically connected to the electronic device located outside the housing 200 through the first terminal 110a.

[0069] It should be noted that the housing 200 of the present invention is provided with a first isolation slot 230a, and the first isolation slot 230a is connected to the first wiring hole 220a. The first isolation slot 230a provided on the housing 200 enables the installation cavity 210 to be connected to the outside through the first isolation slot 230a, and the outside air will also fill the first isolation slot 230a. When the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal 110a, the current passing through the first terminal 110a will generate a changing magnetic field, resulting in eddy currents on the housing 200. Since the air magnetic resistance in the first isolation slot 230a is relatively large, the magnetic flux lines of the magnetic field generated by the current passing through the first terminal 110a will avoid the first isolation slot 230a, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, and the electromotive force of the induced magnetic field also decreases. On the other hand, the resistance on the housing 200 will not decrease due to the provision of the first isolation slot 230a. Therefore, according to Joule's law, the heat generated by the eddy current on the housing 200 per unit time will decrease due to the decrease in the electromotive force of the induced magnetic field, the rate of increase of the operating temperature of the three-phase current transformer 10 will also decrease, the working cycle of the three-phase current transformer 10 will also become longer, and the production efficiency of the automated calibration line of the three-phase smart electric energy meter will be higher.

[0070] Without departing from the inventive concept of the present invention, the housing 200 may further be provided with a plurality of isolation grooves from the first wiring hole 220a. Figure 6 As shown, in some embodiments, the housing 200 is further provided with a fifth isolation slot 230e connected to the first wiring hole 220a, and the air in the fifth isolation slot 230e can make the magnetic flux lines of the magnetic field induced by the current of the first terminal 110a avoid the fifth isolation slot 230e, further reducing the magnetic induction intensity, reducing the rate of increase of the working temperature of the three-phase current transformer 10, and improving the production efficiency of the three-phase smart electric energy meter automatic verification assembly line. In some embodiments, the housing 200 is provided with three, four or five isolation slots connected to the first wiring hole 220a.

[0071] Without departing from the inventive concept of the present invention, the present invention does not limit the shape of the first isolation groove 230a. In some embodiments, the first isolation groove 230a may extend along the extension direction of a certain curve. As a preferred embodiment, please refer to Figure 5 As shown, the first isolation slot 230a extends in a straight line. The first isolation slot 230a extends in a straight line, which is beneficial to simplifying the processing of the housing 200 and reducing the overall processing cost of the three-phase current transformer 10.

[0072] The “isolation groove spacing” referred to in the present invention refers to the distance between two inner walls of the isolation groove that are perpendicular to the extension direction. Figure 5As shown, in some embodiments, the housing 200 includes a first connecting plate 240a, and a first isolation groove 230a is provided on the first connecting plate 240a. The first isolation groove 230a extends to the right relative to the first wiring hole 220a, and the spacing of the first isolation groove 230a is the distance between the two inner walls in the up and down directions.

[0073] Those skilled in the art should understand that, ideally, the present invention reduces the magnetic induction intensity of the magnetic field generating eddy current by setting the first isolation groove 230a, thereby achieving the effect of reducing the heat generation of the housing 200, and the spacing of the first isolation groove 230a must be greater than 0. As a preferred solution, the spacing of the first isolation groove 230a should be greater than or equal to 2mm. The spacing of the first isolation groove 230a greater than or equal to 2mm can facilitate the processing of the first isolation groove 230a, and can also further reduce the possibility of the inner walls of the first isolation groove 230a perpendicular to the extension direction contacting each other in the event of accidental deformation of the housing 200, thereby enabling the first isolation groove 230a to more stably maintain the effect of reducing the heat generation of the housing 200.

[0074] For further information, please refer to Figure 5 As shown, Figure 5 The filling piece is not shown. In some embodiments, the three-phase current transformer 10 further includes a filling piece, which is made of a non-ferromagnetic material and at least partially fills the first isolation slot 230a. When the filling piece fills the first isolation slot 230a, since the filling piece is made of a non-ferromagnetic material, the filling piece can also increase the magnetic resistance, thereby allowing the magnetic flux lines to still avoid the first isolation slot 230a, thereby achieving the effect of reducing the heat generated by the housing 200, and the filling piece filled in the first isolation slot 230a can play a blocking role, reducing the amount of external dust entering the installation cavity 210 through the first isolation slot 230a, thereby reducing the possibility of dust in the external environment directly contacting the transformer assembly, and improving the working stability of the three-phase current transformer 10.

[0075] Without departing from the inventive concept of the present invention, the first terminal 110a of the present invention is used to electrically connect the transformer assembly to other electronic devices, and the first terminal 110a can be made of a variety of conductive materials. On the basis of the above scheme, as a preferred scheme, the first terminal 110a is made of non-ferromagnetic material. The non-ferromagnetic material in the above scheme can be copper, aluminum, copper alloy, aluminum alloy, etc. The use of non-ferromagnetic material can further reduce the eddy current induced by the current on the first terminal 110a, and reduce the heat generation of the three-phase current transformer 10.

[0076] For further information, please refer to Figure 2 , Figure 3As shown, in some embodiments, the transformer assembly further includes a second terminal 110b. The housing 200 is further provided with a second wiring hole 220b, the second terminal 110b is penetrated through the second wiring hole 220b, and the first isolation slot 230a extends toward the second wiring hole 220b. The transformer assembly is electrically connected to an external electronic device through the second terminal 110b, and the current passing through the second terminal 110b will also generate eddy currents on the housing 200. Since the first isolation slot 230a extends toward the second wiring hole 220b, the eddy currents induced on the housing 200 by the current passing through the second terminal 110b will also decrease, and the heat generated by the housing 200 will be further reduced.

[0077] As mentioned above, the first terminal 110a can be made of non-ferromagnetic material to reduce the eddy current induced by the current on the first terminal 110a and reduce the heat generation of the three-phase current transformer 10. On the basis of the above solution, those skilled in the art can also use non-ferromagnetic material to make the second terminal 110b, and the current intensity of the eddy current induced on the second terminal 110b by the current passing through the first terminal 110a will also decrease, and the heat generation of the housing 200 will further decrease. On the other hand, the current intensity of the eddy current induced on the first terminal 110a by the current passing through the second terminal 110b will also decrease.

[0078] For further information, please refer to Figure 6 As shown, in some embodiments, the housing 200 is further provided with a fourth isolation slot 230d connected to the second wiring hole 220b. The fourth isolation slot 230d provided on the housing 200 enables the installation cavity 210 to be connected to the outside through the fourth isolation slot 230d, and the outside air will also fill the fourth isolation slot 230d. When the transformer assembly is electrically connected to the three-phase electric energy meter through the second terminal 110b, the current passing through the second terminal 110b will also generate a changing magnetic field, resulting in eddy currents on the housing 200. Since the air magnetic resistance in the fourth isolation slot 230d is relatively large, the magnetic flux lines of the magnetic field generated by the current passing through the second terminal 110b will avoid the fourth isolation slot 230d, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, and the electromotive force of the induced magnetic field also decreases. On the other hand, the resistance on the casing 200 will not decrease due to the provision of the fourth isolation slot 230d. Therefore, according to Joule's law, the heat generated by the eddy current on the casing 200 per unit time will decrease due to the decrease in the electromotive force of the induced magnetic field, and the rate of increase of the operating temperature of the three-phase current transformer 10 will also decrease. The working cycle of the three-phase current transformer 10 will also become, and the production efficiency of the automated calibration assembly line of the three-phase smart electric energy meter will be higher.

[0079] In some embodiments, the transformer assembly includes multiple power frequency transformers, and the transformer assembly isolates the current and voltage of different phases of the three-phase electric energy meter through the multiple power frequency transformers, thereby obtaining accurate information of the three-phase electric energy meter. Figure 3-5 As shown, one of the power frequency transformers is defined as the first power frequency transformer 120a, the positive pole of the first power frequency transformer 120a is connected to the first terminal 110a, the negative pole of the first power frequency transformer 120a is connected to the second terminal 110b, and the first isolation slot 230a is connected to the second terminal hole 220b. When the first power frequency transformer 120a is electrically connected to the three-phase current transformer 10 through the first terminal 110a and the second terminal 110b, a ring-shaped current loop can be formed between the three-phase current transformer 10 and the three-phase electric energy meter, and the ring-shaped current loop will pass through the first terminal 110a and the second terminal 110b, and the magnetic flux lines of the magnetic field generated when the current passes through the first terminal 110a and the second terminal 110b will pass through the area between the first connecting post and the second connecting post. Since the first wiring hole 220a and the second wiring hole 220b are connected through the first isolation groove 230a, the magnetic flux lines of the above-mentioned magnetic field need to pass through the first isolation groove 230a when passing through the area between the first connecting column and the second connecting column, and the air in the first isolation groove 230a will greatly increase the equivalent magnetic path length of the magnetic flux lines, thereby greatly reducing the magnetic induction intensity of the magnetic field generated by the current passing through the first terminal 110a and the second terminal 110b, and the heat generated by the eddy current on the housing 200 per unit time is further reduced, so that the working cycle of the three-phase current transformer 10 is greatly extended.

[0080] The technical effects of the above embodiments are further described in detail below through calculation.

[0081] Please refer to Figure 5 As shown, according to Ampere's loop law, the integral of the magnetic field intensity along the closed path is equal to the sum of the currents enclosed by it. When the housing 200 is not provided with the first isolation slot 230a, the current intensity passing through the first terminal 110a is assumed to be I, the magnetic induction intensity B1 of the magnetic field generated by the housing 200 in the first isolation slot 230a, the diameter of the closed path is D, and the relative magnetic permeability of the housing 200 material is μ r , the vacuum permeability is μ0, then:

[0082]

[0083] When the first isolation slot 230a is provided on the housing 200, the distance that the magnetic flux lines pass through the first isolation slot 230a is H, and the magnetic permeability of air is approximately the magnetic permeability of vacuum, then:

[0084]

[0085] When the current passing through the first terminal 110a is the same, the ratio of the magnetic induction intensity B1 generated in the housing 200 provided with the first isolation slot 230a to the magnetic induction intensity B2 of the magnetic field generated in the housing 200 without the first isolation slot 230a is:

[0086]

[0087] In some embodiments, the housing 200 is made of galvanized steel sheet, and the relative magnetic permeability μ of the galvanized steel sheet is r =220, π is approximated as 3, the average diameter D through which the magnetic lines of force pass is approximated as 16 mm, and the 2 mm spacing of the first isolation slot 230a is approximated as the distance H through which the magnetic lines of force pass in the first isolation slot 230a. Substituting into the above formula, we can get Compared with the housing 200 without the first isolation slot 230a, the magnetic induction intensity of the magnetic field induced by the current passing through the first terminal 110a in the housing 200 with the first isolation slot 230a is approximately one tenth of the original, the current intensity of the eddy current induced by the magnetic field will also be reduced, and the heat generated by the eddy current per unit time will also be further reduced.

[0088] It should be understood that, since the first power frequency transformer 120a is also electrically connected to the three-phase electric energy meter through the second terminal 110b, the current intensity of the eddy current generated by the current passing through the second terminal 110b on the housing 200 having the first isolation slot 230a is also reduced. On the other hand, the above solution can also reduce the parasitic inductance of the first terminal 110a and the second terminal 110b, thereby improving the load carrying capacity of the transformer assembly.

[0089] As mentioned above, the housing 200 may be provided with a fifth isolation groove 230e communicating with the first wiring hole 220a and a fourth isolation groove 230d communicating with the second wiring hole 220b. Based on the above solution, please refer to Figure 7 As shown, the fifth isolation slot 230e or the fourth isolation slot 230d can also be connected to the first wiring hole 220a and the second wiring hole 220b at the same time, so that the distance that the magnetic flux lines of the magnetic field generated by the current passing through the first terminal 110a pass through the isolation slot is increased, further reducing the current intensity of the eddy current.

[0090] Based on the above solution, please refer to Figure 3 , Figure 4As shown, in some embodiments, the transformer assembly further includes a third terminal 110c, a fourth terminal 110d, a fifth terminal 110e, a sixth terminal 110f, a second power frequency transformer 120b and a third power frequency transformer 120c. The housing 200 is further provided with a third wiring hole 220c, a fourth wiring hole 220d, a fifth wiring hole 220e and a sixth wiring hole 220f. The third terminal 110c is penetrated in the third wiring hole 220c, the fourth terminal 110d is penetrated in the fourth wiring hole 220d, the fifth terminal 110e is penetrated in the fifth wiring hole 220e, the sixth terminal 110f is penetrated in the sixth wiring hole 220f, the positive pole of the second power frequency transformer 120b is connected to the third terminal 110c, the negative pole of the second power frequency transformer 120b is connected to the fourth terminal 110d, the positive pole of the third power frequency transformer 120c is connected to the fifth terminal 110e, and the negative pole of the third power frequency transformer 120c is connected to the sixth terminal 110f.

[0091] The first industrial frequency transformer 120a can be electrically connected to the three-phase electric energy meter through the first terminal 110a and the second terminal 110b, the second industrial frequency transformer 120b can be electrically connected to the three-phase electric energy meter through the third terminal 110c and the fourth terminal 110d, and the third industrial frequency transformer 120c can be electrically connected to the three-phase electric energy meter through the fifth terminal 110e and the sixth terminal 110f. The transformer assembly can isolate the three-phase current and voltage of the three-phase electric energy meter respectively through the three industrial frequency transformers.

[0092] In the above embodiment, the housing 200 is further provided with a second isolating groove 230b and a third isolating groove 230c, wherein the second isolating groove 230b is connected to the third wiring hole 220c and the fourth wiring hole 220d, and the third isolating groove 230c is connected to the fifth wiring hole 220e and the sixth wiring hole 220f. The above has described the specific process of reducing the eddy current by the first isolating groove 230a connected to the first wiring hole 220a and the second wiring hole 220b. Based on the same principle, the second isolating groove 230b connected to the third wiring hole 220c and the fourth wiring hole 220d can also reduce the current intensity of the eddy current induced by the third terminal 110c and the fourth terminal 110d, and the third isolating groove 230c connected to the fifth wiring hole 220e and the sixth wiring hole 220f can also reduce the current intensity of the eddy current induced by the fifth terminal 110e and the sixth terminal 110f. On the other hand, the second isolation trench 230 b and the third isolation trench 230 c can also increase the overall resistance of the housing 200 , thereby further reducing the heat generation of the housing 200 .

[0093] For further information, please refer to Figure 3 , Figure 5As shown, in some embodiments, the housing 200 includes a first connecting plate 240a, and the first wiring hole 220a, the second wiring hole 220b, the third wiring hole 220c, the fourth wiring hole 220d, the fifth wiring hole 220e and the sixth wiring hole 220f are all arranged on the first connecting plate 240a. The first connecting plate 240a is a plate-shaped structure, and the arrangement of wiring holes on the first connecting plate 240a is conducive to the processing of the housing 200, thereby reducing the manufacturing cost. In addition, the arrangement of the wiring holes on the same connecting plate can also facilitate the staff to connect the wires connected to other electronic devices to the various wiring posts, making the three-phase current transformer 10 easier to operate.

[0094] Without departing from the inventive concept of the present invention, those skilled in the art can design the specific shape of the housing 200 so that the first connecting plate 240a and other parts of the housing 200 together define a mounting cavity 210 for accommodating the transformer assembly. Figure 3 As shown, in some embodiments, the housing 200 includes a first connecting plate 240a, a second connecting plate 240b, a third connecting plate 240c, a fourth connecting plate 240d, a fifth connecting plate 240e and a sixth connecting plate 240f. The first connecting plate 240a and the third connecting plate 240c are disposed opposite to each other. In the direction from the first connecting plate 240a to the third connecting plate 240c, one end of the fourth connecting plate 240d is connected to the first connecting plate 240a, the other end of the fourth connecting plate 240d is connected to the third connecting plate 240c, one end of the third connecting plate 240c is connected to the first connecting plate 240a, the other end of the third connecting plate 240c is connected to the third connecting plate 240c, one end of the fifth connecting plate 240e is connected to the first connecting plate 240a, the other end of the fifth connecting plate 240e is connected to the third connecting plate 240c, one end of the sixth connecting plate 240f is connected to the first connecting plate 240a, the other end of the sixth connecting plate 240f is connected to the third connecting plate 240c, the second connecting plate 240b, the fourth connecting plate 240d, the fifth connecting plate 240e and the sixth connecting plate 240f are arranged around the first connecting plate 240a and the third connecting plate 240c, and are connected end to end in a clockwise direction. The first connecting plate 240 a , the second connecting plate 240 b , the third connecting plate 240 c , the fourth connecting plate 240 d , the fifth connecting plate 240 e , and the sixth connecting plate 240 f together define the mounting cavity 210 .

[0095] The above connection relationship enables the first connection plate 240a, the second connection plate 240b, the third connection plate 240c, the fourth connection plate 240d, the fifth connection plate 240e and the sixth connection plate 240f to be combined into a polyhedron having a mounting cavity 210, and the transformer assembly can be accommodated in the mounting cavity 210 of the polyhedron. In addition, since the first connection plate 240a, the second connection plate 240b, the third connection plate 240c, the fourth connection plate 240d, the fifth connection plate 240e and the sixth connection plate 240f can all be directly processed and formed on the plate, the material cost of the housing 200 is lower.

[0096] It should be noted that the polyhedron formed by the first connecting plate 240a, the second connecting plate 240b, the third connecting plate 240c, the fourth connecting plate 240d, the fifth connecting plate 240e and the sixth connecting plate 240f in the above embodiment can be a geometric body such as a prism, a cuboid or a cube. As a preferred embodiment, please refer to FIG. 2, the first connecting plate 240a, the second connecting plate 240b, the third connecting plate 240c, the fourth connecting plate 240d, the fifth connecting plate 240e and the sixth connecting plate 240f are all rectangular plates, which is conducive to improving the utilization rate of plate cutting and further reducing the material cost of the housing 200.

[0097] As mentioned above, the first isolation slot 230a connected to the first wiring hole 220a can be connected to the second wiring hole 220b. Figure 2-4 As shown, in some embodiments, the first isolation groove 230a can extend leftward relative to the first wiring hole 220a to the left side of the first connecting plate 240a, then extend from the front side to the rear side of the fifth connecting plate 240e, then extend from the left side to the right side of the third connecting plate 240c, then extend from the rear side to the front side of the sixth connecting plate 240f, and then connect to the second wiring hole 220b from the right side of the first connecting plate 240a.

[0098] As a preferred option, please refer to Figure 4 , Figure 5 As shown, the first isolation groove 230a, the second isolation groove 230b and the third isolation groove 230c are all arranged on the first connecting plate 240a. Through the above solution, each isolation groove can be directly processed and formed on the first connecting plate 240a, thereby reducing the manufacturing cost of the isolation groove.

[0099] For further information, please refer to Figure 5-7As shown, in some embodiments, the first connecting plate 240a includes a first edge 241a and a second edge 241b that are arranged opposite to each other, the first wiring hole 220a, the third wiring hole 220c and the fifth wiring hole 220e are arranged on a side close to the first edge 241a, and the second wiring hole 220b, the fourth wiring hole 220d and the sixth wiring hole 220f are arranged on a side close to the second edge 241b. Since the positive pole of the first power frequency transformer 120a is connected to the first terminal 110a, the positive pole of the second power frequency transformer 120b is connected to the third terminal 110c, and the positive pole of the third power frequency transformer 120c is connected to the fifth terminal 110e, the first wiring hole 220a, the third wiring hole 220c and the fifth wiring hole 220e are arranged on a side close to the first edge 241a, which is conducive to the staff to identify the positive pole of the power frequency transformer through the position of the terminal, thereby facilitating the wiring work of the staff. Based on the same inventive concept, setting the second wiring hole 220b, the fourth wiring hole 220d and the sixth wiring hole 220f on the side close to the second edge 241b is also beneficial for the staff to identify the negative pole of the industrial frequency transformer through the position of the terminal, thereby facilitating the staff's wiring work.

[0100] Based on the above solution, please refer to Figure 5 As shown, in some embodiments, along the extension direction of the first edge 241a (ie Figure 5 In the vertical direction of the first edge 241a, the first wiring hole 220a, the third wiring hole 220c and the fifth wiring hole 220e are arranged in sequence, and the second wiring hole 220b, the fourth wiring hole 220d and the sixth wiring hole 220f are arranged in sequence. Through the above scheme, the first terminal 110a and the second terminal 110b for electrically connecting to the first power frequency transformer 120a, the third terminal 110c and the fourth terminal 110d for electrically connecting to the second power frequency transformer 120b, and the fifth terminal 110e and the sixth terminal 110f for electrically connecting to the third power frequency transformer 120c are arranged in sequence along the extension direction of the first edge 241a, so that the staff can more easily judge the number of the transformer corresponding to each terminal by the position of each terminal, thereby facilitating the wiring work of the staff.

[0101] The present invention also proposes an automatic calibration device, including a three-phase electric energy meter and the three-phase current transformer 10 in any of the above embodiments. The transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal 110a. In some embodiments, the transformer assembly is electrically connected to the standard three-phase electric energy meter through the first terminal 110a. Since the air magnetic resistance in the first isolation slot 230a is relatively large, when the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal 110a, the magnetic flux lines of the magnetic field generated by the current passing through the first terminal 110a will avoid the first isolation slot 230a, so that the magnetic path length of the magnetic field becomes longer, the magnetic induction intensity decreases, and the electromotive force of the induced magnetic field also decreases. On the other hand, the resistance on the housing 200 will not decrease due to the provision of the first isolation slot 230a. Therefore, according to Joule's law, the heat generated by the eddy current on the housing 200 per unit time will decrease due to the decrease in the electromotive force of the induced magnetic field, and the rate of increase of the operating temperature of the three-phase current transformer 10 will also decrease. The working cycle of the three-phase current transformer 10 will also become longer, thereby lengthening the working cycle of the automatic calibration device, and the production efficiency of the three-phase smart electric energy meter automatic calibration assembly line will be higher.

[0102] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for reducing eddy current of a three-phase current transformer, characterized in that: The steps include: A first wiring hole and a second wiring hole are provided on the housing of the three-phase current transformer; wherein the first wiring hole is used to install the positive electrode terminal, and the second wiring hole is used to install the negative electrode terminal; An isolation groove is provided between the first wiring hole and the second wiring hole; wherein the isolation groove is connected to at least one of the first wiring hole and the second wiring hole.

2. The method for reducing eddy current of a three-phase current transformer according to claim 1, characterized in that: The average path of the magnetic flux lines on the shell is a circle with a diameter of D. The distance that the magnetic flux lines on the shell pass through in the isolation slot is H. The relative magnetic permeability of the material of the shell is μ r ; The magnetic induction intensity of the magnetic field generated by the current passing through the first wiring hole or the second wiring hole in the housing provided with the isolation slot is B1, and the magnetic induction intensity of the magnetic field generated by the housing without the isolation slot is B2, and B1 and B2 satisfy 3. A three-phase current transformer manufactured by the method for reducing eddy current of a three-phase current transformer according to claim 1 or 2, characterized in that: The three-phase current transformer comprises: A transformer assembly including a first terminal; The shell is made of ferromagnetic material and has an installation cavity inside, and the transformer assembly is accommodated in the installation cavity; the shell is provided with a first wiring hole, and the first terminal is passed through the first wiring hole; Wherein, the housing is further provided with a first isolation groove connected with the first wiring hole.

4. The three-phase current transformer according to claim 3, characterized in that: The transformer assembly also includes a second terminal; the housing is also provided with a second wiring hole, the second terminal is passed through the second wiring hole, and the first isolation groove extends toward the second wiring hole.

5. The three-phase current transformer according to claim 4, characterized in that: The transformer assembly also includes a first power frequency transformer, the positive pole of the first power frequency transformer is connected to the first terminal, the negative pole of the first power frequency transformer is connected to the second terminal, and the first isolation slot is connected to the second terminal hole.

6. The three-phase current transformer according to claim 5, characterized in that: The transformer assembly also includes a third terminal, a fourth terminal, a fifth terminal, a sixth terminal, a second power frequency transformer and a third power frequency transformer; the housing is also provided with a third wiring hole, a fourth wiring hole, a fifth wiring hole and a sixth wiring hole, the third terminal is inserted through the third wiring hole, the fourth terminal is inserted through the fourth wiring hole, the fifth terminal is inserted through the fifth wiring hole, the sixth terminal is inserted through the sixth wiring hole, the positive pole of the second power frequency transformer is connected to the third terminal, the negative pole of the second power frequency transformer is connected to the fourth terminal, the positive pole of the third power frequency transformer is connected to the fifth terminal, and the negative pole of the third power frequency transformer is connected to the sixth terminal; Wherein, the shell is further provided with a second isolation groove and a third isolation groove, the second isolation groove is connected to the third wiring hole and the fourth wiring hole, and the third isolation groove is connected to the fifth wiring hole and the sixth wiring hole.

7. The three-phase current transformer according to claim 6, characterized in that: The housing includes a first connecting plate, and the first wiring hole, the second wiring hole, the third wiring hole, the fourth wiring hole, the fifth wiring hole and the sixth wiring hole are all arranged on the first connecting plate.

8. The three-phase current transformer according to claim 7, characterized in that: The first isolation groove, the second isolation groove and the third isolation groove are all arranged on the first connecting plate.

9. The three-phase current transformer according to claim 7, characterized in that: The first connecting plate includes a first edge and a second edge that are arranged opposite to each other, the first wiring hole, the third wiring hole and the fifth wiring hole are arranged on a side close to the first edge, and the second wiring hole, the fourth wiring hole and the sixth wiring hole are arranged on a side close to the second edge.

10. The three-phase current transformer according to claim 9, characterized in that: Along the extension direction of the first edge, the first wiring hole, the third wiring hole and the fifth wiring hole are arranged in sequence, and the second wiring hole, the fourth wiring hole and the sixth wiring hole are arranged in sequence.

11. The three-phase current transformer according to claim 4, characterized in that: The housing is also provided with a fourth isolation groove communicated with the second wiring hole.

12. The three-phase current transformer according to claim 3, characterized in that: The housing is also provided with a fifth isolation groove communicated with the first wiring hole.

13. The three-phase current transformer according to claim 3, characterized in that: The three-phase current transformer further includes a filling piece, which is made of a non-ferromagnetic material and at least partially fills the first isolation slot.

14. The three-phase current transformer according to claim 3, characterized in that: The first isolation trench extends along a straight line.

15. The three-phase current transformer according to claim 3, characterized in that: The spacing between the first isolation grooves is greater than or equal to 2 mm.

16. The three-phase current transformer according to claim 3, characterized in that: The first terminal is made of non-ferromagnetic material.

17. Automatic verification device, characterized in that, include: Three-phase energy meter; The three-phase current transformer according to any one of claims 3 to 16, wherein the transformer assembly is electrically connected to the three-phase electric energy meter through the first terminal.

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