CN111235495B - Amorphous nanocrystalline alloy, iron core manufacturing method and wide-range current transformer measuring method - Google Patents
Amorphous nanocrystalline alloy, iron core manufacturing method and wide-range current transformer measuring method Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C45/00—Amorphous alloys
- C22C45/02—Amorphous alloys with iron as the major constituent
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
- B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
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- C—CHEMISTRY; METALLURGY
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C—CHEMISTRY; METALLURGY
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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- C—CHEMISTRY; METALLURGY
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
- C22C33/003—Making ferrous alloys making amorphous alloys
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
- G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/28—Current transformers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0206—Manufacturing of magnetic cores by mechanical means
- H01F41/0213—Manufacturing of magnetic circuits made from strip(s) or ribbon(s)
- H01F41/0226—Manufacturing of magnetic circuits made from strip(s) or ribbon(s) from amorphous ribbons
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Abstract
The invention provides an amorphous nanocrystalline alloy, an iron core and a method for manufacturing a wide-range current transformer for metering, wherein the amorphous nanocrystalline alloy comprises the following components in percentage by mass: 81.0 to 81.6 percent of iron, 8.7 to 9.3 percent of silicon, 6.2 to 6.7 percent of niobium, 1.8 to 2.3 percent of boron, 0.08 to 1.4 percent of copper and 0.07 to 0.13 percent of trace elements. According to the invention, the initial permeability mu and the saturation magnetic flux density B of the iron core prepared from the components can be greatly improved, so that the ratio error epsilon of the current transformer can be greatly reduced, namely, the accuracy of the current transformer is improved, the accurate metering of the current transformer is ensured, and the iron core with the same size has higher initial permeability and magnetic flux density.
Description
Technical Field
The invention relates to the technical field of transformers, in particular to an amorphous nanocrystalline alloy, an iron core and a method for measuring a wide-range current transformer.
Background
The current transformer is one of key devices in an electric power system, and can convert a large-current signal in a primary system of a power grid into a standard small-current signal (1A or 5A) in a specified proportion at high accuracy so as to be convenient for a subsequent secondary metering, measuring and protecting system. Therefore, the conversion precision of the current transformer is closely related to the trade settlement accuracy of the electricity charge, the monitoring of the operation data acquisition and operation state of the power grid and the operation safety of the power grid.
According to the specification of the transformer national standard GB/T20840.2-2013, the highest accuracy level of the current transformer for metering in the current power system is 0.2S level, and the accuracy range and the limit value are shown in Table 1.
TABLE 1 ratio difference limit of current transformer for special purpose (0.2S class)
As can be seen from table 1, the accuracy of current transformer metering is gradually reduced below the rated current of 20%. Actually, the range of variation of the load of many users is very large, and since the primary current is very large when the current transformer is operated at full load, the rated current of the current transformer for metering is set according to the full load current. Under the conditions that large electric equipment of an enterprise is shut down, an electric locomotive passes, and the residence rate of a community is low, the actually used current is probably far lower than 20 percent of the set rated current of the transformer, even lower than 1 percent, and the inaccurate electricity charge measurement is easily caused. Moreover, the principle and empirical data of the current transformer show that the descending trend is that the ratio difference is negative and the phase difference is positive, and the whole phenomenon shows that the electricity charge for metering is reduced, so that the current transformer cannot accurately meter.
Disclosure of Invention
In view of this, the invention provides an amorphous nanocrystalline alloy, aiming at solving the problem that the current transformer in the prior art cannot accurately measure. The invention also provides a method for preparing the iron core by using the amorphous nanocrystalline alloy and a method for manufacturing the wide-range current transformer for metering by using the iron core.
In one aspect, the invention provides an amorphous nanocrystalline alloy, which comprises the following components in percentage by mass: 81.0 to 81.6 percent of iron, 8.7 to 9.3 percent of silicon, 6.2 to 6.7 percent of niobium, 1.8 to 2.3 percent of boron, 0.08 to 1.4 percent of copper and 0.07 to 0.13 percent of trace element.
Further, in the amorphous nanocrystalline alloy, the mass percentages of the components are as follows: 81.1 to 81.4 percent of iron, 8.8 to 9.1 percent of silicon, 6.3 to 6.5 percent of niobium, 1.9 to 2.1 percent of boron, 1.0 to 1.3 percent of copper and 0.08 to 0.11 percent of trace elements.
Further, in the amorphous nanocrystalline alloy, the mass percentages of the components are as follows: 81.3% of iron, 9.0% of silicon, 6.4% of niobium, 2.0% of boron, 1.2% of copper and 0.1% of trace elements.
According to the invention, the initial permeability mu and the saturation magnetic flux density B of the iron core prepared from the components can be greatly improved, so that the specific value error epsilon of the current transformer can be greatly reduced, namely, the accuracy of the current transformer is improved, the accurate metering of the current transformer is ensured, the problem that the current transformer cannot accurately meter in the prior art is solved, and the iron core with the same size has higher initial permeability and magnetic flux density.
On the other hand, the invention also provides a method for preparing the iron core by using the amorphous nanocrystalline alloy, which comprises the following steps: smelting, namely smelting all components in the amorphous nanocrystalline alloy into a master alloy under a vacuum condition, heating the master alloy to a preset temperature, spraying a strip and winding the strip to form an iron core; annealing, namely annealing the wound iron core and cooling to normal temperature; dipping, namely putting the annealed iron core into dipping liquid at normal temperature under vacuum for 20-30 minutes, taking out the iron core from the dipping liquid, and curing at 150-170 ℃ for 83-98 minutes; and a plastic spraying step, namely performing plastic spraying treatment on the solidified iron core.
Further, in the above method for manufacturing an iron core, the smelting step further includes: smelting the components in the amorphous nanocrystalline alloy under vacuum condition at a smelting temperature of 1600-1700 ℃ for a preset time to form a solid master alloy; wherein the smelting temperature is 1650 ℃, and the preset time for smelting is 90 minutes per 500kg of amorphous nanocrystalline alloy; heating the solid master alloy to 1450 ℃ to enable the master alloy to be in a liquid state, and spraying the liquid master alloy to form an alloy strip; and winding the alloy strip into an iron core.
Further, in the above method of manufacturing an iron core, the annealing step further includes: heating the wound iron core to 420 ℃ for the first time within 75-85 minutes, and preserving the heat for 38-42 minutes; heating the iron core subjected to the first heating up to 480 ℃ within 58-64 minutes for the second time, and preserving the heat for 75-83 minutes; heating the iron core subjected to the second heating up to 550-560 ℃ within 78-83 minutes for the third time, and preserving the heat for 125-135 minutes; and cooling the iron core subjected to the third temperature rise to 280 ℃, and then cooling to the normal temperature.
Further, in the method for preparing the iron core, in the dipping step, the dipping solution is nano polymerization paint; and taking the iron core after annealing treatment out of the soaking solution, and curing for 88-94 minutes at 158-165 ℃.
Further, in the above method for manufacturing an iron core, the plastic spraying step further includes: preheating the solidified iron core at 175-185 ℃ for 15-20 minutes; and dip-coating the preheated iron core on a fluidized bed, spraying plastics, and heating for curing.
Further, in the method for preparing the iron core, in the step of spraying plastics, the iron core which is dip-coated and sprayed with plastics is cured for 13-17 minutes at 200 ℃; or curing the iron core coated with the dip-coating plastic at 180 ℃ for 18-22 minutes.
According to the invention, the amorphous nanocrystalline alloy can ensure the integral shape of the iron core through a vacuum smelting and annealing process, and is impregnated, so that the amorphous nanocrystalline alloy has magnetic property, the magnetic property of the prepared iron core can be kept unchanged, and the amorphous nanocrystalline alloy in the amorphous nanocrystalline alloy can be protected. The mechanical property, the electrical insulation intensity and the magnetic conductivity of iron core can be strengthened once more to the plastic spraying processing need not to set up like among the prior art and protects the box, can increase the iron core sectional area under the unchangeable condition of overall dimension of assurance iron core like this for the iron core has wideer working interval, and then can satisfy current transformer wide range, the relevant requirement of high accuracy better, can also prepare the iron core according to the required size of reality.
On the other hand, the invention also provides a method for manufacturing the wide-range current transformer for metering by using the iron core, which comprises the following steps: an insulating buffer layer is arranged on the outer wall of the iron core, wherein the iron core is annular; uniformly winding a primary winding and a secondary winding outside the insulating buffer layer; performing an accuracy test on the iron core wound with the secondary winding, adjusting the iron core when the accuracy requirement is not met, and winding an insulating layer outside the iron core wound with the primary winding and the secondary winding until the accuracy requirement is met; respectively welding the lead wires at the head end and the tail end of the secondary winding with a secondary terminal; and placing the iron core wound with the insulating layer into a mold for pouring and curing to form the current transformer.
According to the current transformer manufactured by the iron core made of the amorphous nanocrystalline alloy, the ratio error of the current transformer can be greatly reduced, the accuracy of the current transformer is effectively improved, the accurate measurement of the current transformer is ensured, the current transformer has a wider range and higher accuracy, the existing operation requirement can be met on the premise of not changing the overall dimension, and the stable operation of the current transformer is ensured.
Drawings
Various additional advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a flowchart of a method of manufacturing an iron core according to an embodiment of the present invention;
fig. 2 is a flowchart of a smelting step in a method for manufacturing an iron core according to an embodiment of the present invention;
fig. 3 is a flowchart of an annealing step in a method for manufacturing an iron core according to an embodiment of the present invention;
fig. 4 is a graph comparing magnetization curves of a core according to an embodiment of the present invention and a core according to the prior art;
fig. 5 is a flowchart of a method for manufacturing a wide-range current transformer for metering by using an iron core according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a current transformer according to an embodiment of the present invention;
fig. 7 is a schematic side view of a current transformer according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Amorphous nanocrystalline alloy example:
the principle of improving the metering accuracy of the current transformer is as follows:
setting the primary current as I 1 The secondary current is I 2 The number of primary turns is N 1n The number of secondary turns is N 2n The secondary impedance is Z 2 Secondary induced potential is E 2 Excited magnetic potential (IN) 0 The number of primary ampere-turns at each primary current Is (IN) 1 Magnetic flux density in the core is B, magnetic field strength is H, magnetic permeability of the core material is mu, average magnetic path length in the core is L, K F Is a constant determined by the horizontal coefficient of the iron core manufacturing process.
The ratio error epsilon (%) of the current transformer is as follows:
and (IN) 0 ＝K F HL (2)
Under the condition of the same iron core size and the same manufacturing process, K F L is invariant, therefore, one can derive (IN) 0 And H are in direct proportion.
And B = μ H (3)
The secondary induced potential is:
due to the secondary impedance Z 2 Is constant and the secondary current is in direct proportion to the secondary induced potential, i.e.
And because the number of primary and secondary turns is a fixed value, a primary current I can be obtained 1 And a secondary current I 2 In relation to (2)
The above derivation can lead to the following conclusions:
according to the derivation of the formulas (1) and (2), the ratio error epsilon of the current transformer is proportional to H. According to the derivation of the formulas (3) to (6), the current value I is determined at any one of the primary currents 1 In case of input, the second inputOutput current I 2 The ratio of the current transformer to the mu H is in a direct proportion relation, and the larger the H is, the larger the ratio error epsilon of the current transformer is. To reduce the ratio error epsilon of the current transformer, H needs to be reduced, and to reduce the value of H, the value of the core permeability mu needs to be increased. To ensure I 1 When the output accuracy reaches 1 per mill of rated current, the iron core needs to have higher magnetic permeability mu. Similarly, in order to enable the current transformer to still output accurately at the rated current of 200%, the iron core needs to have a higher saturation magnetic flux density B, so as to expand the working range of the current transformer.
According to the principle of the current transformer for improving the metering accuracy, the magnetic permeability μ and the saturation magnetic flux density B of the iron core need to be improved. In the embodiment, the iron core material is improved in composition, and specifically, the amorphous nanocrystalline alloy comprises the following components in percentage by mass: 81.0 to 81.6 percent of iron, 8.7 to 9.3 percent of silicon, 6.2 to 6.7 percent of niobium, 1.8 to 2.3 percent of boron, 0.08 to 1.4 percent of copper and 0.07 to 0.13 percent of trace elements. The initial permeability mu and the saturation magnetic flux density B of the iron core prepared from the components can be greatly improved, and then the ratio error epsilon of the current transformer can be greatly reduced, namely, the accuracy of the current transformer is improved, the accurate measurement of the current transformer is ensured, the problem that the current transformer cannot accurately measure in the prior art is solved, and the iron core with the same size has higher initial permeability and magnetic flux density.
Preferably, the mass percentages of the components are as follows: 81.1 to 81.4 percent of iron, 8.8 to 9.1 percent of silicon, 6.3 to 6.5 percent of niobium, 1.9 to 2.1 percent of boron, 1.0 to 1.3 percent of copper and 0.08 to 0.11 percent of trace elements.
More preferably, the mass percentages of the components are as follows: 81.3% of iron, 9.0% of silicon, 6.4% of niobium, 2.0% of boron, 1.2% of copper and 0.1% of trace elements. The initial magnetic permeability mu of the iron core material prepared by the components can be improved from 150000 to 280000, the saturation magnetic flux density B can be improved from 1.10T to 1.25T, the accuracy of the current transformer is improved, and the requirements of various performance indexes of the current transformer are effectively met.
Examples of methods for making iron cores:
the embodiment also provides a method for preparing the iron core, which is carried out by using the amorphous nanocrystalline alloy in the embodiment of the amorphous nanocrystalline alloy. Referring to fig. 1, fig. 1 is a flowchart of a method for manufacturing an iron core according to an embodiment of the present invention. The method for preparing the iron core comprises the following steps:
and a smelting step S1, smelting all components in the amorphous nanocrystalline alloy into a master alloy under a vacuum condition, heating the master alloy to a preset temperature, spraying a strip and winding the strip into an iron core.
Specifically, the components in the amorphous nanocrystalline alloy are placed into a vacuum smelting furnace for smelting. More specifically, referring to fig. 2, the smelting step S1 further includes:
s11, smelting the components in the amorphous nanocrystalline alloy under a vacuum condition at a smelting temperature of 1600-1700 ℃ for a preset time to form a solid master alloy; wherein the smelting temperature is 1650 ℃, and the preset time for smelting is 90 minutes per 500kg of amorphous nanocrystalline alloy.
Specifically, the components in the amorphous nanocrystalline alloy are placed in a vacuum smelting furnace and smelted under the vacuum condition, wherein the smelting temperature is 1600-1700 ℃, and preferably 1650 ℃. The smelted alloy is a solid master alloy, and the temperature of the vacuum smelting furnace is reduced to normal temperature.
The smelting time can be determined according to the actual situation, and the embodiment does not limit the smelting time. Preferably, the smelting time is 90 minutes per 500kg of amorphous nanocrystalline alloy.
In specific implementation, smelting is carried out in a vacuum smelting furnace, so that impurities and useless components in the material can be effectively reduced, and the performance of the material is improved.
The specific implementation process of the amorphous nanocrystalline alloy may be as described above, and this embodiment is not described herein again.
And S12, heating the solid master alloy to 1450 ℃ to enable the master alloy to be in a liquid state, and spraying the liquid master alloy to form an alloy strip.
Specifically, the solid master alloy is placed in an intermediate frequency furnace of a strip making machine to be heated, the heating temperature is 1450 ℃, so that the solid master alloy is heated into liquid master alloy, and the liquid master alloy is sprayed to form the alloy strip.
And S13, winding the alloy strip into an iron core.
And an annealing step S2, annealing the wound iron core, and cooling to normal temperature.
Specifically, the wound iron core is gradually heated in a vacuum annealing furnace and then cooled, and the cooled iron core is moved out of the vacuum annealing furnace and cooled to normal temperature, so that the annealing process of the wound iron core is realized. Referring to fig. 3, the annealing step S2 further includes:
and step S21, heating the wound iron core to 420 ℃ for the first time within 75-85 minutes, and preserving the heat for 38-42 minutes. Specifically, in a vacuum annealing furnace, the temperature of the wound iron core is raised from 0 ℃ to 420 ℃ within 75-85 minutes, and the temperature is kept for 38-42 minutes. Preferably, the wound core is heated to 420 ℃ in 80 minutes and held at this temperature for 40 minutes.
And step S22, carrying out secondary temperature rise on the iron core subjected to the primary temperature rise within 58-64 minutes to 480 ℃, and carrying out heat preservation for 75-83 minutes. Specifically, the temperature is raised from 420 ℃ to 480 ℃ within 58 to 64 minutes, and the temperature is maintained for 75 to 83 minutes. Preferably, the temperature is raised to 480 ℃ over 60 minutes and maintained at this temperature for 80 minutes.
And step S23, performing third temperature rise on the iron core subjected to the second temperature rise within 78-83 minutes to 550-560 ℃, and preserving the heat for 125-135 minutes. Specifically, the temperature is raised from 480 ℃ to 550-560 ℃ within 78-83 minutes, and the temperature is kept for 125-135 minutes. Preferably, the temperature is raised to 550 to 560 ℃ within 80 minutes and maintained at that temperature for 130 minutes.
And S24, cooling the iron core subjected to the third temperature rise to 280 ℃, and then cooling to the normal temperature.
Specifically, after the third temperature rise, the heating of the vacuum annealing furnace is stopped, the iron core subjected to the third temperature rise is cooled to 280 ℃ along with the furnace, the cooled iron core is output to the vacuum annealing furnace, and the cooled iron core is cooled to normal temperature.
And a dipping step S3, namely placing the annealed iron core in a dipping solution at normal temperature under vacuum for 20 to 30 minutes, taking out the iron core from the dipping solution, and curing the iron core at the temperature of between 150 and 170 ℃ for 83 to 98 minutes.
Specifically, the iron core taken out of the vacuum annealing furnace is placed in an immersion liquid, and the whole is immersed in the immersion liquid under a normal temperature vacuum. The dipping solution is nano polymeric paint, so that the dipping solution has a magnetic property memory function, the magnetic property of the subsequently prepared iron core is kept unchanged, and the sizing and protecting effects can be achieved.
Preferably, the annealed iron core is taken out from the immersion liquid and cured at 158 to 165 ℃ for 88 to 94 minutes. More preferably, it is cured at 160 ℃ for 90 minutes.
And a plastic spraying step S4, performing plastic spraying treatment on the solidified iron core.
Specifically, the solidified iron core is preheated, wherein the preheating temperature is 175-185 ℃, and the preheating time is 15-20 minutes. Then, the preheated iron core is placed on a fluidized bed to be dip-coated with spraying plastics, the powder is automatically applied, and the iron core is heated and cured to complete the preparation of the iron core. Wherein the parameters of heating and curing are as follows: curing the iron core subjected to dip coating and plastic spraying for 13-17 minutes at 200 ℃, preferably, the curing time is 15 minutes; or curing the iron core after dip coating and plastic spraying at 180 ℃ for 18-22 minutes, preferably, the curing time is 20 minutes.
In specific implementation, the shape of the prepared iron core can be circular, oval, square or circular.
Referring to fig. 4, a graph comparing the magnetization curves of the iron core made of the amorphous nanocrystalline alloy in the present embodiment with those of the iron core in the prior art is shown in fig. 4, and it can be seen from the graph that the iron core in the present embodiment has higher magnetic permeability and magnetic flux density.
It can be seen that, in this embodiment, the amorphous nanocrystalline alloy can ensure the overall shape of the iron core through the vacuum smelting and annealing processes, and the amorphous nanocrystalline alloy is impregnated to make the amorphous nanocrystalline alloy have magnetic properties, ensure that the magnetic properties of the prepared iron core remain unchanged, and protect the amorphous nanocrystalline alloy inside the iron core. The mechanical property, the electrical insulation intensity and the magnetic conductivity of iron core can be strengthened once more to the plastic spraying processing need not to set up like among the prior art and protects the box, can increase the iron core sectional area under the unchangeable condition of overall dimension of assurance iron core like this for the iron core has wideer working interval, and then can satisfy current transformer wide range, the relevant requirement of high accuracy better, can also prepare the iron core according to the required size of reality.
The embodiment of the method for manufacturing the wide-range current transformer for metering comprises the following steps:
the present embodiment also provides a method for manufacturing a wide-range current transformer for metering by using the iron core, where the method is a method for manufacturing a wide-range current transformer for metering by using the iron core manufactured in the above method for manufacturing an iron core. Referring to fig. 5, fig. 5 is a flowchart of a method for manufacturing a wide-range current transformer for metering by using an iron core according to an embodiment of the present invention. The method comprises the following steps:
and S1, arranging an insulating buffer layer on the outer wall of the iron core, wherein the iron core is annular.
Specifically, referring to fig. 6 and 7, the iron core 1 prepared according to the embodiment of the method for preparing an iron core described above has a ring shape, and the insulating buffer layer 2 is disposed on the outer wall of the iron core 1, and the insulating buffer layer 2 is made of an insulating material. The setting of insulating buffer layer 2 can guarantee that the iron core has stable electromagnetic properties, and then guarantees to measure with wide range current transformer's electromagnetic properties.
During the concrete implementation, insulating buffer layer 2 can be crepe paper or insulating tape for the buffering, and its effect is mainly when guaranteeing to measure with wide-range current transformer ambient temperature change, reduces the oppression to the iron core to guarantee to measure with wide-range current transformer's degree of accuracy and stability. Preferably, the insulating buffer layer 2 is a combination of crepe paper, an electrical self-adhesive tape, a medical thick adhesive tape and the like.
The specific implementation process of the iron core preparation method may refer to the above description, and this embodiment is not described herein again.
And S2, uniformly winding a primary winding and a secondary winding outside the insulation buffer layer.
Specifically, the primary winding and the secondary winding are wound around different portions of the core 1, respectively, and the voltages of the primary winding and the secondary winding are different.
And S3, carrying out accuracy test on the iron core wound with the secondary winding, adjusting when the accuracy requirement is not met, and winding an insulating layer outside the iron core wound with the primary winding and the secondary winding until the accuracy requirement is met.
Specifically, an accuracy test is carried out after the secondary winding is completed, and if the test shows that the accuracy requirement is met, the step S4 is directly carried out; if the test shows that the accuracy requirement is not met, adjustment is needed. During adjustment, the value error and the phase error are adjusted by fractional turn compensation, short-circuit turn compensation, magnetic shunt compensation and/or capacitance and inductance compensation, specifically, the number of turns of the coil in the secondary winding can be adjusted, and other adjustments can be performed according to actual conditions, which is not limited in this embodiment.
After the adjustment is finished, continuing to perform the accuracy test, and if the test shows that the accuracy requirement is met, directly performing the step S4; if the test shows that the accuracy requirement is not met, the adjustment is continued according to the method until the accuracy requirement is met, and the adjustment is not carried out. Then, an insulating layer 4 is wound around the entire outside of the core around which the primary winding and the secondary winding are wound, and referring to fig. 5 and 6, the insulating layer 4 is to insulate the coil 3 of the winding and to ensure insulation between the core 1 and the air and the coil 3 of the winding.
In specific implementation, the insulating layer 4 may be crepe paper or an insulating tape for buffering. The insulating layer 4 is mainly used for reducing the compression on the iron core when the environment temperature changes so as to ensure the accuracy and stability of the wide-range current transformer for metering.
And S4, respectively welding the lead wires at the head end and the tail end of the secondary winding with a secondary terminal.
Specifically, referring to fig. 6 and 7, a secondary lead 5 is led out from the head end and the tail end of the secondary winding, a secondary terminal 6 is welded on each secondary lead 5 according to the fixed length position required by the structure, and the two secondary terminals 6 are used for being connected with the watt-hour meter.
And S5, placing the iron core wound with the insulating layer into a mold for pouring and curing to form the current transformer.
Specifically, the whole iron core 1 wound with the insulating layer 4 is placed in a mold for epoxy resin pouring and curing molding, so that the wide-range current transformer for metering is formed.
Table 2 comparison of the current transformer in this embodiment with the standard basic error limit of the existing current transformer
As can be seen from table 2, compared with the current transformer in the prior art, the current transformer in this embodiment has better accuracy, and effectively reduces the ratio error of the wide-range current transformer for metering.
It can be seen that, in this embodiment, the current transformer manufactured by using the iron core made of the amorphous nanocrystalline alloy can greatly reduce the ratio error of the current transformer, effectively improve the accuracy of the current transformer, ensure the accurate measurement of the current transformer, have a wider range and higher accuracy, meet the existing operation requirement on the premise of not changing the overall dimension, and ensure the stable operation of the current transformer.
It should be noted that the principles of the method for detecting the amorphous nanocrystalline alloy, the method for preparing the iron core by using the amorphous nanocrystalline alloy, and the method for manufacturing the wide-range current transformer for metering by using the iron core in the present invention are the same, and the relevant points can be referred to each other.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. A method for preparing an iron core by using amorphous nanocrystalline alloy is characterized by comprising the following steps:
smelting, namely smelting all components in the amorphous nanocrystalline alloy into a master alloy under a vacuum condition, heating the master alloy to a preset temperature, spraying a strip and winding the strip to form an iron core; the amorphous nanocrystalline alloy comprises the following components in percentage by mass: 81.0 to 81.6 percent of iron, 8.7 to 9.3 percent of silicon, 6.2 to 6.7 percent of niobium, 1.8 to 2.3 percent of boron, 0.08 to 1.4 percent of copper and 0.07 to 0.13 percent of trace element;
annealing, namely annealing the wound iron core and cooling to normal temperature;
dipping, namely putting the annealed iron core into dipping liquid at normal temperature under vacuum for 20-30 minutes, taking out the iron core from the dipping liquid, and curing at 150-170 ℃ for 83-98 minutes;
and a plastic spraying step, namely performing plastic spraying treatment on the solidified iron core.
2. The method of making an iron core of claim 1 wherein the step of smelting further comprises:
smelting the components in the amorphous nanocrystalline alloy under vacuum condition at a smelting temperature of 1600-1700 ℃ for a preset time to form a solid master alloy; wherein the smelting temperature is 1650 ℃, and the preset time for smelting is 90 minutes per 500kg of amorphous nanocrystalline alloy;
heating the solid master alloy to 1450 ℃ to enable the master alloy to be in a liquid state, and spraying the liquid master alloy to form an alloy strip;
and winding the alloy strip into the iron core.
3. The method of making a core according to claim 1, wherein said annealing step further comprises:
heating the wound iron core to 420 ℃ for the first time within 75-85 minutes, and preserving the heat for 38-42 minutes;
carrying out secondary temperature rise on the iron core subjected to the primary temperature rise within 58-64 minutes to 480 ℃, and preserving the heat for 75-83 minutes;
heating the iron core subjected to the second heating up to 550-560 ℃ within 78-83 minutes for the third time, and preserving the heat for 125-135 minutes;
and cooling the iron core subjected to the third temperature rise to 280 ℃, and then cooling to the normal temperature.
4. The method of manufacturing a core according to claim 1, wherein in the impregnating step,
the impregnating solution is nano polymeric paint;
and taking the iron core after annealing treatment out of the impregnating solution, and curing at 158-165 ℃ for 88-94 minutes.
5. The method of making a core according to claim 1, wherein said step of injection molding further comprises:
preheating the solidified iron core at 175-185 ℃ for 15-20 minutes;
and dip-coating the preheated iron core on a fluidized bed, spraying plastics, and heating for curing.
6. The method for manufacturing an iron core according to claim 5, wherein in the injection molding step,
curing the iron core coated with the dip-coating plastic at 200 ℃ for 13-17 minutes; alternatively, the first and second electrodes may be,
curing the iron core after dip coating and plastic spraying at 180 ℃ for 18-22 minutes.
7. A method for manufacturing a wide-range current transformer for metering by using the iron core manufactured by the method for manufacturing the iron core according to any one of claims 1 to 6, which is characterized by comprising the following steps:
arranging an insulating buffer layer on the outer wall of the iron core, wherein the iron core is annular;
uniformly winding a primary winding and a secondary winding outside the insulating buffer layer;
carrying out accuracy test on the iron core wound with the secondary winding, and adjusting when the accuracy requirement is not met, and winding an insulating layer outside the iron core wound with the primary winding and the secondary winding until the accuracy requirement is met;
respectively welding the lead wires at the head end and the tail end of the secondary winding with a secondary terminal;
and placing the iron core wound with the insulating layer into a mold for pouring and curing to form the current transformer.
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| CN111880138B (en) * | 2020-08-19 | 2022-11-08 | 国网福建省电力有限公司 | Zero-sequence current transformer measurement accuracy optimization method based on ferromagnetic characteristics |
| CN113053650A (en) * | 2021-03-15 | 2021-06-29 | 浙江天际互感器有限公司 | Preparation method of current transformer iron core |
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