Ceramic capacitor dielectric, method of manufacture and voltage transformer

Abstract

The application discloses a ceramic capacitor dielectric, a preparation method and a voltage transformer. The ceramic capacitor dielectric exhibits excellent capacitance stability in a wide temperature range. Through testing, the capacitance change rate is +0.06% in a temperature range of-40 DEG C to 20 DEG C; and the capacitance change rate is-0.10% in a temperature range of 20 DEG C to 70 DEG C. The excellent temperature characteristic enables the voltage transformer adopting the ceramic capacitor dielectric to maintain a highly stable voltage division ratio and measurement accuracy in an extreme temperature difference environment such as a severe winter and a scorching summer, and fundamentally solves the measurement error problem caused by temperature drift of the ceramic capacitor material.

Description

Technical Field

[0001] This invention relates to the field of ceramic capacitor technology, and in particular to a ceramic capacitor dielectric, a preparation method, and a voltage transformer. Background Technology

[0002] Voltage transformers are key devices in power systems for voltage measurement, energy metering, and relay protection. Currently, commonly used voltage transformers are mainly divided into two categories: electromagnetic voltage transformers and electronic voltage transformers.

[0003] Electromagnetic voltage transformers operate based on the principle of electromagnetic induction. Their primary winding is connected to the high-voltage power grid, while the secondary winding outputs a low-voltage signal for use by instruments and protection devices. However, when overvoltage harmonics or ferroresonance occur in the power system, the iron core is prone to saturation, leading to secondary voltage distortion. In severe cases, this can cause insulation breakdown or even explosion of equipment. The use of coils and iron cores in the production of electromagnetic voltage transformers not only results in high consumption of national copper and iron resources but also leads to high power consumption during operation, which is inconsistent with the principles of low-carbon and environmental protection.

[0004] Electronic voltage transformers include resistive voltage transformers and capacitive voltage transformers. Common capacitive voltage transformers use thin-film capacitors as voltage-dividing elements, offering advantages such as small size and fast response. However, the extremely thin dielectric layer of thin-film capacitors results in weak high-voltage withstand capability, often requiring multiple capacitors connected in series to meet the withstand voltage requirements. This not only increases structural complexity but also reduces system reliability. Furthermore, thin-film capacitor materials suffer from rapid aging and significant capacitance decay over time, leading to significant deviations in metering accuracy after long-term operation, making it difficult to meet the power grid's demand for long-term stable metering.

[0005] In recent years, ceramic capacitor voltage transformers have attracted widespread attention due to their stable performance, high voltage resistance, low power consumption, harmonic protection, and simple manufacturing process. Ceramic capacitors employ a monolithic sintered thick-plate structure, overcoming the shortcomings of thin-film capacitors such as poor high voltage resistance and susceptibility to aging, demonstrating significant advantages in voltage withstand capability and long-term stability.

[0006] However, the dielectric constant and capacitance of existing ceramic capacitor dielectrics change significantly under different ambient temperatures, leading to voltage division ratio drift. This, in turn, increases the ratio error and phase error of the transformer, making it difficult to meet the all-weather metering requirements of the power grid for accuracy levels of 0.2 and above. Therefore, it is necessary to design a ceramic capacitor dielectric with high temperature stability and a voltage transformer made from it. Summary of the Invention

[0007] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a ceramic capacitor dielectric, a preparation method and a voltage transformer.

[0008] In a first aspect, the present invention provides a ceramic capacitor dielectric, comprising:

[0009] The first component, accounting for 65% to 75%, includes 0.5 to 0.6 moles of barium carbonate, 0.3 to 0.4 moles of titanium dioxide, and 0.1 to 0.2 moles of strontium carbonate;

[0010] The second component, accounting for 10% to 20%, includes 0.35 to 0.45 moles of zinc oxide, 0.2 to 0.3 moles of calcium carbonate, 0.25 to 0.35 moles of silicon dioxide, and 0.03 to 0.05 moles of manganese carbonate.

[0011] The third component, accounting for 12% to 18%, includes 0.6 to 0.65 moles of lanthanum and 0.35 to 0.4 moles of samarium.

[0012] Secondly, the present invention provides a method for preparing a ceramic capacitor dielectric, which specifically includes the following steps:

[0013] S1. The first component, the second component, and the third component are identified by their respective proportions and percentages.

[0014] S2. The first component is subjected to wet mixing, drying and calcination for 10 hours in sequence;

[0015] S3. The calcined first and third components are sequentially pressed into blocks, calcined, coarsely crushed and finely ground, and dried to obtain a preliminary mixture.

[0016] S4. The second component is mixed into the preliminary mixture to form a secondary mixture;

[0017] S5. Grind the secondary mixture to below 10nm, add binder, dry and granulate to form ceramic powder;

[0018] S6. The ceramic powder is pressed and sintered to form the ceramic capacitor dielectric.

[0019] According to the technical solution provided in the embodiments of this application, after step S6, the following step is also included: sintering a silver layer on the surface of the ceramic capacitor dielectric to obtain a ceramic capacitor.

[0020] According to the technical solution provided in the embodiments of this application, in steps S2 and S3, the calcination temperature is 1000℃~1100℃ and the calcination time is 2~3 hours.

[0021] Thirdly, the present invention provides a voltage transformer comprising three ceramic capacitor dielectrics, with silver electrodes covering both sides of the ceramic capacitor dielectrics to form ceramic capacitors. The three ceramic capacitors are connected in parallel via a high-voltage connecting wire and a low-voltage connecting wire. The head of the high-voltage connecting wire is connected to a high-voltage terminal, and the tail of the low-voltage connecting wire is connected to a low-voltage terminal. A low-voltage capacitor is connected to the bottom of the low-voltage terminal, and a signal output electrode and a ground wire are connected to the bottom of the low-voltage capacitor.

[0022] According to the technical solution provided in the embodiments of this application, the high-voltage terminal block, the high-voltage connecting wire, the three parallel ceramic capacitors, the grounding wire, the low-voltage terminal block, the low-voltage capacitor, the signal output electrode, and the low-voltage connecting wire are all uniformly cast in a dense insulating layer, and the outer side of the insulating layer is in close contact with the skirt edge.

[0023] According to the technical solution provided in the embodiments of this application, the bottom of the insulating layer has a first wire hole for the signal output electrode wire to pass through, and a second wire hole for the grounding wire to pass through.

[0024] According to the technical solution provided in the embodiments of this application, a fixing nut is also provided at the bottom of the insulating layer.

[0025] According to the technical solution provided in the embodiments of this application, the insulating layer is made of dense insulating material, and the skirt is made of organic polymer material.

[0026] According to the technical solution provided in the embodiments of this application, the cross-sectional shape of the insulating layer is circular.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] Excellent capacitance stability over a wide temperature range, supporting high-precision metering: The ceramic capacitor dielectric of this invention exhibits extremely excellent capacitance stability over a wide temperature range. Tests show that the capacitance change rate is +0.06% within the temperature range of -40℃ to 20℃, and -0.10% within the temperature range of 20℃ to 70℃. This superior temperature characteristic enables voltage transformers using the ceramic capacitor dielectric of this invention to maintain a highly stable voltage division ratio and metering accuracy even in extreme temperature environments such as frigid winters and scorching summers, fundamentally solving the metering error problem caused by temperature drift in ceramic capacitor materials.

[0029] An optimized solid-state reaction pathway ensures stable dielectric properties: In the preparation method of this invention, the first component (BaCO3-TiO-SrCO3) is first mixed with the third component (rare earth elements La and Sm) and calcined. This process design allows the rare earth elements to preferentially undergo a sufficient solid-state reaction with the first component matrix, forming a stable crystal lattice structure, thereby obtaining a stable dielectric constant and good electrical properties. Simultaneously, this step avoids premature contact and reaction between the rare earth elements and the second component (ZnO, CaCO3, SiO2, MnCO3), preventing the rare earth elements from being consumed or interfered with by the low-valence oxides in the second component, thus ensuring the full utilization of the rare earth modification effect.

[0030] With excellent temperature stability and high accuracy across the entire measurement range, based on the superior performance of the ceramic capacitor dielectric, the voltage transformer of this invention exhibits extremely high measurement accuracy in whole-machine testing. In extreme temperature tests ranging from -40℃ to +70℃, the ratio error variation is 0.00%~0.18%, and the phase error variation is 0′~3′. This data far exceeds the limits for 0.2-class voltage transformers (ratio error ≤ ±0.2%, phase error ≤ ±10′) in the national standard GB / T 20840.7-2007. At room temperature (27℃), the ratio error remains constant at -0.14% within the 80%~120% rated voltage range. This demonstrates that the voltage transformer of this invention achieves a perfect balance between high accuracy at room temperature and high stability across the entire temperature range, solving the industry pain point of measurement inaccuracies caused by temperature drift in traditional ceramic capacitors.

[0031] The ceramic capacitor used in this invention's transformer possesses high withstand voltage strength and excellent insulation performance. A single ceramic capacitor can withstand a 42kV power frequency withstand voltage test without breakdown or flashover. Partial discharge is 0pC under both 14.4kV and 8.3kV test conditions. Its application in voltage transformers, combined with a fully enclosed cast insulation structure, effectively eliminates safety hazards such as partial discharge, flashover, and even explosions caused by insulation aging and moisture in traditional electromagnetic transformers, significantly improving the reliability of power grid operation. Furthermore, because the ceramic capacitor only charges and discharges during metering and has extremely high impedance, the current is very small, resulting in minimal power consumption. Additionally, the ceramic capacitor itself has good filtering characteristics, effectively reducing the impact of overvoltage harmonics on the equipment, making its operation safer and more stable.

[0032] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0033] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0034] Figure 1 A flowchart illustrating the steps of a method for preparing a ceramic capacitor dielectric according to an embodiment of this application;

[0035] Figure 2 This is a schematic diagram of the voltage transformer in the embodiments of this application;

[0036] Figure 3 This is a schematic diagram of the installation structure of the high-voltage terminal and the low-voltage terminal in the embodiments of this application.

[0037] The following are the labels in the diagram: 1. High-voltage terminal; 2. High-voltage connecting wire; 3. Ceramic capacitor; 4. Insulation layer; 5. Skirt; 6. Fixing nut; 7. Grounding wire; 8. Low-voltage terminal; 9. Low-voltage capacitor; 10. Signal output electrode; 11. Low-voltage connecting wire; 12-1. First wire hole; 12-2. Second wire hole; 13. Silver electrode. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] An embodiment of the present invention provides a ceramic capacitor dielectric, comprising:

[0042] The first component, comprising 75%, includes 0.6 moles of barium carbonate, 0.3 moles of titanium dioxide, and 0.1 moles of strontium carbonate; the total mole fraction is 1, constituting the first component.

[0043] The second component, accounting for 10%, includes 0.4 moles of zinc oxide, 0.25 moles of calcium carbonate, 0.3 moles of silicon dioxide, and 0.05 moles of manganese carbonate.

[0044] The third component, accounting for 15%, includes 0.6 moles of lanthanum and 0.4 moles of samarium.

[0045] The first component is the main material, and the synthesized powder is barium strontium titanate. The third component is rare earth elements, which ensure the electrical performance and stability of the product. The electrical performance includes withstand voltage, partial discharge, temperature rise and dielectric loss. The second component is used to ensure the sintering characteristics of ceramic capacitors, increase the ceramic density, reduce the sintering temperature and widen the sintering temperature range.

[0046] This embodiment is designed according to 10kV power grid metering. The thickness of the ceramic capacitor dielectric is 14mm. Nine ceramic capacitor dielectrics are selected as test samples. After being coated with silver, they are divided into three groups for breakdown test, partial discharge test and lightning strike test respectively.

[0047] Three samples were selected for the breakdown test. The test was conducted for 1 minute under a 42kV power frequency withstand voltage environment. None of the three samples broke down, which met the breakdown test standard.

[0048] Three samples were selected for the partial discharge test, with test voltages of 14.4kV and 8.3kV. The actual measured partial discharge amount was 0pC, which is far better than the standard limit (among which, according to GB / T20840.7-2007 Instrument Transformers Part 7: Electronic Voltage Transformers, the standard limit for the 14.4kV test voltage is 50pC, and the standard limit for the 8.3kV test voltage is 20pC), indicating that the insulation condition of the samples is excellent.

[0049] In the lightning strike test, at 75kV, 15 positive polarity strikes and 15 negative polarity strikes were applied respectively, for a total of 30 strikes. At 85kV, 2 positive polarity strikes and 2 negative polarity strikes were applied respectively, for a total of 4 strikes. No flashover, breakdown or mechanical damage occurred in any of the samples.

[0050] In summary, ceramic capacitors possess excellent withstand voltage and breakdown performance, high dielectric strength, extremely low partial discharge levels, and are less prone to insulation degradation during long-term operation, resulting in a significantly extended service life. They also exhibit outstanding resistance to lightning surges, effectively protecting against common lightning strikes in power grids and ensuring the safe operation of voltage transformers under adverse weather conditions.

[0051] Based on this, six samples from two batches were selected for sintering characteristic testing, and the results are shown in Table 1. Sintering Characteristics.

[0052] Table 1. Sintering characteristics

[0053] As can be seen from Table 1, the volume fraction of the ceramic capacitor dielectric is no higher than 0.10% in the temperature ranges of -40℃ to 20℃ and 20℃ to 70℃. Under extreme temperature difference environments such as severe winter and hot summer, it can still maintain a highly stable voltage division ratio and metering accuracy, fundamentally solving the metering error problem caused by temperature drift of traditional ceramic capacitor materials.

[0054] Example 2

[0055] An embodiment of the present invention provides a method for preparing a ceramic capacitor dielectric, used to prepare the ceramic capacitor dielectric described in Example 1, specifically including the following steps:

[0056] S1. The first component, the second component, and the third component are identified by their respective proportions and percentages.

[0057] S2. The first component is subjected to wet mixing, drying and calcination for 10 hours in sequence;

[0058] In step S2, the first component is placed in a ball mill and wet-mixed for 10 hours using deionized water as the medium. The ball mill speed is controlled at 200 rpm, and the ball-to-material ratio is 5:1 to ensure thorough mixing. After mixing, the slurry is poured out and dried in an oven at 80°C for 12 hours to remove moisture. The dried powder is then calcined in air at 1050°C for 3 hours in a box-type resistance furnace to promote solid-phase reaction and compound formation. After calcination, the sample is allowed to cool naturally to room temperature for subsequent use.

[0059] S3. The calcined first and third components are sequentially pressed into blocks, calcined, coarsely crushed and finely ground, and dried to obtain a preliminary mixture.

[0060] In step S3, the calcined first and third components are pressed into blocks under appropriate pressure using a press. After pressing, the blocks are calcined in a high-temperature environment at 1080℃ for 2 hours to achieve phase transformation and sintering of the materials. The calcined blocks are then subjected to coarse and fine grinding in a ball mill, with grinding parameters controlled to refine the powder particle size to below 1.5μm. Finally, the powder is dried at a constant temperature to remove residual moisture and obtain a dry and uniform powder.

[0061] S4. The second component is mixed into the preliminary mixture to form a secondary mixture;

[0062] S5. Grind the secondary mixture to below 10nm, add binder, dry and granulate to form ceramic powder;

[0063] In step S5, the secondary mixture is ground at high speed by a nano-grinding mill to a particle size of less than 10 nm. Then, a pre-prepared PVA (polyvinyl alcohol) solution is added as a binder. After thorough mixing, the mixture is dried and granulated by a spray granulation tower under controlled temperature, airflow and pressure conditions to obtain a dry granule product with uniform particle size distribution and good flowability.

[0064] S6. The ceramic powder is pressed and sintered to form the ceramic capacitor dielectric.

[0065] In some embodiments, the following steps are included after step S6:

[0066] A ceramic capacitor is obtained by sintering a silver layer on the surface of the ceramic capacitor dielectric.

[0067] In the preparation method of this invention, the first component (BaCO3-TiO-SrCO3) and the third component (rare earth elements La and Sm) are first mixed and calcined. This process design allows the rare earth elements to preferentially undergo a sufficient solid-state reaction with the matrix of the first component, forming a stable crystal lattice structure, thereby obtaining a stable dielectric constant and good electrical properties. At the same time, this step avoids premature contact and reaction between the rare earth elements and the second component (ZnO, CaCO3, SiO2, MnCO3), preventing the rare earth elements from being consumed or interfered with by the low-valence oxides in the second component, ensuring the full play of the rare earth modification effect, and ultimately ensuring that the ceramic capacitor dielectric has stable temperature characteristics.

[0068] In some embodiments, the thickness of the ceramic capacitor dielectric can be adjusted according to the grid voltage requirements to adapt to the needs of various grid metering equipment, such as 10kV grids and 35kV grids.

[0069] Example 3

[0070] An embodiment of the present invention provides a voltage transformer, comprising three ceramic capacitor dielectrics as described in Embodiment 1. The two sides of the ceramic capacitor dielectrics are covered with silver electrodes 13 to form ceramic capacitors 3. The three ceramic capacitors 3 are connected in parallel through a high-voltage connecting wire 2 and a low-voltage connecting wire 11. The head of the high-voltage connecting wire 2 is connected to a high-voltage terminal 1, and the tail of the low-voltage connecting wire 11 is connected to a low-voltage terminal 8. The bottom of the low-voltage terminal 8 is connected to a low-voltage capacitor 9, and the bottom of the low-voltage capacitor 9 is connected to a signal output electrode 10 and a ground wire 7.

[0071] In some embodiments, the high-voltage terminal 1, the high-voltage connecting wire 2, the three parallel ceramic capacitors 3, the grounding wire 7, the low-voltage terminal 8, the low-voltage capacitor 9, the signal output electrode 10, and the low-voltage connecting wire 11 are all uniformly cast in a dense insulating layer 4, and the outer side of the insulating layer 4 is in close contact with the skirt 5.

[0072] In some embodiments, the bottom of the insulating layer 4 has a first wire hole 12-1 through which the signal output electrode 10 wire passes, and a second wire hole 12-2 through which the grounding wire 7 wire passes. When the wire diameter is small, they can be combined into a single wire hole.

[0073] In some embodiments, a fixing nut 6 is also provided at the bottom of the insulation layer 4. The fixing nut 6 is used for the installation of the entire voltage transformer.

[0074] In some embodiments, the insulating layer 4 is made of a dense insulating material, such as epoxy resin, glass, ceramic, etc.; the skirt 5 is made of an organic polymer material, such as silicone, epoxy resin, etc.

[0075] In some embodiments, the cross-sectional shape of the insulating layer 4 is circular.

[0076] Example 4

[0077] The applicant prepared a ceramic capacitor voltage transformer of model CCEVT / JZ-12 according to the voltage transformer structure of Example 3 and the requirements of 10kV power grid meter. The applicant selected the corresponding 10kV power grid resistive voltage transformer and electromagnetic voltage transformer and obtained the corresponding active power of the transformer as shown in Table 2. Comparison of Active Power of Various Types of Transformers.

[0078]

[0079] As can be clearly seen from Table 2, the power consumption of resistive voltage transformers is 278.33 times that of capacitive voltage transformers, while the power consumption of electromagnetic voltage transformers is 1511.17 times that of capacitive voltage transformers. Capacitive voltage transformers consume almost no power and are especially suitable for applications with dense substations and a large number of transformers.

[0080] Example 5

[0081] The applicant manufactured a ceramic capacitor voltage transformer of model CCEVT / JZ-12 according to the voltage transformer structure of Example 3 and the requirements of a 10kV power grid meter, and sent it to the Electric Power Industry Electrical Equipment Quality Inspection and Testing Center of China Electric Power Research Institute Co., Ltd. for testing.

[0082] The testing items include: 1. Terminal marking inspection; 2. Power frequency withstand voltage test of primary voltage terminals; 3. Partial discharge measurement; 4. Accuracy test; 5. Rated lightning impulse test and interrupted lightning impulse test; 6. Wet test of outdoor electronic voltage transformers; 7. Overheat withstand capability test; 8. Short circuit withstand capability test; 9. Power frequency withstand voltage test of primary voltage terminals (retest); 10. Partial discharge measurement (retest); 11. Accuracy test (retest).

[0083] The testing was conducted in accordance with GB / T20840.1-2010 Instrument Transformers Part 1: General Technical Requirements and GB / T20840.7-2007 Instrument Transformers Part 7: Electronic Voltage Transformers.

[0084] The tests showed that all items met the standards. Of particular note is the fourth item, the accuracy test, which includes the basic accuracy test and the test on the relationship between accuracy and temperature.

[0085] (1) Basic accuracy test; ambient temperature: 27℃; relative humidity: 60%; test results are as follows.

[0086]

[0087] (2) Test on the relationship between accuracy and temperature; ambient temperature: 27℃; relative humidity: 58%; test results are as follows.

[0088]

[0089] The two test results clearly show that in the extreme temperature test ranging from -40℃ to +70℃, the ratio error of the transformer is 0.00%~0.18%, and the phase error is 0′~3′. This data is far superior to the limit requirements of the national standard GB / T20840.7-2007 for 0.2-class voltage transformers (ratio error ≤ ±0.2%, phase error ≤ ±10′). At room temperature of 27℃, the ratio error remains constant at -0.14% within the range of 80%~120% of the rated voltage. This indicates that the voltage transformer of the present invention achieves a perfect balance between high accuracy at room temperature and high stability across the entire temperature range, achieving stable 0.2-class measurement accuracy.

[0090] In the description of this specification, the terms "connection," "installation," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0091] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0092] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A ceramic capacitor dielectric, characterized in that, include: The first component, accounting for 65% to 75%, includes 0.5 to 0.6 moles of barium carbonate, 0.3 to 0.4 moles of titanium dioxide, and 0.1 to 0.2 moles of strontium carbonate; The second component accounts for 10% to 20%; It includes 0.35–0.45 mol of zinc oxide, 0.2–0.3 mol of calcium carbonate, 0.25–0.35 mol of silicon dioxide, and 0.03–0.05 mol of manganese carbonate; The third component, accounting for 12% to 18%, includes 0.6 to 0.65 moles of lanthanum and 0.35 to 0.4 moles of samarium.

2. A method for preparing a ceramic capacitor dielectric, used to prepare the ceramic capacitor dielectric of claim 1, characterized in that, Specifically, the steps include the following: S1. The first component, the second component, and the third component are identified by their respective proportions and percentages. S2. The first component is subjected to wet mixing, drying and calcination for 10 hours in sequence; S3. The calcined first and third components are sequentially pressed into blocks, calcined, coarsely crushed and finely ground, and dried to obtain a preliminary mixture. S4. The second component is mixed into the preliminary mixture to form a secondary mixture; S5. Grind the secondary mixture to below 10nm, add binder, dry and granulate to form ceramic powder; S6. The ceramic powder is pressed and sintered to form the ceramic capacitor dielectric.

3. The method for preparing a ceramic capacitor dielectric according to claim 2, characterized in that, Step S6 is followed by the following steps: A ceramic capacitor is obtained by sintering a silver layer on the surface of the ceramic capacitor dielectric.

4. The method for preparing a ceramic capacitor dielectric according to claim 2, characterized in that, In steps S2 and S3, the calcination temperature is 1000℃~1100℃, and the calcination time is 2~3 hours.

5. A voltage transformer, characterized in that, The device includes three ceramic capacitor dielectrics as described in claim 1. The two sides of the ceramic capacitor dielectrics are covered with silver electrodes (13) to form ceramic capacitors (3). The three ceramic capacitors (3) are connected in parallel through a high-voltage connecting wire (2) and a low-voltage connecting wire (11). The head of the high-voltage connecting wire (2) is connected to a high-voltage terminal (1), and the tail of the low-voltage connecting wire (11) is connected to a low-voltage terminal (8). The bottom of the low-voltage terminal (8) is connected to a low-voltage capacitor (9), and the bottom of the low-voltage capacitor (9) is connected to a signal output electrode (10) and a ground wire (7).

6. A voltage transformer according to claim 5, characterized in that, The high voltage terminal (1), high voltage connecting wire (2), three parallel ceramic capacitors (3), grounding wire (7), low voltage terminal (8), low voltage capacitor (9), signal output electrode (10), and low voltage connecting wire (11) are all uniformly cast in a dense insulating layer (4), and the outer side of the insulating layer (4) is in close contact with the skirt (5).

7. A voltage transformer according to claim 6, characterized in that, The bottom of the insulating layer (4) has a first wire hole (12-1) through which the signal output electrode (10) wire passes, and a second wire hole (12-2) through which the ground wire (7) wire passes.

8. A voltage transformer according to claim 6, characterized in that, The bottom of the insulation layer (4) is also provided with a fixing nut (6).

9. A voltage transformer according to claim 6, characterized in that, The insulating layer (4) is made of dense insulating material, and the skirt (5) is made of organic polymer material.

10. A voltage transformer according to claim 6, characterized in that, The cross-sectional shape of the insulating layer (4) is circular.

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