Measurement circuit for partial discharge test of high-voltage electrical equipment
By connecting a high-precision capacitive voltage divider in parallel at both ends of the high-voltage electrical equipment test piece, combined with a transformer and current-limiting resistor, the problem of inaccurate traditional high-voltage measurement is solved, and more accurate partial discharge measurement is achieved, which is suitable for various high-voltage scenarios.
Patent Information
- Application Number
- CN202422605453.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2034-10-28
AI Technical Summary
In traditional high-voltage measurement methods, the accuracy of high-voltage values is affected by distributed capacitance, magnetic leakage and nonlinear factors, resulting in inaccurate partial discharge value measurements.
A high-precision capacitive voltage divider is connected in parallel at both ends of the test object, and the partial discharge of high-voltage electrical equipment is directly measured using a low-voltage meter. Combined with a transformer and current-limiting resistor, the test method is optimized to reduce errors.
The accuracy of partial discharge measurement is improved, measurement errors caused by factors such as inaccurate transformer ratio or temperature changes are reduced, and a more objective evaluation of internal defects of the test product is achieved.
Smart Images
Figure CN223377427U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of high-voltage measurement and relates to a partial discharge test measurement circuit for high-voltage electrical equipment. Background Art
[0002] As the infrastructure supporting the operation of modern society, the operational reliability of the power system is crucial. High-voltage electrical equipment, a key component of the power system, operates under high loads and uninterrupted conditions for long periods of time. The quality of its insulation performance is directly related to the stability and safety of the entire power system. Insulation degradation often begins with partial discharge (PD). In the initial stages of PD, the discharge energy is relatively small, and a complete discharge channel fails to form. However, long-term and continuous PD has a cumulative effect on the insulation material. This cumulative effect gradually erodes the insulation material's performance, leading to insulation degradation and ultimately, potentially, insulation breakdown. Therefore, measuring PD is a key means of insulation monitoring and an effective method for assessing the long-term safe operation of electrical equipment.
[0003] Many factors influence PD values, including power supply, environmental factors, and system connections. The accuracy of high-voltage values has a significant impact on PD values. Traditional high-voltage measurements are performed indirectly through the transformer's instrument coil. However, due to factors such as distributed capacitance, magnetic flux leakage, and nonlinearity, this voltage deviates from the actual voltage experienced by the test piece. Consequently, the high-voltage conditions used for PD measurement are inaccurate, and consequently, the PD values are also inaccurate. Utility Model Content
[0004] The purpose of the utility model is to provide a partial discharge test measurement circuit for high-voltage electrical equipment, which directly obtains the sampling voltage by connecting a high-precision capacitive voltage divider in parallel at both ends of the test piece, and measures it through a low-voltage meter with a high-voltage scale, thereby solving the technical problem of inaccurate high-voltage measurement values in the existing technology.
[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: a partial discharge test measurement circuit for high-voltage electrical equipment includes a voltage regulator, a transformer, a partial discharge numerical measurement unit, a high-precision capacitive voltage divider, a test piece and a current-limiting resistor; the input end of the transformer is connected to the output end of the voltage regulator, the output end of the transformer is connected to the input end of the current-limiting resistor, the output end of the current-limiting resistor is connected to the partial discharge numerical measurement unit, one end of the high-precision capacitive voltage divider and the test piece is connected to the partial discharge numerical measurement unit, and the other end is connected to the output end of the transformer and grounded.
[0006] Furthermore, the transformer includes a primary coil and a high-voltage coil. The primary coil is wound around the transformer input end for connecting to a voltage regulator, and the high-voltage coil is wound around the transformer output end for connecting to a current limiting resistor and a partial discharge value measurement unit.
[0007] Furthermore, the partial discharge value measurement unit includes an input unit and a partial discharge tester; the output end of the current limiting resistor is connected to the input end of the input unit, the output end of the input unit is connected to the input end of the partial discharge tester, and the output end of the partial discharge tester is connected to the high-voltage coil and grounded.
[0008] Furthermore, it also includes a coupling capacitor; the input end of the coupling capacitor is connected to the output end of the current limiting resistor, and the output end of the coupling capacitor is connected to the input end of the input unit.
[0009] Furthermore, it also includes a low-voltage electric meter; the input end of the low-voltage electric meter is connected to the high-precision capacitive voltage divider, and the output end is grounded.
[0010] Furthermore, the high-precision capacitive voltage divider is a 1000:1 high-precision capacitive voltage divider.
[0011] Furthermore, the input voltage of the transformer is 0-380V.
[0012] Furthermore, the output voltage of the transformer is 0-150 kV.
[0013] Furthermore, the ratio of the input voltage to the output voltage of the transformer is 1:400.
[0014] Furthermore, the range of the low-voltage electric meter is: 0-150V.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects:
[0016] The utility model discloses a partial discharge test measurement circuit for high-voltage electrical equipment, comprising a voltage regulator, a transformer, a partial discharge value measurement unit, a high-precision capacitor voltage divider and a test piece. The voltage regulator is used for mains connection, the transformer input end is connected to the voltage regulator output end, the transformer output end is connected to the partial discharge value measurement unit, the high-precision capacitor voltage divider and the test piece are connected in parallel to the partial discharge value measurement unit and are grounded. By strictly controlling experimental conditions, optimizing test methods and accurately recording and analyzing data, the high-voltage conditions of the partial discharge experiment can be made more accurate, thereby objectively evaluating the internal defects of the test piece through the measurement values of a partial discharge tester. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.
[0018] Figure 1 The utility model is a circuit diagram of a partial discharge test measurement circuit for high-voltage electrical equipment.
[0019] Reference numerals:
[0020] 1-voltage regulator; 2-transformer; 21-primary coil; 22-high-voltage coil; 3-high-precision capacitor voltage divider; 4-test sample; 5-current-limiting resistor; 6-input unit; 7-partial discharge tester; 9-coupling capacitor; 10-low-voltage meter. DETAILED DESCRIPTION
[0021] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.
[0022] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the numbers used in this manner are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, products, or apparatus.
[0023] The present invention is described in further detail below with reference to the accompanying drawings:
[0024] Example 1
[0025] The utility model provides a partial discharge test and measurement circuit for high-voltage electrical equipment, comprising a voltage regulator 1, a transformer 2, a high-precision capacitive voltage divider 3, a test piece 4, a current-limiting resistor 5, a partial discharge value measurement unit, and a low-voltage ammeter 10. The transformer 2 comprises a primary coil 21 and a high-voltage coil 22, and the partial discharge value measurement unit comprises an input unit 6, a partial discharge tester 7, and a coupling capacitor 9.
[0026] The input voltage of transformer 2 is 0-380V, and the output voltage is 0-150kV. The voltage conversion is achieved through the principle of electromagnetic induction. Under ideal conditions, the ratio of the voltage at the input and output ends of transformer 2 is equal to the ratio of their turns, that is:
[0027]
[0028] in, and are the voltages at the input and output of transformer 2, and are the number of turns at the input and output ends of transformer 2 respectively.
[0029] The input voltage is 0-380V, and the output voltage is 0-150kV. It should be noted that 1kV = 1000V, so 150kV = 150000V.
[0030]
[0031] Because the number of turns must be an integer, and in practical applications, to achieve more accurate voltage conversion and better performance, the turns ratio is typically chosen to be close to, but slightly greater or less than, the theoretical value. Transformer 2 has a turns ratio of approximately 1:395, meaning that for every one turn at the input, there are 395 turns at the output. This design ensures that transformer 2 can achieve a voltage of 0–150 kV at the output when the input voltage is 0–380 V.
[0032] It should be noted that the calculations here are based on ideal conditions. In practice, transformer performance is affected by a variety of factors, such as core loss, coil resistance, and magnetic flux leakage. Therefore, in actual applications, design and adjustment are necessary based on specific needs and conditions. In this embodiment, the ratio of the input voltage to the output voltage of transformer 2 is 1:400, so the turns ratio of transformer 2 is approximately 1:400.
[0033] like Figure 1As shown, a partial discharge test and measurement circuit for high-voltage electrical equipment includes: a voltage regulator 1, a transformer 2, a partial discharge value measurement unit, a high-precision capacitive voltage divider 3, a test piece 4 and a current-limiting resistor 5. The transformer 2 includes a primary coil 21 and a high-voltage coil 22. The partial discharge value measurement unit includes an input unit 6, a partial discharge tester 7, and a coupling capacitor 9.
[0034] The primary coil 21 of transformer 2 is connected to the output of voltage regulator 1. The high-voltage coil 22 is connected to current-limiting resistor 5, a partial discharge value measurement unit, a high-precision capacitor voltage divider 3, and the output of test sample 4, and is grounded. The output of current resistor 5 is connected to coupling resistor 9, the high-precision capacitor voltage divider 3, and the input of test sample 4. The output of coupling resistor 9 is connected to the input of input unit 6. The output of input unit 6, the output of high-precision capacitor voltage divider 3, and the output of test sample 4 are connected to high-voltage coil 22. Partial discharge tester 7 has one end connected to input unit 6 and the other end connected to high-precision capacitor voltage divider 3. Low-voltage ammeter 10 has one end connected to high-precision capacitor voltage divider 3 and the other end connected to test sample 4.
[0035] The current-limiting resistor 5 is connected in series with the high-voltage coil 22 and the coupling resistor 9 to limit the current in the branch circuit, preventing excessive current from damaging other components. The operating principle is to reduce current by increasing the total resistance. When the current in the circuit is too high, the current-limiting resistor 5 limits the flow of current, thereby protecting other electronic components from damage. The resistance of the current-limiting resistor determines the degree of current limitation it has; the larger the resistance, the stronger the current limitation.
[0036] The current-limiting resistor 5 provides overload protection and current limiting. Overload protection prevents excessive current from flowing through the coupling capacitor 9, the high-precision capacitive voltage divider 3, and the test piece 4, thereby preventing damage to the components due to current overload. Current limiting can precisely control the current and limit it to a predetermined safe range.
[0037] The working principle of the coupling capacitor 9 is based on the impedance characteristics of the capacitor to signals of different frequencies. For high-frequency signals, the impedance presented by the coupling capacitor 9 is small, which is equivalent to a short circuit, allowing the high-frequency signal to pass smoothly; while for industrial frequency signals or low-frequency signals, the impedance presented by the coupling capacitor 9 is large, which is basically equivalent to an open circuit, thereby preventing industrial frequency current or low-frequency current from entering the weak current system.
[0038] Coupling capacitor 9 performs signal transmission, isolation, and protection functions. It is used in power networks to transmit high-frequency signals, implement carrier waves, and perform communication functions. In electronic circuits, it couples signals between different circuits, enabling signal transmission and processing. Isolation and protection: Coupling capacitor 9 couples and isolates high-voltage and low-voltage currents, preventing power-frequency or low-frequency currents from entering the low-voltage system, thereby protecting personnel.
[0039] The high-voltage measurement location of the partial discharge test is transferred from the transformer 2 to the test piece 4. A high-precision capacitive voltage divider 3 is connected in parallel at both ends of the test piece 4. The low-voltage meter 6 directly obtains the high-voltage measurement value. The partial discharge value is measured and displayed by the partial discharge tester 7. This can reduce the influence of leakage magnetic field, nonlinearity and external circuits of the transformer 2, make the high-voltage conditions of the partial discharge test more accurate, and then obtain more accurate partial discharge measurement values, so as to objectively evaluate the insulation defects inside the test piece 4.
[0040] The high-precision capacitive voltage divider 3 is a 1000:1 high-precision capacitive voltage divider. The high-precision capacitive voltage divider 3 uses the capacitive voltage division principle to convert a high-voltage signal into a low-voltage signal. Its voltage division ratio reaches 1000:1, that is, there is a fixed ratio of 1000 times between the high-voltage side voltage and the low-voltage side voltage.
[0041] Traditional high-voltage measurement is to obtain an instrument voltage that is proportional to the high-voltage voltage through the instrument coil of the transformer 2, and then measure and display it through a low-voltage meter 10 with a high-voltage scale. The utility model adopts a method of connecting a high-precision voltage divider in parallel at both ends of the test piece 4 to directly obtain the sample voltage, and then measure and display it through a low-voltage meter 10 with a high-voltage scale. Specifically, the traditional high-voltage measurement principle is simple, easy to implement, and can improve the safety of measurement, but the accuracy and stability of the transformer 2 may be affected by various factors, such as temperature, humidity, and electromagnetic interference. In addition, under extremely high voltage or special environments, special specifications may need to be customized, which is costly. The utility model connects a high-precision capacitor voltage divider 3 in parallel at both ends of the test piece 4. The high-precision capacitor voltage divider 3 can directly reduce the high voltage to the measurement range of the low-voltage meter 10 while maintaining high measurement accuracy. The low-voltage meter 10 is connected to the output end of the high-precision capacitor voltage divider 3 to directly measure and display the sample voltage. Due to the high accuracy of the high-precision capacitor voltage divider 3, the accurate value of the high-voltage side voltage can be directly obtained through the low-voltage reading without the need for complex calculations.
[0042] In summary, a partial discharge test measurement circuit for high-voltage electrical equipment has high measurement accuracy and simple structure. It is suitable for various high-voltage measurement scenarios, including extreme high voltage and special environments. In addition, it reduces measurement errors caused by factors such as inaccurate transformer ratio or temperature changes.
[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.
Claims
1. A partial discharge test and measurement circuit for high-voltage electrical equipment, characterized by: It includes a voltage regulator (1), a transformer (2), a partial discharge numerical measurement unit, a high-precision capacitive voltage divider (3), a test piece (4) and a current-limiting resistor (5); The input end of the transformer (2) is connected to the output end of the voltage regulator (1), the output end of the transformer (2) is connected to the input end of the current limiting resistor (5), the output end of the current limiting resistor (5) is connected to the partial discharge value measurement unit, one end of the high-precision capacitive voltage divider (3) and the test piece (4) is connected to the partial discharge value measurement unit, and the other end is connected to the output end of the transformer (2) and is grounded.
2. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 1, characterized in that: The transformer (2) comprises a primary coil (21) and a high-voltage coil (22); the primary coil (21) is wound around the input end of the transformer (2) and is used to be connected to the voltage regulator (1); the high-voltage coil (22) is wound around the output end of the transformer (2) and is used to be connected to the current-limiting resistor (5) and the partial discharge value measurement unit.
3. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 2, characterized in that: The partial discharge value measurement unit includes an input unit (6) and a partial discharge tester (7); The output end of the current limiting resistor (5) is connected to the input end of the input unit (6), the output end of the input unit (6) is connected to the input end of the partial discharge tester (7), and the output end of the partial discharge tester (7) is connected to the high-voltage coil (22) and is grounded.
4. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 3, characterized in that: Also included is a coupling capacitor (9); The input end of the coupling capacitor (9) is connected to the output end of the current-limiting resistor (5), and the output end of the coupling capacitor (9) is connected to the input end of the input unit (6).
5. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 1, characterized in that: Also included is a low voltage electric meter (10); The input end of the low-voltage electric meter (10) is connected to the high-precision capacitive voltage divider (3), and the output end is grounded.
6. The partial discharge test and measurement circuit for high-voltage electrical equipment according to claim 1, characterized in that: The high-precision capacitive voltage divider (3) is a 1000:1 high-precision capacitive voltage divider.
7. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 1, characterized in that: The input voltage of the transformer (2) is 0-380V.
8. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 1, characterized in that: The output terminal voltage of the transformer (2) is 0-150 kV.
9. The high-voltage electrical equipment partial discharge test measurement circuit according to claim 1, characterized in that: The ratio of the input terminal voltage to the output terminal voltage of the transformer (2) is 1:
400.
10. The high-voltage electrical equipment partial discharge test and measurement circuit according to claim 5, characterized in that: The measuring range of the low-voltage electric meter (10) is 0-150V.