Partial discharge measurement capability verification circuit and test method
By designing a local discharge measurement capacity verification circuit including a voltage voltage circuit, a square wave output circuit, a resistor division and a capacitor, the problem of the lack of local discharge measurement capacity verification circuits and testing methods in the existing technology, realizing high high Verification of local discharge measurement capabilities for accuracy and flexibility.
Patent Information
- Application Number
- CN202411706086.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-01-21
AI Technical Summary
At present, there is a lack of verification circuits and testing methods for local discharge measurement capabilities, and it is impossible to effectively verify the working quality and detection level of the laboratory.
Design a local discharge measurement capacity verification circuit including power supply, voltage voltage circuit, square wave output circuit, resistor division and capacitors, and provide a stable voltage through the voltage voltage circuit. The device sets the calibration and measurement gear, and uses a capacitor to capture the local discharge signal.
This circuit can improve measurement accuracy and flexibility, adapt to the partial discharge measurement needs of different electronic equipment, fill the gaps in the existing technology, and provide a capability verification solution with simple structure and strong stability.
Smart Images
Figure CN119335340A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of partial discharge testing, and in particular relates to a partial discharge measurement capability verification circuit and a testing method. Background Art
[0002] Proficiency testing is a verification activity that ensures that the laboratory maintains a high level of calibration and testing by assessing, supervising and confirming its capabilities. Proficiency testing uses inter-laboratory comparisons to determine the laboratory's testing capabilities. Participating in proficiency testing can provide the laboratory with objective evidence to evaluate the reliability and validity of the data it issues.
[0003] At present, various types of electrical equipment are widely used in power grids. One of the indicators of the quality of electrical equipment is to measure its partial discharge. Partial discharge measurement is one of the important detection methods for electrical equipment defects. Partial discharge refers to electrical discharge in which the insulation between conductors is only partially bridged. This discharge can occur near the conductor or not near the conductor.
[0004] Partial discharge measurement capability verification can provide early warning of whether the quality or level of a laboratory's work is satisfactory and whether potential problems need to be investigated, but there are currently no calibrators and test methods for partial discharge measurement capability verification. Summary of the invention
[0005] The purpose of the present invention is to overcome the problem that there is no partial discharge measurement capability verification circuit at present, and propose a partial discharge measurement capability verification circuit and a test method.
[0006] In order to achieve the above object, the present invention adopts the following technical scheme: In a first aspect, the present invention provides a partial discharge measurement capability verification circuit, comprising a power supply, a voltage stabilizing circuit, a square wave output circuit, a resistor voltage divider and a capacitor, wherein the input end of the voltage stabilizing circuit is connected to the power supply, the output end of the voltage stabilizing circuit is connected to the input end of the square wave output circuit, the output end of the square wave output circuit is connected to the input end of the resistor voltage divider, the output end of the resistor voltage divider is connected to one end of the capacitor, the other end of the capacitor is the output end of the capability verification circuit, and the resistor voltage divider is set to a first calibration gear and a second measurement gear.
[0007] Furthermore, a first switch is arranged between the input end of the voltage stabilizing circuit and the power supply, the voltage stabilizing circuit includes a voltage stabilizer, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor, the input end of the voltage stabilizer is connected to the power supply through the first switch, the output end of the voltage stabilizer is connected to the input end of the square wave output circuit, the first capacitor and the second capacitor are arranged at the input end of the voltage stabilizer, the third capacitor and the fourth capacitor are arranged at the output end of the voltage stabilizer, and the power supply adopts a DC power supply.
[0008] Furthermore, the first capacitor and the second capacitor are both tantalum capacitors, and the third capacitor and the fourth capacitor are both high-frequency capacitors.
[0009] Further, the resistive voltage divider includes a high-voltage arm, a low-voltage arm and a second switch, one end of the high-voltage arm is connected to the output end of the square wave output circuit, the other end of the high-voltage arm is connected to one end of the low-voltage arm and one end of the capacitor, the second switch is arranged between the other end of the high-voltage arm and one end of the low-voltage arm, the other end of the low-voltage arm is grounded, the low-voltage arm includes a first low-voltage arm and a second low-voltage arm, the second switch connects the high-voltage arm with the first low-voltage arm in the first calibration position, and the second switch connects the high-voltage arm with the second low-voltage arm in the second measurement position.
[0010] Further, the resistor divider includes a third resistor, a fourth resistor, a fifth resistor and a second switch, one end of the third resistor is connected to the output end of the square wave output circuit, the other end of the third resistor is connected to one end of the second switch and one end of the capacitor, the other end of the second switch is connected to one end of the fourth resistor or one end of the fifth resistor, the second switch connects the other end of the third resistor and one end of the fourth resistor in the first calibration position, the second switch connects the other end of the third resistor and one end of the fifth resistor in the second measurement position, and the other end of the fourth resistor and the other end of the fifth resistor are grounded.
[0011] Furthermore, the capacitor is an NPO capacitor.
[0012] Furthermore, the square wave output circuit includes a multivibrator and an inverter, the input end of the multivibrator is connected to the output end of the voltage stabilizing circuit, the output end of the multivibrator is connected to the input end of the inverter, and the output end of the inverter is connected to the input end of the resistor divider.
[0013] Furthermore, the multivibrator circuit adopts a NE555 chip, and the inverter adopts a 74HC04 chip.
[0014] In a second aspect, the present invention provides a partial discharge measurement calibrator, comprising the partial discharge measurement capability verification circuit.
[0015] In a third aspect, the present invention provides a partial discharge measurement capability verification test method, using the partial discharge measurement calibrator, comprising the following steps: Connecting a partial discharge measurement calibrator to a measurement loop, wherein the measurement loop includes a coupling capacitor, a coupling device, a coaxial cable and a partial discharge measuring instrument, wherein the low-voltage output end of the coupling capacitor is connected to the input end of the coupling device, the output end of the coupling device is connected to the partial discharge measuring instrument via a coaxial cable, the grounding terminal of the coupling device is grounded, the output terminal of the partial discharge measurement calibrator is connected to the high-voltage end of the coupling capacitor, and the grounding end of the partial discharge measurement calibrator is grounded; The resistance voltage divider is set to the first calibration position, the partial discharge measurement calibrator is turned on, and the partial discharge measurement system is calibrated. When the charge amount measured by the partial discharge measurement system reaches the first charge amount, the scale factor is saved, and the partial discharge measurement calibrator is turned off; The resistance voltage divider is set to the second measurement position, the partial discharge measurement calibrator is turned on, the measured second charge amount is saved, and the partial discharge measurement calibrator is turned off; Disconnect the partial discharge measurement calibrator from the measurement circuit; Repeat the above steps to measure the second charge for multiple times, calculate the average value of the multiple second charge amounts, and record the measurement data; the measurement data includes the test date, atmospheric conditions, the upper and lower limits of the frequency actually selected by the partial discharge measuring instrument, the background noise level, the capacitance of the coupling capacitor, the second charge amount, and the average value of the multiple second charge amounts.
[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a partial discharge measurement capability verification circuit, wherein the voltage stabilizing circuit provides a stable voltage input for the square wave output circuit, thereby reducing the influence of power supply voltage fluctuation on the partial discharge measurement result, and the square wave output circuit can generate a controllable square wave signal, and the resistor voltage divider is not only used to reduce the voltage for measurement, but also sets a first calibration gear and a second measurement gear, thereby providing higher measurement accuracy and flexibility, and the capacitor, as the output end of the capability verification circuit, has a high sensitivity to the partial discharge signal. When partial discharge occurs inside the power equipment, the capacitor can capture these weak discharge signals, and provide key data for subsequent analysis and evaluation, and by adjusting the gear of the resistor voltage divider and the parameters of the square wave output circuit, the verification circuit can adapt to the partial discharge measurement capability verification requirements of different electronic devices, and the present invention fills the gap in partial discharge measurement capability verification, solves the problem that there is no partial discharge measurement capability verification test method and sample at present, and the samples existing in the market are all multifunctional, and the visual selection of coulomb quantity cannot meet the capability verification requirements, and has a simple structure, strong stability, and all components are fully sealed, and there is no interface display, which complies with the capability verification regulations. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 The figure is a general architecture diagram of a partial discharge measurement capability verification circuit.
[0018] Figure 2 The utility model relates to a voltage stabilizing circuit module of a partial discharge measurement capability verification circuit.
[0019] Figure 3 The utility model discloses a square wave output module circuit of a partial discharge measurement capability verification circuit.
[0020] Figure 4 The utility model relates to a resistor voltage divider and a standard capacitor of a partial discharge measurement capability verification circuit.
[0021] Figure 5 This is a sample overall circuit for verifying the partial discharge measurement capability.
[0022] Figure 6 The figure is a measurement circuit diagram of a partial discharge measurement capability verification test method. DETAILED DESCRIPTION
[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments 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 creative work should fall within the scope of protection of the present invention.
[0024] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.
[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged 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 are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device 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 inherent to these processes, methods, products or devices.
[0027] Embodiment 1 See also Figure 1 ,and Figure 4 A partial discharge measurement capability verification circuit comprises a power supply, a voltage stabilizing circuit, a square wave output circuit, a resistor voltage divider and a capacitor C7, wherein the input end of the voltage stabilizing circuit is connected to the power supply, the output end of the voltage stabilizing circuit is connected to the input end of the square wave output circuit, the output end of the square wave output circuit is connected to the input end of the resistor voltage divider, the output end of the resistor voltage divider is connected to one end of the capacitor C7, the other end of the capacitor C7 is the output end of the capability verification circuit, and the resistor voltage divider is set to a first calibration gear and a second measurement gear.
[0028] The power supply of this embodiment provides the electric energy required by the entire verification circuit. The voltage stabilizing circuit receives the electric energy from the power supply and converts it into a stable DC voltage output. The function of the voltage stabilizing circuit is to ensure that the subsequent circuits, especially the square wave output circuit, can operate in a stable voltage environment and reduce the measurement error caused by voltage fluctuations. The square wave output circuit receives the stable DC voltage provided by the voltage stabilizing circuit and generates a controllable square wave signal. The square wave signal has a clear frequency and duty cycle and can be used to simulate and detect partial discharge phenomena in power equipment. The resistor divider receives the square wave signal generated by the square wave output circuit and divides it to a range suitable for measurement. The resistor divider sets a first calibration gear and a second measurement gear to perform accurate voltage measurements under different test requirements. The capacitor is connected to the output end of the resistor divider as the output end of the capability verification circuit. The capacitor can capture and store partial discharge signals to provide key data for subsequent analysis and evaluation.
[0029] See also Figure 2A first switch is set between the input end of the voltage stabilizing circuit and the power supply. The voltage stabilizing circuit includes a voltage stabilizer, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4. The input end of the voltage stabilizer is connected to the power supply through the first switch, and the output end of the voltage stabilizer is connected to the input end of the square wave output circuit. The first capacitor C1 and the second capacitor C2 are set at the input end of the voltage stabilizer, and the third capacitor C3 and the fourth capacitor C4 are set at the output end of the voltage stabilizer. The power supply adopts a DC power supply.
[0030] The setting of the first switch allows the user to open or close the connection between the power supply and the voltage stabilizing circuit as needed. This provides additional safety when testing, maintaining or replacing components of the circuit, preventing damage or danger caused by accidental power-on. The switch can also serve as a protection mechanism for the circuit to prevent damage to the voltage stabilizing circuit or other subsequent circuits due to power failure or abnormal voltage input. The voltage stabilizer is the core component of the voltage stabilizing circuit, which can convert unstable input voltage into a stable output voltage. Capacitors are set at the input and output ends of the voltage stabilizer respectively (the first capacitor C1 and the second capacitor C2 are at the input end, and the third capacitor C3 and the fourth capacitor C4 are at the output end). These capacitors play a filtering role, which can smooth the input and output voltages, reduce voltage fluctuations and noise, and thus improve the stability and reliability of the voltage stabilizing circuit. Using a DC power supply as the input avoids problems such as frequency changes and waveform distortion caused by an AC power supply, and further improves the output stability and accuracy of the voltage stabilizing circuit. The selection and optimized design of components such as the voltage stabilizer and capacitor enable the entire voltage stabilizing circuit to maintain low power consumption while providing a stable output voltage, which helps to save energy and extend the service life of the equipment.
[0031] The first capacitor C1 and the second capacitor C2 are both tantalum capacitors, which have a higher energy density than traditional electrolytic capacitors. Using tantalum capacitors at the input end of the voltage stabilization circuit can effectively filter out high-frequency noise and interference signals in the power supply, and improve the stability and performance of the circuit. The third capacitor C3 and the fourth capacitor C4 are both high-frequency capacitors, which have fast charging and discharging capabilities and can respond to voltage changes in a short time, thereby maintaining the stability of the output voltage. Using high-frequency capacitors at the output end of the voltage stabilization circuit can further smooth the output voltage, reduce voltage fluctuations and noise, and improve the output quality of the circuit.
[0032] See also Figure 4 and Figure 5The resistor divider includes a high-voltage arm, a low-voltage arm and a second switch, one end of the high-voltage arm is connected to the output end of the square wave output circuit, the other end of the high-voltage arm is connected to one end of the low-voltage arm and one end of the capacitor C7, the second switch is arranged between the other end of the high-voltage arm and one end of the low-voltage arm, the other end of the low-voltage arm is grounded, the low-voltage arm includes a first low-voltage arm and a second low-voltage arm, the second switch connects the high-voltage arm and the first low-voltage arm in the first calibration gear, and the second switch connects the high-voltage arm and the second low-voltage arm in the second measurement gear.
[0033] The resistor voltage divider of this embodiment reduces the high voltage generated by the square wave output circuit to a range suitable for measurement through the voltage division effect of the high voltage arm and the low voltage arm. This voltage division function enables the circuit to process high voltage signals while ensuring measurement accuracy. The first calibration gear is used to calibrate the circuit to ensure measurement accuracy; the second measurement gear is used for actual measurement to meet different test requirements.
[0034] See also Figure 4 and Figure 5 The resistor divider includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a second switch, one end of the third resistor R3 is connected to the output end of the square wave output circuit, the other end of the third resistor R3 is connected to one end of the second switch and one end of the capacitor C7, the other end of the second switch is connected to one end of the fourth resistor R4 or one end of the fifth resistor R5, the second switch connects the other end of the third resistor R3 and one end of the fourth resistor R4 in the first calibration gear, the second switch connects the other end of the third resistor R3 and one end of the fifth resistor R5 in the second measurement gear, and the other end of the fourth resistor R4 and the other end of the fifth resistor R5 are grounded.
[0035] Capacitor C7 is an NPO capacitor.
[0036] NPO capacitors are monolithic ceramic capacitors with temperature compensation characteristics. The amplitude of the capacitance value changing with temperature is very small, so it has high accuracy and stability. NPO capacitors have low loss and excellent high-frequency characteristics, and can maintain stable capacitance performance in high-frequency circuits. The high-precision voltage division function of the resistor divider combined with the high accuracy and stability of the NPO capacitor can significantly improve the measurement accuracy of the partial discharge measurement capability verification circuit. The low loss and high-frequency characteristics of the NPO capacitor help reduce noise interference and signal distortion in the circuit, thereby enhancing the stability of the circuit. At the same time, the design of the resistor divider also ensures the stability of the output voltage, further improving the overall stability of the circuit.
[0037] See also Figure 3The square wave output circuit includes a multivibrator and an inverter, wherein the input end of the multivibrator is connected to the output end of the voltage stabilizing circuit, the output end of the multivibrator is connected to the input end of the inverter, and the output end of the inverter is connected to the input end of the resistor divider.
[0038] The multivibrator generates a stable square wave signal. After the inverter is inverted, the stability and quality of the output signal are further improved. This design enables the square wave output circuit to output high-quality square wave signals to meet various application requirements. Since both the multivibrator and the inverter can be adjusted and controlled as needed, the entire square wave output circuit has high flexibility. Users can adjust the circuit parameters according to actual needs to adapt to different application scenarios.
[0039] The multivibrator circuit adopts NE555 chip, and the inverter adopts 74HC04 chip.
[0040] The NE555 chip is a high-precision, high-stability bipolar integrated circuit that can generate a stable pulse signal. This feature enables the multivibrator to output a high-precision square wave signal to meet the needs of various high-precision timing pulses. The 74HC04 chip is a high-speed CMOS logic chip with a fast response time and low latency. This enables the inverter to quickly invert the input signal and output a stable square wave signal. The 74HC04 chip is manufactured using a CMOS process and has low power consumption and noise. This helps reduce energy loss and noise interference in the circuit and improves the overall performance of the circuit. Both the NE555 chip and the 74HC04 chip are commonly used integrated circuit chips with relatively low prices and are easy to purchase. This effectively controls the cost of the square wave output circuit and reduces the cost of the entire electronic device. .
[0041] Embodiment 2 A partial discharge measurement calibrator comprises the partial discharge measurement capability verification circuit described in the first embodiment.
[0042] Embodiment 3 A partial discharge measurement capability verification test method, using a partial discharge measurement calibrator described in the second embodiment, comprises the following steps: Connect the partial discharge measurement calibrator to the measurement circuit, see Figure 6 , the measurement loop includes a coupling capacitor, a coupling device, a coaxial cable and a partial discharge measuring instrument, the low-voltage output end of the coupling capacitor is connected to the input end of the coupling device, the output end of the coupling device is connected to the partial discharge measuring instrument through the coaxial cable, the grounding terminal of the coupling device is grounded, the output terminal of the partial discharge measurement calibrator is connected to the high-voltage end of the coupling capacitor, and the grounding terminal of the partial discharge measurement calibrator is grounded; The resistance voltage divider is set to the first calibration position, the partial discharge measurement calibrator is turned on, and the partial discharge measurement system is calibrated. When the charge amount measured by the partial discharge measurement system reaches the first charge amount, the scale factor is saved, and the partial discharge measurement calibrator is turned off; The resistance voltage divider is set to the second measurement position, the partial discharge measurement calibrator is turned on, the measured second charge amount is saved, and the partial discharge measurement calibrator is turned off; Disconnect the partial discharge measurement calibrator from the measurement circuit; Repeat the above steps to measure the second charge for multiple times, calculate the average value of the multiple second charge amounts, and record the measurement data; the measurement data includes the test date, atmospheric conditions, the upper and lower limits of the frequency actually selected by the partial discharge measuring instrument, the background noise level, the capacitance of the coupling capacitor, the second charge amount, and the average value of the multiple second charge amounts.
[0043] This embodiment can ensure the accuracy of the partial discharge measurement system within the entire measurement range by connecting the partial discharge measurement calibrator to the measurement loop and using different gears of the resistor divider for calibration and measurement. During the calibration process, when the charge measured by the partial discharge measurement system reaches the preset first charge, the scale factor is saved. This step provides an accurate benchmark for subsequent measurements. By repeatedly measuring the second charge multiple times and calculating the average value, the measurement error can be further reduced and the reliability of the measurement results can be improved. By using the partial discharge measurement calibrator and the resistor divider, the calibration and measurement process can be completed quickly, saving test time. Accurate calibration and measurement can reduce unnecessary repeated testing and equipment replacement costs, thereby reducing the overall test cost. The test method takes into account factors such as background noise level and the capacitance of the coupling capacitor, which helps to reduce the impact of electromagnetic interference on the measurement results and improve the safety of the test.
[0044] Embodiment 4 See also Figure 1 ,A partial discharge measurement capability verification circuit is composed of a power source, a switch, a voltage stabilizing circuit module, a square wave output module, a resistor voltage divider and a standard capacitor.
[0045] The power supply provides energy for the entire circuit, and the power supply can be a DC battery.
[0046] The switch control capability verifies the start and stop of the circuit. The switch has the characteristics of reliable connection, clear indication, high stability, etc., and will not cause abnormal startup due to accidental contact or collision during transportation.
[0047] The voltage stabilization circuit module solves the problem of unstable voltage caused by power supply difference and voltage reduction caused by long-term use. The principle of the voltage stabilization circuit is that when the input voltage is higher than a certain voltage value, the output voltage is a fixed voltage value.
[0048] Optionally, the voltage stabilizing circuit module uses a high-precision AMS1117 chip, whose input voltage is a high-potential DC voltage and outputs a 5V DC voltage. Figure 2 As shown. Capacitors C1 and C2 are input filter capacitors, preferably tantalum capacitors; capacitors C3 and C4 are output filter capacitors, preferably high-frequency capacitors.
[0049] Optionally, the square wave output module uses NE555 chip and 74HC04 chip. NE555 chip has the advantages of small size, light weight, reliable stability, strong current supply capacity at the output end, high timing accuracy and high temperature stability.
[0050] Use NE555 chip to build multivibrator circuit to generate square wave with adjustable frequency and duty cycle; use 74HC04 inverter to improve the pulse steepness of circuit output, so that the rising edge time of pulse waveform reaches the standard requirement of ≤60ns. Select appropriate capacitor and resistor values to make the frequency and step voltage duration meet the requirements. The output voltage of voltage regulator circuit module is used as the input voltage of NE555 chip and 74HC04 chip to ensure the accuracy and stability of voltage. Square wave output module circuit as shown Figure 3 The duty cycle of the output square wave and the number of pulses per second are controlled by adjusting the resistors R1, R2 and the capacitors C5, C6.
[0051] See also Figure 4 The resistor divider uses a voltage divider ratio of N:1. R3 is the high-voltage arm of the resistor divider, R4 is the low-voltage arm 1, and R5 is the low-voltage arm 2. Switch 2 is a single-pole double-throw switch. When switch 2 is set to position 1, it is connected to R4. When switch 2 is set to position 2, it is connected to resistor R5. The output voltage is controlled by adjusting the switch to position 1 or 2. If the resistance value of the high-voltage arm and the low-voltage arm of the resistor divider is too large, the rise time of the square wave will be prolonged. If the resistance value is too small, the load carried by the 74HC04 chip will be too large, the power consumption will increase, and the output voltage will be unstable.
[0052] Furthermore, multi-level resistor voltage dividers can be designed to output different values of charge.
[0053] According to the charge formula: Q = UC(1) It can be seen that the resistor divider and standard capacitor are the last part of the components and are also one of the most important components. The stability of the resistance and capacitance values is crucial. The resistors use high-precision resistors and the capacitors use NPO capacitors with temperature compensation characteristics.
[0054] Combining the above functional modules, we can get Figure 5 The sample overall circuit is shown.
[0055] This embodiment also provides a partial discharge measurement capability verification test method, Figure 6 This is the measurement circuit diagram.
[0056] The specific implementation steps are as follows: a) The low-voltage output end of the coupling capacitor is connected to the input end of the coupling device, the output end of the coupling device is connected to the partial discharge measuring instrument through a coaxial cable, and the grounding terminal of the coupling device is grounded; b) Adjust the upper and lower frequency limits and bandwidth of the partial discharge measuring instrument to meet the standard requirements, or select a partial discharge measuring instrument whose frequency range meets the standard requirements; c) Adjust the background noise to be less than 5pC; d) Connect the sample output terminal to the high voltage end of the coupling capacitor and the sample ground terminal to the ground. Set the sample gear switch to "Gear 1", turn on the sample, calibrate the partial discharge measurement system, and make the current partial discharge measurement system measure the charge Q1 (Q1 is related to the component parameters in the sample, and will be notified to the proficiency verification party before the proficiency verification test), save the current scale factor, and turn off the sample; e) Connect the sample output terminal to the high voltage end of the coupling capacitor and the sample ground terminal to the ground. Set the sample position switch to "position 2", turn on the sample, read the charge Q2 measured by the partial discharge measurement system, and turn off the sample; f) dismantling samples; g) Repeat steps d) to f) above three times, measure three groups of charge quantities Q2, and calculate the average value.
[0057] h) Record the test date, atmospheric conditions, upper and lower frequency limits of the PD instrument, background noise level, capacitance of the coupling capacitor, three measured charges and their average value, and other remarks.
[0058] This embodiment has a simple structure, strong stability, all components are sealed, and there is no interface display, which complies with the capability verification regulations. In the measurement regulations, the sample calibrates the loop in the gear 1 state and measures the value in the gear 2 state, which complies with the partial discharge measurement capability verification regulations. The circuit and test method in this embodiment fill the gap in the partial discharge measurement capability verification.
[0059] Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.
[0060] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, they can also make several simple deductions or substitutions, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.
Claims
1. A partial discharge measurement capability verification circuit, characterized in that: It includes a power supply, a voltage stabilizing circuit, a square wave output circuit, a resistor divider and a capacitor. The input end of the voltage stabilizing circuit is connected to the power supply, the output end of the voltage stabilizing circuit is connected to the input end of the square wave output circuit, the output end of the square wave output circuit is connected to the input end of the resistor divider, the output end of the resistor divider is connected to one end of the capacitor, the other end of the capacitor is the output end of the capability verification circuit, and the resistor divider is set to a first calibration position and a second measurement position.
2. A partial discharge measurement capability verification circuit according to claim 1, characterized in that: A first switch is arranged between the input end of the voltage stabilizing circuit and the power supply. The voltage stabilizing circuit comprises a voltage stabilizer, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor. The input end of the voltage stabilizer is connected to the power supply through the first switch, and the output end of the voltage stabilizer is connected to the input end of the square wave output circuit. The first capacitor and the second capacitor are arranged at the input end of the voltage stabilizer, and the third capacitor and the fourth capacitor are arranged at the output end of the voltage stabilizer. The power supply adopts a DC power supply.
3. A partial discharge measurement capability verification circuit according to claim 2, characterized in that: The first capacitor and the second capacitor are both tantalum capacitors, and the third capacitor and the fourth capacitor are both high-frequency capacitors.
4. A partial discharge measurement capability verification circuit according to claim 1, characterized in that: The resistive voltage divider includes a high-voltage arm, a low-voltage arm and a second switch, one end of the high-voltage arm is connected to the output end of the square wave output circuit, the other end of the high-voltage arm is connected to one end of the low-voltage arm and one end of the capacitor, the second switch is arranged between the other end of the high-voltage arm and one end of the low-voltage arm, the other end of the low-voltage arm is grounded, the low-voltage arm includes a first low-voltage arm and a second low-voltage arm, the second switch connects the high-voltage arm and the first low-voltage arm in the first calibration gear, and the second switch connects the high-voltage arm and the second low-voltage arm in the second measurement gear.
5. A partial discharge measurement capability verification circuit according to claim 1, characterized in that: The resistor divider includes a third resistor, a fourth resistor, a fifth resistor and a second switch, one end of the third resistor is connected to the output end of the square wave output circuit, the other end of the third resistor is connected to one end of the second switch and one end of the capacitor, the other end of the second switch is connected to one end of the fourth resistor or one end of the fifth resistor, the second switch connects the other end of the third resistor and one end of the fourth resistor in the first calibration position, the second switch connects the other end of the third resistor and one end of the fifth resistor in the second measurement position, and the other end of the fourth resistor and the other end of the fifth resistor are grounded.
6. A partial discharge measurement capability verification circuit according to claim 1, characterized in that: The capacitor is an NPO capacitor.
7. A partial discharge measurement capability verification circuit according to claim 1, characterized in that: The square wave output circuit includes a multivibrator and an inverter, the input end of the multivibrator is connected to the output end of the voltage stabilizing circuit, the output end of the multivibrator is connected to the input end of the inverter, and the output end of the inverter is connected to the input end of the resistor divider.
8. A partial discharge measurement capability verification circuit according to claim 7, characterized in that: The multivibrator circuit adopts NE555 chip, and the inverter adopts 74HC04 chip.
9. A partial discharge measurement calibrator, characterized in that: The invention comprises a partial discharge measurement capability verification circuit as described in any one of claims 1 to 8.
10. A partial discharge measurement capability verification test method, using the partial discharge measurement calibrator according to claim 9, characterized in that: The steps include: Connecting a partial discharge measurement calibrator to a measurement loop, wherein the measurement loop includes a coupling capacitor, a coupling device, a coaxial cable and a partial discharge measuring instrument, wherein the low-voltage output end of the coupling capacitor is connected to the input end of the coupling device, the output end of the coupling device is connected to the partial discharge measuring instrument via a coaxial cable, the grounding terminal of the coupling device is grounded, the output terminal of the partial discharge measurement calibrator is connected to the high-voltage end of the coupling capacitor, and the grounding end of the partial discharge measurement calibrator is grounded; The resistance voltage divider is set to the first calibration position, the partial discharge measurement calibrator is turned on, and the partial discharge measurement system is calibrated. When the charge amount measured by the partial discharge measurement system reaches the first charge amount, the scale factor is saved, and the partial discharge measurement calibrator is turned off; The resistance voltage divider is set to the second measurement position, the partial discharge measurement calibrator is turned on, the measured second charge amount is saved, and the partial discharge measurement calibrator is turned off; Disconnect the partial discharge measurement calibrator from the measurement circuit; Repeat the above steps to measure the second charge for multiple times, calculate the average value of the multiple second charge amounts, and record the measurement data; the measurement data includes the test date, atmospheric conditions, the upper and lower limits of the frequency actually selected by the partial discharge measuring instrument, the background noise level, the capacitance of the coupling capacitor, the second charge amount, and the average value of the multiple second charge amounts.