Hydro-generator excitation de-excitation zinc oxide valve plate overvoltage test module

Abstract

The invention discloses a hydro-generator excitation de-excitation zinc oxide valve plate overvoltage test module, relates to a hydro-generator overvoltage test device, and aims to solve the problems of complex operation, poor operation flexibility and low test precision of the existing zinc oxide valve plate overvoltage test. One end of a zinc oxide resistor serves as a direct-current high-voltage anode input end; the other end of the zinc oxide resistor is connected with a fixed end of the potentiometer; the other fixed end of the potentiometer is used as a direct-current high-voltage cathode input end; the mobile end of the potentiometer is used for connecting one end of the tested excitation and de-excitation zinc oxide valve plate, and the direct-current high-voltage cathode input end is used for connecting the other end of the tested excitation and de-excitation zinc oxide valve plate; the current detection unit is used for detecting the current value of the excitation de-excitation zinc oxide valve plate to be detected; and the voltage detection unit is used for detecting the voltage value of the excitation de-excitation zinc oxide valve plate to be detected. The device has the beneficial effects of simplicity and convenience in operation, convenience in carrying, high test precision and accurate and reliable result, and can meet test requirements of valve plates of various specifications.

Description

Technical Field

[0001] This invention relates to an overvoltage testing device for a hydro-generator. Background Technology

[0002] As a core component of the power system, the safe and stable operation of hydro-generators directly affects the reliability of the power grid. The generator rotor excitation winding is a critical component of the generator set and is frequently subjected to various overvoltage attacks during operation: when a fault occurs inside the generator set or at the output terminal, or during normal shutdown, sudden changes in the excitation current can cause transient overvoltages across the rotor winding; when the generator set is subjected to significant disturbances during operation, a statically excited synchronous generator may generate forward or reverse overvoltages on the rotor excitation winding; typical demagnetization and overvoltage protection devices mainly consist of demagnetization switches, zinc oxide valve plates, silicon controlled rectifier triggers, silicon controlled rectifier elements, diodes, and current transformers, etc. The overvoltage of the zinc oxide valve plate... The action value (usually referenced by the voltage corresponding to 1mA DC current) is a core parameter for evaluating protection performance, directly determining the action threshold and protection level of the protection device. However, the field testing technology for the overvoltage action value of zinc oxide valve discs used in the excitation and demagnetization of hydroelectric generators still suffers from the following technical shortcomings: First, existing testing equipment is typically bulky and heavy, requiring transport to the generator excitation system site for on-site testing; complex wiring necessitates operation by specialized technicians, resulting in lengthy preparation times; and the large testing equipment is inconvenient to operate in the complex spatial environment of hydroelectric power stations. Second, existing testing methods typically use fixed-range test voltages, making it difficult to adapt to the testing needs of different models and voltage levels of zinc oxide valve discs; for different valve discs with action voltages ranging from hundreds to thousands of volts, different specifications of testing instruments or ranges are required, resulting in insufficient testing flexibility. Finally, existing testing equipment has high requirements for the testing environment; in humid environments with strong electromagnetic interference at hydroelectric power stations, testing accuracy and stability are difficult to guarantee; furthermore, existing testing equipment requires an external power supply, which is inconvenient in certain maintenance scenarios.

[0003] In summary, the existing technology lacks a dedicated device that is easy to operate, portable, and suitable for on-site testing of the overvoltage action value of the excitation and demagnetization zinc oxide valve plate of a hydro-generator. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of complex operation, poor operational flexibility and low testing accuracy of existing zinc oxide valve plate overvoltage testing, and to propose an overvoltage testing module for excitation and demagnetization zinc oxide valve plates of hydro-generators.

[0005] The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in this invention includes a current detection unit, a voltage detection unit, and a DC voltage divider circuit;

[0006] The DC voltage divider circuit includes a zinc oxide resistor and a potentiometer;

[0007] One end of the zinc oxide resistor serves as the positive input terminal of the DC high voltage; the other end of the zinc oxide resistor is connected to one fixed terminal of the potentiometer; the other fixed terminal of the potentiometer serves as the negative input terminal of the DC high voltage; and the movable terminal of the potentiometer is used to connect one end of the tested excitation and demagnetization zinc oxide valve plate, and the negative input terminal of the DC high voltage is used to connect the other end of the tested excitation and demagnetization zinc oxide valve plate.

[0008] The current detection unit is used to detect the current value of the tested excitation and demagnetization zinc oxide valve plate.

[0009] The voltage detection unit is used to detect the voltage value of the tested excitation and demagnetization zinc oxide valve plate.

[0010] Furthermore, it also includes an insulation resistance tester;

[0011] The DC high voltage positive output terminal of the insulation resistance tester is connected to one end of the zinc oxide resistor; the DC high voltage negative output terminal of the insulation resistance tester is connected to the other fixed terminal of the potentiometer.

[0012] Furthermore, the output DC voltage range of the insulation resistance tester is 1000V.

[0013] Furthermore, the resistance value of the zinc oxide resistor is 500MΩ.

[0014] Furthermore, the potentiometer has a resistance of 10 MΩ.

[0015] Furthermore, the DC voltage divider circuit also includes a current-limiting resistor;

[0016] The current-limiting resistor is connected in series between the other fixed terminal of the potentiometer and the DC high-voltage negative input terminal.

[0017] Furthermore, the resistance value of the current-limiting resistor is 10MΩ.

[0018] Furthermore, the voltage detection unit is connected in parallel between the moving end of the potentiometer and the DC high voltage negative input terminal; and the voltage detection unit is a high voltage voltmeter with a range of 0-1000V.

[0019] Furthermore, the current detection unit is connected in series with the moving end of the potentiometer, and the current detection unit is a milliammeter with a range of 0-10mA.

[0020] Furthermore, the current detection unit, voltage detection unit, and DC voltage divider circuit are all encapsulated within an insulating housing, and the potentiometer adjustment knob, the display interface of the voltage detection unit, and the display interface of the current detection unit are all located on the panel of the insulating housing.

[0021] The method of using the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in this invention is as follows:

[0022] (1) Connect the DC high voltage positive output terminal of the insulation resistance tester to the DC high voltage positive input terminal of the zinc oxide resistor, and connect the DC high voltage negative output terminal of the insulation resistance tester to the DC high voltage negative input terminal of the potentiometer.

[0023] (2) Connect one end of the zinc oxide valve plate to be tested to the moving end of potentiometer 5, and connect the other end of the zinc oxide valve plate to be tested to the DC high voltage negative input terminal of potentiometer;

[0024] (3) Start the insulation resistance tester and output a DC high voltage signal;

[0025] (4) Adjust the resistance of the potentiometer so that the DC voltage displayed by the voltage detection unit changes linearly from small to large;

[0026] (5) Monitor the current reading of the current detection unit. When the current reading of the current detection unit reaches 1.00mA, record the voltage value displayed by the voltage detection unit.

[0027] (6) The voltage value of the recorded voltage detection unit is the overvoltage action value of the tested excitation and demagnetization zinc oxide valve plate.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. Simple to operate, significantly reducing the testing threshold;

[0030] This invention employs a modular integrated design, encapsulating the current detection unit, voltage detection unit, and DC voltage divider circuit within an insulated housing. The panel retains only essential adjustment knobs and a display interface. Testers simply connect the insulation resistance tester and the valve under test following simple wiring steps, adjust the potentiometer, and observe the ammeter reading to directly read the voltage action value when the current reaches 1.00mA. The entire operation process is clear and intuitive, requiring no specialized technicians and effectively solving the problems of existing testing equipment requiring professional operation and lengthy preparation times.

[0031] 2. Compact size, easy to carry and use on site;

[0032] The test module of this invention adopts a compact packaging structure, which is much smaller than traditional large test equipment, and can be easily carried to the site of hydropower station excitation system. Especially under the conditions of narrow space and complex environment at hydropower station sites, this invention can adapt to various test scenarios, overcome the shortcomings of existing test equipment such as large size, heavy weight, difficult transportation, and poor operation convenience, and significantly improve the flexibility and efficiency of on-site testing.

[0033] 3. The voltage is continuously adjustable to meet the testing needs of various valve plates;

[0034] This invention achieves continuous linear adjustment of the output voltage through a DC voltage divider circuit composed of a zinc oxide resistor and a potentiometer. By adjusting the potentiometer resistance, the output voltage can be smoothly varied from small to large over a wide range, adapting to the testing requirements of different models and voltage levels of zinc oxide valves with operating voltages ranging from hundreds to thousands of volts. Compared to existing technologies that use fixed test voltage levels and require changing different specifications of testing instruments or ranges, this invention offers extremely high testing flexibility and versatility.

[0035] 4. High testing accuracy and reliable results;

[0036] This invention employs a milliammeter (range 0-10mA) directly connected in series to detect the circuit current, and a high-voltage voltmeter (range 0-1000V) connected in parallel to detect the voltage across the valve plate. When the current detection unit reading accurately reaches 1.00mA, the voltage value of the voltage detection unit is recorded simultaneously. This voltage value is the overvoltage action value of the valve plate under test. This synchronous detection method avoids the errors caused by the asynchrony of voltage and current in traditional testing methods, resulting in high testing accuracy and good repeatability, and meeting the precise measurement requirements of the core parameters of the zinc oxide valve plate's protective performance.

[0037] 5. Multiple protection designs ensure safe and reliable testing;

[0038] This invention incorporates a dual protection mechanism in its circuit design, consisting of a zinc oxide resistor (500MΩ) and a current-limiting resistor (10MΩ). The zinc oxide resistor itself possesses nonlinear volt-ampere characteristics, providing auxiliary protection under overvoltage conditions. The current-limiting resistor effectively limits the maximum current in the circuit, protecting the insulation resistance tester and test module from damage even in the event of valve plate breakdown or short circuit. Simultaneously, the insulating housing provides excellent electrical insulation and mechanical protection, adapting to the harsh environment of hydropower stations with high humidity and electromagnetic interference, ensuring the safety of the testing process and the reliability of the equipment.

[0039] 6. Simple structure, easy maintenance, and long service life;

[0040] The circuit structure of this invention is simple, mainly composed of passive components (resistors, potentiometers) and conventional testing instruments. It lacks complex electronic control units, resulting in a low failure rate and simple maintenance. All components are of commonly used industrial specifications, making them easy to procure and replace, and the overall lifespan is long, reducing equipment operation and maintenance costs.

[0041] In summary, this invention effectively solves the technical defects of existing zinc oxide valve plate overvoltage testing, such as complex operation, poor flexibility, low testing accuracy, bulky equipment, and weak environmental adaptability. It provides a special on-site testing device for the overvoltage action value of excitation and demagnetization zinc oxide valve plates of hydro-generators that is easy to operate, portable, accurate, safe, and reliable, and has significant practical value and promotion prospects. Attached Figure Description

[0042] Figure 1 The circuit diagram is shown in Specific Embodiment 1 for an overvoltage test module of a hydro-generator excitation and demagnetization zinc oxide valve plate.

[0043] Wherein, H1 is one connection end of the tested excitation and demagnetization zinc oxide valve plate; H2 is the other connection end of the tested excitation and demagnetization zinc oxide valve plate. Detailed Implementation

[0044] Specific Implementation Method 1: Combination Figure 1 This embodiment describes an overvoltage testing module for a hydro-generator excitation and demagnetization zinc oxide valve plate, which includes a current detection unit 2, a voltage detection unit 3, and a DC voltage divider circuit.

[0045] The DC voltage divider circuit includes a zinc oxide resistor 4 and a potentiometer 5;

[0046] One end of the zinc oxide resistor 4 serves as the positive input terminal of the DC high voltage; the other end of the zinc oxide resistor 4 is connected to one fixed terminal of the potentiometer 5; the other fixed terminal of the potentiometer 5 serves as the negative input terminal of the DC high voltage; and the movable terminal of the potentiometer 5 is used to connect one end of the tested excitation and demagnetization zinc oxide valve plate, and the negative input terminal of the DC high voltage is used to connect the other end of the tested excitation and demagnetization zinc oxide valve plate.

[0047] The current detection unit 2 is used to detect the current value of the tested excitation and demagnetization zinc oxide valve plate;

[0048] The voltage detection unit 3 is used to detect the voltage value of the tested excitation and demagnetization zinc oxide valve plate.

[0049] In this embodiment, the working principle of the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of the hydro-generator is as follows: A high-voltage DC signal from the DC insulation tester 1 is input to the overvoltage test module. The DC voltage divider circuit of the voltage test module adjusts the output to a linearly adjustable DC voltage. This output voltage is connected to the tested excitation and demagnetization zinc oxide valve plate. When the output current of the current detection unit 2 is greater than 1mA, the value of the voltage detection unit 3 is recorded. This value of the voltage detection unit 3 is the overvoltage action value of the tested excitation and demagnetization zinc oxide valve plate. For example, when the insulation resistance tester 1 is set to 1000V, the test button of the insulation resistance tester 1 is pressed, and the module potentiometer value is slowly adjusted (from small to large) until the current detection unit 2 displays 1.00mA. The voltmeter value of the voltage detection unit 3 is then recorded. If the voltage detection unit 3 indicates 655.0V, then the overvoltage action value of the tested excitation and demagnetization zinc oxide valve plate is 655.0V. By using the zinc oxide resistor 4 in conjunction with the potentiometer 5 in a DC voltage divider circuit, the output voltage is linearly adjustable, which can adapt to the testing requirements of zinc oxide valve plates of different models and voltage levels. By adopting a combination of series current detection and parallel voltage detection, the current and voltage status of the valve plate under test can be monitored simultaneously. When the current reaches the 1mA threshold, the action voltage value can be accurately read, resulting in high testing accuracy. The overall circuit structure is simple, eliminating the need for a complex control unit, thus reducing equipment cost and failure rate. The commonly used insulation resistance tester 1 can be directly used as a high-voltage signal source, eliminating the need for a dedicated high-voltage power supply and improving the convenience of on-site testing.

[0050] Specific Implementation Method 2: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method 1. In this implementation method, it also includes an insulation resistance tester 1.

[0051] The DC high voltage positive output terminal of the insulation resistance tester 1 is connected to one end of the zinc oxide resistor 4; the DC high voltage negative output terminal of the insulation resistance tester 1 is connected to the other fixed terminal of the potentiometer 5.

[0052] In this embodiment, the specific implementation method of the high-voltage signal source is clarified. The DC high voltage required for testing can be generated by using the insulation resistance tester 1 commonly available at the hydropower station site, without the need to purchase additional dedicated high-voltage equipment. The connection method between the insulation resistance tester 1 and the test module is simple and clear, which facilitates quick wiring on site. It makes full use of existing equipment resources, significantly reducing testing costs and equipment carrying burden.

[0053] Specific Implementation Method 3: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of the hydro-generator described in Specific Implementation Method 2. In this implementation method, the output DC voltage range of the insulation resistance tester 1 is 1000V.

[0054] In this embodiment, for the typical operating voltage range (hundreds to thousands of volts) of the excitation and demagnetization zinc oxide valve plate of the hydro generator, the 1000V range can cover the testing requirements of most commonly used valve plates; the fixed range simplifies the operation process and avoids test errors or equipment damage caused by improper range selection; the parameters of the subsequent current limiting resistor 6 and potentiometer 5 are matched to ensure that the output voltage range after voltage division is suitable for the valve plate under test.

[0055] Specific Implementation Method Four: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method One. In this implementation method, the resistance value of the zinc oxide resistor 4 is 500MΩ.

[0056] In this embodiment, the high resistance of 500MΩ and the potentiometer (10MΩ) form a voltage division ratio of approximately 50:1, which can divide the 1000V input voltage into an adjustable range of approximately 0-20V. After adjustment by the potentiometer, a test voltage suitable for the valve under test can be accurately output. The high resistance design limits the loop current, and together with the current-limiting resistor 6, it can effectively protect the zinc oxide valve under test and the test instrument. The zinc oxide resistor 4 itself has non-linear volt-ampere characteristics, which can play an auxiliary protection role in overvoltage conditions, improving test safety.

[0057] Specific Implementation Method 5: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method 1. In this implementation method, the resistance value of the potentiometer 5 is 10MΩ.

[0058] In this embodiment, the 10MΩ potentiometer 5 is reasonably matched with the 500MΩ zinc oxide resistor to ensure the linearity and accuracy of the voltage division adjustment; the resistance value is moderate, neither too small as to cause insufficient voltage division ratio, nor too large as to cause a decrease in adjustment sensitivity, thus achieving a balance between adjustment accuracy and operational convenience.

[0059] Specific Implementation Method Six: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method One. In this implementation method, the DC voltage divider circuit also includes a current-limiting resistor 6.

[0060] The current-limiting resistor 6 is connected in series between the other fixed terminal of the potentiometer 5 and the DC high-voltage negative input terminal.

[0061] In this embodiment, the introduction of the current-limiting resistor 6 further limits the maximum current of the test circuit, effectively protecting the insulation resistance tester and the test module from damage even if the valve under test breaks down or short-circuits; it improves the safety of the test process and prevents the risk of overcurrent caused by the failure of the valve under test; and it forms a dual protection mechanism with the zinc oxide resistor 4, enhancing the reliability of the equipment in complex field environments.

[0062] Specific Implementation Method Seven: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method Six. In this implementation method, the resistance value of the current limiting resistor 6 is 10MΩ.

[0063] In this embodiment, the 10MΩ current-limiting resistor 6 has a resistance value equivalent to that of potentiometer 5, ensuring that the total impedance of the circuit changes smoothly during adjustment and that the voltage output has good linearity. This resistance value can limit the maximum current of the circuit to the microampere level (1000V / 520MΩ≈1.9μA), which is far below the range of the milliammeter, resulting in significant protection. The choice of resistance value takes into account both the current-limiting effect and the test sensitivity, and will not affect the accurate detection of the 1mA operating current due to excessive current limiting.

[0064] Specific Implementation Method Eight: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method One. In this implementation method, the voltage detection unit 3 is connected in parallel between the moving end of the potentiometer 5 and the DC high voltage negative input terminal; and the voltage detection unit 3 is a high voltage voltmeter with a range of 0-1000V.

[0065] In this embodiment, the 0-1000V range of the high-voltage voltmeter is perfectly matched with the output range of the insulation resistance tester 1, and can directly display the actual operating voltage value of the valve under test without conversion; the high-voltage voltmeter has high input impedance, and has minimal impact on the circuit under test when tested in parallel, ensuring test accuracy; the wide range design can adapt to the testing needs of valves with different voltage levels, and has strong versatility; the digital display is intuitive and clear, making it easy for on-site operators to read the values ​​accurately.

[0066] Specific Implementation Method Nine: This implementation method further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Implementation Method One. In this implementation method, the current detection unit 2 is connected in series with the moving end of the potentiometer 5, and the current detection unit 2 is a milliammeter with a range of 0-10mA.

[0067] In this embodiment, the 0-10mA range accurately covers the detection requirements of the zinc oxide valve plate's operating current (1mA reference value), with high resolution, accurately capturing the 1.00mA operating point; the milliammeter is connected in series in the circuit, directly reflecting the actual current flowing through the valve plate under test, ensuring accurate and reliable detection; the range is moderate, avoiding both insufficient reading accuracy near 1mA due to an excessively large range and frequent over-range errors due to an excessively small range; the digital display facilitates accurate judgment of whether the current has reached the 1.00mA threshold.

[0068] Specific Embodiment Ten: This embodiment further defines the overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator described in Specific Embodiment One. In this embodiment, the current detection unit 2, the voltage detection unit 3, and the DC voltage divider circuit are all encapsulated in an insulating shell. The adjustment knob of the potentiometer 5, the display interface of the voltage detection unit 3, and the display interface of the current detection unit 2 are all located on the panel of the insulating shell.

[0069] In this embodiment, the overall modular packaging is compact and small in size, making it easy to carry to various complex spatial environments at hydropower stations. The insulated shell provides excellent electrical insulation and mechanical protection, adapting to the harsh environment of hydropower stations with high humidity and electromagnetic interference, ensuring test safety. The control panel centrally arranges adjustment knobs and display interface, providing a user-friendly interface and simple operation, allowing tests to be completed without the need for professional technicians. The integrated design reduces the amount of on-site wiring work, shortens test preparation time, and improves on-site testing efficiency. The encapsulation structure protects internal precision components, improving the reliability and service life of the equipment.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A test module for overvoltage of excitation and demagnetization zinc oxide valve plates of hydro-generators, characterized in that, It includes a current detection unit (2), a voltage detection unit (3), and a DC voltage divider circuit; The DC voltage divider circuit includes a zinc oxide resistor (4) and a potentiometer (5); One end of the zinc oxide resistor (4) serves as the positive input terminal of the DC high voltage; the other end of the zinc oxide resistor (4) is connected to one fixed terminal of the potentiometer (5); the other fixed terminal of the potentiometer (5) serves as the negative input terminal of the DC high voltage; and the movable terminal of the potentiometer (5) is used to connect one end of the tested excitation and demagnetization zinc oxide valve plate, and the negative input terminal of the DC high voltage is used to connect the other end of the tested excitation and demagnetization zinc oxide valve plate. The current detection unit (2) is used to detect the current value of the tested excitation and demagnetization zinc oxide valve plate; The voltage detection unit (3) is used to detect the voltage value of the tested excitation and demagnetization zinc oxide valve plate.

2. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, It also includes an insulation resistance tester (1); The DC high voltage positive output terminal of the insulation resistance tester (1) is connected to one end of the zinc oxide resistor (4); the DC high voltage negative output terminal of the insulation resistance tester (1) is connected to the other fixed terminal of the potentiometer (5).

3. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 2, characterized in that, The output DC voltage range of the insulation resistance tester (1) is 1000V.

4. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The resistance of the zinc oxide resistor (4) is 500 MΩ.

5. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The resistance of the potentiometer (5) is 10MΩ.

6. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The DC voltage divider circuit also includes a current-limiting resistor (6); The current-limiting resistor (6) is connected in series between the other fixed terminal of the potentiometer (5) and the DC high voltage negative input terminal.

7. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 6, characterized in that, The resistance value of the current-limiting resistor (6) is 10MΩ.

8. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The voltage detection unit (3) is connected in parallel between the moving end of the potentiometer (5) and the DC high voltage negative input terminal; and the voltage detection unit (3) is a high voltage voltmeter with a range of 0-1000V.

9. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The current detection unit (2) is connected in series with the moving end of the potentiometer (5), and the current detection unit (2) is a milliammeter with a range of 0-10mA.

10. The overvoltage test module for the excitation and demagnetization zinc oxide valve plate of a hydro-generator according to claim 1, characterized in that, The current detection unit (2), voltage detection unit (3) and DC voltage divider circuit are all encapsulated in an insulating shell. The adjustment knob of the potentiometer (5), the display interface of the voltage detection unit (3) and the display interface of the current detection unit (2) are all located on the panel of the insulating shell.

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