Special testing device for graphite contact high-voltage switch based on 20A constant current source

Abstract

The utility model relates to a special testing device for a graphite contact high-voltage switch based on a 20A constant current source, which relates to the field of high-voltage switch testing and comprises a microprocessor module, a constant current source module, an output terminal module, a current output test line module, a voltage signal test input line module, a signal acquisition and conditioning module and a speed measurement sensor module. The constant current source module outputs 20A direct current to the contact of the graphite contact high-voltage switch to be tested; the voltage test line collects the voltage between the contacts in a built-in four-wire system mode, and the voltage is processed by the signal acquisition conditioning module and then sent to the microprocessor module. The speed measurement sensor collects the speed of the moving rod. And the microprocessor module determines the action time of the silver-plated main contact according to the voltage signal and performs compensation calculation to obtain the action time of the graphite arc contact as the closing or opening time. The utility model solves the problem that the traditional method cannot accurately measure the time parameter of the graphite contact high-voltage switch, and has the advantages of accurate measurement and strong interference resistance.

Description

Technical Field

[0001] This utility model relates to the field of high-voltage switch testing, and in particular to a special testing device for graphite contact high-voltage switches based on a 20A constant current source. Background Technology

[0002] High-voltage switches with graphite contacts are widely used in power grids due to their excellent breaking performance. Unlike ordinary switches, their opening and closing process involves the sequential operation of two stages: the silver-plated main contacts and the graphite arc contacts. Standards stipulate that the opening and closing time should be determined based on the timing of the graphite arc contacts.

[0003] Currently, the common method for testing the timing parameters of high-voltage switches is the voltage jump isolation method. This method indirectly determines the timing of action by applying a voltage signal to the switch contacts and observing the changes in circuit state caused by the opening and closing of the contacts. However, this method typically uses a small test current. For graphite contact switches, the contact resistance of the silver-plated main contacts is extremely low, making it difficult for a small current to generate a sufficiently significant voltage jump signal. This results in an inability to clearly and reliably distinguish between silver-silver contacts and silver-graphite contacts, thus hindering effective and accurate timing parameter testing of graphite contact switches. Although some solutions have attempted to improve sampling accuracy, they have not changed the fundamental limitation of small test current. In practical applications, low-current solutions are susceptible to line impedance and interference, exhibiting poor stability, and often require heavy test leads, leading to complex and costly testing. Utility Model Content

[0004] In view of the above problems, this application proposes a dedicated testing device for graphite contact high-voltage switches based on a 20A constant current source, the device comprising:

[0005] Microprocessor module;

[0006] A constant current source module, electrically connected to the microprocessor module, is used to output a DC test current to the high-voltage switch of the graphite contact under test under the control of the microprocessor module.

[0007] The output terminal module is electrically connected to the output terminal of the constant current source module;

[0008] The current output test lead module is used to connect between the output terminal module and the moving and stationary contacts of the graphite contact high-voltage switch under test;

[0009] The voltage signal test input line module is used to connect between the same pair of moving and stationary contacts of the graphite contact high voltage switch under test, and its test clamping position is located inside the corresponding test clamping position of the current output test line module.

[0010] The signal acquisition and conditioning module has its input terminal electrically connected to the voltage signal test input line module via an input terminal, and its output terminal electrically connected to the microprocessor module. It is used to isolate, amplify, and perform analog-to-digital conversion on the voltage signal acquired by the voltage signal test input line module.

[0011] The speed sensor module is electrically connected to the microprocessor module and is used to collect the stroke and speed information of the moving contact of the high-voltage switch of the graphite contact being tested.

[0012] Preferably, the constant current source module is a DC constant current source with an open-circuit voltage of 10V and a constant current output of 20A.

[0013] Preferably, the signal acquisition and conditioning module includes:

[0014] An isolation operational amplifier unit, connected to the input terminal, is used to provide electrical isolation for the acquired voltage signal;

[0015] An amplification and filtering unit, connected to the isolation operational amplifier unit, is used to amplify and low-pass filter the isolated voltage signal;

[0016] An analog-to-digital converter unit, connected to the amplification and filtering unit and the microprocessor module, is used to convert the amplified and filtered analog voltage signal into a digital signal.

[0017] Preferably, the isolation operational amplifier unit employs a high-linearity analog isolation operational amplifier.

[0018] Preferably, the device further includes a trigger circuit, which is electrically connected to the microprocessor module and is used to access the opening and closing control circuit of the graphite contact high-voltage switch under test, and to provide the microprocessor module with a synchronous trigger signal for opening and closing actions.

[0019] Preferably, the microprocessor module is configured to: determine the contact or separation time of the silver-plated main contact of the graphite contact high-voltage switch under test based on the digital signal output by the signal acquisition and conditioning module.

[0020] Preferably, the microprocessor module is configured to: perform compensation calculations based on the speed information collected by the speed sensor module and the pre-stored graphite nozzle length corresponding to the model of the high-voltage switch of the graphite contact being tested, on the basis of the contact or separation time of the silver-plated main contact, to obtain the contact or separation time of the graphite arc contact as the closing or opening time.

[0021] Preferably, the microprocessor module is further configured to: when no valid speed information is acquired by the speed sensor module, compensate for the contact or separation time of the silver-plated main contact according to a preset typical speed characteristic value, so as to obtain the contact or separation time of the graphite arc contact.

[0022] Preferably, the microprocessor module has at least two different graphite nozzle length values ​​pre-stored to correspond to different types or specifications of graphite contact high-voltage switches under test.

[0023] The technical solution provided in this application has at least the following technical effects or advantages:

[0024] This invention improves the signal-to-noise ratio and stability of the test signal through a 20A high-current constant current source excitation and a built-in four-wire voltage acquisition system, enabling clear capture of the actuation point of the silver-plated main contact of the graphite contact high-voltage switch. Combined with speed measurement information and pre-stored mechanical parameters, intelligent compensation is performed to accurately calculate the actuation time of the graphite arc contact that conforms to the standard. This device solves the problem of traditional methods being unable to accurately test the timing parameters of graphite contact high-voltage switches, and has the advantages of high measurement accuracy, strong field adaptability, and low testing cost. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This utility model provides a structural schematic diagram of a special testing device for graphite contact high-voltage switches based on a 20A constant current source.

[0027] The components represented by each number in the attached diagram are explained below:

[0028] Microprocessor module 101, trigger circuit 102, constant current source module 103, output terminal module 104, current output test line module 105, voltage signal test input line module 106, input terminal module 107, isolation operational amplifier unit 108, amplification and filtering unit 109, analog-to-digital converter unit 110, speed sensor module 111, graphite contact high-voltage switch 201, first grounding switch 202, and second grounding switch 203. Detailed Implementation

[0029] This invention provides a dedicated testing device for graphite contact high-voltage switches based on a 20A constant current source, which solves the technical problems in the prior art, such as the inability to accurately distinguish and measure the action time of the silver-plated main contact and the graphite arc contact of the graphite contact high-voltage switch due to the insufficient test current, low signal-to-noise ratio in on-site testing, poor stability, and stringent requirements on the specifications of the test leads.

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0032] In the description of this application, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use the present invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the present invention can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the present invention with unnecessary detail. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0033] Examples, as shown in the appendix Figure 1 As shown, this application provides a dedicated testing device for graphite contact high-voltage switches based on a 20A constant current source, comprising:

[0034] Microprocessor module 101, trigger circuit 102, constant current source module 103, output terminal module 104, current output test line module 105, voltage signal test input line module 106, input terminal module 107, isolation operational amplifier unit 108, amplification and filtering unit 109, analog-to-digital converter unit 110, speed sensor module 111.

[0035] Specifically, the device includes:

[0036] Microprocessor module;

[0037] A constant current source module, electrically connected to the microprocessor module, is used to output a DC test current to the high-voltage switch of the graphite contact under test under the control of the microprocessor module.

[0038] The output terminal module is electrically connected to the output terminal of the constant current source module;

[0039] The current output test lead module is used to connect between the output terminal module and the moving and stationary contacts of the graphite contact high-voltage switch under test;

[0040] The voltage signal test input line module is used to connect between the same pair of moving and stationary contacts of the graphite contact high voltage switch under test, and its test clamping position is located inside the corresponding test clamping position of the current output test line module.

[0041] The signal acquisition and conditioning module has its input terminal electrically connected to the voltage signal test input line module via an input terminal, and its output terminal electrically connected to the microprocessor module. It is used to isolate, amplify, and perform analog-to-digital conversion on the voltage signal acquired by the voltage signal test input line module.

[0042] The speed sensor module is electrically connected to the microprocessor module and is used to collect the stroke and speed information of the moving contact of the high-voltage switch of the graphite contact being tested.

[0043] Preferably, the signal acquisition and conditioning module includes:

[0044] An isolation operational amplifier unit, connected to the input terminal, is used to provide electrical isolation for the acquired voltage signal;

[0045] An amplification and filtering unit, connected to the isolation operational amplifier unit, is used to amplify and low-pass filter the isolated voltage signal;

[0046] An analog-to-digital converter unit, connected to the amplification and filtering unit and the microprocessor module, is used to convert the amplified and filtered analog voltage signal into a digital signal.

[0047] The microprocessor module 101 is electrically connected to the control terminal of the constant current source module 103, the output terminal of the trigger circuit 102, the digital output terminal of the analog-to-digital converter unit 110, and the output terminal of the speed sensor module 111.

[0048] The current output terminal of the constant current source module 103 is connected to the output terminal module 104. The output terminal module 104 is connected to the moving contact side and the stationary contact side of the graphite contact high voltage switch 201 under test through the current output test lead module 105.

[0049] The two test clips of the voltage signal test input line module 106 are respectively connected to the same pair of moving and stationary contacts of the graphite contact high-voltage switch 201, and their clamping points are located inside the corresponding test clips of the current output test line module 105 to form a four-wire measurement circuit. The other end of the voltage signal test input line module 106 is connected to the input terminal module 107.

[0050] The input terminal module 107 is sequentially connected to the isolation operational amplifier unit 108, the amplification and filtering unit 109, and the analog-to-digital converter unit 110. The output terminal of the analog-to-digital converter unit 110 is connected to the microprocessor module 101.

[0051] The input terminal of the trigger circuit 102 is used to connect to the opening and closing control circuit of the graphite contact high voltage switch 201.

[0052] The first grounding switch 202 and the second grounding switch 203 should be in the open state during testing.

[0053] Since the closing and opening processes of graphite contact high-voltage switches involve two stages, the timing parameter should be based on the actuation moment of the graphite arc contact. Because the contact resistance of the silver-plated main contact is extremely small, typically tens of milliohms, traditional low-current testing, according to Ohm's law U=I×R, would only produce a voltage change of a few millivolts, easily drowned out by noise and unreliable. This invention, by outputting a 20A high-current constant source, enables the same contact resistance to produce a significant voltage change of hundreds of millivolts, greatly improving the signal-to-noise ratio and thus laying the foundation for accurately capturing the actuation moment of the silver-plated main contact.

[0054] After obtaining the reference time, since the moving contact needs to travel a fixed mechanical stroke, i.e. the graphite nozzle length, between the action of the silver-plated main contact and the action of the graphite arc contact, this utility model obtains the speed of the moving contact in real time through a speed sensor, and uses the physical principle of time = length / speed to perform compensation calculation, so as to accurately derive the final action time that meets the standard.

[0055] This utility model provides a special testing device for graphite contact high-voltage switches based on a 20A constant current source. Its working principle and process are as follows:

[0056] Before testing, based on the model of the graphite contact high-voltage switch 201 under test, the corresponding graphite nozzle length parameters were set in the microprocessor module 101. (See attached...) Figure 1 Complete all wiring and ensure that the first grounding switch 202 and the second grounding switch 203 are disconnected.

[0057] At the start of the test, after receiving a start command or capturing the synchronization signal of the graphite contact high-voltage switch operation through the trigger circuit 102, the microprocessor module 101 immediately controls the constant current source module 103 to start, outputting a 20A DC constant current test current to the graphite contact high-voltage switch 201. Simultaneously, the microprocessor module 101 synchronously acquires two data streams at a high sampling rate: one is a digital voltage signal processed by the isolation operational amplifier unit 108, the amplification and filtering unit 109, and the analog-to-digital converter unit 110; the other is the moving contact stroke and speed signal acquired by the speed sensor module 111.

[0058] During the closing process of the graphite contact high-voltage switch, when the silver-plated main contact makes contact, the circuit resistance experiences its first significant drop, and the voltage signal exhibits its first characteristic jump. The microprocessor module 101 identifies this jump point using an algorithm, determining it as the contact moment of the silver-plated main contact, and records this moment as T1. Next, the moving contact continues to move until the graphite arc contact makes contact. Since the moving contact needs to travel a fixed mechanical stroke, i.e., the graphite nozzle length L, between the contact of the silver-plated main contact and the contact of the graphite arc contact, the microprocessor module 101 uses the real-time velocity information V collected after the silver-plated main contact contact moment, i.e., time T1, combined with the pre-stored graphite nozzle length L, to calculate the compensation time ΔT = L / V. Therefore, the standard closing moment, i.e., the graphite arc contact moment T2 = T1 + ΔT, is found. The measurement principle for the opening process is the opposite.

[0059] If the speed sensor module 111 is not installed on site, the microprocessor module 101 can call the preset typical speed characteristic value for compensation calculation, and can still complete the basic test.

[0060] By combining the above hardware architecture with software algorithms, this invention achieves high-precision and high-reliability measurement of the closing and opening times of graphite contact high-voltage switches.

[0061] In this embodiment of the invention, in order to provide a sufficiently strong test excitation signal to overcome the measurement difficulties caused by the small contact resistance of the graphite contact, the constant current source module is set as a DC constant current source with an open circuit voltage of 10V and a constant current output of 20A, so as to ensure that a significant voltage change of more than millivolts can be generated on the contact resistance of tens of milliohms, thereby providing a high signal-to-noise ratio original signal basis for the subsequent signal processing circuit to clearly capture and distinguish the action moment of the silver-plated main contact and the graphite arc contact.

[0062] Preferably, the constant current source module is a DC constant current source with an open-circuit voltage of 10V and a constant current output of 20A.

[0063] Specifically, the constant current source module 103 is a DC constant current source with an open-circuit voltage of 10V and a constant current output of 20A. For example, this constant current source module can be composed of a power switching device, a current sampling resistor, an error amplifier, and a drive circuit to form a closed loop, ensuring that even if the resistance of the circuit under test varies within the range of tens of milliohms, the output current can remain stable at 20A, providing a high signal-to-noise ratio excitation signal for detection.

[0064] Preferably, the isolation operational amplifier unit employs a high-linearity analog isolation operational amplifier.

[0065] Specifically, the signal acquisition and conditioning module includes an isolation operational amplifier unit 108, an amplification and filtering unit 109, and an analog-to-digital converter unit 110. The isolation operational amplifier unit 108 is connected to the input terminal module 107 and is used to electrically isolate the acquired voltage signal, preventing high-voltage side interference from entering the low-voltage control side. For example, an analog isolation amplifier can be used to achieve high-linearity isolated transmission. The amplification and filtering unit 109 is connected to the isolation operational amplifier unit 108 and is used to amplify and low-pass filter the isolated voltage signal. For example, an operational amplifier and resistive-capacitive components can be used to construct the gain and filter circuit. The analog-to-digital converter unit 110 is connected to the amplification and filtering unit 109 and the microprocessor module 101 and is used to convert the amplified and filtered analog voltage signal into a digital signal. For example, a multi-channel high-resolution ADC chip can be used to achieve synchronous and accurate digitization of the signal.

[0066] Preferably, the device further includes a trigger circuit, which is electrically connected to the microprocessor module and is used to access the opening and closing control circuit of the graphite contact high-voltage switch under test, and to provide the microprocessor module with a synchronous trigger signal for opening and closing actions.

[0067] Specifically, in this embodiment of the present invention, a dedicated testing device for graphite contact high-voltage switches based on a 20A constant current source further includes a trigger circuit 102. The trigger circuit 102 is electrically connected to the microprocessor module 101 and is used to access the opening and closing control circuit of the graphite contact high-voltage switch 201 under test, and to provide the microprocessor module 101 with a synchronous trigger signal for opening and closing actions. For example, the trigger circuit can be composed of a high-speed optocoupler and a signal shaping circuit. When a voltage jump in the control circuit is detected, a pulse signal with a clear edge is generated and sent to the microprocessor module 101.

[0068] Preferably, the microprocessor module is configured to: determine the contact or separation time of the silver-plated main contact of the graphite contact high-voltage switch under test based on the digital signal output by the signal acquisition and conditioning module.

[0069] Preferably, the microprocessor module is configured to: perform compensation calculations based on the speed information collected by the speed sensor module and the pre-stored graphite nozzle length corresponding to the model of the high-voltage switch of the graphite contact being tested, on the basis of the contact or separation time of the silver-plated main contact, to obtain the contact or separation time of the graphite arc contact as the closing or opening time.

[0070] Preferably, the microprocessor module is further configured to: when no valid speed information is acquired by the speed sensor module, compensate for the contact or separation time of the silver-plated main contact according to a preset typical speed characteristic value, so as to obtain the contact or separation time of the graphite arc contact.

[0071] Specifically, the microprocessor module 101 is configured to perform the following processes:

[0072] First, based on the digital signal output by the signal acquisition and conditioning module, the contact or separation time of the silver-plated main contacts of the graphite contact high-voltage switch 201 under test is determined. For example, by analyzing the voltage waveform in real time, the sampling point index where the voltage first abruptly changes is found. During the closing process, this abrupt change is a voltage drop, and during the opening process, this abrupt change is a voltage rise. Combining this with the known sampling rate, the precise moment can be calculated.

[0073] Secondly, the microprocessor module 101 performs compensation calculations based on the speed information collected by the speed sensor module 111 and the pre-stored graphite nozzle length corresponding to the model of the graphite contact high-voltage switch 201 under test, and on the basis of the determined contact or separation time of the silver-plated main contact, to obtain the contact or separation time of the graphite arc contact as the closing or opening time.

[0074] For example, for a graphite contact high-voltage switch, the pre-stored graphite nozzle length is 24.9 mm. If the speed sensor measures the average speed of the moving contact after the silver-plated main contact actuates to be 1.2 m / s, then the compensation time is 24.9 mm / 1.2 m / s = 20.75 ms. Adding this compensation time to the actuation time of the silver-plated main contact yields the standard closing time.

[0075] Furthermore, the microprocessor module 101 is also configured to compensate for the contact or separation time of the silver-plated main contact based on a preset typical speed characteristic value when no valid speed information is acquired from the speed sensor module 111, so as to obtain a usable contact or separation time of the graphite arc contact. The preset typical speed characteristic value is the average movement speed of the tested graphite contact high-voltage switch model under standard operating conditions, representing the typical mechanical characteristics of the moving contact of that model of graphite contact high-voltage switch during the opening and closing process. For example, based on a large amount of historical test data of the same model of graphite contact high-voltage switch or technical parameters provided by the manufacturer, this typical speed characteristic value can be set to a fixed value or a speed-time curve related to operating conditions, so as to estimate the closing or opening time in sensorless mode.

[0076] Furthermore, preferably, the microprocessor module pre-stores at least two different graphite nozzle length values ​​to correspond to different types or specifications of the graphite contact high-voltage switches under test.

[0077] Specifically, the microprocessor module 101 pre-stores at least two different graphite nozzle length values ​​to correspond to different types or specifications of graphite contact high-voltage switches under test. Among them, the pre-stored graphite nozzle length value is a key structural parameter of different models of graphite contact high-voltage switches, representing the fixed travel distance between its graphite arc contact and silver-plated main contact.

[0078] For example, based on the design drawings or technical manuals of different series of graphite contact high-voltage switches, the graphite nozzle length data of the corresponding model can be pre-stored in the memory of the microprocessor module 101. During actual testing, the user selects the specific model of the graphite contact high-voltage switch to be tested through the human-machine interface, and the microprocessor module 101 automatically calls the pre-stored graphite nozzle length value matching that model for subsequent time compensation calculations, thereby ensuring the accuracy and adaptability of the measurement results for different models of graphite contact high-voltage switches.

[0079] Through the specific implementation methods described above, this utility model embodiment achieves the following technical effects:

[0080] This utility model provides a dedicated testing device for graphite contact high-voltage switches based on a 20A constant current source. By employing a 20A high-current constant current source for excitation and a built-in four-wire precision voltage acquisition system, the signal-to-noise ratio and anti-interference capability of the test signal are improved, thereby enabling clear and reliable capture of the operating point of the silver-plated main contact of the graphite contact high-voltage switch. Furthermore, by integrating real-time speed information with pre-stored mechanical parameters specific to the graphite contact high-voltage switch model, intelligent and precise compensation for the operating moment of the graphite arc contact is achieved. Ultimately, this device effectively solves the fundamental problem that traditional low-current testing methods cannot accurately measure the time parameters of graphite contact high-voltage switches, while reducing the stringent requirements on the specifications of on-site test leads. It possesses advantages such as high measurement accuracy, strong environmental adaptability, convenient operation, and low overall cost.

[0081] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0082] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0083] This specification and accompanying drawings are merely illustrative examples of this application and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Therefore, if such modifications and variations fall within the scope of this application and its equivalents, this application intends to include such modifications and variations.

Claims

1. A special test device for high-voltage switches with graphite contacts based on a 20A constant current source, characterized in that, The device comprises: a microprocessor module; a constant current source module electrically connected to the microprocessor module, for outputting a direct current test current to a measured graphite contact high-voltage switch under the control of the microprocessor module; an output terminal module electrically connected to an output terminal of the constant current source module; a current output test line module for being connected between the output terminal module and a moving contact and a static contact of the measured graphite contact high-voltage switch; a voltage signal test input line module for being connected between a same pair of moving contact and static contact of the measured graphite contact high-voltage switch, and a test clamping position of the voltage signal test input line module is located inside a corresponding test clamping position of the current output test line module; a signal acquisition and conditioning module, an input end of which is electrically connected to the voltage signal test input line module through an input terminal, and an output end of which is electrically connected to the microprocessor module, for isolating, amplifying and analog-digital converting a voltage signal acquired by the voltage signal test input line module; a speed sensor module electrically connected to the microprocessor module, for acquiring stroke and speed information of the moving contact of the measured graphite contact high-voltage switch.

2. The graphite contact high-voltage switch special test device based on the 20A constant current source according to claim 1, characterized in that, The constant current source module is a direct current constant current source with an open circuit voltage of 10 V and a constant current output of 20 A.

3. The graphite contact high-voltage switch special test device based on the 20A constant current source of claim 1, wherein, The signal acquisition and conditioning module comprises: an isolation operational amplifier unit connected to the input terminal, for electrically isolating the acquired voltage signal; an amplification and filtering unit connected to the isolation operational amplifier unit, for amplifying and low-pass filtering the isolated voltage signal; an analog-digital converter unit connected to the amplification and filtering unit and the microprocessor module, for converting the amplified and filtered analog voltage signal into a digital signal.

4. The graphite contact high voltage switch special test device based on 20A constant current source of claim 3, wherein, The isolation operational amplifier unit adopts a high linearity analog isolation operational amplifier.

5. The graphite contact high voltage switch special test device based on 20A constant current source of claim 1, wherein, Further comprising a trigger circuit electrically connected to the microprocessor module, for accessing a breaking and closing control loop of the measured graphite contact high-voltage switch, and providing a synchronous trigger signal of breaking and closing action for the microprocessor module.

6. The graphite contact high voltage switch special test device based on 20A constant current source of claim 1, wherein, At least two different graphite nozzle length values are pre-stored in the microprocessor module, for corresponding to different types or specifications of the measured graphite contact high-voltage switch.

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