Pre-failure short circuit test method for gapless metal oxide arrester

Abstract

The invention discloses a pre-failure short circuit test method for a gapless metal oxide arrester, belongs to the field of lightning protection, and particularly relates to a method for continuously applying voltage to a to-be-tested arrester and simultaneously monitoring the voltage at two ends of the arrester and the value of current flowing through the arrester until the to-be-tested arrester reaches a pre-failure. Through the test method, the test requirements of the lightning arrester pre-failure short circuit in the international standard IEC 60099-4 are met; meanwhile, one testing method can meet the requirements of to-be-tested lightning arresters of different specifications.

Description

Technical Field

[0001] This invention relates to a pre-failure short-circuit test method for gapless metal oxide surge arresters, belonging to the field of surge protection. Specifically, it is a method that continuously applies voltage to the surge arrester under test while monitoring the voltage across the surge arrester and the current flowing through the surge arrester until the surge arrester under test reaches a pre-failure state. Background Technology

[0002] A surge arrester is an electrical device that can release the energy of lightning or, in addition to, the operating overvoltage energy of the power system, protect electrical equipment from the damage of transient overvoltages (lightning overvoltage, operating overvoltage, power frequency transient overvoltage impacts) without causing a grounding short circuit in the system.

[0003] With increasingly stringent requirements for the quality of lightning protection engineering, the operational status of surge arresters is crucial for the reliable operation of power systems and the protection of personnel safety. Pre-failure short-circuit testing of surge arresters is an important step in verifying their performance.

[0004] The international standard IEC 60099-4 specifies the various indicators for the pre-failure short-circuit test of surge arresters, and the corresponding minimum and maximum rated voltages for various types and designs of fault open-circuit or fault short-circuit surge arresters. Summary of the Invention

[0005] The purpose of this invention is to provide a pre-failure short-circuit test method for gapless metal oxide surge arresters.

[0006] The method includes: Step S1, selecting the preset voltage value of the programmable power supply output and the range of the shunt resistor switch according to the surge arrester under test; Step S2, collecting the real-time voltage and current values ​​across the surge arrester under test through the testing device; Step S3, comparing the real-time voltage value across the surge arrester under test with the standard voltage value of the surge arrester under test. If they are not equal, adjusting the preset voltage value of the programmable power supply output; if they are equal, collecting the real-time voltage and current values ​​across the surge arrester under test and outputting them to the processor; Step S4, the processor generating a two-dimensional voltage and current curve based on the time, voltage, and current values; Step S5, comparing the two-dimensional voltage and current curve with the standard two-dimensional voltage and current curve. If they are consistent, the product is judged to be qualified; if they are inconsistent, the product is judged to be qualified.

[0007] Furthermore, step 2 also includes step 21, whether the preset test time has been reached. If the preset test time has been reached, proceed to step S4; if the preset time has not been reached, continue data collection.

[0008] Furthermore, in step S5, a two-dimensional voltage and current curve is collected using an oscilloscope. If the current value suddenly exceeds the normal value within a preset time, it is judged as unqualified; if the current value is stable, it is judged as qualified.

[0009] Furthermore, in step S3, if the real-time voltage across the surge arrester under test is different from the standard voltage value of the surge arrester under test, the voltage value output by the programmable power supply is adjusted so that the real-time voltage across the surge arrester under test approaches the standard voltage value.

[0010] Furthermore, in step S1, the preset voltage value is sent to the programmable power supply via a control command from the processor.

[0011] Furthermore, the processor includes a host computer and an ARM controller. The host computer communicates with the ARM controller via a serial interface. The host computer sends a resistance level instruction to the ARM controller according to a preset voltage value. The ARM controller executes the corresponding resistance level switch according to the received instruction for the shunt resistor switch. The host computer sends a start instruction and real-time voltage value to the ARM controller. The ARM controller controls the programmable power supply to start according to the received start instruction and preset voltage value. The host computer sends a stop instruction to the ARM controller. The ARM controller controls the programmable power supply to stop voltage output and stop the test according to the received stop instruction. The voltage and current acquisition device communicates with the host computer through a network communication interface to obtain the voltage and current values ​​of the surge arrester. At the same time, the host computer generates a voltage-current-time curve from the real-time voltage and current values ​​acquired during the test.

[0012] Furthermore, the ARM controller communicates with the programmable power supply via an SPI module.

[0013] Furthermore, in step S3, if the real-time voltage across the surge arrester under test is higher than the standard voltage value of the surge arrester under test, the voltage value output by the programmable power supply is adjusted to be lower than the preset voltage value; if the real-time voltage value across the surge arrester under test is lower than the standard voltage value of the surge arrester under test, the voltage value output by the programmable power supply is adjusted to be higher than the preset voltage value.

[0014] Furthermore, the current flowing through the surge arrester under test is maintained within the range of 10-30A.

[0015] Furthermore, different shunt resistor switch settings can be selected based on the different specifications of the surge arrester under test.

[0016] The device works as follows: the host computer communicates with the ARM controller via a serial interface, using a serial method for human-computer interaction; the host computer sends a resistance range command to the ARM controller according to the preset voltage value, and the ARM controller switches according to the received shunt resistor switch range; the host computer sends a start command and a preset voltage value to the ARM controller, and the ARM controller controls the programmable power supply to start and output the corresponding voltage according to the received start command and preset voltage value; the host computer sends a stop command to the ARM controller, and the ARM controller controls the programmable power supply to stop voltage output and stop the test according to the received stop command; the voltage and current acquisition unit communicates with the host computer through a network communication interface to obtain the voltage and current values ​​of the surge arrester, and at the same time, the host computer will generate a voltage-current-time curve from all the voltage and current values ​​obtained during the test.

[0017] The advantages of this invention are: the test method meets the test requirements of the international standard "IEC 60099-4" for pre-failure short circuit of surge arresters; at the same time, one test method can meet the requirements of surge arresters of different specifications. Attached Figure Description

[0018] Figure 1 This is a flowchart of the first embodiment of the pre-failure short-circuit test method for a gapless metal oxide surge arrester according to the present invention;

[0019] Figure 2 This is a flowchart of a second embodiment of the pre-failure short-circuit test method for a gapless metal oxide surge arrester according to the present invention;

[0020] Figure 3 This is a schematic diagram of the test device 20 for the pre-failure short-circuit test method of a gapless metal oxide surge arrester according to the present invention;

[0021] Figure 4 This is a two-dimensional voltage and current curve of a pre-failure short-circuit test method for a gapless metal oxide surge arrester according to the present invention.

[0022] In the diagram: 10… Surge arrester under test, 21… Voltage probe, 22… Current coil, 23… Voltage and current acquisition device, 24… Shunt resistor switch, 25… Programmable power supply, 26… Processor, 261… Host computer, 262… ARM controller, 27… Overcurrent protector. Detailed Implementation

[0023] Please see Figure 1 The test method includes: Step S1, determining the preset voltage value output by the programmable power supply 25 based on the voltage across the surge arrester 10 under test and the setting of the shunt resistor switch 24; wherein, the setting of the shunt resistor switch 24 is determined based on the preset voltage value; Step S2, after... Figure 3The test device 20 shown collects the real-time voltage and current values ​​across the surge arrester 10 under test. Step S3: Compare the real-time voltage value across the surge arrester 10 under test with the standard voltage value of the surge arrester 10 under test. If they are not equal, adjust the programmable power supply 25 to output a preset voltage value. If they are equal, continuously collect the real-time voltage and current values ​​across the surge arrester 10 under test for a preset time and output them to the processor 26. Step S4: The processor 26 generates a two-dimensional voltage and current curve based on time, voltage, and current. Step S5: Compare the two-dimensional voltage and current curve with the standard two-dimensional voltage and current curve. If they are consistent, the product is judged to be qualified. If they are inconsistent, the product is judged to be qualified.

[0024] like Figure 2 As shown: In step S5, a two-dimensional voltage and current curve can be collected using an oscilloscope. If the current suddenly exceeds the preset value within a preset time, it is judged as unqualified; if the current value is stable, it is judged as qualified.

[0025] In step S3, if the real-time voltage value across the surge arrester 10 under test is different from the standard voltage value of the surge arrester 10 under test, the preset voltage value output by the programmable power supply 25 is adjusted so that the real-time voltage across the surge arrester 10 under test approaches the standard voltage value.

[0026] Specifically, in step S3, if the real-time voltage across the surge arrester 10 under test is higher than the standard voltage value of the surge arrester 10 under test, the voltage value output by the programmable power supply 25 is adjusted to be lower than the preset voltage value; if the real-time voltage value across the surge arrester 10 under test is lower than the standard voltage value of the surge arrester 10 under test, the voltage value output by the programmable power supply 25 is adjusted to be higher than the preset voltage value.

[0027] The following example illustrates the procedure of this test method: First, the surge arrester under test (SUT) 10 is calculated to have a voltage of 1.15Uc applied across it, as specified in the IEC 60099-4 standard. In this embodiment, the Uc of the SUT 10 is 6000, resulting in a voltage of 6900V across it. The resistance of the shunt resistor switch 24 is between 100 ohms and 5000 ohms. The boost ratio of the boost circuit T1 is 1:20. The preset voltage value of the programmable power supply 25 is 345V. The standard 60099-4 specifies that the test time and data acquisition time are 3-5 minutes. In this embodiment, it is set to 4 minutes. When the voltage and current acquisition device 23 collects information that the real-time voltage value of the voltage probe 21 is lower than 6900V, it is processed by the processor 26 and a 355V voltage is sent to the programmable power supply 25 to boost the voltage of the boost circuit T1. When the real-time voltage value of the voltage probe 21 at both ends of the surge arrester 10 under test is higher than 6900V, it is processed by the processor 26 and a 335V voltage is sent to the programmable power supply 25 to boost the voltage of the boost circuit T1. In this embodiment, after 10 seconds of adjustment, it stabilizes at around 6900V.

[0028] Within the set test time of 4 minutes, the output two-dimensional voltage and current curves are as follows: Figure 4 As shown: The voltage across the stable voltage probe 21 is 6900V, the shunt resistor switch 24 has a resistance of 2500 ohms, and the current value of the current coil 22 remains stable at 2-3 mA output. At 58 seconds, the current in the current coil 22 suddenly increases, as... Figure 4 As shown: The surge arrester 10 under test undergoes voltage regulation at both ends for the first 10 seconds, adjusting it to a stable 6900V. During the test, at 58 seconds, as... Figure 4 As shown: The current through the current coil 22 suddenly increases sharply, indicating that the surge arrester 10 under test is a defective product.

[0029] like Figure 3 As shown: The pre-failure short-circuit test device 20 for gapless metal oxide surge arresters of the present invention includes: surge arrester under test 10, voltage probe 21, current coil 22, voltage and current acquisition device 23, shunt resistor switch 24, programmable power supply 25, processor 26, overcurrent protector 27, and boost coil T1.

[0030] Among them, a programmable power supply (25) is a power supply whose output parameters such as current, voltage, and power can be changed through a specific programming interface. Programmable power supplies utilize microprocessors, digital signal processors, analog circuits, and other technologies, combined with advanced control algorithms and software, to achieve precise control and adjustment of multiple parameters such as output current, voltage, and power. Programmable power supplies are divided into two types: open-loop control and closed-loop control.

[0031] The voltage output by the programmable power supply 25 is boosted by the boost coil T1. The output of the boost coil T1 is connected to the shunt resistor switch 24, and the other output is connected to the current coil 22. The two ends of the surge arrester 10 under test are respectively connected to the output of the shunt resistor switch 24 and the output of the current coil 22. At the same time, the voltage probe 21 is also connected to the output of the shunt resistor switch 24 and the current coil 22 to detect the real-time voltage across the surge arrester 10 under test. The two ends of the voltage and current acquisition device 23 are respectively connected to the voltage probe 21 and the current coil 22. The output of the voltage and current acquisition device 23 is connected to the processor 26. After the processor 26 analyzes and compares the collected voltage and current data, the output voltage of the programmable power supply 25 can be adjusted.

[0032] The processor 26 includes a host computer 261 connected to an ARM controller 262 via a serial interface. The ARM (Advanced RISC Machines) processor 262 is the first RISC microprocessor designed for the market by Acorn Computers Ltd.

[0033] Among them, such as Figure 3 As shown: The shunt resistor switch 24 may include a first resistor R1 and a first switch K1 in the first position; a second resistor R2 and a second switch K2 in the second position; and a third resistor R3 and a third switch K3 in the third position. Since the shunt requirements of different models of surge arresters 10 under test are different, the shunt resistors of different models of surge arresters 10 under test are different during the test, thus requiring the selection of different shunt resistors.

[0034] To better match the test products of different models of surge arresters 10 under test, the shunt resistor switch 24 can have multiple positions to meet different test requirements, or it can be a sliding resistor.

[0035] The overcurrent protector 27 is connected to the neutral line of the test device 20 to protect the entire circuit when the current of the entire test device 20 suddenly increases.

[0036] The working principle of the device 20 is as follows: Communication is achieved through a serial method for human-machine interaction; the host computer 261 sends a command to the ARM controller 262 to switch the shunt resistor 24 according to the set voltage; the ARM controller 262 controls the switching of the shunt resistor 24 according to the received command; the host computer 261 sends a start command and a preset voltage value to the ARM controller 262; the ARM controller 262 controls the programmable power supply 25 to start and output the preset voltage according to the received start command and output voltage value; the host computer 261 sends a stop command to the ARM controller 262; the ARM controller 262 controls the programmable power supply 25 to stop voltage output and stop the test according to the received stop command; the voltage and current acquisition device 23 communicates with the host computer 261 through a network communication interface to obtain the real-time voltage and current values ​​of the surge arrester 10 under test; at the same time, the host computer 262 will generate a voltage-current-time curve from the real-time voltage and current values ​​obtained during the test, and analyze whether the surge arrester 10 under test is qualified through the voltage-current-time curve.

[0037] The present invention can also be performed using other testing devices 20, as long as the voltage value across the surge arrester 10 under test and the current value flowing through the surge arrester 10 under test can be collected in real time. The testing device can be designed in various ways, which will not be elaborated here.

[0038] The advantages of this invention are: the international standard IEC 60099-4 clarifies the test requirements for pre-failure short circuits of surge arresters through this test method; at the same time, one test method can meet the requirements of surge arresters of different specifications.

[0039] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pre-failure short-circuit test method for gapless metal oxide surge arresters, characterized in that: include: Step S1: Select the preset voltage value of the programmable power supply output and the range of the shunt resistor switch according to the surge arrester under test; Step S2: The real-time voltage and current values ​​at both ends of the surge arrester under test are collected through the testing device; Step S3: Compare the real-time voltage value across the surge arrester under test with the standard voltage value of the surge arrester under test. If they are not equal, adjust the preset voltage value output by the programmable power supply. If they are equal, collect the real-time voltage and current values ​​across the surge arrester under test and output them to the processor; Step S4: The processor generates a two-dimensional voltage and current curve based on the time, voltage, and current values; Step S5: Compare the two-dimensional voltage and current curve with the standard two-dimensional voltage and current curve. If they are consistent, the product is deemed qualified; if they are inconsistent, the product is deemed qualified.

2. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: Step 2 also includes step 21, whether the preset test time has been reached. If the preset test time has been reached, proceed to step S4. If the preset time has not been reached, continue data collection.

3. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: Step S5: Collect two-dimensional voltage and current curves using an oscilloscope. If the current value suddenly exceeds the normal value within a preset time, it is judged as unqualified; if the current value is stable, it is judged as qualified.

4. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: In step S3, if the real-time voltage across the surge arrester under test is different from the standard voltage value of the surge arrester under test, the voltage value output by the programmable power supply is adjusted so that the real-time voltage across the surge arrester under test approaches the standard voltage value.

5. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: The preset voltage value in step S1 is sent to the programmable power supply via a control command sent by the processor.

6. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1 or 5, characterized in that: The processor includes a host computer and an ARM controller. The host computer communicates with the ARM controller via a serial interface. The host computer sends a resistance range instruction to the ARM controller according to a preset voltage value. The ARM controller executes the corresponding resistance range switching according to the received instruction for the shunt resistor switch. The host computer sends a start instruction and real-time voltage value to the ARM controller. The ARM controller controls the programmable power supply to start according to the received start instruction and preset voltage value. The host computer sends a stop instruction to the ARM controller. The ARM controller controls the programmable power supply to stop voltage output and stop the test according to the received stop instruction. The voltage and current acquisition device communicates with the host computer through a network communication interface to obtain the voltage and current values ​​of the surge arrester. At the same time, the host computer generates a voltage-current-time curve from the real-time voltage and current values ​​acquired during the test.

7. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 6, characterized in that: The ARM controller communicates with the programmable power supply via the SPI module.

8. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: In step S3, if the real-time voltage across the surge arrester under test is higher than the standard voltage value of the surge arrester under test, adjust the voltage value output by the programmable power supply to be lower than the preset voltage value. If the real-time voltage across the surge arrester under test is lower than the standard voltage of the surge arrester under test, adjust the voltage output of the programmable power supply to be higher than the preset voltage.

9. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: The current flowing through the surge arrester under test should be maintained within the range of 10-30A.

10. The pre-failure short-circuit test method for gapless metal oxide surge arresters as described in claim 1, characterized in that: Different shunt resistor switch settings can be selected based on the different specifications of the surge arrester under test.

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