Nondestructive testing method for withstand voltage of superconducting cable

Abstract

The invention discloses a non-destructive testing method for the withstand voltage of a superconducting cable, and relates to the technical field of the withstand voltage testing of the superconducting cable, and the method comprises the following steps: 1, respectively dispersing a testing end and a non-testing end of the superconducting cable, and numbering each strand of the superconducting cable; step 2, connecting the positive electrode and the negative electrode of the insulation resistance tester with the test end; step 3, setting the maximum test voltage and the dwell time, gradually increasing the voltage to the maximum test voltage, and obtaining a withstand voltage test result according to the insulation resistance data of the insulation resistance tester; the superconducting cable is provided with at least two layers of strands. According to the invention, the insulation resistance tester is adopted to carry out the withstand voltage test, and the leakage current protection mechanism of the insulation resistance tester is utilized to realize the nondestructive test of the withstand voltage between the internal strands of the superconducting cable, thereby providing reliable technical guarantee for the quality control, maintenance and repair and long-term operation of the superconducting cable.

Description

Technical Field

[0001] The present application relates to the technical field of superconducting cable withstand voltage testing, and in particular to a non-destructive testing method for superconducting cable withstand voltage. Background Art

[0002] As the demand for power transmission continues to increase, superconducting cables have become an important power transmission technology due to their low resistance and efficient energy transmission performance. The key advantage of superconducting cables is that they can achieve almost lossless power transmission at low temperatures. However, in the actual application of superconducting cables, how to effectively test the withstand voltage performance between their internal strands is still a technical problem that needs to be solved urgently.

[0003] Existing superconducting cable withstand voltage test methods mainly include DC withstand voltage test and AC withstand voltage test, which usually rely on traditional electrical testing techniques such as voltage breakdown test and current leakage test.

[0004] However, the above-mentioned prior art may cause physical damage to the superconducting cable during the testing process, and it is difficult to achieve non-destructive testing of the withstand voltage between the strands inside the superconducting cable. Summary of the invention

[0005] The present application provides a non-destructive testing method for the withstand voltage of a superconducting cable, which is used to solve the problem that the existing superconducting cable withstand voltage testing technology is difficult to achieve non-destructive testing of the withstand voltage between strands inside the superconducting cable.

[0006] On the one hand, the present application provides a non-destructive testing method for the withstand voltage of a superconducting cable, comprising the following steps: Step 1: Separate the test end and the non-test end of the superconducting cable and number each strand of the superconducting cable.

[0007] Step 2: Connect the positive and negative poles of the insulation resistance tester to the test end.

[0008] Step three, setting the maximum test voltage and the voltage holding time, gradually increasing the voltage to the maximum test voltage, and obtaining the withstand voltage test result according to the insulation resistance data of the insulation resistance tester.

[0009] The superconducting cable has at least two layers of strands.

[0010] In a possible implementation, in step 1, before dispersing the superconducting cable, the position of each branch wire is recorded.

[0011] In a possible implementation, in step 1, after the superconducting cable is dispersed, the insulating varnish on each strand of the test end is removed, and the end face of the non-test end is insulated and wrapped.

[0012] In a possible implementation, in step 2, when it is necessary to test the withstand voltage value between the strands in a layer, the positive and negative poles of the insulation resistance tester are respectively connected to the separated strands in the layer.

[0013] When the withstand voltage value of the interlayer strands needs to be tested, the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

[0014] In a possible implementation, the step of connecting the positive and negative electrodes of the insulation resistance tester to the separated strands in the layer includes: The strands in the layer are divided into two groups of spaced strands, the two groups of spaced strands are adjacent to each other, the two groups of spaced strands are connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two groups of spaced strands respectively.

[0015] In a possible implementation, the step of connecting the positive and negative electrodes of the insulation resistance tester to two adjacent layers of strands of wire respectively includes: Each layer of strands of two adjacent layers of strands is connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

[0016] In a possible implementation, in step three, when gradually increasing the voltage to the maximum test voltage, the voltage value increased each time is 100-500V.

[0017] In a possible implementation, in step three, the holding time is 30-60s.

[0018] In a possible implementation, in step 3, obtaining a withstand voltage test result according to the insulation resistance data of the insulation resistance tester includes: Observe the changes in the insulation resistance data. If there is no error in the insulation resistance data, the withstand voltage test is qualified. If there is an error in the insulation resistance data, the withstand voltage test is unqualified.

[0019] A non-destructive testing method for superconducting cable withstand voltage in the present application has the following advantages: By using an insulation resistance tester to perform voltage withstand tests and utilizing the leakage current protection mechanism of the insulation resistance tester, non-destructive testing of the voltage withstand between strands inside superconducting cables is achieved, providing reliable technical support for quality control, maintenance and long-term operation of superconducting cables.

[0020] By recording the position of each strand before dispersing the superconducting cable, confusion of positions when numbering the strands is avoided, thereby avoiding invalid data from erroneously testing non-adjacent strands or layers.

[0021] By dispersing the non-test ends of the superconducting cable and insulating the end faces of the non-test ends, it is prevented that during the test, the conductors of the non-test ends will not be connected due to arcing due to the close distance, which will render the test data invalid.

[0022] By connecting the positive and negative poles of the insulation resistance tester to two groups of separated strands respectively, the withstand voltage test between the strands in a layer is achieved.

[0023] By connecting the positive and negative poles of the insulation resistance tester to two adjacent layers of strands respectively, the withstand voltage test of the interlayer strands is achieved.

[0024] By gradually increasing the voltage to the maximum test voltage and setting the voltage value for each increase, it is possible to prevent the insulation layer from being directly punctured due to excessive voltage.

[0025] The stability of the insulation layer of the superconducting cable strands was tested by setting the pressure holding time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic flow chart of a non-destructive testing method for superconducting cable withstand voltage provided in an embodiment of the present application; Figure 2 A schematic diagram of a test of the withstand voltage between strands within a layer provided in Example 1 of the present application; Figure 3 A schematic diagram of the test of the withstand voltage value of the interlayer strands provided in Example 2 of the present application. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] like Figure 1 As shown, the embodiment of the present application provides a non-destructive testing method for the withstand voltage of a superconducting cable, comprising the following steps: Step 1: Separate the test end and the non-test end of the superconducting cable and number each strand of the superconducting cable.

[0030] Step 2: Connect the positive and negative poles of the insulation resistance tester to the test end.

[0031] Step three, setting the maximum test voltage and the voltage holding time, gradually increasing the voltage to the maximum test voltage, and obtaining the withstand voltage test result according to the insulation resistance data of the insulation resistance tester.

[0032] The superconducting cable has at least two layers of strands.

[0033] Specifically, in Examples 1 to 4, a superconducting cable with two layers of strands is used for the withstand voltage test, and the two layers of strands include a center layer strand and a side layer strand, wherein the center layer strand has one strand and the side layer strand has six strands. In other possible embodiments, superconducting cables with other layers of strands may also be used for the withstand voltage test.

[0034] Exemplarily, in step 1, before dispersing the superconducting cable, the position of each branch wire is recorded.

[0035] Exemplarily, in step 1, after the superconducting cable is dispersed, the insulating varnish on each strand of the test end is removed, and the end face of the non-test end is insulated and wrapped.

[0036] Specifically, in Examples 1 to 4, the insulation wrapping uses insulating tape.

[0037] Exemplarily, in step 2, when it is necessary to test the withstand voltage value between the strands in a layer, the positive and negative poles of the insulation resistance tester are respectively connected to the separated strands in the layer.

[0038] When the withstand voltage value of the interlayer strands needs to be tested, the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

[0039] Exemplarily, the step of connecting the positive and negative electrodes of the insulation resistance tester to the separated strands in the layer includes: The strands in the layer are divided into two groups of spaced strands, the two groups of spaced strands are adjacent to each other, the two groups of spaced strands are connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two groups of spaced strands respectively.

[0040] Exemplarily, the step of connecting the positive and negative electrodes of the insulation resistance tester to two adjacent layers of strands of wire comprises: Each layer of strands of two adjacent layers of strands is connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

[0041] Exemplarily, in step three, when gradually increasing the voltage to the maximum test voltage, the voltage value increased each time is 100-500V.

[0042] Exemplarily, in step three, the holding time is 30-60s.

[0043] Exemplarily, in step three, obtaining a withstand voltage test result according to the insulation resistance data of the insulation resistance tester includes: Observe the changes in the insulation resistance data. If there is no error in the insulation resistance data, the withstand voltage test is qualified. If there is an error in the insulation resistance data, the withstand voltage test is unqualified.

[0044] Specifically, the testing principle of the insulation resistance tester is as follows: the insulation resistance tester tests the insulation resistance by detecting the leakage current between the strands. When the leakage current exceeds the set value, the insulation resistance data will be reported as an error, and the insulation resistance tester will automatically discharge to protect the insulation layer between the strands from being broken down.

[0045] Embodiment 1: Specifically, in Example 1, in step 1, the test end and the non-test end of the superconducting cable are separated, and each strand of the superconducting cable is numbered; before the superconducting cable is dispersed, the position of each strand is recorded; after the superconducting cable is dispersed, the insulating paint on each strand of the test end is removed, and the end face of the non-test end is insulated.

[0046] In Example 1, in step 2, the withstand voltage value between the strands in the test layer is first divided into two groups of separated strands, the two groups of separated strands are adjacent, the two groups of separated strands are connected together, and the positive and negative poles of the insulation resistance tester are connected to the two groups of separated strands, respectively. Figure 2 As shown, 1, 3, 5 are a group of separated strands of the edge layer, 2, 4, 6 are another group of separated strands of the edge layer, and the separated strands 1, 3, 5 are connected to the positive electrode after being connected, and the separated strands 2, 4, 6 are connected to the negative electrode after being connected.

[0047] In Example 1, in step three, the maximum test voltage is set to 2000V, the voltage holding time is 30s, the test is started from 500V, and the voltage is increased after the test is correct to continue testing, and the voltage value increased by 500V each time.

[0048] In Example 1, after measurement, when the voltage was increased to 2000V, the leakage current test value was 2.09nA, the insulation resistance was 976GΩ, and there was no error in the insulation resistance data, indicating that the withstand voltage value between the strands in the edge layer of the tested superconducting cable can meet the requirement of 2000V, and the withstand voltage test is qualified.

[0049] Embodiment 2: Specifically, in Example 2, in step 1, the test end and the non-test end of the superconducting cable are separated, and each strand of the superconducting cable is numbered; before the superconducting cable is dispersed, the position of each strand is recorded; after the superconducting cable is dispersed, the insulating paint on each strand of the test end is removed, and the end face of the non-test end is insulated.

[0050] In Example 2, in step 2, the withstand voltage value of the interlayer strands is tested. First, each layer of strands of two adjacent layers of strands is connected together, and the positive and negative poles of the insulation resistance tester are connected to the adjacent two layers of strands, respectively. Figure 3 As shown, the strands of the side layers are connected to the positive electrode, and the strands of the center layer are connected to the negative electrode.

[0051] In Example 2, in step 3, the maximum test voltage is set to 500V, the voltage holding time is 60s, the test is started from 100V, and the voltage is increased after the test is correct to continue testing, and the voltage value increased each time is 100V.

[0052] In Example 2, after measurement, when the voltage was increased to 500V, the leakage current test value was 0.55nA, the insulation resistance was 909GΩ, and no error was reported in the insulation resistance data, indicating that the interlayer strand withstand voltage value of the tested superconducting cable can meet the requirement of 500V and the withstand voltage test is qualified.

[0053] Embodiment 3: Specifically, in Example 3, in step 1, the test end and the non-test end of the superconducting cable are separated, and each strand of the superconducting cable is numbered; before the superconducting cable is dispersed, the position of each strand is recorded; after the superconducting cable is dispersed, the insulating paint on each strand of the test end is removed, and the end face of the non-test end is insulated.

[0054] In Example 3, in step 2, the withstand voltage value between the strands in a test layer is first divided into two groups of separated strands, the two groups of separated strands are adjacent, the two groups of separated strands are respectively connected together, and the positive and negative poles of the insulation resistance tester are respectively connected to the two groups of separated strands.

[0055] In Example 3, in step three, the maximum test voltage is set to 1000V, the voltage holding time is 45s, the test is started from 200V, and the voltage is increased after the test is correct to continue testing, and the voltage value increased by 200V each time.

[0056] In Example 3, after measurement, when the voltage was increased to 1000V, the leakage current test value was 1.49nA, the insulation resistance was 671GΩ, and there was no error in the insulation resistance data, indicating that the withstand voltage value between the strands in the edge layer of the tested superconducting cable can meet the requirement of 1000V, and the withstand voltage test is qualified.

[0057] Embodiment 4: In Example 4, in step 2, the withstand voltage value of the interlayer strands is tested by first connecting each layer of two adjacent layers of strands together, and connecting the positive and negative poles of the insulation resistance tester to the two adjacent layers of strands respectively.

[0058] The remaining steps of Example 4 are the same as those of Example 3.

[0059] In Example 4, after measurement, when the voltage was increased to 1000V, the leakage current test value was 1.02nA, the insulation resistance was 980GΩ, and no error was reported in the insulation resistance data, indicating that the withstand voltage value of the interlayer strands of the tested superconducting cable can meet the requirement of 1000V and the withstand voltage test is qualified.

[0060] The embodiment of the present application uses an insulation resistance tester to perform a withstand voltage test and utilizes the leakage current protection mechanism of the insulation resistance tester to achieve non-destructive testing of the withstand voltage between the internal strands of the superconducting cable, thereby providing reliable technical guarantees for the quality control, maintenance and long-term operation of the superconducting cable.

[0061] By recording the position of each strand before dispersing the superconducting cable, confusion of positions when numbering the strands is avoided, thereby avoiding invalid data from erroneously testing non-adjacent strands or layers.

[0062] By dispersing the non-test ends of the superconducting cable and insulating the end faces of the non-test ends, it is prevented that during the test, the conductors of the non-test ends will not be connected due to arcing due to the close distance, which will render the test data invalid.

[0063] By connecting the positive and negative poles of the insulation resistance tester to two groups of separated strands respectively, the withstand voltage test between the strands in a layer is achieved.

[0064] By connecting the positive and negative poles of the insulation resistance tester to two adjacent layers of strands respectively, the withstand voltage test of the interlayer strands is achieved.

[0065] By gradually increasing the voltage to the maximum test voltage and setting the voltage value for each increase, it is possible to prevent the insulation layer from being directly punctured due to excessive voltage.

[0066] The stability of the insulation layer of the superconducting cable strands was tested by setting the pressure holding time.

[0067] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A non-destructive testing method for the withstand voltage of a superconducting cable, characterized in that: The following steps are involved: Step 1, separating the test end and the non-test end of the superconducting cable, and numbering each strand of the superconducting cable; Step 2, connecting the positive and negative poles of the insulation resistance tester to the test end; Step 3, setting the maximum test voltage and the voltage holding time, gradually increasing the voltage to the maximum test voltage, and obtaining the withstand voltage test result according to the insulation resistance data of the insulation resistance tester; The superconducting cable has at least two layers of strands; In step three, obtaining the withstand voltage test result according to the insulation resistance data of the insulation resistance tester includes: Observe the changes in the insulation resistance data. If there is no error in the insulation resistance data, the withstand voltage test is qualified. If there is an error in the insulation resistance data, the withstand voltage test is unqualified.

2. A non-destructive testing method for superconducting cable withstand voltage according to claim 1, characterized in that: In step 1, before dispersing the superconducting cable, the position of each strand is recorded.

3. A non-destructive testing method for superconducting cable withstand voltage according to claim 1, characterized in that: In step 1, after the superconducting cable is dispersed, the insulating varnish on each strand of the test end is removed, and the end face of the non-test end is insulated and wrapped.

4. A non-destructive testing method for superconducting cable withstand voltage according to claim 1, characterized in that: In step 2, when it is necessary to test the withstand voltage value between the strands in a layer, the positive and negative poles of the insulation resistance tester are respectively connected to the separated strands in the layer; When the withstand voltage value of the interlayer strands needs to be tested, the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

5. A non-destructive testing method for superconducting cable withstand voltage according to claim 4, characterized in that: The step of connecting the positive and negative electrodes of the insulation resistance tester to the separated strands in the layer comprises: The strands in the layer are divided into two groups of spaced strands, the two groups of spaced strands are adjacent to each other, the two groups of spaced strands are connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two groups of spaced strands respectively.

6. A non-destructive testing method for superconducting cable withstand voltage according to claim 4, characterized in that: The step of connecting the positive and negative electrodes of the insulation resistance tester to two adjacent layers of strands comprises: Each layer of strands of two adjacent layers of strands is connected together respectively, and the positive and negative poles of the insulation resistance tester are connected to the two adjacent layers of strands respectively.

7. A non-destructive testing method for superconducting cable withstand voltage according to claim 1, characterized in that: In step three, when the voltage is gradually increased to the maximum test voltage, the voltage value increased each time is 100-500V.

8. A non-destructive testing method for superconducting cable withstand voltage according to claim 1, characterized in that: In step three, the holding time is 30-60s.

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