A method for determining the macroscopic electrical properties of a buffer layer based on carbon black conditions

Abstract

The present invention relates to a method for determining the macroscopic electrical properties of a buffer layer according to the carbon black condition, and the method comprises the following steps: S1: placing a semiconductive buffer tape in a 50°C dryer for drying; S2: cutting the semiconductive buffer tape after drying; S3: placing the cut semiconductive buffer tape in a container filled with water for stirring, stirring once every T time, and the stirring time is not less than a preset value; S4: detecting the conductivity of water soaked with the semiconductive buffer tape, and determining the macroscopic electrical properties of the buffer layer according to the detection result of the conductivity. The present invention can accurately detect the electrical properties of the buffer layer of an XLPE high-voltage cable, is simple and fast, has strong versatility, and belongs to the technical field of cable defect detection.

Description

Technical Field

[0001] The invention relates to the technical field of cable defect detection, and in particular to a method for determining the macroscopic electrical performance of a buffer layer according to carbon black conditions. Background Art

[0002] The buffer layer has semi-conductive properties, which enables good electrical contact between the insulating shielding layer and the metal sheath. Good electrical performance of the buffer layer is one of the necessary conditions to ensure reliable and safe operation of the cable.

[0003] In recent years, many cable failures have been found to be caused by buffer layer ablation. The main reason for ablation is the precipitation of white powder in the buffer layer. The white powder reduces the conductivity of the buffer layer, resulting in the loss of effective electrical connection between the aluminum sheath and the insulation shielding layer.

[0004] The existing method of measuring the volume resistivity of the buffer layer is used to measure the electrical performance of the cable buffer layer. The volume resistivity of the buffer layer is used to reflect the macroscopic electrical performance of the buffer layer, that is, a weight is applied to one end of the buffer layer, and the resistivity between the two ends of the buffer layer is measured with an instrument. The existing detection method mainly has the following problems:

[0005] 1. The buffer layer has a fluffy porous structure. Applying different weights will cause different degrees of deformation, resulting in certain errors.

[0006] 2. If the bottom area of ​​the weight is different from the area of ​​the sample, the pressure generated will be different, causing the buffer layer to deform to different degrees.

[0007] 3. The electrical connection between the buffer layer and the measuring instrument electrodes will seriously affect the resistivity measurement results. Summary of the invention

[0008] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a method for determining the macroscopic electrical properties of a buffer layer according to the carbon black conditions, which has high detection accuracy, is simple and fast, and has strong versatility.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions, the method comprising the following steps:

[0011] S1: Place the semi-conductive buffer tape in a 50°C dryer and dry it;

[0012] S2: cutting the dried semi-conductive buffer tape;

[0013] S3: putting the cut semi-conductive buffer tape into a container filled with water and stirring it, stirring it once every T time, and the stirring time is not less than a preset value;

[0014] S4: Detecting the conductivity of water soaked with the semi-conductive buffer tape, and determining the macroscopic electrical properties of the buffer layer according to the conductivity detection result.

[0015] As a preferred embodiment, in step S4, the macroscopic electrical properties of the semiconductive buffer tape are measured using a conductivity test method taking temperature compensation into account.

[0016] As a preferred embodiment, before using the conductivity test method taking temperature compensation into account to measure the macroscopic electrical properties of the semiconductive buffer tape, the method further includes the following steps: pretreating the water soaked with the semiconductive buffer tape.

[0017] As a preferred method, the method for pretreating the water soaked with the semi-conductive buffer tape is: filtering the water soaked with the semi-conductive buffer tape using a funnel and filter paper.

[0018] As a preferred embodiment, in step S4, the measurement needs to be repeated three times, and the average value of all test conductivity measurement values ​​is taken as the test value;

[0019] Using the formula k25 = kt / [1+α(t-25)],

[0020] The conductivity when the solution temperature is normalized to 25°C; kt is the conductivity of the solution when the temperature is at room temperature t°C; k25 is the conductivity of the solution when the temperature is 25°C; α is the solution temperature coefficient, which is taken as 0.02; the average value of the 25°C normalized values ​​of all test conductivities is taken as the final value to measure the electrical performance of the buffer layer.

[0021] Preferably, in step S1, the drying time is at least 1 hour.

[0022] As a preferred embodiment, in step S2, the dried semi-conductive buffer tape is cut into 9 square pieces of the same size, and the area of ​​the square piece is 80 mm*80 mm.

[0023] As a preferred embodiment, in step S3, the T time is 10 minutes, and the preset value is 3 minutes.

[0024] As a preference, in step S3, the stirring times are no less than 3 times.

[0025] As a preference, the volume of the container is 400-500 ml, and the water content in the container is 200 ml.

[0026] In general, the present invention has the following advantages:

[0027] 1. The method of the present invention converts the measured resistivity of the buffer layer (loose porous medium) into the measured conductivity of the treated buffer layer carbon black solution, thereby eliminating the error caused by the fluffy porous structure of the buffer layer in the original resistivity measurement process.

[0028] 2. The method of the present invention no longer requires the application of a heavy object, thereby avoiding the measurement result error caused by the different contact conditions between the buffer layer and the measuring device.

[0029] 3. The method of the present invention melts the carbon black in the buffer layer into water by uniform stirring, and normalizes the measurement environment by temperature compensation, which can better reflect the macroscopic electrical properties of the buffer layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flowchart of the steps of a method for determining the macroscopic electrical properties of a buffer layer based on carbon black conditions.

[0031] Figure 2 Schematic diagram of the buffer layer in the detection instrument at each detection step.

[0032] Among them, 1 is a pair of scissors, 2 is a beaker, and 3 is a quantitative funnel. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with specific implementation methods.

[0034] A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions, the method comprising the following steps:

[0035] S1: Dry the semi-conductive buffer tape in a 50°C dryer;

[0036] S2: cutting the dried semi-conductive buffer tape;

[0037] S3: putting the cut semi-conductive buffer tape into a container filled with water and stirring it, stirring it once every T time, and the stirring time is not less than a preset value;

[0038] S4: Detecting the conductivity of water soaked with the semi-conductive buffer tape, and determining the macroscopic electrical properties of the buffer layer according to the conductivity detection result.

[0039] In step S4, the macroscopic electrical performance of the semiconductive buffer tape is measured using a conductivity test method taking temperature compensation into account.

[0040] The conductivity of water soaked with the semi-conductive buffer tape can be tested using a conductivity meter that complies with the requirements of JJG 2059-2014 and GB / T17650.2-2021. The conductivity meter should have a range of 10-1μS / mm to 10-2μS / mm and should be equipped with suitable electrodes.

[0041] Before measuring the macroscopic electrical properties of the semi-conductive buffer tape using the conductivity test method considering temperature compensation, the following steps are also included: pre-treating the water soaked with the semi-conductive buffer tape.

[0042] The method for pre-treating the water soaked with the semi-conductive buffer belt is: using a funnel and filter paper to filter the water soaked with the semi-conductive buffer belt. Using a funnel and quantitative filter paper to filter the water soaked with the semi-conductive buffer belt; when the buffer belt is a structure of carbon black composite conductive fiber, the water soaked with the semi-conductive buffer belt should be filtered with a funnel and quantitative filter paper. If it is not filtered, the fibers and carbon black dispersed in the water will affect the conductivity measurement results.

[0043] In step S4, the measurement needs to be repeated three times, and the average value of all test conductivity measurement values ​​is taken as the test value;

[0044] Utilization formula k 25 =k t / [1+α(t-25)],

[0045] The conductivity of the solution is normalized to 25°C; where k t k is the conductivity of the solution at room temperature t℃; 25 is the conductivity of the solution at 25°C; α is the solution temperature coefficient, which is taken as 0.02; the average value of the 25°C normalized values ​​of all test conductivities is taken as the final value to measure the electrical performance of the buffer layer.

[0046] In step S1, the drying time is at least 1 hour.

[0047] In step S2, the dried semi-conductive buffer tape is cut into 9 square pieces of the same size, and the area of ​​the square piece is 80 mm*80 mm.

[0048] In step S3, the T time is 10 minutes, and the preset value is 3 minutes.

[0049] In step S3, the stirring times are no less than 3 times.

[0050] The volume of the container is 400-500 ml, and the water content in the container is 200 ml.

[0051] The temperature compensation method of this embodiment is to convert the conductivity measured in step S4.

[0052] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for determining the macroscopic electrical properties of a buffer layer according to the carbon black condition, by converting the measured resistivity of the buffer layer into the measured conductivity of the treated carbon black solution of the buffer layer, It is characterized in that The method comprises the following steps: S1: Dry the semi-conductive buffer tape in a 50°C dryer; S2: cutting the dried semi-conductive buffer tape; S3: putting the cut semi-conductive buffer tape into a container filled with water and stirring it, stirring it once every T time, and the stirring time is not less than a preset value; S4: Detecting the conductivity of water soaked with the semi-conductive buffer tape, and determining the macroscopic electrical properties of the buffer layer according to the conductivity detection result.

2. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 1, Features: In step S4, the macroscopic electrical performance of the semiconductive buffer tape is measured using a conductivity test method taking temperature compensation into account.

3. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 2, Features: Before measuring the macroscopic electrical properties of the semi-conductive buffer tape using the conductivity test method considering temperature compensation, the following steps are also included: pre-treating the water soaked with the semi-conductive buffer tape.

4. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 3, Features: The method for pretreating the water soaked with the semi-conductive buffer tape is: filtering the water soaked with the semi-conductive buffer tape using a funnel and filter paper.

5. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 2, Features: In step S4, the measurement needs to be repeated three times, and the average value of all test conductivity measurement values ​​is taken as the test value; Using the formula k25=kt / [1+α(t-25)], The conductivity when the solution temperature is normalized to 25°C; kt is the conductivity of the solution when the temperature is at room temperature t°C; k25 is the conductivity of the solution when the temperature is 25°C; α is the solution temperature coefficient, which is taken as 0.02; the average value of the 25°C normalized values ​​of all test conductivities is taken as the final value to measure the electrical performance of the buffer layer.

6. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 1, Features: In step S1, the drying time is at least 1 hour.

7. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 1, Features: In step S2, the dried semi-conductive buffer tape is cut into 9 square pieces of the same size, and the area of ​​the square piece is 80 mm*80 mm.

8. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 1, Features: In step S3, the T time is 10 minutes, and the preset value is 3 minutes.

9. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 8, Features: In step S3, the stirring times are no less than 3 times.

10. A method for determining the macroscopic electrical properties of a buffer layer according to carbon black conditions according to claim 1, Features: The volume of the container is 400-500 ml, and the water content in the container is 200 ml.

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