Method for measuring direct-current resistance of aluminum conductor of electric wire and cable

Abstract

The invention provides a method for measuring the direct-current resistance of an aluminum conductor of an electric wire and cable. The method comprises the steps of equipment erection, equipment connection, preheating calibration and measurement, repeated measurement and the like. The target to-be-tested sample is arranged on the double-arm bridge clamp according to the preset specification and is kept in the stretched and straightened state, a long-section sample does not need to be cut from a finished cable, and the problems that the cut length of the sample is large, operation is complex, and time and labor are consumed are effectively solved. By monitoring the stretching state of the target to-be-tested sample and testing the environmental parameters in real time, it is ensured that the sample is always in a stretched state and the environmental parameters are stable in the measurement process, measurement errors caused by fluctuation of the environmental parameters in the prior art are effectively avoided, and the accuracy and reliability of measurement results are improved. The measurement deviation caused by equipment system errors or environmental interference is further eliminated by circularly measuring for multiple times, switching the current direction and calculating the resistance value in combination with a formula. The method has the advantages of simplicity in operation, low implementation cost and convenience in popularization and implementation.

Description

Technical Field

[0001] This application belongs to the technical field of cable testing, and particularly relates to a method for measuring the DC resistance of aluminum conductors in wire and cable. Background Art

[0002] In the prior art, the method for measuring the DC resistance of aluminum conductors in wire and cable plays a crucial role in the quality inspection and performance evaluation of wire and cable. It can accurately reflect the electrical conductivity of the conductor and provide important data support for the design, production, and use of the cable. However, there are some deficiencies in the current measurement methods on the market.

[0003] In the prior art, according to the provisions of Article 4.4 in Part 4: Conductor DC Resistance Test of Test Methods for Electrical Properties of Wire and Cable GB / T 3048.4-2007, for the form test of large cross-section aluminum conductor specimens, the recommended specimen length is as follows: for a conductor cross-section of (95 - 185) mm 2 , take 3 m; for a conductor cross-section of 240 mm 2 and above, take 5 m. In case of disputes, for a conductor cross-section of 185 mm 2 and below, take 5 m; for a conductor cross-section of 240 mm 2 and above, take 10 m. This measurement method requires cutting finished cables of different lengths (3 - 10) m from the finished cable for measurement, which will increase the operation difficulty of measuring the conductor resistance due to the increased length and weight of the cable, consume more manpower, material resources, and time, and is not conducive to quickly measuring the conductor resistance value in a limited position and space.

[0004] In addition, the existing measurement methods also have certain limitations in terms of measurement accuracy, measurement efficiency, and applicable range. For example, the measurement accuracy is greatly affected by factors such as specimen length and environmental temperature, making it difficult to ensure the accuracy and reliability of the measurement results; the measurement process is cumbersome, requiring multiple measurements and calculations, which is time-consuming and laborious; for some wire and cable with special structures or new materials, the existing methods may not be applicable or may not be able to accurately measure their DC resistance. Summary of the Invention

[0005] This application aims to solve the technical problem that in the prior art, the cable resistance is usually measured according to the method specified in GB / T 3048.4-2007 to achieve quality inspection of the cable. In the actual operation process, it is necessary to cut finished cables of different lengths (3 - 10) m from the finished cable for measurement, which will increase the operation difficulty of measuring the conductor resistance due to the increased length and weight of the cable, consume more manpower, material resources, and time, and is not conducive to quickly and accurately measuring the conductor resistance value in a limited position and space, and proposes a method for measuring the DC resistance of aluminum conductors in wire and cable.

[0006] The present application adopts the following solution, a method for measuring the DC resistance of an aluminum conductor of a wire and cable, including the following steps:

[0007] Equipment setup: Place the target sample to be tested with a preset specification on the double-arm bridge fixture, and keep the target sample to be tested in a stretched and straightened state;

[0008] Equipment connection: Connect the resistance measuring instrument to the preset connection points on the double-arm bridge fixture, start the resistance measuring instrument, and adjust the test environment parameters of the target sample to be tested within the preset range;

[0009] Preheating, calibration and measurement: After preheating and zero-adjusting the resistance tester, select the corresponding gear of the resistance tester according to the size specification of the target sample to be tested to measure the resistance value of the target sample to be tested. During the measurement process, monitor the stretching state of the target sample to be tested and the test environment parameters, so that the target sample to be tested is in a straightened state during the measurement process, and the test environment parameters are kept within the preset range;

[0010] Repeated measurement: Repeat the preheating, calibration and measurement steps N times. Define the current direction in the target sample to be tested during the Nth test as A, and define the current direction in the target sample to be tested during the N-1th test as B. The A and the B are opposite to each other. Define the resistance value of the target sample to be tested obtained in each test as R N , the resistance value R of the target sample to be tested M is:

[0011]

[0012] In some possible embodiments, the cross-sectional area of the target sample to be tested is 95 mm 2 -300 mm 2 , the length of the target sample to be tested is 1.3 m - 1.5 m, and the potential measurement distance of the double-arm bridge fixture is 1 m.

[0013] In some possible embodiments, the test environment parameters include environmental temperature, air humidity and environmental temperature fluctuation;

[0014] The environmental temperature is 15°C - 25°C, the air humidity is 45% - 85%, and the environmental temperature fluctuation is ±1°C / min.

[0015] In some possible embodiments, in the equipment setup, it further includes pretreatment of the target sample to be tested;

[0016] The pretreatment of the target sample to be tested includes the following steps:

[0017] After stripping the insulation, sheath or other coverings on the surface of the cable to be tested, the test specimen to be tested is obtained;

[0018] Wipe the exposed conductor part of the test piece to be tested with a pretreatment solvent to remove the oxide layer on the exposed part of the test piece to be tested. After wiping, the test piece to be stabilized is obtained;

[0019] When the test environment parameters are within the preset range, transfer the test piece to be stabilized wrapped with an isolation film to the environment to be tested for stabilization treatment for 1 h - 2 h, and then the target test sample is obtained.

[0020] In the actual implementation process, by wrapping the isolation film on the conductor surface and performing stabilization treatment, the aluminum conductor can be protected to the greatest extent from being rapidly oxidized.

[0021] In the actual implementation process, by wiping the exposed conductor part of the test piece to be tested with a pretreatment solvent, the aluminum oxide on the surface of the aluminum conductor can be effectively removed within a short time, reducing the influence of this substance on the resistance value.

[0022] In some possible embodiments, the pretreatment solvent is selected from any one or a mixture of more than one of absolute ethanol, isobutanol, isoamyl alcohol, and methanol.

[0023] In some possible embodiments, in the equipment setup, tightening members are provided at both ends of the target test sample, and the tightening members are used to tighten and compact the ends of the target test sample.

[0024] In the actual implementation process, by providing tightening members at both ends of the target test sample, the defects that the target test sample is not tight enough or the target test sample is not clamped tightly enough in the bridge fixture can be made up for, and the conductor single wires at both ends of the target test sample can be prevented from spreading.

[0025] In some possible embodiments, the tightening member includes a tightening ring and an adjusting assembly provided on the tightening ring, and the adjusting assembly is used to adjust the cross-sectional radius of the tightening ring to tighten and compact the ends of the target test sample.

[0026] In some possible embodiments, in the equipment connection, a tension tester is further provided on the target test sample. When the target test sample is matched and arranged on the double-arm bridge fixture, the tension tester is used to measure the tension during the stretching process of the target test sample.

[0027] In some possible embodiments, it is defined that the resistance value of the target test sample obtained by measuring the target test sample by the method of GB / T 3048.4 - 2007 is R D , the R D and the R M satisfy the following relationship:

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] In the actual implementation process, the traditional method for testing the resistance of wire and cable usually refers to the provisions of Article 4.4 in Section 4: DC Resistance Test of Conductors in Test Methods for Electrical Properties of Wire and Cable - Part 4: Test of DC Resistance of Conductors, GB / T3048.4-2007. For the form test of large-section aluminum conductor specimens, the recommended specimen length is as follows: for a conductor cross-section of (95 - 185) mm 2 , take 3m; for a conductor cross-section of 240mm 2 and above, take 5m. In case of disputes, for a conductor cross-section of 185mm 2 and below, take 5m; for a conductor cross-section of 240mm 2 and above, take 10m. During the measurement process, it is necessary to cut finished cables with lengths ranging from 3m to 10m from the finished cables for measurement. This sampling method will increase the operation difficulty when measuring the conductor resistance due to the increased length and weight of the cables, and it requires more manpower, material resources and time, which is not conducive to quickly measuring the conductor resistance value at the limited position and space.

[0030] By improving the specifications of the target sample to be tested and the test conditions, the present application measures the resistance value per unit length of 1m, and only 1 tester is required to complete the test, which can avoid the negative impacts caused by the excessive length and high self-weight of the test sample itself. By reducing the measurement of long cables, the resistance measurement value of the aluminum conductor can be accurately obtained, saving the inspection cost of the enterprise, reducing losses and improving the detection efficiency.

[0031] The present application provides a method for measuring the DC resistance of aluminum conductors in wire and cable, which includes steps such as equipment setup, equipment connection, preheating calibration and measurement, and repeated measurement. By setting the target sample to be tested on the double-arm bridge fixture according to the preset specifications and keeping it in a stretched and straightened state, there is no need to cut long samples from the finished cable, effectively solving the problems of large sample cutting length, complex operation, time-consuming and laborious. By real-time monitoring the stretching state of the target sample to be tested and the test environment parameters, it is ensured that the sample is always in a straightened state and the environment parameters are stable during the measurement process, effectively avoiding the measurement errors caused by the fluctuation of environment parameters in the prior art and improving the accuracy and reliability of the measurement results. By measuring multiple times in a cycle and switching the current direction, and calculating the resistance value in combination with the formula, the measurement deviation caused by equipment system errors or environmental interference is further eliminated, significantly improving the measurement accuracy. It has the advantages of simple operation, low implementation cost, effectively shortening the cable quality inspection time, and being convenient for popularization and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of the target sample to be tested in the present application;

[0033] Figure 2It is a reference diagram in the cable resistance test process of this application;

[0034] Figure 3 It is a reference diagram in the cable resistance test process of this application;

[0035] Figure 4 It is a trend diagram of the measured resistance values of Example 1 and Comparative Example 1 of this application;

[0036] Figure 5 It is a trend diagram of the relative deviation between the measured resistance values of Example 1 and Comparative Example 1 of this application;

[0037] Figure 6 It is a trend diagram of the measured resistance values of Example 2 and Comparative Example 2 of this application;

[0038] Figure 7 It is a trend diagram of the relative deviation between the measured resistance values of Example 2 and Comparative Example 2 of this application;

[0039] Figure 8 It is a trend diagram of the measured resistance values of Example 3 and Comparative Example 3 of this application;

[0040] Figure 9 It is a trend diagram of the relative deviation between the measured resistance values of Example 3 and Comparative Example 3 of this application. Detailed implementation manners

[0041] Combined with Figures 1-9 The technical solution proposed in this application will be further described with reference to the content shown.

[0042] The cable is measured for resistance with reference to the following method:

[0043] (i) A method for measuring the DC resistance of an aluminum conductor of a wire and cable, comprising the following steps:

[0044] Step 101. After stripping the insulation, sheath or other covering on the surface of the cable to be measured, the test specimen to be tested is obtained;

[0045] The exposed conductor part of the test specimen to be tested is wiped with a pretreatment solvent to remove the oxide layer on the exposed part of the test specimen to be tested. After wiping, the test specimen to be stabilized is obtained;

[0046] After the cable is processed according to the preset specifications, when the test environment parameters are within the preset range, the test specimen to be stabilized covered with an isolation film is transferred to the environment to be tested for stabilization treatment for 1h - 2h, and then the target test sample is obtained.

[0047] Among them, the pretreatment solvent is anhydrous ethanol;

[0048] Among them, the preset specification is that the cross-sectional area of the test sample is 95mm2 -300 mm 2 , the length of the target sample to be measured is 1.3 m - 1.5 m;

[0049] Step 102. Place the target sample to be measured with a preset specification on a double-arm bridge fixture and keep the target sample in a stretched and straightened state;

[0050] Among them, the potential measurement distance of the double-arm bridge fixture is 1 m;

[0051] Among them, tightening members 1 are provided at both ends of the target sample to be measured, and the tightening members 1 are used to tighten and compact the ends of the target sample to be measured;

[0052] Among them, the tightening member 1 includes a tightening ring 10 and an adjusting assembly 11 provided on the tightening ring 10. The adjusting assembly 11 is used to adjust the cross-sectional radius of the tightening ring 10 to tighten and compact the ends of the target sample to be measured;

[0053] Among them, a tension tester is further provided on the target sample to be measured. When the target sample to be measured is properly placed on the double-arm bridge fixture, the tension tester is used to measure the tension during the stretching process of the target sample to be measured;

[0054] The tension tester is common knowledge in the art. For details, see website A below and will not be elaborated here;

[0055] Website A:

[0056] https: / / www.gkzhan.com / st234302 / product_10585535.html;

[0057] Among them, the tension tester is also signal-connected to a buzzer. When the tension value measured by the tension tester does not fall within the target preset range, the buzzer emits a beep;

[0058] Step 103. Connect a resistance measuring instrument to the preset connection points on the double-arm bridge fixture, start the resistance measuring instrument, and adjust the test environment parameters of the target sample to be measured within the preset range;

[0059] Among them, the test environment parameters include environmental temperature, air humidity, and environmental temperature fluctuation;

[0060] The environmental temperature is 15°C - 25°C, the air humidity is 45% - 85%, and the environmental temperature fluctuation is ±1°C / min.

[0061] Step 104. After preheating the resistance tester and zeroing it, select the corresponding range of the resistance tester according to the size specification of the target sample to be measured, so as to measure the resistance value of the target sample to be measured. During the measurement process, monitor the stretching state of the target sample to be measured and the test environment parameters, so that the target sample to be measured is in a straightened state during the measurement process, and the test environment parameters are maintained within a preset range;

[0062] Step 105. Repeat Step 104 for N times. Define that during the Nth test process, the current direction in the target sample to be measured is A, and define that during the (N - 1)th test process, the current direction in the target sample to be measured is B, where A is opposite to B. Define the resistance value of the target sample to be measured obtained from each test as R N The resistance value R of the target sample to be measured M is:

[0063] Example 1

[0064] Refer to the method for measuring the DC resistance of aluminum conductors of wire and cable described in (i) to measure the target samples to be measured with the following specifications;

[0065] The specifications of the target samples to be measured are as follows: the cross-section is 185 mm 2 , the total length is 1.3 m, the potential measurement distance of the double-arm bridge fixture is 1 m, the number of cycles of Step 104 is 10 times, the ambient temperature is 20.3 °C, the air humidity is 60%, and the ambient temperature fluctuation is ±1 °C / min.

[0066] Example 2

[0067] Refer to the method for measuring the DC resistance of aluminum conductors of wire and cable described in (i) to measure the target samples to be measured with the following specifications;

[0068] The specifications of the target samples to be measured are as follows: the cross-section is 240 mm 2 , the total length is 1.4 m, the potential measurement distance of the double-arm bridge fixture is 1 m, the number of cycles of Step 104 is 10 times, the ambient temperature is 20.7 °C, the air humidity is 62%, and the ambient temperature fluctuation is ±1 °C / min.

[0069] Example 3

[0070] Refer to the method for measuring the DC resistance of aluminum conductors of wire and cable described in (i) to measure the target samples to be measured with the following specifications;

[0071] The specifications of the target samples to be measured are as follows: the cross-section is 300 mm 2, with a total length of 1.5 m, a potential measurement distance of 1 m for the double-arm bridge fixture, 10 cycles in step 104, an ambient temperature of 20.6 °C, an air humidity of 66%, and an ambient temperature fluctuation of ±1 °C / min.

[0072] Comparative Example 1

[0073] The target sample to be measured was measured according to the provisions of GB / T 3048.4-2007. The difference between the target sample to be measured in Comparative Example 1 and that in Example 1 is that: in Comparative Example 1, the total length of the target sample to be measured was adjusted to 5.2 m, and the potential measurement distance of the double-arm bridge fixture was 5 m.

[0074] Comparative Example 2

[0075] The target sample to be measured was measured according to the provisions of GB / T 3048.4-2007. The difference between the target sample to be measured in Comparative Example 2 and that in Example 2 is that: in Comparative Example 2, the total length of the target sample to be measured was adjusted to 5.2 m, and the potential measurement distance of the double-arm bridge fixture was 5 m.

[0076] Comparative Example 3

[0077] The target sample to be measured was measured according to the provisions of GB / T 3048.4-2007. The difference between the target sample to be measured in Comparative Example 3 and that in Example 3 is that: in Comparative Example 2, the total length of the target sample to be measured was adjusted to 5.2 m, and the potential measurement distance of the double-arm bridge fixture was 5 m.

[0078] Record the data measured in each test of Examples 1-3 and Comparative Examples 1-3. Define the resistance value of the target sample to be measured measured with reference to (i) as R M , and define the resistance value of the target sample to be measured measured according to GB / T3048.4-2007 (i.e., the measurement method used in Comparative Examples 1-3) as R D , and measure R with reference to the following formula A M and R D of the relative deviation, and draw the corresponding trend chart based on the measured data. The test results are shown in Table 1 below and Figures 4-9 as shown;

[0079] Formula A:

[0080] Table 1 Data Measured in Examples 1-3 and Comparative Examples 1-3

[0081]

[0082]

[0083] Continued Table 1

[0084]

[0085] As shown in Table 1 above and Figures 4-9 As can be seen, the present application provides a method for measuring the DC resistance of an aluminum conductor of a wire and cable, which includes steps such as equipment erection, equipment connection, preheating calibration and measurement, and repeated measurement. By replacing the target test sample with a specification of 3m - 10m with a target sample to be measured with a test length of 1m, and controlling the test environmental conditions, the accuracy of cable resistance measurement is effectively improved, the difficulty of cable resistance measurement is reduced, the limitation caused by the length and weight of the cable itself is overcome, and the technical problem that the resistance measurement of cable samples usually requires the cooperation of two operators is solved, significantly improving the efficiency of cable resistance quality inspection.

[0086] The present application provides a method for measuring the DC resistance of an aluminum conductor of a wire and cable, which includes steps such as equipment erection, equipment connection, preheating calibration and measurement, and repeated measurement. By placing the target sample to be measured on the double-arm bridge fixture according to a preset specification and keeping it in a stretched and straight state, there is no need to cut a long sample from the finished cable, effectively solving the problems of large sample cutting length, complex operation, and time-consuming and laborious. By real-time monitoring the stretching state of the target sample to be measured and the test environmental parameters, it is ensured that the sample is always in a straight state and the environmental parameters are stable during the measurement process, effectively avoiding the measurement errors caused by environmental parameter fluctuations in the prior art, and improving the accuracy and reliability of the measurement results. By measuring multiple times in a cycle and switching the current direction, and calculating the resistance value in combination with a formula, the measurement deviation caused by equipment system errors or environmental interference is further eliminated, significantly improving the measurement accuracy. It has the advantages of simple operation, low implementation cost, effectively shortening the cable quality inspection time, and being convenient for popularization and implementation.

[0087] The above has introduced the embodiments provided by the present invention in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for measuring the DC resistance of an aluminum conductor of a wire and cable, characterized in that, The following steps are involved: Equipment setup: Place the target sample to be tested with preset specifications on the double-arm bridge fixture, and keep the target sample to be tested in a stretched and straight state; Equipment connection: Connect the resistance meter to the preset connection points on the double-arm bridge fixture, start the resistance meter, and adjust the test environment parameters of the target sample to within the preset range; Preheating, calibration, and measurement: After preheating and zeroing the resistance tester, select the gear of the resistance tester according to the size specifications of the target sample to measure the resistance value of the target sample. During the measurement, monitor the tensile state of the target sample and the test environment parameters to ensure that the target sample is in a straight state during the measurement process and the test environment parameters remain within the preset range; Repeated measurement: Repeat the preheating, calibration, and measurement steps N times. During the Nth test process, define the current direction in the target sample to be measured as A, and during the (N - 1)th test process, define the current direction in the target sample to be measured as B, where A is opposite to B. Define the resistance value of the target sample to be measured obtained from each test as R N , the resistance value R of the target sample to be measured M is as follows:

2. The measuring method for the DC resistance of an aluminum conductor of a wire and cable according to claim 1, characterized in that The cross-sectional area of the target sample to be measured is 95 mm 2 - 300 mm 2 , the length of the target sample to be measured is 1.3 m - 1.5 m, and the potential measurement distance of the double-arm bridge fixture is 1 m.

3. The measuring method for the DC resistance of an aluminum conductor of a wire and cable according to claim 1, characterized in that The test environment parameters include ambient temperature, air humidity and ambient temperature fluctuation; The ambient temperature is 15° C.-25° C., the air humidity is 45%-85%, and the ambient temperature fluctuation is ±1° C. / min.

4. A method for measuring the DC resistance of an aluminum conductor of a wire and cable according to claim 1, characterized in that, The equipment setup also includes pre-processing of target samples to be tested; The target sample pretreatment comprises the following steps: After stripping off the insulation, sheath or other covering on the surface of the cable to be tested, the test piece to be tested is obtained; Use a pretreatment solvent to wipe the exposed conductor part of the test piece to remove the oxide layer on the exposed part of the test piece. After the wiping is completed, the test piece to be stabilized is obtained; When the test environment parameters are within the preset range, the test piece to be stabilized, which is covered with the isolation film, is transferred to the test environment and stabilized for 1-2 hours to obtain the target test sample.

5. A method for measuring the DC resistance of an aluminum conductor of a wire and cable according to claim 4, characterized in that, The pretreatment solvent is selected from any one of anhydrous ethanol, isobutanol, isopentanol, methanol, or a mixture of more than one of them.

6. The measurement method of the DC resistance of the aluminum conductor of a wire and cable according to claim 1, wherein During the erection of the equipment, tightening members (1) are provided on both ends of the target sample to be tested, and the tightening members (1) are used to tighten and compact the ends of the target sample to be tested.

7. A method for measuring the DC resistance of an aluminum conductor of a wire and cable according to claim 6, characterized in that, The tightening member (1) comprises a tightening ring (10) and an adjusting assembly (11) provided on the tightening ring (10), wherein the adjusting assembly (11) is used to adjust the cross-sectional radius of the tightening ring (10) so as to tighten and compact the end of the target sample to be tested.

8. A method for measuring the DC resistance of an aluminum conductor of a wire and cable according to claim 1, characterized in that, During the equipment connection, a tension force tester is also provided on the target sample to be tested. When the target sample to be tested is matched and arranged on the double-arm bridge fixture, the tension force tester is used to measure the tension force of the target sample to be tested during the stretching process.

9. The measuring method for the DC resistance of an aluminum conductor of a wire and cable according to claim 1, characterized in that, Define the resistance value of the target sample to be measured as R after measuring the target sample to be measured by the method of GB / T 3048.4-2007 D , where the R D and the R M satisfy the following relationship:

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