Method for testing inter-strand short circuit of film-covered wire

Abstract

The invention provides a film-covered wire inter-strand short circuit test method, which comprises the following steps that S1, a film-covered wire with the length of L is taken as a sample wire, insulating layers at the two ends of the sample wire are stripped, an inner stranded wire of the sample wire is split into multiple strands of independent wire harnesses, each strand of wire harness comprises n conductors, and all the conductors in each strand of wire harness are welded into independent joints; s2, different wire harness joints are selected at the two ends of the sample wire to form inter-strand combinations, and the direct-current resistance value of each inter-strand combination is measured; s3, when the resistance value of the inter-strand combination is close to the theoretical single-strand resistance, judging that the two joints are the same strand of wire harness and marking the same serial number; s4, measuring resistance values of inter-strand combinations with different numbers, and if a non-infinite resistance value exists, judging that a short circuit exists; according to the ratio K = R0 / R of the short-circuit resistance value R of the inter-strand combination to the resistance R0 of the single conductor, the number k of the short-circuit conductors is calculated, and k is set to be smaller than or equal to 3. By adopting the method, accurate positioning and quantitative analysis of the short circuit problem can be realized, and the method has the advantages of high efficiency, reliability and easiness in implementation.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical testing, and in particular relates to a method for testing short circuits between strands of a membrane-coated wire. Background Art

[0002] Insulation failure or accidental short circuits between conductors are common quality issues during the production and use of film-coated wire. This type of wire is composed of multiple enameled wire strands twisted together at a specific lay length. Due to various manufacturing processes, short circuits between strands can cause additional eddy currents, negating the original purpose of the film-coated wire to reduce high-frequency effects. However, traditional methods for detecting short circuits between strands have the following drawbacks:

[0003] (1) Visual inspection method: cannot detect hidden short circuits of internal conductors and is inefficient;

[0004] (2) Continuity test method: It can only determine the existence of a short circuit, but cannot quantify the number of short-circuited conductors;

[0005] (3) Insulation resistance test method: It is greatly affected by environmental humidity and test voltage, and cannot distinguish short-circuit paths. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for testing short circuits between strands of film-coated wire, which can accurately locate the short circuit position and quantitatively analyze the number of short-circuited conductors, solve the problem that the existing technology cannot quantify the number of short-circuited conductors, and set an allowable threshold for the number of short-circuited conductors (such as ≤3).

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A method for testing short circuits between strands of a film-coated wire comprises the following steps:

[0009] S1. Sample wire preparation: Take a film-wrapped wire of length L as the sample wire, strip the insulation layer at both ends of the sample wire, split the inner twisted wire into multiple independent wire bundles, each wire bundle contains n conductors, and weld all the conductors in each wire bundle into independent joints;

[0010] S2. Strand combination resistance test: Select different wire harness connectors at both ends of the sample line to form strand combinations, and measure the DC resistance value of each strand combination;

[0011] S3, number marking: When the resistance value of the strand combination is close to the theoretical single strand resistance, the two connectors are determined to be the same strand and marked with the same number;

[0012] S4, short circuit determination:

[0013] Measure the resistance values of different numbered strand combinations. If the measured resistance value is infinite, it is determined that there is no short circuit in the corresponding strand combination; if the measured resistance value is not infinite, it is determined that there is a short circuit in the corresponding strand combination;

[0014] According to the ratio of the short-circuit resistance value R of the strand combination to the resistance R0 of a single conductor, K=R0 / R, the number of short-circuit conductors k is calculated, and it is set that k≤3 is allowed.

[0015] As a preferred embodiment of the present invention, the determination threshold of the number of short-circuited conductors in step 4 is determined by the following method:

[0016] The resistance R0 of a single conductor is obtained by measurement or calculation using the theoretical formula R0 = ρ*L / A, where ρ is the resistivity of the conductor material, L is the length of the sample line, and A is the cross-sectional area of the conductor;

[0017] Set the short-circuit resistance threshold to R t =R0 / 3, R≥R t When , it is determined that the number of short-circuited conductors k is less than or equal to 3.

[0018] As a preferred embodiment of the present invention, the resistance measurement in step 2 is performed using a four-wire method or a micro-ohmmeter.

[0019] As a preferred solution of the present invention, the wire bundle splitting in step 1 needs to ensure that the twisting degree of each wire bundle is stable and there is no cross-twisting between the wire bundles.

[0020] The method for testing short circuits between strands of a film-coated wire provided by the present invention has the following beneficial effects compared with the prior art:

[0021] (1) Accurate quantification: Accurate counting of short-circuit conductors is achieved through the resistance-conductor number model;

[0022] (2) Efficient detection: Combining number marking and measurement, it can locate the short circuit position and improve detection efficiency;

[0023] (3) Wide applicability: can be extended to test cables of different materials, cross-sectional areas and twisted structures;

[0024] (4) Process optimization: Provide data support for wiring harness design and insulation material selection. DETAILED DESCRIPTION

[0025] The following provides a specific embodiment of the present invention. It should be understood that the present invention is not limited to the embodiment described below, and the technical concept of the present invention can be implemented in combination with other well-known technologies or other technologies with the same functions as those well-known technologies.

[0026] The method for testing short circuits between strands of a film-coated wire according to an embodiment of the present invention comprises the following steps:

[0027] S1. Sample wire preparation: Take a 10-meter-long film-wrapped wire as the sample wire, strip off the insulation layer at both ends of the sample wire, and split the inner twisted wire into 5 independent wire bundles. Each wire bundle contains 260 conductors with a diameter of 0.05mm. All conductors in each wire bundle are welded into independent joints to form testable electrical nodes.

[0028] It should be noted that the splitting of the wire harness needs to ensure that the twisting degree of each wire harness is stable and there is no cross-twisting between the wire harnesses; and in the actual splitting process, since each wire harness of the membrane-wrapped wire has a certain twisting degree, it will not spread out and is easy to identify, so the strands will not be mixed together.

[0029] S2. Strand combination resistance test: Select different wire harness connectors at both ends of the sample line to form strand combinations, and measure the DC resistance value of each strand combination;

[0030] It should be noted that resistance measurements are performed using a four-wire method or a micro-ohmmeter to eliminate the influence of contact resistance on the test results.

[0031] S3. Number marking: When the resistance value of the strand combination is close to the theoretical single strand resistance, the two connectors are determined to be the same strand and marked with the same number (such as A1-A1', B1-B1').

[0032] S4, short circuit determination:

[0033] Measure the resistance values of different numbered strand combinations. If the measured resistance value is infinite, it is determined that there is no short circuit in the corresponding strand combination; if the measured resistance value is not infinite, it is determined that there is a short circuit in the corresponding strand combination;

[0034] According to the ratio of the short-circuit resistance value R of the strand combination to the resistance R0 of a single conductor, K=R0 / R, the number of short-circuit conductors k is calculated, and it is set that k≤3 is allowed.

[0035] Furthermore, the determination threshold of the number of short-circuited conductors in step 4 is determined by the following method:

[0036] The resistance R0 of a single conductor is obtained by measurement or calculation using the theoretical formula R0 = ρ*L / A, where ρ is the resistivity of the conductor material, L is the length of the sample line, and A is the cross-sectional area of the conductor;

[0037] Set the short-circuit resistance threshold to R t =R0 / 3, when R≥R t When , it is determined that the number of short-circuited conductors k is less than or equal to 3.

[0038] Therefore, this embodiment converts the subjective "allowing a small number of short circuits" into an objective numerical standard by setting a threshold value of k≤3, thereby providing an operational basis for production quality inspection.

[0039] For example:

[0040] The resistance value R of test number A1-B1' is 57.28Ω, R0=100.88Ω;

[0041] k = R0 / R = 100.88 / 57.28≈1.76. It is determined that k is less than 3, which meets the threshold requirement.

[0042] If the resistance of a certain combination of strands is 19.258Ω, then k≈5.24, and it is determined that k is greater than 3 strands, which exceeds the threshold requirement and the product is unqualified.

[0043] In summary, the short-circuit testing method for film-coated wire strands in the present invention achieves precise location and quantitative analysis of short-circuit problems by splitting the wire harness, welding individual joints, measuring the combined resistance between strands, and combining a quantitative relationship model between resistance and the number of short-circuited conductors to set an allowable threshold (e.g., ≤3 short-circuited conductors). This method can be applied to quality testing of cables in fields such as power, communications, and automotive, offering the advantages of high efficiency, reliability, and ease of implementation.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for testing short circuit between strands of a film-coated wire, characterized in that: The following steps are involved: S1. Sample wire preparation: Take a film-wrapped wire of length L as the sample wire, strip the insulation layer at both ends of the sample wire, split the inner twisted wire into multiple independent wire bundles, each wire bundle contains n conductors, and weld all the conductors in each wire bundle into independent joints; S2. Strand combination resistance test: Select different wire harness connectors at both ends of the sample line to form strand combinations, and measure the DC resistance value of each strand combination; S3, number marking: When the resistance value of the strand combination is close to the theoretical single strand resistance, the two connectors are determined to be the same strand and marked with the same number; S4, short circuit determination: Measure the resistance values of different numbered strand combinations. If the measured resistance value is infinite, it is determined that there is no short circuit in the corresponding strand combination; if the measured resistance value is not infinite, it is determined that there is a short circuit in the corresponding strand combination; According to the ratio of the short-circuit resistance value R of the strand combination to the resistance R0 of a single conductor, K=R0 / R, the number of short-circuit conductors k is calculated, and it is set that k≤3 is allowed.

2. The method for testing short circuit between strands of a film-covered wire according to claim 1, wherein: The threshold for determining the number of short-circuited conductors in step 4 is determined as follows: The resistance R0 of a single conductor is obtained by measurement or calculation using the theoretical formula R0 = ρ*L / A, where ρ is the resistivity of the conductor material, L is the length of the sample line, and A is the cross-sectional area of the conductor; Set the short-circuit resistance threshold to R t =R0 / 3, when R≥R t When , it is determined that the number of short-circuited conductors k is less than or equal to 3.

3. The method for testing short circuit between strands of a film-covered wire according to claim 1, wherein: The resistance measurement in step 2 is performed using the four-wire method or a micro-ohmmeter.

4. The method for testing short circuit between strands of a film-covered wire according to claim 1, wherein: When splitting the wire harness in step 1, ensure that the twisting degree of each wire harness is stable and there is no cross-twisting between the wire harnesses.