Relationship between DC resistance and cross-section of compressed copper conductor
In practical applications, the design of compressed copper conductors needs to consider many factors, including compression coefficient, stranding structure, material resistivity, etc.
For example, for a 95 mm² compressed copper conductor, its kilometer resistance should not exceed 0.193Ω/km, which needs to be achieved through a reasonable stranding structure and single wire diameter.
The compression process will increase the resistivity of the conductor, so it is necessary to introduce corresponding correction factors during design, such as compression coefficient K3 and stranding coefficient K2, to ensure that the final resistance value meets the standard requirements.
The relationship between the cross-sectional area and DC resistance of compressed copper conductors can be summarized by the following points:
1. Inverse relationship: The cross-sectional area A is inversely proportional to the DC resistance R, that is, the larger the cross-sectional area, the smaller the DC resistance.
2. Compression effect: The compression process will cause the conductor to harden, thereby increasing the resistivity, which needs to be adjusted through the correction factor.
3. Design requirements: According to national standards (such as GB/T3956), the DC resistance value of the conductor is the key indicator to measure its qualification, and the cross-sectional area is only the basis for design and calculation.
4. Adjustment in practical application: In the production process, in order to reduce costs, the cross-sectional area may be reduced to the minimum value to meet the DC resistance requirements, but this practice may affect the overall performance of the cable.
Therefore, when designing and manufacturing compressed copper conductors, it is necessary to comprehensively consider factors such as cross-sectional area, compression coefficient, and material resistivity to ensure that the DC resistance of the conductor meets the standard requirements and meets the performance requirements in practical applications.
The specific calculation method of the compression coefficient K3 and twisting coefficient K2 of the compressed copper conductor is as follows:
Compression coefficient K3：
Compression coefficient K3 refers to the ratio of the actual cross-sectional area of the conductor after compression to the theoretical cross-sectional area when not compressed. According to the evidence, the value of the compression coefficient is usually 0.90, which is empirical data based on production experience and process tests.
Twisting coefficient K2 ：
The twisting coefficient K2 refers to the ratio of the actual length of a single wire to the length of the twisted wire pitch within a twist pitch.
Other related parameters
1. Single wire diameter: For stranded conductors with a single wire diameter greater than 0.6 mm, K2 is 1.02; for stranded conductors with a single wire diameter not greater than 0.6 mm, K2 is 1.04.
2. Cabling coefficient: For single-core and non-cabled multi-core cables, it is 1, and for cabled multi-core cables, it is 1.02.
In summary, the specific calculation method of the compaction coefficient K3 and twisting coefficient K2 of compacted copper conductors is as follows: Compressive coefficient K3: Usually the value is 0.90.