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『Calculation of current carrying capacity of wires』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
1. Calculation standard for current carrying capacity of wires
The calculation of current carrying capacity of wires needs to comprehensively consider factors such as wire cross-sectional area, material, laying method, environmental temperature, and heat dissipation conditions. The following are specific calculation standards and methods:
1. Basic formula and parameters Basic formula: Current carrying capacity=wire cross-sectional area multiplied by conductor current density.
. The current carrying capacity range of copper core wires is usually 5~8A/mm2, while that of aluminum core wires is 3~5A/mm2. General formula: I=K × S × Δ θ, where K is the conductivity coefficient (related to material and laying method); S is the cross-sectional area (mm2); Δ θ is the allowable temperature rise (the difference between the conductor temperature and the ambient temperature).2. Common calculation methods for small section wires (≤ 10mm2) mnemonic method: 2.5mm2 aluminum core wire: current carrying capacity ≈ 2.5 × 9=22.5A; 4mm2 aluminum core wire: current carrying capacity ≈ 4 × 8=32A ("Add one up and subtract one in order" refers to the coefficient decreasing by one for each increase in cross-sectional area).
. Correction of copper core wire: The current carrying capacity of copper core is about 1.3 times that of aluminum core, for example, the current carrying capacity of 2.5mm2 copper core wire is ≈ 22.5 × 1.3 ≈ 29 A. Formula for large section wires (>10mm2): 35mm2 aluminum core wire: current carrying capacity ≈ 35 × 3.5=122.5A. After correction according to "double grouping minus point five", it is reduced to 42 A (specific standards need to be combined in practice). Formula method: Directly use I=K
III. International and Domestic Standards: Chinese National Standard (GB/T 5023-2007) 1mm2 copper core wire: long-term current carrying capacity 8-15A; 2.5mm2 copper core wire: current carrying capacity 22A; 10mm2 copper core wire: current carrying capacity 60-70A (universal value for household and industrial use).
. The International Electrotechnical Commission (IEC 60287) provides detailed methods for calculating cable current carrying capacity, including loss calculation, thermal resistance analysis, etc., which are suitable for complex environments such as overhead conductors and cable tunnels.Fourth, key influencing factors: laying method, pipe laying method, family: reduced heat dissipation, reduced current carrying capacity by about 20%~30%;
; Aerial laying: Good heat dissipation, current carrying capacity can be increased by 10% to 15%. Conductor material copper core wire: better conductivity than aluminum core, with a current carrying capacity about 30% higher, but at a higher price; Aluminum core wire: lightweight and low-cost, but requires a larger cross-sectional area to achieve the same current carrying capacity. For every 10 ℃ increase in ambient temperature, the current carrying capacity decreases by about 5% to 8% (which needs