Three core 60A x 0.48 Ω=28.8V
Conclusion: Under the rated current carrying capacity, the voltage drop of 400m long, 25mm2 single core, two core and three core aluminum cable is 36.5V, 33.6V and 28.8V respectively.
According to the table, the conductor DC resistance (maximum) of the 25 square meter aluminum cable is 1.2 Ω/km. The ampacity of the 25 square meter single core aluminum cable is 76A2 core aluminum cable, 70A, and the ampacity of the three core aluminum cable is 60A. The calculated DC resistance of the 400 meter cable r: r=1.2 Ω/km x 0.4km=0.48 Ω, the calculated voltage drop Vr: single core 76A x 0.48 Ω=36.5V, two core 70A x 0.48 Ω=33.6V, three core 60A x 0.48 Ω=28.8V Conclusion: Under the rated current carrying capacity, the voltage drop of 400m long, 25mm2 single core, two core and three core aluminum cable is 36.5V, 33.6V and 28.8V respectively.
The carrying capacity of 25mm ² aluminum cable is 85A in the air and 93A in the soil. It is smaller, and it is recommended to be 35mm2. 1. The 25mm ² length is 200m, the resistance value is R=200 * 2.9 * 10 ^ (- 2)/25=0.232 Ω, the current of 45kw three-phase asynchronous motor is 90A, and the voltage drop of 2.5m ² aluminum cable is 90 * 0.232=21V. 3. The allowable voltage drop is 5% * 380=19V. 4. 21V is larger than 19V, so the conductor is smaller, and the size of 35mm2 can be selected.
