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 25 square aluminum cable is 1.2 Ω/km. The ampacity of 25m2 single core aluminum cable is 76A2 core aluminum cable, 70A three core aluminum cable, 60A. Calculate the DC resistance of 400m cable r: r=1.2 Ω/kmx0.4km=0.48 Ω Calculate the voltage drop Vr: single core 76Ax0.48 Ω=36.5V two core 70Ax0.48 Ω=33.6V three core 60Ax0.48 Ω=28.8V Conclusion: Under the rated carrying capacity, the voltage drop of 400m long, 25 mm2 single core, two core and three core aluminum cable is 36.5V, 33.6V and 28.8V respectively.
 The ampacity of 25 mm2 aluminum cable is 85A in air and 93A in soil. It is a little smaller, 35 mm2 is recommended. 1. The length of 25mm ² 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, 25mm ² aluminum cable at 200m is 90 * 0.232=21V. 3. The allowable voltage drop is 5% * 380=19V. 4. 21V ＞ 19V, so the conductor is small, and the size of 35mm2 can be selected to be larger.