40 kilowatts of three-phase air conditioning need to use 25 square millimeters of copper wire cable.
40 kW power current calculation: three-phase: P = 1.732UIcosφ, P: power; U: voltage; I: current; cosφ: power factor, resistive loads to take 1, inductive (such as motor) loads to take 0.85. Calculation: the root 3 = 1.732, I = P / (1.732 × U × cos φ) = 40 / (1.732 × 380V × 0.85)=72A.
According to the wire current cross-reference table, 40KW loads should at least choose 25-square-millimeter copper-core wires. 25-square-millimeter copper-core wires are safe for open-wire laying with an intermittent flow rate of about 126A.
The 40KW air conditioner uses a single-phase power supply with an operating current of less than 80A, and considering that the air conditioner start-up current is larger than the normal operating current, it is necessary to use 25-square-millimeter copper wire cables. square millimeter copper wire cable. Of course, you can use three-phase power supply, so that the wire can choose a little thinner (each phase of the line connected to six air conditioners, the wire only need to use 16 square millimeters of copper wire can be).
Expanded
Look at the three-phase air conditioning need to use how much cable, first of all, you need to look at what type of equipment belongs to and then look at the power supply voltage and other selection elements. If the motor type load 380V voltage rated current about 80A or so, it is recommended to select at least the frame rated current 160A.
40KW of electrical equipment, whether it is heating equipment or inductive equipment, its operating current should be 80A or less. This can be done through the conductor's current-carrying capacity and electrician selection of wire mnemonics can be carried out to choose; or through experience can also be selected. Cable line can be viewed as three wires through the pipe laid wire.
The electrician's mnemonic is: 2.5 times nine, up minus one to go. Thirty-five times three point five, double double group minus point five. Conditions have changed plus discount, high temperature nine fold copper upgrade. The number of tubes worn is two, three, four, eight, seven, six percent off the full load flow.
The electrician's mnemonic inside the choice of 35 square meters of aluminum cable or 25 square meters of copper cable.