Talking about the relationship between the cross-sectional area of ​​cable conductor and current

The safe current carrying capacity of the 2.5 square millimeter copper power cord --28A.

The safe current carrying capacity of the 4 square millimeter copper power cord - 35A.

The safe current carrying capacity of the 6 square millimeter copper power cord - 48A.

The safe current carrying capacity of the 10 square millimeter copper power cord - 65A.

The safe current carrying capacity of the 16 square millimeter copper power cord - 91A.

The safe current carrying capacity of the 25 square millimeter copper power cord - 120A.

Aluminum core wire, the wire diameter should be 1.5-2 times of the copper wire.

The copper current is less than 28A, and it is safe to take 10A per square millimeter.

If the copper current is greater than 120A, it will be 5A per square millimeter.

The impedance of a wire is proportional to its length and inversely proportional to its wire diameter. When using the power supply, pay attention to the wire and wire diameter of the input and output wires. In order to prevent the current from being too large, the wire is overheated and an accident is caused.

The conductor diameter is generally calculated as follows:

Copper wire: S= IL / 54.4*U`

Aluminum wire: S= IL / 34*U`

In the above formula: I——Maximum current passing through the wire (A)

L——the length of the wire (M)

U`——Full power supply drop (V)

S——cross-sectional area of ​​the wire (MM2)

First, the safe current carrying capacity of the copper wire current-carrying wire is generally determined according to the maximum temperature of the core, cooling conditions and laying conditions. The normal current carrying capacity of copper wire is 5~8A/mm2, and the safe current carrying capacity of aluminum wire is 3~5A/mm2. For example, the recommended value of 2.5 mm2 BVV copper wire safe current carrying capacity is 2.5×8A/mm2=20A 4 mm2. The recommended value of BVV copper wire safe current carrying capacity is 4×8A/mm2=32A.

2. Calculate the cross-sectional area of ​​the copper wire. Use the recommended value of the safe current carrying capacity of the copper wire to 5~8A/mm2, and calculate the upper and lower ranges of the cross-sectional area S of the selected copper wire: S=< I /(5~8)>=0.125 I ~ 0.2 I(mm2) S-----Cu wire cross-sectional area (mm2) I-----load current (A)

Third, the power calculation general load is divided into two types, one type of resistive load, one is an inductive load. For the calculation of the resistive load: P = UI For the calculation of the fluorescent lamp load: P = UIcosф, where the power factor of the fluorescent lamp load is cosф = 0.5. Different inductive loads have different power factors. When calculating household appliances, the power factor cosφ can be taken as 0.8. For example, if a household has a total power of 6000 watts, the maximum current is I=P/Ucosф=6000/220*0.8=34(A). However, in general, home appliances cannot be used at the same time. So add a common coefficient, the common coefficient is generally 0.5. Therefore, the above calculation should be rewritten as I = P * number / Ucosф = 6000 * 0.5 / 220 * 0.8 = 17 (A) That is, the total current value of this family is 17A. The total brake air switch cannot use 16A, it should be greater than 17A.

Estimated vocabulary:

Multiply by 9.5 and multiply by nine.

Thirty-five by three-five, and the two groups are reduced by five.

The conditions have been changed and converted, and the high temperature ninefold copper upgrade.

The number of tubes to be worn is two to three, and eighty-seven percent is full of current.

Estimated vocabulary description:

(1) The current carrying capacity (safety current) of various insulated wires (rubber and plastic insulated wire) is not directly indicated, but is expressed by "multiplied by a certain number of cross sections", which is obtained by mental arithmetic. The multiple is reduced as the cross section increases?

"Two to five times multiplied by nine, go up one minus one" is a variety of aluminum core insulated wire of 2.5 square inches and below, the current carrying capacity is about 9 times the number of sections. For example, a 2.5 wire has a current carrying capacity of 2.5 x 9 = 22.5 (A). The multiple of the current carrying capacity and the number of cross-sections of the wires from 4 squares and above is lined up along the line number, and the multiples are successively decremented by 1, that is, 4×8, 6×7, 10×6, 16×5, 25×4.

"Thirty-five times three-five-five, double-group reduction five points", is 35 times the wire current carrying capacity is 3.5 times the number of sections, that is, 35 × 3.5 = 122.5 (A). For wires from 50 and above, the multiple relationship between the current carrying capacity and the number of sections becomes a set of two two line numbers, and the multiples are successively reduced by 0.5. That is, the current carrying capacity of the 50 and 70 wires is three times the number of sections; the current carrying capacity of the 95 and 120 square wires is 2.5 times the number of the cross-sectional areas, and so on.

"The conditions have been changed and converted, and the high temperature ninefold copper upgrade." The above-mentioned port is determined by the aluminum core insulated wire and the bright coating at an ambient temperature of 25 ° C. If the aluminum core insulated wire is applied in an area where the ambient temperature is higher than 25 °C for a long time, the current carrying capacity of the wire can be calculated according to the above-mentioned calculation method of the mouth and then 10% off; when the copper wire is insulated, the copper core is used. Its current carrying capacity is slightly larger than that of the same specification aluminum wire. The above-mentioned port method can be used to calculate the current carrying capacity of one wire number than the aluminum wire. For example, the current carrying capacity of 16 square copper wire can be calculated by 25mm2 aluminum wire.