Wires are usually called “cables”. They are carriers for transmitting electrical energy and are the basic conditions for forming loops between electrical equipment. The important components of wire transmission are usually made of copper or aluminum materials.
The cost of wires used in different applications is different. For example, precious metal materials are rarely used as wires. Wires can also be divided according to application conditions. For example, if the current is large, we will use high-current wires.
Therefore, wires are very flexible in actual applications. So, when we choose to buy, what kind of inevitable relationship exists between the wire diameter and the current.
Relationship between wire diameter and current
In our daily life, common wires are very thin. The reason is that the current they carry when working is very small. In the power system, the output current of the low-voltage side of the transformer is usually the sum of the current used by the user, ranging from a few hundred amperes to thousands of amperes.
Then we choose a large wire diameter to meet sufficient overcurrent capacity. Obviously, the diameter of the wire is proportional to the current, that is, the larger the current, the thicker the cross-sectional area of the wire.
The relationship between the cross-sectional area of the wire and the current is very obvious. The current carrying capacity of the wire is also related to the temperature. The higher the temperature, the greater the resistivity of the wire, the greater the resistance, and the greater the power consumption.
Therefore, in terms of selection, we try to choose a wire slightly larger than the rated current, which can effectively avoid the above situation.
The cross-sectional area of the wire is generally calculated according to the following formula:
Copper wire: S = (IL) / (54.4 △U)
Aluminum wire: S = (IL) / (34 △U)
Where: I — Maximum current passing through the wire (A)
L — Length of the wire (M)
△U — Allowable voltage drop (V)
S — Cross-sectional area of the wire (MM2)
The current that can normally pass through the cross-sectional area of the wire can be selected according to the total amount of current it needs to conduct, which can generally be determined according to the following jingle:
Rhyme for wire cross-sectional area and current
Ten is five, one hundred is two, two five three five four three boundaries, seventy nine five two and a half times, copper wire upgrade calculation
For aluminum wires below 10 mm2, multiply the square millimeters by 5 to know the current ampere of the safe load. For wires above 100 square millimeters, multiply the cross-sectional area by 2; for wires below 25 square millimeters, multiply by 4; for wires above 35 square millimeters, multiply by 3; for wires between 70 and 95 square millimeters, multiply by 2.5. For copper wires, go up a level, for example, 2.5 square millimeters of copper wire is calculated as 4 square millimeters. (Note: The above can only be used as an estimate and is not very accurate.)
In addition, if it is indoors, remember that for copper wires with a core cross-sectional area of less than 6 mm2, it is safe if the current per square millimeter does not exceed 10A.
Within 10 meters, the current density of the wire is 6A/mm2, 10-50 meters, 3A/mm2, 50-200 meters, 2A/mm2, and less than 1A/mm2 for wires above 500 meters. The impedance of the wire is proportional to its length and inversely proportional to its wire diameter. Please pay special attention to the wire material and wire diameter when using the power supply. To prevent excessive current from overheating the wires and causing an accident.
Post time: Jul-01-2024
