The position of wires in the industrial control process is very important, and the use of frequency converters, industrial computers, sensors, and other equipment is indispensable for cable lines. The flow rate refers to the amount of current passed by a cable line when transmitting electrical energy. Under thermal stability conditions, the cable current carrying capacity when the cable conductor reaches the long-term allowable working temperature is called the long-term allowable current carrying capacity of the cable.

In practical projects, different cable types can be selected according to the long-term allowable current carrying capacity of the cables under different environments and conditions, and the required number of cables and laying forms can be determined. Therefore, it is of great significance to calculate the long-term allowable current carrying capacity of the cable.

Let's first talk about the internal factors that will affect the current carrying capacity of the wire in use:

1. Core area

That is to say, the "wire diameter" we often say, is not the cross-sectional area of the whole wire that determines the current carrying capacity, but the cross-sectional area of the conductor inside the wire. The thicker the wire, the greater the current-carrying capacity. The thickness of the conductor is approximately proportional to the magnitude of the current. It is the diameter that is proportional to the current, not the cross-sectional area. For cables of the same material, the thicker the cable, the stronger its current-carrying capacity. Therefore, the thicker the cable, the better its current-carrying properties. Under the same current, the heat dissipation performance is better. Choose thin cables, if the current is too large, there will be dangers of overheating, melting, burning, etc.

2. Material conductivity

It depends on the conductor material, such as ordinary copper wire and aluminum wire, the conductivity of copper material is at least 30% higher than that of aluminum. In addition to the substance of the raw material, it also depends on the purity of the raw material. Taking copper as an example, the conductivity of high-purity copper is much higher than that of secondary copper.

3. Thermal conductivity of the insulating layer

In addition to preventing electric shock, the role of the insulating layer also has the same important role as the Anti-electric shock flame retardant. The better the thermal conductivity of the thermal insulation material, the better the flame retardancy. Therefore, the quality of the insulating material determines the current carrying capacity of the wire from another aspect.

External factors that affect wire current carrying capacity:

In addition to some external factors that will reduce the current carrying capacity of the cable under certain circumstances, there are also internal factors that can determine the current carrying capacity of the wire, which are mainly determined by the following three points:

1. length

The longer the cable, the lower the load-carrying capacity. The difference between the carrying capacity of one kilometer and the carrying capacity of 10,000 meters is not an order of magnitude.

2. temperature

The higher the temperature, the lower the current-carrying capacity of the wire. This is the most common problem and the main reason why cables used in buildings need to be thicker than plug-in cables. In many cases, the ambient temperature is uncontrollable, and the ventilation effect, sunlight, cable density, etc. will affect the ambient temperature, thereby affecting the current carrying capacity of the cable.

3. Cable density

If multiple cables are too close together, the charge will be concentrated somewhere in the conductors instead of being evenly distributed, which will greatly reduce the cable's current-carrying capacity. Reasonably arrange the cable spacing and increase the cable spacing.

Summarized by Easybom.