In China, the land is vast, and different temperature zones are distributed from the south to the north, and there is often a relatively large temperature difference between the north and the south.
Therefore, when selecting materials for integrated wiring, we should pay attention to the minimum and maximum temperatures of wiring places.
Choose the cable that can be used in the corresponding maximum and minimum temperatures to avoid reworking and damage to the cable.
The ZMS cable team has checked the information that the temperature in January in China can reach below -20℃.
In July, the temperature can reach about 50°C. So, let's take -20℃ and 60℃ as the test environment temperature.
So how should the cable be laid and preserved in this extremely high and low-temperature environment?
Let's analyze it from all aspects below.
Whenever the temperature is too low in the season, most of the installation of construction personnel in the installation of cable will have found that the usual good quality wire and cable products, there are often some wire body hardening, insulation sheath off damage, and other phenomena.
Many builders think that the wire and cable products themselves have quality problems, and cable manufacturers also insist that the product has been inspected at the factory, and is a qualified product, often leading to misunderstandings between the two sides.
This situation, not necessarily due to the quality of the product is not qualified, but due to the winter temperature being too low.
The insulation or outer protective layer of wire and cable is made of ordinary plastic or rubber-like material.
When the product is in a low-temperature environment, it will become stiff and hard, and brittle, resulting in the outer skin will be damaged by the slightest external force.
In the cold winter, especially in the north, the outdoor temperature is more than a dozen degrees below zero, and the surface temperature may be even lower.
Therefore, if the wire and cable products are placed outdoors or directly on the ground, it is likely that the product sheathing phenomenon.
And the temperature level not only affects the outer sheath but also affects the cable resistance.
The temperature rises, and the insulation resistance coefficient decreases.
This is due to the increase in thermal movement, the generation, and migration of ions are increased, under the action of voltage, the conduction current formed by the ion movement increases, and thus the insulation resistance decreases.
Theory and practice show that the insulation resistance coefficient decreases exponentially with increasing temperature, while the conductance increases exponentially with increasing temperature.
So, how to prevent the outer sheath of the cable from falling off in the cold season?
The following measures are taken at different stages.
Wire and cable in the factory from the loading and unloading to the means of transport, to carry out reasonable warmth and protection measures.
For example, the use of sealed transport equipment, and cable products are prohibited from direct contact with the outside cold air.
Then put a layer of soft cushion to the product, such as soft foam or mattress type.
Load gently, do not load roughly, while avoiding excessive bending of the product.
When arriving at the destination or construction site, the product supplier had better send someone to supervise to prevent rough work when unloading the products.
It is better to store the products indoors and put a layer of isolation layer on the surface of the storage, such as wooden board, bedding, foam, etc., to prevent the products from freezing and moisture.
Pay attention to prevent direct contact between the product and the ground will be the phenomenon of scratching the outer skin of the wire and cable, gently take and put.
It is best to choose to work in the midday or afternoon when the temperature is warmer.
If the conditions can be used before the use of equipment such as heaters in advance to the product "warm up" so that the product to the best-performing state.
If it is buried, you can lay a layer of protection in the cable trench in advance, such as fabric, or foam.
If it is installed through the pipe, make sure that there are no bumpy hooks inside and outside the pipe to prevent the wire from being scratched. Iron pipe, in particular, pays attention to the purchase of quality qualified iron pipe.
Poor quality iron pipe tubes may have a large number of sharp raised points inside the pipe, most likely to scratch the outer skin of the wire.
In addition to the protection of cable products, it is also important to choose the right cable.
We all know that the conductor temperature rises when the conductor passes through the load current.
The conductor has an insulation layer, the conductor temperature should not exceed the maximum long-term allowable temperature that the conductor insulation withstands, after which the conductor will be damaged.
When the conductor is laid, according to the laying method and the distance of the support point, the conductor has a minimum allowable cross-section.
That is, the most cost-efficient way to choose.
We all know that the current through the conductor, due to the existence of line impedance, will produce a pressure drop in the line.
If the voltage drop is too large, the voltage at the end of the line, that is, the load side is too low, which will cause the equipment can not to work or have an impact on the life equipment.
Therefore, this requires that the voltage drop should not be too large, which requires a reasonable choice of cable cross-section.
Whether it is the distribution circuit or motor circuit, when the line fault, the protection device should act according to the specified time.
Can reliable action and cable cross-section have a great relationship, so we choose the cable to consider the requirements of reliable action protection?
Cable or electrical equipment in the event of a fault, the cable to meet the thermal stability requirements.
To meet this requirement, the size of the cable cross-section should be considered.
Combine the above conditions, the largest cross-section of which will be the final result.
The above is about the preventive protection measures that should be taken for the cable at low temperatures.
Copyright ? 2010 - 2025 zmscable.com All Rights Reserved.
