The connection between soil thermal resistivity and manufacture of electric cables
When you think about the manufacture of electrical cables, soil thermal resistivity testing is not one of the things which will normally come to your mind. However, as manufacturing processes become better, manufacturers and installers of electrical cables are finding themselves really dependent on some of these researches and outcomes. Even though the designs and calculations needed to create underground cables have been known for a long time, it is hard to ignore the impact the soil has in these cables. Here are a few things you ought to know about this connection.
Soil thermal resistivity and cable life
The life of an underground electrical cable depends on a number of factors. When a cable is transmitting electricity, it gives off some amount of heat. This heat should be easily transmitted through the soil, leaving the area near the cable cool. However, when the heat is too much and the soil is not conducting the heat well, a lot of the heat will be retained near the cable. The higher temperatures lead to a decrease in the cable life of the wires. Thermal resistance is therefore a very integral part of the entire design.
Factors that determine thermal resistivity in soil
There are a number of factors which affect the thermal resistivity of soil. These include the quartz content in the soil, water, other organic matter and air. When testing for the resistivity, the researchers must therefore investigate these four components and see how each of them affects it. The soil with ideal resistivity will have very few spaces for air to pack into; the soil should have a high concentration of organic matter, the presence of water, although better than air, also lowers conductivity.
The relationship between soil density and thermal resistivity
Another factor that affects the ability of soils to transmit heat is their density. For a soil to have that ideal resistivity, it must be as densely packed as possible. Normally, soils which can sustain the growth of plants usually have enough resistivity to transmit the heat from cables. However, whether the soil is closely packed or not, the presence of organic matter in it lowers its resistivity, making it bad for cables.
These are the things that industrial cable manufacturers have to think about when they are creating cables. There are calculations which are made to determine the best wire thickness for underground cables. However, reliable results can only be achieved through checking the resistivity of the soil at sensible intervals.
