Introduction to Underground Cables

Underground cables refer to cables that are often buried underground compared to common overhead lines, hence they are also known as underground cables. A cable is a wire made of one or more insulated conductors wrapped in an insulation layer and a protective layer, used to transmit power or information from one location to another. After entering modern society, due to the shortage of urban land, high traffic pressure, and urban construction, underground cable transmission is widely used in large cities. Compared to overhead lines, cables have advantages such as small footprint, reliable transmission, and strong anti-interference ability. This article provides a detailed introduction to the construction plan, protective measures, survey procedures, basic requirements for directly buried cables, and underground cable fault locator.

classification

Unlike elevated high-voltage lines, cables are often laid in cable trenches, tunnels, pipelines, or indoors. After entering modern society, due to the shortage of urban land, high traffic pressure, and urban construction, underground cable transmission is widely used in large cities. Compared to overhead lines, cables have advantages such as small footprint, reliable transmission, and strong anti-interference ability.

Classification of cables: Cables include power cables, control cables, compensation cables, shielded cables, high-temperature cables, computer cables, signal cables, marine cables, etc.

advantage

Compared to overhead cables, underground cables have the following advantages:

1. Less damage from adverse weather conditions (mainly lightning, wind, and freezing)

2. Reduce the emission range of electromagnetic fields (EMF) and enter the surrounding area. However, depending on the depth of underground cables, larger electromotive forces may be encountered. [2] The current in the cable conductor generates a magnetic field, but a tighter combination of underground power cables reduces the combined external magnetic field and can provide further magnetic shielding.

3. Underground cables require a narrow enclosure of approximately 1-10 meters to be installed (up to 30 meters for 400kV cables during construction), while overhead lines require a enclosure of approximately 20-200 meters wide to be permanently unobstructed for safety, maintenance, and repair purposes.

4. Underground cables will not cause harm to low altitude flying aircraft or wildlife.

5. Less affected by conductor theft, illegal connections, sabotage, and armed conflict damage.

6. Bury public utility lines to make room for more large trees on the sidewalk, transmit environmental benefits, and increase property value.

shortcoming

And underground cables also have drawbacks such as being expensive, difficult to identify, difficult to repair broken cables, and potential damage or electric shock to the cables when excavating the ground by people who are unaware of their existence.