A wire consisting of one or more conductors and insulation, which can withstand a certain amount of voltage, is called a cable. And the cable is called an underground cable if a certain amount of voltage is transmitted and distributed by digging into the ground.
Electric power transmission and distribution are carried out by underground cables in cities, densely populated areas, and areas where overhead lines are not feasible or dangerous.
Since the transmission or distribution of electrical power in an underground cable system is very expensive, however, in many cases, electricity is supplied underground as per necessity or technical requirement.
However, in our country, the use of underground substations, and service main connections has been limited for so long, but submarine cables have been used in Patuakhali to Bhola transmission line and Siddhirganj and Haripur lines. Apart from this, the Poly-electricity Board is installing light-insulated aerial cables.
Cables are made of aluminum or copper twisted wire core, PVC or oiled paper insulation, waterproof metallic sheath, metallic armor, etc.
What is Underground Cable?
Conductors with sufficient insulation to withstand a certain amount of voltage are used in underground transmission and distribution lines. It is called underground cable.
Underground cables are convenient to use in densely populated, low-voltage distribution systems. In our country, the underground cable is more used in substations, and service connections. The transmission system now requires very limited underground cables in our country. Cables are made of aluminum or copper twisted wire core, PVC or oiled paper insulation, anti-birth metallic coating, metallic armor, etc.
Advantages of Underground Cables
There are several advantages of underground cable, which are highlighted below-
1. Underground systems are safer where overhead lines are dangerous or inconvenient and underground cables are used in densely populated urban areas.
2. Since the cable is taken underground, it is free from the effects of storms, wind, lightning, etc., so frequent faults do not occur. So it does not require constant maintenance.
3. Underground cables are very useful in maintaining the beauty and safety of urban areas.
4. In an underground system, conductor spacing is less, resulting in a less inductive reactance-induced drop in the line. As a result, the quality of voltage regulation is significantly improved.
5. As the cable is routed underground, there is no inductance effect on the communication circuit. As a result, there is no interruption in the communication line.
6. The underground system is free from lightning surges, thus reducing maintenance costs.
Disadvantages of Underground Cables
The underground system also has some disadvantages. These are-
1. The initial cost of an underground system is high.
2. Because the cable is underground, it is difficult to locate the fault-free cable in case of a fault.
3. Attempts are made to limit the working voltage of underground cables to 33 KV considering insulation cost.
4. Because the conductor spacing in underground cable systems is very small, the capacitance value of the cable is very high, thereby drawing more charging current from the line.
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