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The principle difference between underground and overhead cable is thermal dissipation.
With overhead cable, heat can dissipate into the air, and wind can improve the rate of thermal dissipation. On the other hand, overhead cable is exposed to solar gain that will result in some heating.
With underground cable, heat dissipation is governed by the thermal conductivity of the soil. The Neher-McGrath formulas can be used to calculate thermal conductivity and the required derating of conductors.
Comparing the two, an overhead cable generally has a higher thermal ampacity than an underground cable of the same material, dimensions and insulation.
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What is underground power transmission?
power cables under ground rather then overhead.
What happens to the ground when there is a thundercloud overhead?
When a thundercloud is overhead, the intense electric fields generated can induce a positive charge on the ground below. This in turn can result in the ground becoming positively charged, leading to a potential difference between the cloud and the ground. If the potential difference becomes large enough, it can result in a lightning discharge.
Why are the cables of the national grid are above the ground and not buried underground?
undergroud cables would be: -much more expensive -much more difficult to repair -difficult to bury where they cross canals, rivers and roads. also, overhead cables are high above the ground, underground cables could affect people more because the cales wouldn't be very deep
What is the purpose of ground wires in overhead transmission lines?
connection of the ground of all the transmission lines and used as a communication cable between protection devices
Why are the insulation resistance values higher for test between phase than between phase and ground?
When testing two cables there is twice the the amount of insulation, as opposed to one cable to ground.
What is difference between original ground level and normal ground level?
hi
What is the difference between Stolon and Rhizoid?
rhizoids are below-ground, stolons are above-ground
What is the difference between airspeed and ground speed?
YOU HAVE TO BE KIDDN ME RIGHT?
What is the difference between overhead transmission line and under ground transmission line?
Um. One is hung above your head on telephone poles and the other is ran underground in conduit? Unless you meant something else? Also burying cable costs ~10 times as much for transmission lines as overhead. It also usually has a lower power carrying capability, since it cannot dissipate heat as readily as an overhead conductor.
What is the difference between underground and above ground?
underground has soil or is wet and above ground is dry or grassy
When making an overhead throw in soccer how many feet must stay in contact with the ground?
Bothe feet must remain on the ground while making an overhead throw.
What is the difference between fishing and harvesting?
harvesting is on ground and fishing is in water
