Which one is best.Overhead transmission system or Underground transmission system?

at first this not completely question because , in some cases may be the overhead transmission system is better 

but generaly the  under ground system is prefered because low propability of faults  specially in dust ( un clear) areas 

so to give clear answer we should compare between o.h.t system and underground system according to  

1- propabilty of faults

2- cost 

3- production of reactive power 

4- nature of area (mountain -smooth lands - desert - industrial - agriculture )

underground transmitions accoding to IEEE regulations safty and standerd.

Under ground transmission. why because to reduce the cost recuired to constract steel towers,also it is good for big towns having more population,the probabilty of fault to occur is also less when compared with overhead.

For high voltage and long distance transmision of electrical power, the only sole solution is Overhead lines, for short and populated areas and for low voltage distribtion purposes, underground cables are safe mean

For me the best is underground transmission for the safety.

Underground cables are safer to the public, animals and environment compared to the overhead lines i.e. there are no issues such as people getting in contact with fallen lines. The overhead cables can be brought down and human, animal intervention, weather as well vegetation such as trees.

The underground cables are less impacted by these conditions and not affected by trees, animals, accidents, wind, storms and other physical interference that may lead to broken poles and short circuits or cable breakages.

OVERHEAD TRANSMISSION SYSTEM ID THE BEST WHERE RIGHT OF WAY IS NO CONSTRAIN. BETTER OPERATION AND MAINTENANCE IS POSSIBLE. LESS OUTAGE AND QUIC FAULT REMOVAL

UNDER GROUND LINE SYSTEM IS GOOD. LESS AMOUNT  OF LOSS

This question can be accurtely answered depending on engineering and economical constraints. The limitations includes, but not limited to, the folllowing:

- Cost: Even though the installation of transmission lines are not really low in price, underground systems require more digging and installation work. On top of that, maintenace cost is lower for overhead lines, because of the ease of acccess. For these two reasons, in terms of cost (initial investment) and maintenace, overhead lines are more cost-effective.

- Lines seperations: Underground lines are closely seperated, which make the conductors act as stronger capacitors. As a result, underground lines have higher capacitance, which affects the the Ferranti effect (higher receiving end than sending end). Plus, with higher capacitance, more charging current is drawn. And for that reason, underground lines have length limitations.

- Safety: Overhead lines are supported by long towers, which obstacle flying objects, birds, and even vehicles. However, underground systems are more isolated and less problamatic with public activities.

- Insulation: Unlike underground lines, overhead lines have a better heat dissipation surrounding, which allow them to operate in high voltage.

- Faults and interrupts: Overhead lines are exposed to lightings, Corona, and many other exterior factors that cause damages as well. However, undeground lines are more isolated and protected.

Overhead Transmission system

over head tramsmission system is best

Transmission and distribution of electric power can be carried out by overhead as well as underground systems. Comparison between overhead and underground is given below:

1.    Public Safety: Underground system is safer than overhead system.

2.    Initial Cost:  Underground system is more expensive

3.    Flexibility:  Overhead system is more flexible than underground system. In overhead system new conductors can be laid along the existing ones for load expansion. In case of underground system new conductors are to be laid in new channels.

4.    Working Voltage: The underground system cannot be operated above 66 KV because of insulation difficulties but overhead system can be designed for operation up to 400 KV or higher even.

5.    Maintenance Cost: Maintenance cost of underground system is very low in comparison with that of overhead system.

6.    Frequency of Faults or Failures: As the cables are laid underground, so these are not easily accessible. The insulation is also better, so there are very few chances of power failures or fault as compared to overhead system.

7.    Frequency of Accidents: The chances of accidents in underground system are very low as compared to overhead system.