Differentiate between overhead transmission and underground transmission.

Differentiate between overhead transmission and underground transmission.
by

1 Answer

Answer :

Points
Overhead line 
Underground cable
Capital cost 
Less
More
Erecting cost 
Less
More
Time require for completion of work
Less
More
Flexibility
More flexibility
No flexibility 
Future expansion in voltage level
System voltage can be increased easily
System voltage cannot be increased
Overload capacity  More
Less
Fault finding 
Easy
Difficult  
Charging Current
Less
More
Chances of fault
More
Less
Chances of accident 
More
No chances of accident
Safety
Less
More
Radio interference
Produces radio interferences
Not produces radio interferences 
Short cute route 
Difficult
Possible
Theft Of energy
More possibility
Less possibility
Voltage drop
More
Less
Power factor
Less
More
Reliability 
Less
More
Life 
Less
More
Space consumed
Space consumed 
No space consumed
Appearance
Not good 
Very good 
by

Related questions

Why underground service connections are service connections are costly than overhead service connection

Description : Why underground service connections are service connections are costly than overhead service connection

Last Answer : Reason: Underground service connection is given by underground cable. This cable is costly than bare conductor. Sometimes cable trench is required for cable laying, which requires additional cost. So underground service connections are costly than overhead service connection.

Why are overhead transmission lines not insulated?

Description : Why are overhead transmission lines not insulated?

Last Answer : Insulators are useful to help separate electrical conductors when they come into physical contact. Overhead Transmission Lines Are Not Insulated: The overhead transmission line is carrying extreme high voltage and ... a whole lot of thick insulation to absorb the heat produced by such high voltage.

Draw and explain the construction of underground cables.

Description : Draw and explain the construction of underground cables. 

Last Answer : Underground cables:   OR Explanation:- i) Core or conductor: * It function is carry current. * Cable may have single or more than single core conductor. * Conductor ... handling of cables. * It is similar to bedding & consists of fiborous material such as jute. 

Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above

Description : Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above

Last Answer : (b) overhead

State the procedure for laying / installation of underground cable.

Description : State the procedure for laying / installation of underground cable.  

Last Answer : 1) Direct laying Cable: or Trench laying method: Procedure: * For laying of a cable trench about 1.5m deep and 0.5m wide is made along the cable route. * A ... over. * Cables laid in this manner are usually plain lead covered because troughing affords good mechanical protection. 

Why don't we burry power lines underground ?

Description : Why don't we burry power lines underground ?

Last Answer : Because conductor used for power transmission are not insulated and if we do so it create phase to ground fault causing interruptions to supply.

The underground system cannot be operated above?

Last Answer : The underground system cannot be operated above 66 kV.

what is the use of bedding on underground cable?

Description : what is the use of bedding on underground cable?

Last Answer : Bedding is the layer above the lead sheath it protects the lead sheath from corrosion that means it gives chemical protection to metallic sheath(lead sheath)

State properties of conductor material used for overhead conductor.

Description : State properties of conductor material used for overhead conductor. 

Last Answer : Following are the properties of conductor material:-   1. High conductivity :- Material should have high conductivity 2. High mechanical strength:- Material should have sufficiently high mechanical strength ... available & less costly. 9. Scrap Value: - Material should have high scrap value. 

Define service connection and state types connection and state types of overhead service connection

Description : Define service connection and state types connection and state types of overhead service connection

Last Answer : Service Connection:- It is the input conductor or wire which is carried out from supply company (authorities) pole to consumers' main board or premises. Types of overhead service ...  1. Overhead service connection with Bare conductor 2. Overhead service connection with weather proof cable  

A minimum clearance of 6.3 m to ground is required for overhead lines when operating voltages are :

Description : A minimum clearance of 6.3 m to ground is required for overhead lines when operating voltages are :  (A) less than 66 kV (B) lie between 66 kV and 110 kV (C) more than 165 kV (D) lie between 110 kV and 165 kV

Last Answer : A minimum clearance of 6.3 m to ground is required for overhead lines when operating voltages are : lie between 66 kV and 110 kV

lf a travelling-wave travelling along a loss-less overhead line does not result in any reflection after it has

Description : lf a travelling-wave travelling along a loss-less overhead line does not result in any reflection after it has reached the far end, then the far end of the line is

Last Answer : lf a travelling-wave travelling along a loss-less overhead line does not result in any reflection after it has reached the far end, then the far end of the line is terminated into a resistance equal to surge impedance of the line

Overhead lines for power supply to tramcars are at a minimum height of?

Last Answer : Overhead lines for power supply to tramcars are at a minimum height of 10 m.

Overhead system can be designed for operation up to?

Last Answer : Overhead system can be designed for operation up to 400 kV.

Why ACSR conductor is used for overhead lines?

Description : Why ACSR conductor is used for overhead lines?

Last Answer : It has high tensile strength 

By which of the following systems electric power may be transmitted ? (a) Overhead system (b) Underground system (c) Both (a) and (b) (d) None of the above

Description : By which of the following systems electric power may be transmitted ? (a) Overhead system (b) Underground system (c) Both (a) and (b) (d) None of the above

Last Answer : (c) Both (a) and (b)

State the limitations of EHVAC transmission line.

Description : State the limitations of EHVAC transmission line. 

Last Answer : Following are the Limitations of EHVAC Transmission:   1. Insulation cost increases as voltage increases 2. Skin effect is more 3. Proximity effect is more. 4. Corona loss increases. 5. Radio ... 18. EHVAC is economical only for bulk amount of power is to be transmitted over long distance. 

State the effects of low power factor on efficiency and voltage regulation of short transmission lines.

Description : State the effects of low power factor on efficiency and voltage regulation of short transmission lines. 

Last Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor) 

State the advantages of use of high voltage in transmission of Electric power.

Description : State the advantages of use of high voltage in transmission of Electric power. 

Last Answer : Advantages: 1. As Transmission voltage increases, current decreases. 2. As current decreases, cross section of conductor decreases. 3. As cross section of conductor decreases, its ... high voltage transmission line, successful interconnection of transmission line is possible than low voltage. 

State line parameters of transmission line.

Description : State line parameters of transmission line. 

Last Answer : Following are the of Line parameters of transmission line:  1. Resistance  2. Inductance  3. Capacitance

State features of wireless power transmission.

Description : State features of wireless power transmission. 

Last Answer : Features of wireless power transmission:  1. Energy delivered anywhere in the world 2. Zero fuel cost 3. Less losses 4. Less use of copper wires 5. More efficiency 6. Minimum long- ... on cables would never exist in the transmission.  7. Power theft would be not possible at all. 

State the classification of transmission lines depending on length of transmission lines.

Description : State the classification of transmission lines depending on length of transmission lines. 

Last Answer : A) According to Voltage level: ( 2 Marks)  a) High voltage Transmission Line (HV) up to 33 KV  b) Extra High Voltage Transmission Line (EHV) above 33 KV up to 400 KV  c) Ultra ... Transmission Line: - The length of Long transmission Line is above 200KM and its line voltage is above 100KV

What is the material used for overhead transmission lines?

Description : What is the material used for overhead transmission lines?

Last Answer : Answer: ACSR conductors are employed.

Which of the following materials is used for overhead transmission lines ? (a) Steel cored aluminium (b) Galvanised steel (c) Cadmium copper (d) Any of the above

Description : Which of the following materials is used for overhead transmission lines ? (a) Steel cored aluminium (b) Galvanised steel (c) Cadmium copper (d) Any of the above

Last Answer : (d) Any of the above

Where have all the fire hydrants gone?

Description : Where have all the fire hydrants gone?

Last Answer : I have a yellow one in my yard. My house insurance was discounted because of that.

For an overhead line, the surge impedance is taken as (a) 20-30 ohms (b) 70—80 ohms (c) 100—200 ohms (d) 500—1000 ohms (e) none of the above

Description : For an overhead line, the surge impedance is taken as (a) 20-30 ohms (b) 70—80 ohms (c) 100—200 ohms (d) 500—1000 ohms (e) none of the above

Last Answer : (c) 100—200 ohms

Overhead system can be designed for operation up to (a) 11 kV (b) 33 kV (c) 66 kV (d) 400 kV

Description : Overhead system can be designed for operation up to (a) 11 kV (b) 33 kV (c) 66 kV (d) 400 kV

Last Answer : (c) 66 kV

The material commonly used for sheaths of underground cables is (a) lead (b) rubber (c) copper (d) iron

Description : The material commonly used for sheaths of underground cables is (a) lead (b) rubber (c) copper (d) iron

Last Answer : (a) lead

The underground system cannot be operated above (a) 440 V (b) 11 kV (c) 33 kV (d) 66 kV

Description : The underground system cannot be operated above (a) 440 V (b) 11 kV (c) 33 kV (d) 66 kV

Last Answer : (d) 66 kV

What are the building restrictions concerning power/transmission lines?

Description : What are the building restrictions concerning power/transmission lines?

Last Answer : There is none in North Carolina—- They just put in a transmission line right down the road with houses at 75 foot set-back from road on both sides of the road. The towers are taller than the driveways are long!

Transmission leaks?

Description : Transmission leaks?

Last Answer : Purple.

Explain some of the methods to improve the strength of transmission system?

Description : Explain some of the methods to improve the strength of transmission system?

Last Answer :  Introducing or adding of new transmission lines in to the system to avoid the overloading of the existing lines  Application of devices such as series capacitors in the right location of ... system  Adoption of multi-voltage levels an multi-circuits in the existing ac transmission system

What are the factors that limit the maximum power transfer capability in a transmission line?

Description : What are the factors that limit the maximum power transfer capability in a transmission line?

Last Answer : Answer: Some of the factors which limits the maximum power transfer are: 1. Electrical phase shift 2. Voltage drop 3. Thermal effects in the line

What are the problems associated with EHV transmission?

Description : What are the problems associated with EHV transmission?

Last Answer : Answer: The problems associated with EHV transmission are corona loss and radio interference, requirement of heavy supporting structures and insulation requirments

What for series and shunt compensation provided in EHV transmission lines?

Description : What for series and shunt compensation provided in EHV transmission lines?

Last Answer : Answer: Series capacitance is provided in EHV lines to artificially reduce the series reactance of the line so as to improve stability, voltage regulation and transmission efficiency Shunt compensation ... reduce the line susceptance so as to improve the voltage regulation under light load condition

Series capacitors on transmission lines are of little use when the load VAR requirement is (a) large (b) small (b) fluctuating (d) any of the above

Description : Series capacitors on transmission lines are of little use when the load VAR requirement is (a) large (b) small (b) fluctuating (d) any of the above

Last Answer : (b) small

In the analysis of which of the following lines shunt capacitance is neglected ? (a) Short transmission lines (b) Medium transmission lines (c) Long transmission lines (d) Medium as well as long transmission lines

Description : In the analysis of which of the following lines shunt capacitance is neglected ? (a) Short transmission lines (b) Medium transmission lines (c) Long transmission lines (d) Medium as well as long transmission lines

Last Answer : (a) Short transmission lines

For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV

Description : For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV

Last Answer : (a) 150 to 220 kV

Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above

Description : Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above

Last Answer : (b) short-circuit current of the system is increased

For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV

Description : For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV

Last Answer : (a) 132 kV

The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above

Description : The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above

Last Answer : (c) synchronous motors

Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km

Description : Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km

Last Answer : (a) 20—25 km

Which of the following characteristics should the line supports for transmission lines possess ? (a) Low cost (b) High mechanical strength (c) Longer life (d) All of the above

Description : Which of the following characteristics should the line supports for transmission lines possess ? (a) Low cost (b) High mechanical strength (c) Longer life (d) All of the above

Last Answer : (d) All of the above

Which of the following relays is used on long transmission lines ? (a) Impedance relay (b) Mho's relay (c) Reactance relay (d) None of the above

Description : Which of the following relays is used on long transmission lines ? (a) Impedance relay (b) Mho's relay (c) Reactance relay (d) None of the above

Last Answer : (b) Mho's relay

A 3-phase 4 wire system is commonly used on (a) primary transmission (b) secondary transmission (c) primary distribution (d) secondary distribution

Description : A 3-phase 4 wire system is commonly used on (a) primary transmission (b) secondary transmission (c) primary distribution (d) secondary distribution

Last Answer : (d) secondary distribution

A feeder, in a transmission system, feeds power to (a) distributors (b) generating stations (c) service mains (d) all of the above

Description : A feeder, in a transmission system, feeds power to (a) distributors (b) generating stations (c) service mains (d) all of the above

Last Answer : (a) distributors

Transmission line insulators are made of (a) glass (b) porcelain (c) iron (d) P.V.C.

Description : Transmission line insulators are made of (a) glass (b) porcelain (c) iron (d) P.V.C.

Last Answer : B

In transmission lines the cross-arms are made of (a) copper (b) wood (c) R.C.C. (d) steel

Description : In transmission lines the cross-arms are made of (a) copper (b) wood (c) R.C.C. (d) steel

Last Answer : (d) steel

High voltage transmission lines use (a) suspension insulators (b) pin insulators (c) both (a) and (b) (d) none of the above

Description : High voltage transmission lines use (a) suspension insulators (b) pin insulators (c) both (a) and (b) (d) none of the above

Last Answer : (a) suspension insulators

Which of the following is the demerit of a 'constant voltage transmission system' ? (a) Increase of short-circuit current of the system (b) Availability of steady voltage at all loads at the line terminals (c) Possibility of better protection for the line due to possible use of higher terminal reactants (d) Improvement of power factor at times of moderate and heavy loads (e) Possibility of carrying increased power for a given conductor size in case of long-distance heavy power transmission

Description : Which of the following is the demerit of a 'constant voltage transmission system' ? (a) Increase of short-circuit current of the system (b) Availability of steady voltage at all loads at ... of carrying increased power for a given conductor size in case of long-distance heavy power transmission

Last Answer : (a) Increase of short-circuit current of the system