# Why transmission voltages are high?

Why transmission voltages are high?

Transmission voltage is always higher because of it uses

If current is high then I2R losses will be more .If I2R losses is more then heat generated is more. By heat or increasing temperature resistance will also be increase which will decrease transmission efficiency.

Also we know P = V x I

where, P = Power,

V = voltage,

I  = current.

By changing the value of voltage and current we can get constant power. By increase the voltage we are decreasing current which is advantageous. That's why transmission voltages is high.

## Related questions

Description : What is meant by extra high voltage transmission?

Last Answer : HT & LT  two types transmission in industrial line

Description : The sending end and receiving end voltages of a three-phase transmission line are 10 kV/ph and 9.5 kV/ph, respectively. If the resistance drop is 150 V/ph and receiving end power factor is 0.8, the sending end power factor is (A) 0.745 lagging (B) 0.775 lagging (C) 0.8 lagging (D) 0.85 lagging

Description : Pin type insulators are generally not used for voltages beyond (a) 1 kV (b) 11 kV (c) 22 kV (d) 33 kV

Last Answer : (d) 33 kV

Description : A uniformly-loaded D.C. distributor is fed at both ends with equal voltages. As compared to a similar distributor fed at one end only, the drop at the middle point is (a) one-fourth (b) one-third (c) one-half (d) twice (e) none 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

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

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

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.

Description : Why high voltage is used in power transmission?

Last Answer : The primary reason that power is transmitted at high voltages is to increase efficiency. ... The lower current that accompanies high voltage transmissionreduces resistance in the conductors aselectricity flows ... This means that thin, light-weight wires can beused in long-distance transmission.

Description : What are the advantages of high voltage transmission?

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 ... line increases  12. As transmission voltage increases power handling capacity of transmission line increases

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

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

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

Description : What is the material used for overhead 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Description : Which of the following are the constants of the transmission lines ? (a) Resistance (b) Inductance (c) Capacitance (d) All of the above

Last Answer : (d) All of the above

Description : Which of the following materials is not used for transmission and distribution of electrical power ? (a) Copper (b) Aluminium (c) Steel (d) Tungsten

Description : In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above

Last Answer : (b) secondary winding

Description : The steel used in steel cored conductors is usually (a) alloy steel (b) stainless steel (c) mild steel (d) high speed steel (e) all of the above

Last Answer : (c) mild steel

Description : The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more

Last Answer : (c) sending end voltage is more

Description : The material generally used for armour of high voltage cables is (a) aluminium (b) steel (c) brass (d) copper

Description : The material commonly used for insulation in high voltage cables is (a) lead (b) paper (c) rubber (d) none of the above

Description : Why does surge impedance loading (SIL) increase with increase in voltage level?

Last Answer : Answer: SIL varies as the square of the operating voltage, so SIL increases with increase in voltage level

Description : Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above

Description : The angular displacement between two interconnected stations is mainly due to (a) armature reactance of both alternators (b) reactance of the interconnector (c) synchronous reactance of both the alternators (d) all of the above

Last Answer : (a) armature reactance of both alternators

Description : When an alternator connected to the bus-bar is shut down the bus-bar voltage will (a) fall (b) rise (c) remain unchanged (d) none of the above

Last Answer : (c) remain unchanged

Description : The frequency of voltage generated, in case of generators, can be increased by (a) using reactors (b) increasing the load (c) adjusting the governor (d) reducing the terminal voltage (e) none of the above

Description : When the interconnector between two stations has large reactance (a) the transfer of power will take place with voltage fluctuation and noise (b) the transfer of power will take place with least loss ... out of step be¬cause of large angular displacement between the stations (d) none of the above

Last Answer : (c) the stations will fall out of step be¬cause of large angular displacement between the stations

Description : The effect of corona can be detected by (a) presence of ozone detected by odour (b) hissing sound (c) faint luminous glow of bluish colour (d) all of the above

Last Answer : (d) all of the above

Description : Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ? (a) Static condenser (b) Synchronous condenser (c) Tap changing transformer (d) Booster transformer

Last Answer : (d) Booster transformer

Description : For aluminium, as compared to copper, all the following factors have higher values except (a) specific volume (6) electrical conductivity (c) co-efficient of linear expansion (d) resistance per unit length for same cross-section

Last Answer : (6) electrical conductivity

Description : Aluminium has a specific gravity of (a) 1.5 (b) 2.7 (c) 4.2 (d) 7.8

Description : The current drawn by the line due to corona losses is (a) non-sinusoidal (b) sinusoidal (c) triangular (d) square