Generating station to a switching station/step-down transformer station.
Transmission line connects Generating station to a switching station/step-down transformer station.
A 3-phase 4-wire system is commonly used for Secondary Distribution.
RMS line to line voltage
The rated voltage of a 3-phase power is given as RMS line to line voltage.
9.9 kV is usually not the generating voltage.
In a Transmission system the feeder supplies power to Distributors.
Its current carrying capacity
Feeder is designed mainly from the point of view of Its current carrying capacity.
Voltage drop in it
Distributors are designed from the point of view of Voltage drop in it.
All of the above
Transmission and Distribution of electric power by underground system is superior to overhead system in respect of Appearance and public safety, Maintenance cost and Frequency of faults, power failure and accidents.
Heavy initial cost
The main drawback of underground system over overhead system is Heavy initial cost.
The main drawback of overhead system over underground system is Surge problem.
One-fourth of original value
By increasing the Transmission voltage double of its original value, the same power can be dispatched keeping the line loss One-fourth of original value.
Both (b) and (c)
The volume of copper required for an ac Transmission line is inversely proportional to Voltage and Power factor.
For the same conductor length, same amount of power, same losses and same maximum voltage to earth, The system required minimum conductor area is 3-wire dc.
3-phase, 4-wire system
3-phase, 4-wire system distribution system is preferred for good efficiency and high economy.
The approximate cost ratio of a 220 kV underground cable transmission and 220 kV O/H transmission is 13.
Reduction in transmission losses.
The main reason for using high voltage for long distance power transmission is reduction in transmission losses.
66 kV is suitable for transmission of power over 60 km.
If 3 MW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will be 33 kV.
The highest transmission voltage used in India is 765 kV.