Four Types Of  Distribution Feeders Systems:

• Radical 
• Parallel Feeders
• Ring Main
• Meshed

 Radical :

Radical is the simplest and least expensive to construct. This is used when the generating station is at the center and different feeder radiate to the different direction and power flow is only in one direction.

So, it has one feeder line for the group of customer. If some problem such as power failure, short circuit arises at one spot, entire feeder  line will go down.

Parallel Feeders :

This feeders system is used when we need continuous power supply for 24 hours. In this feeder system a parallel separate feeder line is followed with the main feeder line. Whenever there is a fault in the main line, the power didn't cut at the consumer and is fed from the separate feeder line, this is the main advantage of the parallel feeder over the radical feeder.

The main disadvantage is the construction cost of the parallel feeder is more. 

Ring Mesh :

Meshed System:

Types of Transmission line on the basis of distance:

• Short Transmission Line ranges from zero to 80 Km and operating voltage of 0 to 20 Kilovolt. Shunt capacitance is so small that it can be omitted entirely with little loss of accuracy.

• Medium transmission  line ranges from 80 to 200 km and operating voltage of 20 to 100 kilovolt.
• Long transmission line ranges from 80 to 200 km and operating voltage above 100 kilovolt. Mho relay is used in long transmission line.

A small LT line is a lower voltage Line which is 230 volt for single phase supply and 400 volts for 3 phase supply.

HT Line is for High Voltage Line which starts from 11 kV, 33 KV, 220 KV, 400 KV and more.

Note:

A Transmission line is used in reference to the transmission system and used for sending Electrical power from the generating Station to the substation. Power is Transmitted via transmitted line to the substation, where transmission voltage are more than 132KV

A Feeder is used with respect to the distribution system and used for sending power from substation to the consumer/load end. 

Characteristic Impedance

When the receiving end voltage is equal to IZ, the current and voltage waves are travelling in one direction, without any reflection of either current and voltage waves. The line is terminated in its characteristics impedance Zc and line is known as infinite line.

Ferranti effect.

When long or medium transmission line is open circuit or on light load the receiving end voltage is greater than the sending end voltage, this effect of increase in the voltage at the receiving end is known as the Ferranti effect. This effect is absence in short transmission line because of negligible shunt capacitance.