SOLUTION

The transmission line feeding power on either side of the main transmission line is called secondary transmission.

Detailed explanation

At the generating station, electrical power is generated with the help of three-phase alternators running in parallel. The voltage level is 11 kV but the voltage level may be 6.6 kV, 22 kV, or 33 kV depending upon the capacity of the generating station. After the generating station, actual transmission and distribution start.

Primary transmission: It is basically with the help of overhead transmission lines. For the economic aspects, the voltage level is increased to 132 kV, 220 kV or more, with the help of a step-up transformer. Hence this transmission is also called high voltage transmission. The primary transmission uses 3 phase 3 wire system.

Secondary transmission:

• The transmission line feeding power on either side of the main transmission line is called secondary transmission.
• The primary transmission line continues via transmission towers till the receiving stations.
• At the receiving stations, the voltage level is reduced to 22 kV or 33 kV using the step-down transformer.
• There can be more than one receiving station.
• Then at the reduced voltage level of 22 kV or 33 kV, the power is then transmitted to various substations using an overhead 3 phase 3 wire system.
• This is the secondary transmission.
• The conductors used for the secondary transmission are called feeders.