Section outline

  • Introduction:

    Electric power can be transmitted or disributed either by means of underground cables or by overhead lines. The underground cables are rarely used for power transmission due to two main reasons. Firstly, power is generally transmitted over long distances to load centres. Obviously, the installation costs for underground transmission will be very heavy. Secondly, electric power has to be transmitted at
    high voltages for economic reasons. It is very difficult to provide proper insulation† to the cables to withstand such higher pressures. Therefore, as a rule, power transmission over long distances is carried out by using overhead lines. With the growth in power demand and consequent rise in voltage levels, power transmission by overhead lines has assumed considerable importance.

    Learning Objectives:

    • To gather knowledge about line insulators and their performance characteristics
    • To know how to erect transmission and distribution lines, requirement criteria

    Lecture Contents:

    • Insulators
    • Types of Insulators
    • Potential Distribution over Suspension Insulator String
    • String Efficiency
    • Methods of Improving String Efficiency 

    Learning Outcomes:

    The students will be able to 
    • Get ideas about insulators and their applications
    • Apply the methods of equalizing potential distribution; special types of insulators, testing of insulators