The undesirable property of an electrical insulating material is

Consider a three-phase, 50Hz, 11kV distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self capacitance of the insulator is 5 times, the shunt capacitance between the link and the ground, as shown in the figure. The voltages across the two insulators are

The insulation strength of an EHV transmission line is mainly governed by

In a transmission line each conductor is at 20 kV and is supported by a string of 3 suspension insulators. The air capacitance between each cap-pin junction and tower is one-fifth of the capacitance C of each insulator unit. A guard ring, effective only over the line-end insulator unit is fitted so that the voltages on the two units nearest the line-end are equal                 

(a) Calculate the voltage on the line-end unit

(b) Calculate the value of capacitance  required

Each conductor of a 33KV, 3-phase system is suspended by a string of three similar insulars. The ratio of shunt capacitance to mutual capacitance is 0.1. Calculate the voltage across each insulator, and the string efficiency.

The insulation level of a 400 kV EHV overhead transmission line is decided on the basis of

In a string of three identical suspension insulator units supporting a transmission line conductor, if the self capacitance of each unit is denoted as C Farads, the capacitance of each connector pin to ground can be taken as 0.1 C Farads. Determine the voltage distribution across the string if the maximum permissible voltage per unit is given as 20kV. Also determine the string efficiency.