A string insulator has 4 units. The voltage across the bottom-most unit is 33.33% of the total voltage. Its string efficiency is

In a string of suspension insulators, the voltage distribution across the different units of a string could be made uniform by the use of a grading ring, because it

The number of discs in a string of insulators for 400 kV AC overhead line lies in the range of

The number of discs in a string of insulators for 220 kV AC overhead transmission line lies in the range of

In a three unit insulator string, voltage across the lowest unit is 17.5 kV and string efficiency is 84.28%. The total voltage across the string will be equal to

Two insulator discs of identical capacitance value C make up a string for a 22 kV, 50 Hz, single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is

Consider the following statements : Overhead transmission lines are provided with earth wires
1. To protect the transmission line from direct lightning strike
2. To protect the transmission line insulation from the indirect lightning strike
3. To balance the line currents
4. To provide path for neutral current
Which of these statements is/are correct ?

A string insulator has 5 units. The voltage across the bottom most unit is 25% of the total voltage. The string efficiency is