A New Approach to the Study of Voltage Distribution along a Suspension Insulator String

The cap and pin insulator string, though a simple element in a power system, has the responsibility of carrying the live conductor while insulating it properly from the tower arm. In properly designing the insulator string, it will be necessary to assess the voltage distribution along it to ensure that no unit will get unduly stressed beyond its capacity. There are standard methods available to determine the voltage distribution along an insulator string. However, all these methods have limitations. This paper describes a novel method for accurately computing the voltage distribution along a string insulator which can be used for either short or long strings with no restrictions whatsoever. The computation allows to accommodate the capacitance between the metal work of the string and the tower and the capacitance between the metal cap of the string and the guard ring. The paper also describes two new simple equations that can be used to determine the voltage distribution along an insulator string irrespective of whether it is short or long.