Voltage Distribution Over Insulator String-:
Here, C=Capacitor f each unit/disc.
kC=The capacitor of each joint to the earthed tower that can be assumed.
We can easily find out string efficiency of ‘n’ number of an insulators by these formula.
∴ Capacitance to earth = k × self capacitance=kC
ηs= String efficiency.
v1 = Voltage across the lowest unit connected to the line conductor.
vn = The voltage across the ‘n’ units of the arm.
Considered that V be the voltage across the string and v1, v2,…..,vn the voltage drops across the units. 1,2,3…,n, starting from the cross arm towards the line conductor.
By applying KCL (Kirchoff Current Law) at the node P.
The capacitance of each unit and k lies between 0.1 and 0.2
ip+1 = ip + Ip
i = V. jwc
Vn+1 jwc = (V1+V2+V3+……+Vn) jwkC+Vn.jwC
Vn+1 = (V1+V2+V3+…..Vn-1) k+Vn . (1+k)