An insulator string for $66$KV$,$

a$.$ calculate the number of insulators and the string efficiency by neglecting the shunt capacitance

between the joint and metal work, if each insulator can stand maximum $11$ kV

b$.$ use the number of insulator that is calculated in part a to calculate the voltage distribution and string

efficiency for the below cases

i$.$ including the shunt capacitance between the joint and metal work $(25\%$ of the insulator capacitance$).$

ii$..$ including the shunt capacitance between the joint and metal work $(25\%$ of the insulator

capacitance$)$ and having a guard ring $($ its capacitance $15\%$ of insulator capacitance$).$