If the self$-$capacitance of each unit in a string of three suspension insulators is C$,$ the shunting capacitance of the connecting metal work of each insulator to earth is $015$ C and to line is $01$ C$,$ calculate $($i$)$ the voltage across each insulator as a percentage of the line voltage to earth without a guard ring and $($ii$)$ the string efficiency of the system if a guard ring increases the capacitance to the line of metal work of the lowest insulator to $03$ C$.$