String efficiency of overhead insulator approaches to 100%, when
(1) shunt capacitance approaches zero.
(2) potential across each disc is the same.
(3) shunt capacitance approaches infinity.
(4) potential across each disc is different.
1
2 and 4
2
2 and 3
3
3 and 4
4
1 and 4
5
1 and 2