The loss of lead sheath and armor in long distance single-core submarine cable would lower the ampacity even cause the electrical fault of the cable. To solve the problem

we proposed two solutions

namely replacing the steel wire armour by aluminum wire armour（which has smaller relative permeability） and stringing resistances in lead sheath and armour circuit. Based on theoretical analysis

a thermal cycling test system of submarine cable in shore environment was designed and used to conduct a series of comparative experiments for 110 k V single-core submarine cables

including mutual inductance tests

loss tests

temperature rise tests and so on. The principle and effect of the methods in reducing the cable loss

protecting the cable and upgrading the ampacity were explored and verified. The results show that the lead covered circulation has a shielding effect on armour layer. Changing armour material and stringing resistances can enhance the submarine cable’s ampacity by 24.2% and 9.68%

respectively.