You Do Need power plug adapter while traveling from New Caledonia to South Sudan.

Here is Why You Need An Adapter

The outlet and plug type used in South Sudan are C and D and in New Caledonia are C and F. This is how they look like.

New Caledonia

In New Caledonia, outlets of type C and F are in use.

Type C

Type F

South Sudan

In South Sudan, outlets of type C and D are in use.

Type C

Type D