You Do Need power plug adapter while traveling from Pitcairn Islands 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 Pitcairn Islands is I. This is how they look like.

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I

South Sudan

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

Type C

Type D