You Do Need power plug adapter while traveling from El Salvador 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 El Salvador are A and B. This is how they look like.

El Salvador

In El Salvador, outlets of type A and B are in use.

Type A

Type B

South Sudan

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

Type C

Type D