You Do Need power plug adapter while traveling from South Sudan to Equatorial Guinea.

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea are C and E and in South Sudan are C and D. This is how they look like.

South Sudan

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

Type C

Type D

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E