Compatibility summary
Your Singapore plug may fit in South Sudan outlets, as both use at least one common plug type.
Plug comparison
Singapore plug types: G
South Sudan plug types: C D G
Both countries share at least one plug type (G and C D G), so some plugs may work without an adapter. Check your appliance.
Voltage comparison
Singapore: 230V, 50Hz
South Sudan: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.