The table below summarises the plug types, voltage and frequency of electrical current in both Angola and Nigeria.
|Plug Types||C||D, G|
|Frequency of electrical current||50Hz||50Hz|
Angola uses Plug Type C.
The voltages found in Angola (220V) and Nigeria (240V) are not exactly the same, but the difference is tolerable, so you should not need a transformer.
The frequency found in Angola and Nigeria is exactly the same (50Hz). Timing devices and appliances that use motors will function as expected under this frequency.