please find below the definitions for "Residual Earth Fault protection" and "Source Ground Return"

1- Residual Earth Fault protection: The function determines the zero-phase sequence current, i.e. the vector sum of the phase and neutral currents

2-Source Ground Return :Using a special external sensor, this function directly
measures the fault current returning to the transformer via the
earth cable and It detects faults both upstream and downstream of the circuit
breaker.

Please note that it is recommended for Source Ground Return to consider:
1- The maximum distance between the sensor and the circuit breaker is ten meters
2- Use a 4P circuit breaker in order to isolate the neutral when the breaker is open and in order also to avoid the effect of the third harmonic which is flowing mainly on the neutral bar, and which could provoke unexpected tripping.

Kindly find attached guide for Ground fault protection, where you can find the following:

- page 18: for installation precautions.
- pages 34 to 36 :how to make choice concerning the GFP (Ground Fault protection) based on the installation conditions.
- page 37 to 51 wiring and Schneider offer according to GFP.

Released for:Schneider Electric Nigeria