There are two types of ground-fault protection:
1- Residual:
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.
In case of 3 pole breaker (4-wire system), for ground-fault protection, it is mandatory to install an external CT for calculating the current to ground, thanks to a vectorial sum of phases and neutral currents. While for the 4 pole CB, it is not mandatory to install an external CT.
1- Residual:
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.
In case of 3 pole breaker (4-wire system), for ground-fault protection, it is mandatory to install an external CT for calculating the current to ground, thanks to a vectorial sum of phases and neutral currents. While for the 4 pole CB, it is not mandatory to install an external CT.
Released for: Schneider Electric Saudi Arabia
