That part of the earth fault loop impedance which is external to the circuit under consideration. For the supply cable it will be the impedance external to the installation. For other circuits, it is the sum of the impedance of the circuits on the supply side of the circuit under consideration and the impedance external […]
Z2 – That part of the earth fault loop impedance which comprises the impedance under earth fault conditions of the circuit protective conductor (cpc) of the circuit under consideration.
Z1 – That part of the earth fault loop impedance which comprises the impedance under earth fault conditions of the line conductor of the circuit under consideration.
Themaximum value of earth fault loop impedance (Zs) that will allow the protective device in a circuit to disconnect an earth fault within the prescribed time. Example: if themaximum earth fault disconnection time for a circuit is 0.4 s and a fault current Ia = 320 A is required to operate the circuit protective device […]
