Earth-fault loop impedance
Türkçe: Çevrim empedansı
The total impedance of the path a fault current follows (source, line conductor, protective conductor); it decides whether the protective device will trip in time.
// EXPLANATION
The loop impedance Zs is the source impedance plus the resistance of the line and protective conductors. The protection condition is Zs × Ia ≤ U0: the tripping current (Ia) multiplied by the loop impedance must not exceed the line-to-earth voltage. It is measured with a dedicated tester; if it is too high, the cable cross-section is increased or faster protection (an RCD) is used.
// ALSO KNOWN AS
loop impedancefault loop impedanceearth fault loop impedance
// RELATED TERMS
Earthing (grounding)An arrangement that connects the conductive parts of an installation to the ground through a low-resistance path so fault current has a safe way out.
Residual-current deviceA safety device that watches the difference between line and neutral currents and opens the circuit within a fraction of a second when that difference exceeds a threshold.
ImpedanceThe total opposition to alternating current; a combination of resistance and reactance, measured in ohms.
Short circuitA condition where live conductors join through a very low-impedance path, so hundreds of times the normal current flows.
