TN-S system
Türkçe: TN-S sistemi
The source neutral is solidly earthed and the neutral (N) and protective conductor (PE) run separately throughout the installation.
// EXPLANATION
TN-S is one kind of TN network: fault current returns to the source over the PE conductor, and because the loop impedance is low a fuse or breaker opens quickly. Since N and PE are never joined downstream, no load current flows in the PE conductor. In mixed systems such as TN-C-S the split is made at the origin of the installation.
// ALSO KNOWN AS
TN-STN-C-S
// RELATED TERMS
TT systemThe source and the consumer have independent earthings; because fault current returns through the ground an RCD is essential.
IT systemA system whose source is isolated from earth (or earthed through a high impedance); the first earth fault does not cause an outage and insulation is monitored.
Earth-fault loop impedanceThe total impedance of the path a fault current follows (source, line conductor, protective conductor); it decides whether the protective device will trip in time.
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.
