IT system
Türkçe: IT sistemi
A 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.
// EXPLANATION
In an IT system the first earth fault produces only a tiny current, so the circuit does not trip and service continues. An insulation monitoring device raises an alarm so the fault can be cleared; if a second fault appears, protection operates. That is why it is used where supply must not be interrupted, such as operating theatres and intensive care.
// ALSO KNOWN AS
IT systemIT earthing
// RELATED TERMS
TN-S systemThe source neutral is solidly earthed and the neutral (N) and protective conductor (PE) run separately throughout the installation.
TT systemThe source and the consumer have independent earthings; because fault current returns through the ground an RCD is essential.
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.
InsulationMaterial or construction that separates live conductors from each other and from earth and does not conduct current.
