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A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device that interrupts an electrical circuit when the current passing through a conductor is not equal and opposite in both directions, therefore indicating leakage current to ground or current flowing to another powered conductor.
Power system protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults [citation needed] through the disconnection of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the power system stable by isolating only the components ...
64 - Ground Protective Relay; 64F - Field Ground Protection; 64R – Rotor Earth Fault; 64REF – Restricted Earth Fault Differential; 64S – Stator Earth Fault; 64S - Sub-harmonic Stator Ground Protection; 64TN - 100% Stator Ground; 65 - Governor; 66 - Notching or Jogging Device/Maximum Starting Rate/Starts per Hour/Time Between Starts
A ground fault protection relay must trip the breaker to protect the circuit before overheating of the resistor occurs. High-resistance grounding (HRG) systems use an NGR to limit the fault current to 25 A or less. They have a continuous rating, and are designed to operate with a single-ground fault.
If after the first, swift reclose, the recloser closes onto a fault, it is likely that the fault is a secondary class of fault, vegetation contact or equipment failure. An overcurrent fault would indicate a line to line class fault, which can be confirmed by negative phase sequence overcurrent protection, whereas an earth fault can indicate a ...
A ground conductor only carries significant current if there is a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. In that case, circuit protection devices may detect a fault to a grounded metal enclosure and automatically de-energize the circuit, or may provide a warning of a ground fault.
If the wrong type was used on an installation, the level of protection given could be substantially less than that intended, in particular the voltage operated type can only protect against faults or shocks to metalwork connected to the circuit ground, connected to the VOELCB, it cannot detect current leaving a live wire and running to ground ...
Provide a relatively low-impedance path to ground, thereby maintaining the system neutral at or near ground potential. [3] Limit the magnitude of transient overvoltages when restriking ground faults occur. Provide a source of ground fault current during line-to-ground faults. Permit the connection of phase-to-neutral loads when desired. [2]