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In transmission line faults, roughly 65% - 70% are asymmetric line-to-ground faults. [2] double line-to-ground fault - two lines come into contact with the ground (and each other), also commonly due to storm damage. In transmission line faults, roughly 15% - 20% are asymmetric double line-to-ground. [2]
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.
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 Line to Ground or Double Line to Ground fault.
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.
Admittance (Y) parameters may be defined by applying a fixed voltage to one port (V1) of a transmission line with the other end shorted to ground and measuring the resulting current running into each port (I1, I2) [8] [9] and computing the admittance on each port as a ratio of I/V The admittance parameter Y11 is I1/V1, and the admittance ...
In the case of a twisted line the individual conductors of an electric circuit swap places, either in their whole course (at cables) or at certain points (at overhead lines). The mutual influence of electrical conductors is reduced by transposing. The unbalance of the line, which can lead to one-sided loads in three-phase systems, is also ...
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.
Presence of uninterrupted ground fault may pose a significant safety risk: if the current exceeds 4 A – 5 A an electric arc develops, which may be sustained even after the fault is cleared. [27] For that reason, they are chiefly limited to underground and submarine networks, and industrial applications, where the reliability need is high and ...