Search results
Results from the WOW.Com Content Network
Ground loop current induced by stray AC magnetic fields (B, green) Ground loop currents can be induced by stray AC magnetic fields [5] [7] (B, green) which are always present around AC electrical wiring. The ground loop constitutes a conductive wire loop which may have a large area of several square meters.
A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device, more specifically a form of Earth-leakage circuit breaker, that interrupts an electrical circuit when the current passing through line and neutral conductors of a circuit is not equal (the term residual relating to the imbalance), therefore ...
In an electric power system, a fault or fault current is any abnormal electric current. For example, a short circuit is a fault in which a live wire touches a neutral or ground wire. An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire (phase or neutral) or a blown fuse or circuit breaker .
The connection between neutral and earth allows any phase-to-earth fault to develop enough current flow to "trip" the circuit overcurrent protection device. In some jurisdictions, calculations are required to ensure the fault loop impedance is low enough so that fault current will trip the protection (In Australia, this is referred to in AS3000 ...
The resistance path is the total resistance back through the supply transformer; to measure this an engineer will use an "earth fault loop impedance meter". The application of a low voltage allows a small current to pass from the socket back through earth to the supply transformer and distribution board.
In TN, an insulation fault is very likely to lead to a high short-circuit current that will trigger an overcurrent circuit-breaker or fuse and disconnect the L conductors. With TT systems, the earth fault loop impedance can be too high to do this, or too high to do it within the required time, so an RCD (formerly ELCB) is usually employed.
Earth continuity test: this test is to make sure the earthing system is properly connected Live testing. Earth fault loop impedance testing: this test is to check that if a fault did occur, that the system meets requirements to cause a disconnection of the supply within the time limit specified by standards Insulation resistance testing
In those cases, current is induced in the loop when a person makes contact with it and ground. Since this involves real current flow, it is potentially hazardous. This type of induced current occurs most often on long fences and distribution lines built under high-power transmission lines. [8] [9]