during line to ground fault, is there really a current that will flow in the ground, how will the grounding rod help if there is no connection back to the source? please explain how grounding aids tripping of C.B's
The earth really is a conductor. In the US homes, power is fed from the grid as single phase voltage the voltage between the two power conductors is approximately 220 volts AC. At the power plant one conductor is connected to the earth (called grounding in the US, and earthing in some countries). At the residential service connection there are three terminals. The center terminal is connected to a ground rod. Because the earth is a conductor, this provides a path back to the generating plant. The power wires are connected to the other two terminals. Voltage measured between the outer terminals shows 220 volts. Voltage measured between either outer terminal and the center one shows 110 volts. Three wires are run to a branch circuit panel containing circuit breakers. A wire (called hot) feeds 110 volts from a circuit breaker to points of use. Another wire, (called neutral) returns current to the branch circuit panel. A third wire (ground) also goes back to the branch circuit panel. At the point of use, this third wire is connected to conductive parts of appliances, such as a metal kitchen stove. It is a safety feature. If a bare hot conductor were to make contact with the metal, enough current would flow to trip the circuit breaker, removing voltage from the circuit. Imagine this. By its nature plumbing is connected to ground. In this case there is no third wire. A hot wire in a toaster accidentally touches the housing on a toaster. There is no ground connection so no current flows. But there is 110 volts on the toaster housing. The homeowner has one hand on a faucet handle, and reaches over to wipe the toaster. He could be killed. Check out the link for more info.
In maximum mainscontinual distribution structures, the impartial is grounded at the substation transformer and usually at the get right of entry to element to human being premises. If a fault takes position which leads to a stay conductor entering touch with an uncovered conductive section of the package, any cutting-edge will bypass to floor and holiday a circuit breaker.
1. The purpose of the grounding rod is to give electrical equipment and its housings a grounded reference point. Without this the voltages of these might go wandering off to indeterminate levels causing (in extreme cases) arcs to jump on to passers by or door handles to provide major or minor shocks. If there is a fault in equipment which causes an higher voltage part to come into contact with a grounded part then a current may flow into the grounding rod. The return path of this current is through the ground (earth) via another grounded point (e.g of the local supply transformer's star point) and thus into the transformer at its low voltage winding end. If the supply has no such grounding point (this would, by the way, be most odd but it is physically feasible) then there would be no fault current flow but the grounding would still provide a degree of security from high voltages.
