GROUNDING NEUTRAL POWER SYSTEM

In 1910, electric power systems are not grounded. This is due in the electric power systems is still small, so if there is fault current phase to ground fault current is still small, and usually less than 5 amperes. In general, if the fault current of 5 amperes or less, an electric arc that arise in contacts between the disturbed and the ground wire can still be extinguished itself. 

But the systems of power that increasingly large both in length and voltage. Thus the currents that arise in the event the greater the soil disturbance and electric arc that can no longer go out alone. Additional symptoms longer arc of land or ground arcing increasingly prominent. Symptoms of an arc of land is a process of termination (clearing) and at-re (restriking) from the electric arc repeatedly. This phenomenon is very dangerous because it may cause high transient overvoltages that can damage the equipment. 

System grounded in a state of disorder the ground wire

The methods of neutral earthing of the power systems are as follows:

1. Grounding through the resistance (resistance grounding).

2. Grounding through the reactor (reactor grounding).

3. Grounding without impedance (solid grounding).

4. Effective earthing (grounding effective).

5. With an impedance earthing reactors can be fickle (resonant grounding) or ground with Petersen coil.

In the systems are not grounded or delta system, the fault current depends on the capacitive impedance ZA, ZB and ZC, namely the capacitive impedance of each wire-phase to ground.

However, when the system is earthed fault current is no longer dependent only from impedance capacitive wires but also depends on the impedance earthing equipment and tansformator.

Unless the earth with Petersen coil, the impedance earthing device is very small compared to the capacitive impedance, or in other words it is no longer current noise depends on the impedance.

So with a grounded neutral fault current system clearly becomes larger than the current disruption in the delta system, but instead limit the voltage on the phases are not disrupted. So in determining the earthing impedance must be observed that the relationship between the large fault current and voltage that may arise.

System grounded in the disturbanceground wire