Authorized By:

Muhammad Imran Channa

2012-SECR-45

The arc Suppression coil invented in 1917 by WaldemarPetersen , so that’s why it is referred as Petersen coil.An arc suppression is device that is connected to theneutral to limit the capacitive earth fault currentflowing when earth fault occurs in a high or mediumvoltage network. This method grounding is calledresonance grounding , it has been used in Central&Eastern Europe as well as Scandinavian countries formany decades. The Petersen coil chokes fault currentbelow the level of self extinction for overhead networks.By this action all transient faults in overhead networkscan be cleared without tripping the feeder. The basicprinciple of Petersen coil remained unchanged since1917 & it is excellent properties have been mirrored bylow outage rates where it has been used.

When a phase-to-earth fault occur in underground 3phase system , the phase voltage of the faulty phase isreduced to earth potential as capacitance of faulty lineis discharged at the fault location, the phase-to-earthvoltages of other two phases rises by √3.

A charging current “IC” occurs between these phaseto earth capacitances, which will continue to flow viathe fault path while it remains.

IC is three times the charging current of each phaseto earth.

Diagrams Circuit Diagram Vector Diagram

When a phase to earth fault occur in underground 3phase systems, the phase voltage of faulty phase isreduced to ground potential .

This cause the phase voltage in the other two phase torise by √3 times.

This increase in voltage causes a charging current, Icbetween the phase-to-earth capacitances.

Advantages:

The Petersen coil is completely effective in preventing anydamage byan arcing ground.

This coil has the advantages of undergrounded neutralsystem.

Disadvantages:

Due to varying operational conditions, the capacitances ofthe networks changing from time to time. Thereforeinductance “L”of the Petersen coil required readjustment.

The line should be transposed.