Swedish Neutral Earth Fault Neutralization Device (GFN)

GFN (Ground Fault Neutralizer)

The Ground Fault Neutralizer device is capable of fully compensating against all long-term phase-to-earth fault currents (both fundamental and harmonic). In addition, it performs this operation in a very short time. With the use of modern computers and power electronics, the fault current can be completely avoided. This is particularly useful in overhead line networks. It is also useful in industry and city center networks using cable. Because most of the cable faults start as single phase-to-ground. If the fault is not compensated properly, then multi-phase fault occurs by affecting other phases.

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The GFN system consists of three separate components;

Arc Suppression Coil (Petersen Coil)
Control System (Neutral Manager)
Residual Current Compensator (RCC Inverter)

Under normal conditions, the GFN system continuously measures shunt admittance and stores this information.

When an earth fault occurs, these admittances change according to the normal operating condition and the fault condition is detected.

The coil value, which will reduce the capacitive current to the minimum value, is adjusted in order to detect the fault.

The GFN system includes a petersen coil connected between the neutral point of the power system and ground. Thanks to the system that constantly monitors the network, the petersen coil compensates the fault current by generating an inductive reactive current against the capacitive fault current at the time of fault.

At the same time, thanks to its power electronics-based residual current compensator, it also has the feature of absorbing the resistive residual fault current that the petersen coil cannot absorb and poses a risk.