Neutral Earthing Reactors

A neutral earthing reactor is installed between the neutral point of the power system and earth. The reactor limits the amount of fault current that can flow during a fault, reducing its magnitude. This prevents or reduces the damage to equipment caused by an earth fault.

Reactors are typically used where there is a desire to limit the earth fault duty to a magnitude that is relatively close to the magnitude of a three-phase fault. 

Above a few thousand amps it is typically less expensive to use an earthing reactor compared to an earthing resistor.