Air Core Neutral Grounding Reactors

Hilkar Neutral Earthing (Grounding) Reactors (NGRs) are single-phase reactors connected between the neutral point of a transformer or generator and earth to control single line-to-ground fault currents. By introducing a controlled inductive impedance into the grounding path, they limit fault current to a predetermined value.

Neutral Earthing Reactors reduce line-to-ground fault currents to levels that protect transformers, generators, switchgear, and other power system equipment, while maintaining sufficient current for protective relays to detect and isolate the fault. Under normal balanced operating conditions, no current flows through the reactor, resulting in negligible losses.

In addition to reducing short-circuit stresses caused by earth faults, Neutral Earthing Reactors also provide grounding impedance that limits the third-harmonic current component that can be produced by loaded generators, contributing to improved system stability and reliable operation.

A loaded generator can develop a third-harmonic voltage. A Neutral Earthing Reactor provides impedance in the grounding path to limit the third-harmonic current component.