Neutral Grounding Resistor (NGR) is electrical equipment for transformer or generator protection which is placed between the neutral and earth nodes of the system. The topmost purpose of NGR installation is to limit the magnitude of earth fault current so as to prevent severe damages in power system equipment.
An NGR works as a fault current regulator. It limits the fault current with resistance. So, when there is a heavy flow of fault current, it can easily damage the conductor because protection relays require some time to properly isolate the power system.