Resistance grounding solves the problem of transient over-voltages, thereby reducing equipment damage. Over voltages caused by intermittent (arcing) faults, can be held to phase-to-phase voltage by grounding the system neutral through a resistance which limits the ground current to a value equal to or greater than the capacitive charging current of the system. Thus the fault current can be limited, in order to prevent equipment damage. In addition, limiting fault currents to predetermined maximum values permits the designer to selectively co-ordinate the operation of protective devices, which minimizes system disruption and allows for quick location of the fault. The line-to-ground capacitance associated with system components determines the magnitude of zero-sequence charging current. The resistor must be sized to ensure that the ground fault current limit is greater than the system’s total capacitance-to-ground charging current. If not, then transient over-voltages can occur. The charging current of a system can be calculated by summing the zero-sequence capacitance or determining capacitive reactance of all the cable and equipment connected to the system. 
For prevention of resistor burning the Rating power of selected NGR shall be considered regarding the time and amount of NGR through earth fault currents. IEEE-32 is the standard used for rating and testing neutral grounding resistors. The most important parameters to consider from IEEE-32 are: the allowable temperature rises of the element for different