By inserting the Neutral Grounding Resistors with appropriate characteristics, between the neutral point of the transformer and the ground it is possible to limit the ground fault current for a short time to allow a quick localization of the fault without damaging, at the same time, the resistor itself and the other expensive equipments of the network
The resistors must absorb a great energy for very short time, few seconds, and as components of the security system they must assure a high reliability. For this reason it is important to design NGRs optimizing the weight of active material (stainless steel) of the resistor elements according to the maximum acceptable heating overtemperatures.
Versions of NGRs for fixed and mobile Petersen coils applications are available.
TELEMA can also designed and manufactured NGRs to meet specific requirements for installation in seismic zones, on ships or offshore sites. A wide range of optional equipments as transformers, disconnectors, vacuum contactors, surge arresters and others can be associated and installed inside the NGR cubicles providing an integrated solution to optimize the space required at the installation sites.