What is the reason for using NGR (Neutral Grounding Resistor) in a power transformer?

The main reasons for using a Neutral Grounding Resistor in a power transformer. We've explored how Neutral Grounding Resistors limit fault currents, stabilize voltage, reduce transients, and aid in fault detection. These devices are vital for maintaining a safe and reliable electrical power system.
1- The primary purpose of a Neutral Grounding Resistor is to limit the fault current already present in a single line to ground fault. That is why Neutral Grounding Resistors are mostly employed in low and medium voltage (LV and MV). Distribution Networks to ensure generators and transformers remain protected from damaging currents in the event of an earth fault. Alternative protective systems like direct earthling neutral and insulated neutral pose serious disadvantages e.g., transient over-voltages, damaging fault currents with possible arc blast, and difficulties in localizing the ground fault in the insulated systems). That is not the case with the Neutral Grounding Resistor system as it provides a swift response to localize the fault and even prevents the overheating. The Neutral Grounding Resistor acts as a current-limiting device, reducing the fault current magnitude to a level that the transformer and other protective devices can handle. It prevents the fault current from reaching dangerously high levels, which could result in severe damage to the transformer, electrical components, and even pose a safety hazard.
2- The second reason for using a Neutral Grounding Resistor is to stabilize voltage and reduce transients. Transformers are designed to operate at specific voltage levels, and any deviation from these levels can affect the performance of connected equipment. Additionally, switching events or sudden load changes can cause voltage transients, which may damage sensitive devices. By connecting a Neutral Grounding Resistor, we create a path for fault currents to flow to the ground. This grounding path helps stabilize the voltages across the transformer windings during fault conditions and reduces the magnitude of voltage transients. This ensures that the output voltage remains within acceptable limits, minimizing disruptions to the power supply and protecting connected equipment.
3- The third reason for using a Neutral Grounding Resistor is fault detection. Neutral Grounding Resistors can provide valuable information about the occurrence and location of faults in a power system. When a fault occurs, the Neutral Grounding Resistor experiences a voltage drop due to the fault current flowing through it.
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[@noelfaithfulkari2857]

Thanks alot sir. I would like you talk about electrical system protections and relay used for the protections in details, like settings...etc.

[@initiallearnwithme]

Thank you, Sure I will