Neutral Grounding Resistor ( NGR ) is a serially mounted resistor with a secondary neutral on the transformer before being connected to ground
There are two types of NGR, Liquid and Solid
1. Liquid
means that the resistor uses a solution of pure water that is stored in a vessel and salt (NaCl) is added to get the desired resistance value
2. Solid
While the solid type NGR is made of Stainless Steel,
FeCrAl, Cast Iron, Copper Nickel or Nichrome which are set according to their resistance value.
2. PURPOSE OF INSTALLING NGR
1. Neutral Grounding Resistor Used for grounding resistance in industrial power systems. It is generally connected between the ground and neutral of the transformer, generator and grounding transformer.
2. Neutral grounding resistors are used to limit the maximum fault current down to the which does not damage the equipment on the power system, but is sufficient to operate the relay to eliminate interference.
3. MAIN MATERIAL NGR
There are actually only 2 main NGR materials, namely:
1. Enclosure
2. RESISTOR
4. SUPPORTING MATERIALS
NGR Support Materials or commonly called Optional can be installed or not depending on the needs
1. CT (Current Transformer)
2. DS (Disconecting Switch)
3. LBS (Load Break Switch)
4. VC (Vacuum Contactor)