To Manop and All
Here is the link from internet for you and your team to understand the different benefit of the “Solidity Neutral Earthed” VS “Resistance Earthed” for the distribution transformer.
Both PPTC and SSUT, using the Solidity Neutral Earthed of the 11kV/115 kV transformer the would very sensitive to the any fault outside boundary. Such as the case on Thursday night. That the single phase to ground fault at LKB would trig the instantaneous ground over current or 50 G.
The simple solution must be set up since design, to install the Resistance earthed at the STAR point of the step up transformer. But we do not have that resistance install. We have to fight for that installation.
You may see the link in the internet for your understand of the different type of neutral earthed.