As eye watering the cost would be, IMO every substation serving >5MVA of load have their transformers outfitted with ballistic protection and concrete perimeter walls expanded to none BPS/BES substations.
Substations weaknesses are too well known amongst bad actors not to be rectified.
It appears both auto-transformers were indeed damaged at the West End Substation. Aerial footage shows both 230kV disconnects open and associated bushings grounded. Disassembled radiators can be seen in front of the north-west unit.
https://www.youtube.com/watch?v=FGE92ryM5vI&t=6s
Based...
One of the substations mentioned is called "West End 230kV Substation 6910 NC Hwy 211".
Which can be found here on Google maps:
https://www.google.com/maps/@35.21967,-79.5303,515m/data=!3m1!1e3
Viewing Google earth it appears this station has three 230kV incoming lines, two 230/115kV...
"Loop impedance" and "path impedance" are one in the same.
You're thinking of "earth fault loop impedance testing" which differs from calculating the series impedance of a circuit during design.
Hi David, this is simply untrue and a very dangerous assumption:
Please see 110.10, 240.4 and 250.4 (A) (5):
Table 250.122 makes a note of this.
Circuit impedance is required to be taken into consideration in order to allow an over current protective device to open before the thermal...
