115 kV Cable Shield Termination 1

[kmh1]

At a local industrial site they have a set of 30 year old 115 kV single conductor cables terminated using potheads. The shields at the source ends appear to be terminated to ground through a carbon air gap mounted on the cable support structures (see attached photos). Can anyone confirm that the function of these these devices is to act as a spark gap in the event of a surge or fault to the cable shield? The cables are several hundred feet long and I imagine the normal operating voltage at full load would be quite high relative to ground on the cable side of the gap due to induced voltage.

 

[7anoter4]

If the shield is grounded only in a single point the shield induced current is limited-in order to limit the cable heating-but in the same time a build-up induced voltage could be very high and in this case at the second end of the cable the shield is grounded through voltage limiters. See IEEE Std 575/2014 chpt.7 Sheath voltage limiters.