There is a long HVDC power line from northern Quebec Canada to Ayer,
Massachusetts USA. It operates at either +/- 375 kV or +/- 450 kV
depending on source. As I understand it, it is grounded at exactly one
point, near Saint-Claude, Quebec. You can see it on this Google
satellite view: where the power
line ROW runs diagonally on the right side, and the actual grounding
point is the weird circular shape at the upper right. Additionally,
multiple conductors (6) run from the ROW to the circle. The street
view at shows the huge towers
as well as 4 grounding leads, two at the top of the towers and two
others on wooden poles. They are on rather substantial insulators.
Does anyone know any details for this rather odd setup? Why multiple
grounding conductors, and any details of the circular structure?
Do the grounding conductors carry current during normal operation,
perhaps with the line at half power with one side out of service and
the grounding (neutral?) carrying the return current?
1 year ago