Slip rings - copper, or nickel plated copper
 
- slip rings are attached to the yaw shaft (using a small adapter tube which
   doesn’t show) as illustrated in the bottom photo
- hang down leads are then attached to the two slip ring leads, brought
   down through the bore of the yaw shaft and attached to the hang down
   cable coming down the center of the tower to the ground
- strain relief and sealing is done by casting the leads into an epoxy plug in
   the yaw shaft (keying grooves are machined in the bore wall)
- the yaw shaft can be ordered fully ready with hang down leads if desired