Coordination of insulation as a design problem

The factors having influence on insulation design of transmission line and station are briefly reviewed, and it is pointed out that the progress of the art does not yet allow of close design of the insulation structure for insulation strength. The prominent part played by the lightning arrester is stressed, and the fact that it has a marked effect on the coordination of station insulation. Examples of a typical 110-kv. station where no coordination was made, and of a 220-kv. station where a deliberate coordination was attempted, are given, as well as the experience obtained with each.