IEEE 1862-2014

This recommended practice applies to transmission system at 1000 kV ac and above. It defines standard insulation levels and specifies procedures for selecting insulation levels of ac transmission lines and substations. It also specifies reliability criteria under switching and lightning overvoltages. Suggestions on insulation coordination design are described. Overvoltage mitigation measures are recommended according to the characteristics of such ac systems. Some examples of insulation coordination are also presented.