The impetus for both Wagner's and Young's studies was the poor performance,
7.2 flashovers/100 miles-years, of the AG&E - OVEC 345-kV double circuit line,
which had a tower height of 150 feet (46 meters) and employed a shielding angle of
33' [6]. The result of Young's study is shown in Fig. 1, where the recommended
shielding angle is plotted versus tower height. Note that Young's recommendation
resulted in a shielding angle of about 12' for the 345-KV tower while maintaining the
previous recommendation of 30 to 35' for the then normal tower heights of 80 to 90
feet (24 to 27 meters). Subsequently the 345-kV tower was redesigned with a 12'
shielding angle. The line performance was reduced to under l.O/lOOmile-years, but
shielding failure flashovers now occurred to the middle phase since the shielding
angle to the middle phase exceeded that for the top phase. That is, because of
icing, the middle phase conductor was horizontally displaced further than the top
or bottom phase conductors. Thus another lesson was learned: check the shielding
angle to the middle phase for a vertical phase configuration.
The impetus for both Wagner's and Young's studies was the poor performance,7.2 flashovers/100 miles-years, of the AG&E - OVEC 345-kV double circuit line,which had a tower height of 150 feet (46 meters) and employed a shielding angle of33' [6]. The result of Young's study is shown in Fig. 1, where the recommendedshielding angle is plotted versus tower height. Note that Young's recommendationresulted in a shielding angle of about 12' for the 345-KV tower while maintaining theprevious recommendation of 30 to 35' for the then normal tower heights of 80 to 90feet (24 to 27 meters). Subsequently the 345-kV tower was redesigned with a 12'shielding angle. The line performance was reduced to under l.O/lOOmile-years, butshielding failure flashovers now occurred to the middle phase since the shieldingangle to the middle phase exceeded that for the top phase. That is, because oficing, the middle phase conductor was horizontally displaced further than the topor bottom phase conductors. Thus another lesson was learned: check the shieldingangle to the middle phase for a vertical phase configuration.
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