MATHEMATICAL MODELLING - A BASISFOR BUSHINGLOADINGGUIDES

former inwhichtheyaremounted. Thereareseveral approaches. The mostobvious are: A simple mathematical thermal modelisproposed asabasis fora bushing loading guide. Itisdemonstrated tohaveadequate accuracy for 1.Foraspecific design (orfamily oflike designs) conduct aseries of bothsteady-state andtransient bushing hot-spot temperature calcula- thermal overload tests toencompass all permissible transformer overtions. Modelconstants canbederived fromasetof"Overload Qualifi- loads. However, since eachparticular bushing could beinvolved inany cation" tests andrecommendations aremadefortheparameters of oftheextremely widerange ofoverload applications covered bythe significance tothese tests. Threepossible thermal failure modesare 12-16 tables oftransformer conditions showninthetransformer loading examined toestablish abasis forsetting amaximumpermissible hot- guides', I, 2thepossible combinations ofbushing tests becomes overspot temperature during overloads. Limitations onenvironmental fac- whelming. torswhichinfluence thebushing hot-spot temperature arealso discussed.