Uthungelwano luthungelwano oludibanisa izixhobo zokuvelisa umbane kwiintambo zamandla ombane aphezulu ezithwala umbane kumgama othile ukuya kwizitishi ezincinci – “uthumelo”.Xa indawo ekuyiwa kuyo ifikelelwe, izitishi ezincinci zinciphisa amandla ombane "okusasazwa" kwimigca yombane ophakathi kwaye emva koko ukuya kwimigca yombane ephantsi.Ekugqibeleni, i-transformer kwipali yefowuni iyayinciphisa kwi-voltage yendlu ye-120 volts.Jonga lo mzobo ungezantsi.

Igridi iyonke inokucingelwa ukuba yenziwe ngamacandelo amakhulu amathathu: ukuvelisa (izityalo kunye ne-step up transformers), ukuhanjiswa (iintambo kunye neziguquli ezisebenza ngaphezu kwe-100,000 volts - 100kv) kunye nokusabalalisa (iintambo kunye neziguquli ezingaphantsi kwe-100kv).Iintambo zothumelo zisebenza kumandla ombane aphezulu kakhulu 138,000 volts (138kv) ukuya kuma-765,000 volts (765kv).Iintambo zothumelo zinokuba nde kakhulu - kwimizila karhulumente nakwimizila yelizwe.

Kwimigca emide, amandla ombane aphezulu asebenzayo asetyenziswa.Ngokomzekelo, ukuba i-voltage iphindwe kabini, i-current inqunyulwa kwisiqingatha sexabiso elifanayo lamandla ahanjiswayo.Ilahleko yokuhanjiswa komgca ilingana nesikwere sangoku, ngoko ke umgca omde "ulahleko" unqunywe ngumlinganiselo wesine ukuba i-voltage iphindwe kabini.Imigca "yokusasaza" yenziwa yasekhaya kuzo zonke izixeko kunye neendawo ezingqongileyo kwaye iphume ngendlela efana nomthi weradial.Esi sakhiwo sinjengomthi sikhulela ngaphandle kwisitishi esingaphantsi, kodwa ngeenjongo zokuthembeka, sikholisa ukuqulatha ubuncinci uqhagamshelo olugciniweyo olunye olungasetyenziswanga kwisitishi esikufutshane.Olu qhagamshelo lunokwenziwa ukuba lusebenze ngokukhawuleza kwimeko kaxakeka ukuze ummandla wesikhululo esingaphantsi wondliwe ngesinye isitishi.