Igridi yinethiwekhi edibanisa izityalo zokuvelisa umbane kwiintambo zombane eziphezulu ezithwala umbane umgama othile ukuya kwizikhululo zombane - "ukudluliselwa". Xa kufikelelwa kwindawo ekuyiwa kuyo, izizikhululo zombane zinciphisa i-voltage "yokusasazwa" kwiintambo zombane eziphakathi zize ziqhubekele phambili kwiintambo zombane eziphantsi. Okokugqibela, i-transformer ekwipali yefowuni iyinciphisa ibe yi-voltage yasekhaya eyi-120 volts. Jonga umzobo ongezantsi.

Igridi iyonke ingacingwa njengeyakhiwe ngamacandelo amathathu amakhulu: ukuveliswa (izityalo kunye neetransformers ezinyukayo), uthumelo (imigca kunye neetransformers ezisebenza ngaphezulu kwe-100,000 volts - 100kv) kunye nokusasazwa (imigca kunye neetransformers ezingaphantsi kwe-100kv). Imigca yothumelo isebenza kwi-voltage ephezulu kakhulu ye-138,000 volts (138kv) ukuya kwi-765,000 volts (765kv). Imigca yothumelo ingaba nde kakhulu - kwimigca yelizwe kunye nemigca yasemaphandleni.

Kwimigca emide, kusetyenziswa ii-voltage eziphezulu ezisebenzayo. Umzekelo, ukuba i-voltage iphindwe kabini, i-current iyanqunyulwa phakathi ukuze kubekho amandla afanayo adluliselwayo. Ukulahleka kokudluliselwa kwemigca kuhambelana nesikwere samandla athunyelwayo, ngoko ke "ukulahleka" kwemigca emide kuyanqunyulwa nge-factor yesine ukuba i-voltage iphindwe kabini. Imigca "yokusasazwa" ifumaneka kuzo zonke izixeko nakwiindawo ezingqongileyo kwaye iphuma ngendlela efana neyomthi ojikelezayo. Olu lwakhiwo olufana nomthi lukhula lusuka kwi-substation, kodwa ngeenjongo zokuthembeka, ludla ngokuqulatha ubuncinci uqhagamshelo olunye olungasetyenziswanga kwi-substation ekufutshane. Olu qhagamshelo lunokwenziwa ngokukhawuleza xa kukho imeko engxamisekileyo ukuze indawo ye-substation inikwe amandla yi-substation eyahlukileyo.