Igridi iyinethiwekhi exhumanisa izitshalo zokuphehla ugesi nezintambo zikagesi eziphezulu ezithwala ugesi ibanga elithile ziye eziteshini ezincane - "ukudluliselwa". Uma kufinyelelwa endaweni, iziteshi ezincane zinciphisa i-voltage "yokusabalalisa" emigqeni kagesi ephakathi bese ziqhubeka ziye emizileni kagesi ephansi. Ekugcineni, i-transformer epalini yocingo iyinciphisa ibe yi-voltage yasekhaya engama-volts angu-120. Bheka umdwebo ongezansi.

Igridi iyonke ingacatshangwa njengeyakhiwe izingxenye ezintathu ezinkulu: ukukhiqiza (izitshalo kanye nama-transformer akhuphukayo), ukudlulisa (imigqa nama-transformer asebenza ngaphezu kwama-volts ayi-100,000 - 100kv) kanye nokusatshalaliswa (imigqa nama-transformer angaphansi kwe-100kv). Imigqa yokudlulisa isebenza ngama-voltage aphezulu kakhulu angu-138,000 volts (138kv) kuya kuma-volts ayi-765,000 (765kv). Imigqa yokudlulisa ingaba yinde kakhulu - ngaphesheya kwemigqa yesifundazwe ngisho nemigqa yasemaphandleni.

Emigqeni emide, kusetshenziswa ama-voltage aphezulu asebenza kahle kakhulu. Isibonelo, uma i-voltage iphindwe kabili, ugesi unqunywa phakathi ukuze kube nenani elifanayo lamandla adluliswayo. Ukulahlekelwa kokudluliselwa komugqa kuhambisana nesikwele sogesi, ngakho-ke "ukulahlekelwa" komugqa omude kunqunywa ngesilinganiso sesine uma i-voltage iphindwe kabili. Imigqa "yokusabalalisa" itholakala emadolobheni nasezindaweni ezizungezile futhi iphuma ngendlela efana nesihlahla esijikelezayo. Lesi sakhiwo esifana nesihlahla sikhula sisuka esiteshini esincane, kodwa ngezinhloso zokuthembeka, ngokuvamile siqukethe okungenani uxhumano olulodwa olungasetshenziswanga olungasetshenziswanga esiteshini esincane esiseduze. Lokhu kuxhumeka kungavulwa ngokushesha uma kwenzeka isimo esiphuthumayo ukuze indawo yesiteshi esincane inikezwe amandla yisiteshi esincane esihlukile.