Lub grid yog ib lub network uas txuas cov chaw tsim hluav taws xob rau cov kab hluav taws xob siab uas nqa hluav taws xob mus rau qee qhov deb mus rau cov chaw hloov hluav taws xob - "kev xa hluav taws xob". Thaum mus txog qhov chaw, cov chaw hloov hluav taws xob txo qhov hluav taws xob rau "kev faib tawm" rau cov kab hluav taws xob nruab nrab thiab tom qab ntawd mus rau cov kab hluav taws xob qis. Thaum kawg, lub transformer ntawm tus ncej xov tooj txo nws mus rau qhov hluav taws xob hauv tsev ntawm 120 volts. Saib daim duab hauv qab no.

Tag nrho lub network tuaj yeem xav txog tias muaj peb ntu tseem ceeb: kev tsim hluav taws xob (cov nroj tsuag thiab cov transformers nce), kev xa hluav taws xob (cov kab thiab transformers ua haujlwm siab dua 100,000 volts - 100kv) thiab kev faib tawm (cov kab thiab transformers hauv qab 100kv). Cov kab xa hluav taws xob ua haujlwm ntawm qhov hluav taws xob siab heev 138,000 volts (138kv) txog 765,000 volts (765kv). Cov kab xa hluav taws xob tuaj yeem ntev heev - hla cov kab hauv xeev thiab txawm tias cov kab hauv tebchaws.

Rau cov kab ntev dua, cov hluav taws xob siab siv tau zoo dua. Piv txwv li, yog tias qhov hluav taws xob raug ob npaug, tam sim no raug txiav ib nrab rau tib lub zog xa mus. Kev poob ntawm kev xa kab yog proportional rau lub square ntawm tam sim no, yog li cov "kev poob" ntawm kab ntev raug txiav los ntawm plaub yog tias qhov hluav taws xob raug ob npaug. Cov kab "Kev faib tawm" raug nyob thoob plaws cov nroog thiab thaj chaw ib puag ncig thiab kiv cua tawm hauv txoj kev zoo li tsob ntoo radial. Cov qauv zoo li tsob ntoo no loj hlob tawm ntawm lub chaw hloov pauv, tab sis rau lub hom phiaj kev ntseeg siab, nws feem ntau muaj tsawg kawg ib qho kev sib txuas thaub qab tsis siv rau lub chaw hloov pauv nyob ze. Kev sib txuas no tuaj yeem ua haujlwm sai sai yog tias muaj xwm txheej ceev kom thaj chaw ntawm lub chaw hloov pauv tuaj yeem pub los ntawm lwm lub chaw hloov pauv.