Lub zog ua haujlwm muaj nyob rau hauv ob qho tib si fais fab nroj tsuag thiab substations. Nws tuaj yeem siv lub zog AC lossis DC lub zog. Kev ua haujlwm ntawm lub zog siv hluav taws xob yog tsuas yog muab lub zog rau kev tswj xyuas hluav taws xob, cov khoom siv teeb liab, cov khoom siv tsis siv neeg thiab lwm yam khoom siv hluav taws xob ntawm lub tshuab hluav taws xob thaum lub tshuab hluav taws xob thiab lub tshuab hluav taws xob ua haujlwm; nyob rau hauv qhov kev tshwm sim ntawm ib tug Circuit Court tsis ua hauj lwm, nws muab cov kev tswj Circuit Court ntawm lub relay tiv thaiv, cov khoom siv teeb liab thiab Circuit Court breaker.
Fais fab mov los xyuas kom meej tias lawv tuaj yeem ua haujlwm tau zoo; Thaum lub hwj chim ntawm cov nroj tsuag AC cuam tshuam, muab lub zog rau cov khoom thauj xws li teeb pom kev sib tsoo, DC lubricating roj twj thiab AC fais fab mov los xyuas kom meej kev ua haujlwm ntawm kev sib tsoo kev ruaj ntseg loads. Yog li ntawd, nws yog ib qho tseem ceeb heev rau kev khiav hauj lwm lub hwj chim mov, uas yuav tsum tau txhim khu kev qha thiab ywj siab.
