Lub load ntawm lub hwj chim system, xws li hluav taws xob motors, hluav taws xob vuam tshuab, induction furnaces thiab lwm yam khoom siv hluav taws xob, tsis tsuas yog siv lub zog active, tab sis kuj "absorbs" reactive zog. Tsis tas li ntawd, cov transformers ntawm lub hwj chim system kuj xav tau reactive zog. Yog hais tias tag nrho cov reactive hwj chim yog muab los ntawm lub tshuab hluav taws xob, nws tsis yog tsuas yog uneconomical, tab sis kuj voltage tsis zoo, uas cuam tshuam rau kev siv ntawm cov neeg siv.
Lub hwj chim capacitors tuaj yeem "tsim" lub zog reactive hauv sinusoidal AC circuits. Yog hais tias lub capacitors txuas nrog nyob rau hauv parallel mus rau lub load (lub cev muaj zog), los yog lub hwj chim kis tau tus mob cov cuab yeej (transformer), ces lub reactive hwj chim yuav tsum tau los ntawm lub load los yog lub hwj chim kis tau tus mob cov khoom yog raws nraim txiav txim los ntawm capacitor mov.
Kev ua haujlwm ntawm lub capacitor yog reactive zog them nyiaj. Los ntawm in-site reactive fais fab nyiaj them, kab hluav taws xob poob tuaj yeem raug txo; kab hluav taws xob poob tuaj yeem raug txo kom txhim kho qhov hluav taws xob zoo; thiab qhov system fais fab mov muaj peev xwm tuaj yeem txhim kho.