Kev faib tawm transformer txoj haujlwm yog txhawm rau txo qis qis (feem ntau hu ua lub zog hluav taws xob nyob deb nroog). Nws hloov cov tswv yim 35kV lossis 10kV rau hauv cov zis 400V. Cov neeg ua haujlwm fais fab ces xaiv qhov tsim nyog voltage (380V lossis 220V) raws li tus neeg siv xav tau.
Lub tshuab hluav taws xob faib hluav taws xob yog cov khoom siv hluav taws xob zoo li qub hauv lub zog xa hluav taws xob uas xa AC lub zog los ntawm kev hloov AC voltage thiab tam sim no raws li txoj cai ntawm electromagnetic induction.
Nws feem ntau yog ntsia rau ntawm cov khoom siv hluav taws xob lossis hauv cov chaw nres tsheb, thiab feem ntau tuaj yeem txo qhov voltage ntawm 6-10kV mus txog kwv yees li 400V rau cov tswv yim rau cov neeg siv.
Lub hwj chim transformer yog ib qho khoom siv hluav taws xob siv los hloov qhov loj ntawm AC voltage. Nws yog cov khoom siv hluav taws xob zoo li qub uas xa hluav taws xob hluav taws xob los ntawm kev hloov AC voltage thiab tam sim no ntawm ob lossis ntau lub windings ntawm tib zaus, raws li lub hauv paus ntsiab lus ntawm electromagnetic induction.