Lub hauv paus ntsiab lus ntawm kev khiav hauj lwm ntawm lub transformer yog raws li txoj cai ntawm electromagnetic induction. Nws feem ntau muaj peb yam: lub hauv paus kauj, theem ob, thiab cov tub ntxhais hlau (los yog cov tub ntxhais sib nqus). Thaum alternating tam sim no ntws los ntawm lub hauv paus kauj, nws generates ib alternating magnetic flux nyob rau hauv lub core. Qhov kev hloov pauv no dhau los ntawm ob qho tib si thawj thiab theem nrab coils. Raws li txoj cai lij choj ntawm electromagnetic induction, kev hloov pauv ntawm cov hlau nplaum sib nqus dhau los ntawm lub kauj vab induces electromotive force (EMF) nyob rau hauv lub kauj. Qhov loj ntawm qhov induced EMF nyob rau hauv lub thib ob kauj yog ze ze rau qhov sib piv ntawm cov thawj thiab theem nrab coils. Thaum qhov kev hloov pauv ntau dua 1, qhov tso zis hluav taws xob ntawm lub kauj thib ob tshaj qhov hluav taws xob nkag ntawm thawj kauj, ua rau muaj qhov hluav taws xob theem - nce; conversely, thaum lub lem ratio yog tsawg tshaj li 1, qhov tso zis voltage yog qis dua lub input voltage, uas ua rau ib tug voltage theem - down.
Hais txog cov ntsiab lus kev, cov tub ntxhais hlau ua haujlwm los txhim kho cov hlau nplaum sib txuas, txo qis cov hlau nplaum sib nqus, thiab txhim kho kev ua haujlwm ntawm transformer. Cov tub ntxhais feem ntau yog tsim los ntawm stacking silicon steel laminations coated nrog insulating kua roj vanish kom txo eddy tam sim no poob. Lub hauv paus thiab theem nrab coils feem ntau raug mob siv cov xaim hluav taws xob, nrog rau cov xov tooj ntawm cov lem tau txiav txim siab los ntawm qhov hloov pauv qhov xav tau hloov pauv.