Arelayyog ib qho khoom siv hluav taws xob uas siv cov qauv siv hluav taws xob los yog lwm yam kev cuam tshuam lub cev kom ua tiav qhov "automatic on / off" ntawm circuits. Nws lub luag haujlwm tseem ceeb yog los tswj lub on-off ntawm cov loj tam sim no / high voltage circuits nrog me me tam sim no / teeb liab, thaum tseem ua tiav hluav taws xob cais ntawm circuits kom muaj kev ruaj ntseg ntawm kev tswj kawg.

Nws lub luag haujlwm tseem ceeb tuaj yeem muab faib ua peb pawg:

1. Tswj thiab Amplification: Nws tuaj yeem hloov cov kev tswj tsis muaj zog (xws li milliampere-theem tam sim no tso tawm los ntawm ib leeg-chip microcomputers thiab sensors) rau hauv cov hluav taws xob muaj zog txaus los tsav cov khoom siv hluav taws xob siab (xws li lub cev muaj zog thiab cov cua sov), ua haujlwm raws li "sib nqus amplifier". Piv txwv li, hauv cov tsev ntse, cov hluav taws xob me me uas xa los ntawm cov xov tooj ntawm tes tuaj yeem tswj tau los ntawm cov relays kom qhib thiab tawm lub zog ntawm cov cua txias hauv tsev thiab teeb.

2. Kev sib cais hluav taws xob: Tsis muaj hluav taws xob ncaj qha ntawm kev tswj xyuas hluav taws xob (tsis tshua muaj hluav taws xob, me me tam sim no) thiab tswj Circuit Court (siab voltage, tam sim no loj). Kev tswj cov lus qhia tsuas yog kis tau los ntawm electromagnetic lossis optical signals los tiv thaiv qhov hluav taws xob siab los ntawm kev nkag mus rau lub davhlau ya nyob twg thiab ua rau cov khoom puas tsuaj lossis ua rau muaj kev puas tsuaj rau cov neeg ua haujlwm. Qhov no feem ntau pom nyob rau hauv kev tswj circuits ntawm industrial machinery cov cuab yeej thiab cov khoom siv fais fab.

3. Logic thiab Kev Tiv Thaiv: Nws tuaj yeem ua ke los siv cov kev sib txuas ntawm cov logic, xws li kev sib cuam tshuam (tiv thaiv ob lub cev muaj zog los ntawm kev pib ib txhij) thiab ncua kev tswj hwm (kev ncua kev sib txuas ntawm cov load rau qee lub sijhawm tom qab fais fab tuag). Qee qhov tshwj xeeb relays (xws li overcurrent relays thiab overheating relays) kuj tuaj yeem saib xyuas qhov txawv txav ntawm Circuit Court. Thaum qhov tam sim no loj dhau los yog qhov kub thiab txias dhau lawm, lawv yuav txiav tawm Circuit Court los tiv thaiv cov khoom siv hluav taws xob los ntawm kev puas tsuaj ntau dhau.