Lub hauv paus ntsiab lus ntawm kev khiav hauj lwm ntawm ib qho ua tiav ntawm cov khoom siv hluav taws xob tsawg-voltage fais fab faib khoom yog nyob rau hauv lub hauv paus ntsiab lus ntawm lub hwj chim systems. Thaum cov khoom siv hluav taws xob txuas nrog, hluav taws xob hluav taws xob tau xa los ntawm busbars mus rau ntau yam khoom siv hluav taws xob, xws li cov hluav taws xob hluav taws xob thiab cov contactors. Nyob rau hauv ib txwm ua hauj lwm tej yam kev mob, lub Circuit Court breakers nyob twj ywm kaw, thaum lub contactors qhib los yog kaw nyob rau hauv cov lus teb rau kev tswj cov teeb liab, li no enables tswj cov kev twb kev txuas loads.
Thaum lub sijhawm ua haujlwm hauv Circuit Court, cov khoom tiv thaiv- xws li relays thiab fuses - txuas ntxiv saib xyuas cov xwm txheej ntawm lub voj voog nyob rau lub sijhawm. Yog hais tias muaj teeb meem tshwm sim nyob rau hauv lub Circuit Court, relays tsim ib lub teeb liab uas ua rau lub Circuit Court breaker mus txawv tebchaws, yog li cuam tshuam lub Circuit Court thiab tiv thaiv ob qho tib si khoom thiab cov neeg ua haujlwm. Piv txwv li, thermal relays qhib kom cuam tshuam cov tswj Circuit Court nyob rau hauv cov xwm txheej ntawm lub cev muaj zog overload, thaum fuses tshuab kom disconnect lub Circuit Court nyob rau hauv cov kev tshwm sim ntawm ib tug luv luv Circuit Court.
Tam sim no transformers thiab voltage transformers hloov lub tam sim no thiab voltage signals nyob rau hauv lub Circuit Court rau hauv cov teeb liab tsim nyog rau kev siv los ntawm kev ntsuas thiab kev tiv thaiv pab kiag li lawm. Cov cuab yeej ntsuas ntsuas ntsuas qhov ntsuas hluav taws xob tsis ua haujlwm, thaum cov cuab yeej tiv thaiv ntsuas cov teeb liab no txhawm rau txheeb xyuas qhov tsis raug thiab pib ntsuas kev tiv thaiv tsim nyog.
