Lokacin da aka yi amfani da wani irin ƙarfin lantarki ko halin yanzu a kan coil na na'urar relay na lantarki, ƙarfin maganadisu da ke haifar da na'urar ya ratsa ta da'irar maganadisu da ta ƙunshi ƙarfe, karkiya, ɗamarar ɗaki, da ratar iska mai aiki. Karkashin tasirin filin maganadisu, armature yana jan hankalin sandar fuskar karfen ƙarfe, ta haka yana tura lambobin da aka saba buɗe don buɗewa da buɗe lambobin sadarwa na yau da kullun. Lokacin da ƙarfin lantarki ko halin yanzu a cikin nada bai kai wani takamaiman ƙima ba, ƙarfin amsawar injin ya fi ƙarfin jan hankali na lantarki, ɗamarar ta koma yanayinta na farko, lambobin da aka saba buɗewa, kuma rufaffiyar lambobin sadarwa suna rufe.
Sabili da haka, ana iya kallon relay na mota azaman taro wanda ya ƙunshi na'ura mai sarrafawa wanda ke aiki tare da nada da kuma babban da'irar da ke aiki tare da lambobin sadarwa. A cikin da'irar sarrafawa na gudun ba da sanda, ƙaramin halin yanzu mai aiki ne kawai ke nan. Wannan shi ne saboda ƙarfin lamba na maɓallin aiki ƙarami ne kuma ba za a iya amfani da shi don sarrafa lodi kai tsaye tare da manyan buƙatun lantarki ba; Yanayin kunnawa/kashewa kawai za'a iya sarrafa shi ta hanyar lambobin sadarwa.
Relay shine maɓallin sarrafawa da abu mai sarrafawa (mai kunnawa). Ɗaukar relay na famfo a matsayin misali, shine maɓallin sarrafawa don famfo mai, amma coil na relay na man fetur zai iya samar da da'ira kawai ta hanyar ƙasa na sashin sarrafa lantarki (ECU) lokacin da aka kunna transistor a cikin ECU.
