The rated darajar na’urar ta sauya fasalin ƙa’ida ce da masana’anta suka yi don amfanin na’urar ta yau da kullun. Mai canzawa yana aiki ƙarƙashin ƙayyadadden ƙimar ƙima don tabbatar da ingantaccen aiki na dogon lokaci da kyakkyawan aiki. Ƙididdigansa sun haɗa da:

1. Ƙimar da aka ƙididdigewa: Ƙimar da aka ba da tabbacin ikon fitarwa na mai canzawa a cikin jihar da aka ƙididdige shi. An bayyana naúrar a cikin volt-ampere (VA), kilovolt-ampere (kVA) ko megavolt-ampere (MVA). Ƙimar ƙira na ƙarfin ƙididdigewa na firamare na farko da na biyu daidai ne.

2. An kimanta irin ƙarfin lantarki: yana nufin ƙimar garanti na ƙarfin wutar lantarki lokacin da na’urar ba ta da kaya, kuma an bayyana naúrar a cikin volts (V) da kilovolts (kV). Sai dai in an kayyade, ƙimar wutar lantarki tana nufin wutar lantarkin layi.

3. Rated current: yana nufin layin layi da aka ƙididdige shi daga ƙarfin da aka ƙididdigewa da ƙimar ƙarfin lantarki, wanda aka bayyana a cikin A (A).

4. No-load current: yawan adadin kuzarin da ake samu a halin yanzu zuwa halin yanzu lokacin da na’urar taranfofi ke gudana ba tare da kaya ba.

5. Hasara gajere: asarar wutar lantarki mai aiki lokacin da iskar da ke gefe ɗaya ba ta da ɗan gajeren kewayawa kuma ana amfani da iskar da ke ɗaya gefen tare da ƙarfin lantarki don sa iskar biyu ta kai ga ƙimar halin yanzu. An bayyana naúrar a watts (W) ko kilowatts (kW).

6. Rashin hasara: yana nufin asarar wutar lantarki mai aiki na mai canzawa yayin aiki mara nauyi, wanda aka bayyana a cikin watts (W) ko kilowatts (kW).

7. Short-Circuit Volt: wanda kuma aka sani da impedance volt, yana nufin adadin yawan ƙarfin lantarki da ake amfani da shi da kuma ƙimar da aka ƙididdigewa lokacin da iskar da ke gefe ɗaya ta yi gajeriyar kewayawa kuma iskar da ke gefe ta kai ga ƙimar da aka ƙidaya.

8. Ƙungiyar haɗin kai: Yana nuna yanayin haɗin kai na farko da na biyu na windings da kuma bambancin lokaci tsakanin ƙarfin layi, wanda aka bayyana a cikin agogo.