any transformer 35 KVA or larger useally have a primary tap in the front and it will marked 4 points above and 2 points below but some have more than that so double check the nameplate to make sure

i do check transformer lead both " unloaded and loaded to make sure it correct voltage most of my time i set at least one step above the normal voltage by time it loaded up it get to correct level

Merci , Marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)