single-phase voltage transformer which is intended to have one end of its primary winding directly earthed, or a three-phase voltage transformer which is intended to have the star point of its primary winding directly earthed, ühefaasilise pingetrafo, mis on esmase mähise ühe otsaga otse maandatud, või kolmefaasiline pingetrafo, mis on esmase mähise tähtlülituspunktiks otse maandatud