Amortisseur bar with improved interface between free conductor bars and amortisseur ring

An end portion of a free conductor bar of a pole-face winding for the rotor of a large dynamoelectric machine includes a flat at its radially outermost extremity. The end fits loosely within an oversized hole in an amortisseur ring. The presence of the flat displaces the contact line between the end portion and the hole from a thin bridge region of the amortisseur ring to two lines of contact displaced inward into the body of the material of the amortisseur ring. The reduced contact force and the repositioning of the contact location avoids cracking in the amortisseur rings of large dynamoelectric machines.