The three-phase synchronous machine of Problem 4.9 is to be moved to an application which requires that its operating frequency be reduced from 60 to 50 Hz. This application requires that, for the operating condition considered in Problem 4.9, the rms generated voltage equal 13.0 kV line-to-lines. As a result, the machine armature must be rewound with a different number of turns. Assuming a winding factor of kw = 0.928, calculate the required number of series turns per phase.