Generator

If both ends of the windings are brought out as six separate connections, this should give the option of connecting them in star (380V + neutral) or delta (220V without neutral). (If there are 12 connections, that would give some more series/parallel choices). The total KW should be the same.

50Hz is not a normal U.S. frequency; nor is 220V a normal distribution voltage, although there are colloquial references to it.

Rearranging the connections from a star to delta only changes the output configuration so your total KVA rating stays the same. Volts are volts regardless of how you got them.

American voltage is typically 120/240 60Hz For single phase and the most common three phase voltages are 120/208, 120/208/240, 240, or 277/480 for most applications.

There are also a number of less common voltage configurations as well but they tend to be more specific application.