For a delta-connected source feeding a Y-connected load, what is true about the phase voltages?

In a delta-connected source feeding a Y-connected (wye-connected) load, the phase voltages have a specific relation to the line voltages. The correct statement is that each phase voltage of the Y-connected load equals the difference of the corresponding line voltages in the delta configuration.

This relationship arises from how delta and wye configurations interact. In a delta connection, the line voltages are measured across two phases of the delta. To find the phase voltage across the Y-connected load, one must consider the voltage difference between the phases of the delta connection. For example, if you take the voltage across one phase of the Y load, it will correspond to the line voltage measured across two phases of the delta connection.

The other options do not accurately represent the relationship between phase and line voltages in this configuration. While line voltages in a delta are indeed equal to the phase voltages of the delta, the wye configuration does not have this one-to-one equality. Instead, the phase voltages in the wye connection depend on the specific line voltages applied across the delta.

Understanding this phase difference and how voltages relate in different configurations is essential for analyzing three-phase systems effectively.