求翻译：Both wye and delta source connections have important practical applications. The wye source connection is used for long distance transmission of electric power,where resistive losses(I2R)should be minimal.This is due to the fact that the wye connection gives a line voltage that is 3 greater than the delta connection;hence,for the same power,the line current is 3 smaller .The delta source connection is used when three single-phase circuits are desired from a three-phase source.This conversions from three-phase to single-phase is required in residential wiring because household lighting and appliances use single-phase power.Three-phase power is used in industrial wiring where a large power is required.In some applications,it is immaterial whether the load is wye-or delta-connected.是什么意思？

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