To get the energy, you will need both voltage and current. In a 3-phase system, irrespective of Y or delta, in a balanced system, (same load on all three lines), the power is V(line) · I(line) · SquareRoot(3).

Electricity is measure in power, which is the actual work equivalent. It is the rate of energy expenditure times the amount of time that it is expended. The units are watt-hours, or kilowatt-hours.

Does that help?

Brian