
6 Shipboard Electrical Power Systems
values are customarily implied in the power eld, and we will do the same in this
book as well.
For average power, we recognize that the voltage and current that are out of
phase would produce less average power than those in phase with their peaks occur-
ring at the same time. If V and I are in phase (θ = 0), their product P = V × I is always
positive even when both V and I are negative during one half cycle. However, when
θ ≠ 0, the instantaneous power is negative when either V or I is negative and the
other is positive. If positive power means power owing from the source to the load,
then negative ...