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Shipboard Electrical Power Systems
book

Shipboard Electrical Power Systems

by Mukund R. Patel
December 2011
Intermediate to advanced content levelIntermediate to advanced
370 pages
12h 24m
English
CRC Press
Content preview from Shipboard Electrical Power Systems
AC Power Fundamentals 21
unit of volt-ampere reactive (VAR, or kVAR, or MVAR). The power factor cosθ of
the load has no units. The complex power S
˜
, being the product of volts and amperes,
has the unit of volt-ampere (VA, or kVA, or MVA).
Complex power S∠θ = P + j Q is a phasor, with Q out of phase by + 90° from
P as shown by the Power Triangle in Figure1.12. The trigonometry of power tri-
angles gives
S P Q= +
2 2
or
kVA kW kVAR= +
2 2
and
pf
P
S
kW
kVA
= =
or kW = KVA × pf (1.27)
It is noteworthy that the lagging power factor of the load circuit produces a positive
Q, and vice versa. Also, in complex power S
˜
= S∠θ = V
rms
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Publisher Resources

ISBN: 9781439828175