B-6
Computed Parameters, continued
True Power
Factor
Calculated using the True Average Power divided by the Apparent Power. See Note
below for sign information.
Displacement
Power Factor
Calculated using cosine of the phase angle between the fundamental frequency
components of voltage with respect to current (0
= 0
V
- 0
I
). See Note below for sign
information.
NOTE
The sign is the exclusive OR of the sign of the Watts and Vars. Note that for Power
Factor, the words “Lead” and “Lag” are definitive. As far as the signs go, it is assumed
that Lag (inductive) is plus and Lead (capacitive) is minus when energy is delivered to
the load.
In the code, this is implemented as:
Signum Watts: cosine 0
Signum Vars: sine 0
Signum PF: (Signum Watts) * (Signum Vars)
where signum denotes the positive or negative sign.
Source: The diagram above matches Figure 9-26 Relationships Between Watts, Vars, and Volt-
Amperes found on page 228 of the Handbook for Electricity Metering, Ninth Edition, ©1992,
Edison Electric Institute, Washington, D.C., USA.
Continued on next page
WATT
TPF
=
VA
PF
=
cos 0
Quad 2
|
Quad 1
PF Lead - | PF Lag +
Watts - | Watts +
Vars + | Vars +
--------------+--------------
Quad 3
|
Quad 4
PF Lag + | PF Lead -
Watts - | Watts +
Vars - | Vars -
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