GSC60
EN - 134
NOTES
It shall be noted that the expression of the phase Reactive Power with no sine
waveforms, would be wrong. To understand this, it may be useful to consider that both
the presence of harmonics and the presence of reactive power produce, among other
effects, an increase of line power losses due to the increased current RMS value. With
the above given relation the increasing of power losses due to harmonics is added to
that introduced by the presence of reactive power. In effect, even if the two phenomena
contribute together to the increase of power losses in line, it is not true generally that
these causes of power losses are in phase between each other and therefore that can
be summed mathematically
The above given relation is justified by the relative simplicity of its calculation and by
the relative discrepancy between the value obtained using this relation and the true
value
It shall also be noted, how, in case of an electric installation with harmonics, another
parameter called displacement Power Factor (Cosphi) is defined. In practice, this
parameter represents the theoretical limit value that can be reached for Power Factor if
all the harmonics could be eliminated from the electric installation.
Conventions on powers and power factors
As for the recognition of the type of reactive power, of the type of power factor and of the
direction of the active power, the below conventions must be applied. The stated angles
are those of phase-displacement of the current compared to the voltage (for example, in
the first panel the current is in advance from 0° to 90° compared to the voltage):
Equipment under test = Inductive Generator Equipment under test = Capacitive Load
90°
180°
P
act + = 0
Pfc + = -1
Pfi + = -1
P
reactc + = 0
Preacti + = 0
P
act - = Pact
Pfc - = -1
Pfi - = Pf
P
reactc - = 0
P
reacti - = Preact
P
act + = Pact
Pfc + = Pf
Pfi + = -1
P
reactc + = Q
Preacti + = 0
P
act - = 0
Pfc - = -1
Pfi - = -1
P
reactc - = 0
P
reacti - = 0
0°
P
act + = 0
Pfc + = -1
Pfi + = -1
P
reactc + = 0
Preacti + = 0
P
act - = Pact
Pfc - = Pf
Pfi - = -1
P
reactc - = Preact
Preacti - = 0
P
act + = Pact
Pfc + = -1
Pfi + = Pf
P
reactc + = 0
P
reacti + = Preact
P
act - = 0
Pfc - = -1
Pfi - = -1
P
reactc - = 0
Preacti - = 0
270°
Equipment under test = Capacitive Generator Equipment under test = Inductive Load
where:
Symbol Description Remarks
Pact+ Value of the active power +
Positive parameter
(user)
Pfc+ Capacitive power factor +
Pfi+ Inductive power factor +
Preactc+ Value of the capacitive reactive power +
Preacti+ Value of the inductive reactive power +
Pact- Value of the active power -
Negative parameter
(generator)
Pfc- Capacitive power factor -
Pfi- Inductive power factor -
Preactc- Value of the capacitive reactive power -
Preacti- Value of the inductive reactive power -
To Next Page
Loading...
General