Fluke 434-II/435-II/437-II
Users Manual
A-6
Displacement Power Factor (DPF) and Cos
ϕ
Displacement power factor is calculated form fundamental power and apparent power
components. This identical to the Cos
ϕ
of the phase angle between fundamental voltage
and current.
Displacement Power Factor:
X
1
X
1
X
1
S
P
PF
=
System Displacement Power Factor
Υ
and
Δ
:
+
+
=
1
1
1
S
P
PF
Power & Energy Losses
Energy Loss has 2 main components:
•
Line Power Loss, caused by the various currents flowing through the line resistance
(I
2
.R losses)
•
Residual Power Loss, caused by Harmonics and Unbalance
Using the method of symmetrical components the system current components are
calculated.
Active system current:
(
)
+
+
+
+
ϕ
−
ϕ
⋅
=
1
1
1
a
1
i
u
cos
I
I
Reactive system current:
(
)
+
+
+
+
ϕ
−
ϕ
⋅
=
1
1
1
r
1
i
u
sin
I
I
Harmonic system current:
2
HC
2
HB
2
HA
H
I
I
I
I
+
+
=
Unbalance system current:
2
0
1
2
1
U
I
I
I
+
=
−
Neutral current:
Measured directly when using 4 wire (wye) systems
In combination with wiring resistance the line power losses due to this currents can be
calculated (P= I
2
. R)
Residual Power Loss is the loss caused by Harmonic power and Unbalance power.
Reactive Power (var) in itself causes no losses other than I
2
.R losses in the wiring.
Residual harmonic power loss:
1
H
P
P
P
−
=
Residual unbalance power loss:
+
−
=
1
1
U
P
P
P
Classic Method
The default setting for the Fluke 430 series II instruments is to use the Unified method to
measure power. For compatibility reason with guidelines that may exist within
companies, there is also a ‘classic’ method available that utilizes the arithmetic method
for system power as described in IEEE 1459. The method can be changed via the
Function Preference menu. To indicate that classic system with the arithmetic sum
method is used to calculate system power a
∑
(sigma) symbol is used behind the power
parameters e.g. VA
∑
.
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