VEGA
76
EN - 52
The 5
th
and the 11
th
harmonic contrast the current flow through the motors making its
operation harder and shortening their average life.
In general, the higher the ordinal harmonic number , the smaller its energy is and therefore
the impact it will have on the devices (except for transformers).
16.3. POWER AND POWER FACTOR: DEFINITIONS
In a standard electric installation powered by three sine voltages the following is defined:
Phase Active Power:
(n=1,2,3)
)
cos(
I
V
P
n
n
nN
n
ϕ
⋅
⋅
=
Phase Apparent Power:
(n=1,2,3)
n
nN
n
I
V
S
⋅
=
Phase Reactive Power:
(n=1,2,3)
2
2
n
n
n
P
S
Q
−
=
Phase Power Factor:
(n=1,2,3)
n
n
n
F
S
P
P
=
Total Active Power:
3
2
1
P
P
P
P
TOT
+
+
=
Total Reactive Power:
3
2
1
Q
Q
Q
Q
TOT
+
+
=
Total Apparent Power:
2
2
TOT
TOT
TOT
Q
P
S
+
=
Total Power Factor:
TOT
TOT
TOT
F
S
P
P
=
where:
V
nN
=
RMS value of voltage between phase n and Neutral.
I
n
=
RMS value of n phase current.
f
n
=
Phase displacement angle between voltage and current of n phase.
In presence of distorted voltages and currents the previous relations vary as follows:
Phase Active Power:
(n=1,2,3)
)
(
I
V
P
n
k
n
k
n
k
k
n
ϕ
cos
0
∑
∞
=
=
Phase Apparent Power:
(n=1,2,3)
n
nN
n
I
V
S
⋅
=
Phase Reactive Power:
(n=1,2,3)
2
2
n
n
n
P
S
Q
−
=
Phase Power Factor:
(n=1,2,3)
n
n
n
F
S
P
P
=
Distorted Power Factor
(n=1,2,3)
dPF
n
=cos
f
1n
=
phase displacement between the
fundamentals of voltage and
current of n phase
Total Active Power:
3
2
1
P
P
P
P
TOT
+
+
=
Total Reactive Power:
3
2
1
Q
Q
Q
Q
TOT
+
+
=
Total Apparent Power:
2
2
TOT
TOT
TOT
Q
P
S
+
=
Total Power Factor:
TOT
TOT
TOT
F
S
P
P
=
where:
Summary of Contents for VEGA 76
Page 1: ...Copyright HT ITALIA 2004 Release EN 2 00 08 06 2004 VEGA 76 User s Manual...
Page 2: ......
Page 59: ...YAMUS0003HT0...
