VT Characteristics
Variable torque characteristics used for pumps and fans.
60° AVM
Switching pattern called 60°
Asynchronous Vector Modulation (par. F-37 Adv. Switching Pattern).
Power Factor
The power factor is the relation between I
1
and I
RMS
.
Power
factor
=
3
x
U
x
I
1
cos
ϕ
3
x
U
x
I
RMS
The power factor for 3-phase control:
=
I
1
x
cos
ϕ1
I
RMS
=
I
1
I
RMS
since
cos
ϕ1 = 1
The power factor indicates to which extent the frequency converter imposes
a load on the mains supply.
The lower the power factor, the higher the I
RMS
for the same kW performance.
I
RMS
=
I
1
2
+
I
5
2
+
I
7
2
+ .. +
I
n
2
In addition, a high power factor indicates that the different harmonic currents are low.
All frequency converters have built-in DC link reactor in the DC link to have a high power factor and to reduce the THD on the main supply.
AF-650 GP Design Guide
10
1
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