fault, and reconnecting the frequency converter. Restart is
prevented until the trip state is cancelled by activating
reset or, in some cases, by being programmed to reset
automatically. Trip locked may not be used for personal
safety.
VT Characteristics
Variable torque characteristics used for pumps and fans.
VVC
plus
If compared with standard voltage/frequency ratio control,
Voltage Vector Control (VVC
plus
) improves the dynamics
and the stability, both when the speed reference is
changed and in relation to the load torque.
60
°
AVM
Switching pattern called 60
°
Asynchronous Vector
Modulation (See
14-00 Switching Pattern
).
1.1.8 Power Factor
The power factor is the relation between I
1
and I
RMS
.
Power factor =
3 ×
U × I1 × COS
ϕ
3 ×
U × IRMS
The power factor for 3-phase control:
=
I1 × cos
ϕ
1
IRMS
=
I1
IRMS
since cos
ϕ
1 = 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.
IRMS = I1
2 + I
5
2 + I
7
2 + . . + In2
In addition, a high power factor indicates that the different
harmonic currents are low.
The frequency converters' built-in DC coils produce a high
power factor, which minimizes the imposed load on the
mains supply.
How to Read this Design Gui...
VLT
®
Refrigeration Drive Design Guide
MG16G102 - VLT
®
is a registered Danfoss trademark
9
1
1
