being programmed to reset automatically. Do not use trip
for personal safety.
Trip lock
A state entered in fault situations when the frequency
converter is protecting itself and requiring physical
intervention, for example, if the frequency converter is
subject to a short circuit on the output. A locked trip can
only be canceled by cutting off mains, removing the cause
of the fault, and reconnecting the frequency converter.
Restart is prevented until the trip state is canceled by
activating reset or, sometimes, by being programmed to
reset automatically. Trip lock may not be used for personal
safety.
VT characteristics
Variable torque characteristics used for pumps and fans.
VVC
+
If compared with standard voltage/frequency ratio control,
voltage vector control (VVC
+
) improves the dynamics and
the stability, both when the speed reference is changed
and in relation to the load torque.
1.7 Power Factor
The power factor indicates to which extent the frequency
converter imposes a load on the mains supply. The power
factor is the ratio between I
1
and I
RMS
, where I
1
is the
fundamental current, and I
RMS
is the total RMS current
including harmonic currents. The lower the power factor,
the higher the I
RMS
for the same kW performance.
Power factor =
3 × U × I
1 × COSϕ
3 × U × I
RMS
The power factor for 3-phase control:
Power factor =
I
1
× cosϕ1
I
RMS
=
I
1
I
RMS
since cosϕ1 = 1
I
RMS
=
I
1
2
+ I
5
2
+ I
7
2
+ . . + I
n
2
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.
Introduction
VLT
®
Compressor Drive CDS 803
8
Danfoss A/S © 12/2015 All rights reserved.
MG18N202
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