Danfoss VLT FC51, Руководство по конструкции, Страница: 10 / 94

Trip Locked
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, 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.
1.5 Power Factor
The power factor is the relation between I
1
and I
RMS
.
Power factor =
3 ×
U × I1 × COSϕ
3 ×
U × IRMS
The power factor for 3-phase control:
=
I
1
× 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.
IRMS
=
I12
+
I52
+
I72
+ . . +
In
2
In addition, a high-power factor indicates that the different
harmonic currents are low.
Introduction
VLT
®
Micro Drive FC 51 Design Guide
8 MG02K302 - Rev. 2013-12-03
1 1