Danfoss VLT Decentral Drive FCD 302 Design Manual page 11

Introduction
Thermistor
A temperature-dependent resistor placed on the frequency
converter or the motor.
Trip
A state entered in fault situations, for example if the
frequency converter is subject to an overtemperature or
when the frequency converter is protecting the motor,
process, or mechanism. The frequency converter prevents a
restart until the cause of the fault has disappeared. To
cancel the trip state, restart the frequency converter. Do
not use the trip state for personal safety.
Trip lock
The frequency converter enters this state in fault situations
to protect itself. The frequency converter requires physical
intervention, for example when there is a short circuit on
the output. A trip lock can only be canceled by discon-
necting 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.
Do not use the trip lock state 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.
60° AVM
60° asynchronous vector modulation
(parameter 14-00 Switching Pattern).
Power factor
The power factor is the relation between I
3 x U x I cosϕ
1
Power factor =
3 x U x I
RMS
The power factor for 3-phase control:
I1 x cosϕ1
Power factor = =
I
RMS
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
same kW performance.
2 2 2
I = I + I + I + .. + I
RMS 1 5 7
In addition, a high-power factor indicates that the different
harmonic currents are low.
The DC coils in the frequency converters produce a high-
power factor, which minimizes the imposed load on the
mains supply.
Target position
The final target position specified by positioning
commands. The profile generator uses this position to
calculate the speed profile.
MG04H302
Design Guide
and I .
1 RMS
I
1
since cosϕ1 = 1
I
RMS
for the
RMS
2
n
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Commanded position
The actual position reference calculated by the profile
generator. The frequency converter uses the commanded
position as setpoint for position PI.
Actual position
The actual position from an encoder, or a value that the
motor control calculates in open loop. The frequency
converter uses the actual position as feedback for position
PI.
Position error
Position error is the difference between the actual position
and the commanded position. The position error is the
input for the position PI controller.
Position unit
The physical unit for position values.
1 1
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