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VLT
®
HVAC Drive Programming Guide
14-03 Overmodulation
Option:
[0]
Off
[1] *
On
14-04 PWM Random
Option:
[0] *
Off
[1]
On
3.14.3 14-1* Line Power On/Off
Parameters for configuring line failure monitoring and handling.
14-10 Line Failure
Option:
[0] *
No function
[1]
Ctrl. ramp-down
[3]
Coasting
[4]
Kinetic backup
NOTE!
For best performance of controlled ramp-down and kinetic back-up, par.1-03
or
Variable Torque
Figure 3.2: Controlled ramp-down - short line failure. Ramping down to stop, followed by ramping up to reference.
Function:
Selects no overmodulation of the output voltage in order to avoid torque ripple on the motor shaft.
The overmodulation function generates an extra voltage of up to 8% of U
overmodulation, which results in an extra torque of 10–12% in the middle of the oversyncronous
range (from 0% at nominal speed rising to approximately 12% at double nominal speed).
Function:
No change of the acoustic motor switching noise.
Transforms the acoustic motor switching noise from a clear ringing tone to a less noticeable 'white'
noise. This is achieved by slightly and randomly altering the synchronism of the pulse width modu-
lated output phases.
Function:
Select the function at which the adjustable frequency drive must act, when the threshold set in par.
14-11
Line Voltage at Line Fault
via one of the digital inputs (par. 5-1*).
The energy left in the capacitor bank will be used to "drive" the motor, but will be discharged.
The adjustable frequency drive will perform a controlled ramp-down. par.2-10
Off
be set to
[0].
The inverter will turn off and the capacitor bank will back up the control card, thus ensuring a faster
restart when line power is reconnected (for short power zags).
The adjustable frequency drive will ride through by controlling speed for generative operation of
the motor utilizing the moment of inertia of the system as long as sufficient energy is present.
[1] (no automatic energy optimization should be active).
MG.11.C6.22 - VLT
®
is a registered Danfoss trademark
has been reached or a
Line Failure Inverse
Torque Characteristics
should be set to
3 Parameter Description
output voltage without
max
3
command is activated
Brake Function
must
Compressor
[0]
3-135
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