20-38 Air Density Factor [%]
Range:
Function:
100 %
*
[50 - 150
%]
Set the air density factor for conversion
from pressure to flow in % relative to the
air density at sea level at 20
°
C (100% ~
1,2 kg/m
3
).
3.15.4 20-6* Sensorless
Parameters for Sensorless. See also
18-50 Sensorless Readout [unit]
,
16-26 Power Filtered
[kW]
and
16-27 Power Filtered [hp]
.
NOTE
Sensorless unit and Sensorless Information requires set up
by with sensorless specific plug in.
20-60 Sensorless Unit
Option:
Function:
[20]
l/s
[21]
l/min
[22]
l/h
[23]
m³/s
[24]
m³/min
[25]
m³/h
[70]
mbar
[71]
bar
[72]
Pa
[73]
kPa
[74]
m WG
[75]
mm Hg
[120]
GPM
[121]
gal/s
[122]
gal/min
[123]
gal/h
[124]
CFM
[125]
ft³/s
[126]
ft³/min
[127]
ft³/h
[170]
psi
[171]
lb/in²
[172]
in WG
[173]
ft WG
[174]
in Hg
3.15.5 20-7* PID autotuning
The frequency converter PID Closed Loop controller
(parameter group 20-**, FC Drive Closed Loop) can be
auto-tuned, simplifying and saving time during commis-
sioning, whilst ensuring accurate PID control adjustment.
To use auto-tuning it is necessary for the frequency
converter to be configured for closed loop in
.
A Graphical Local Control Panel (LCP) must be used in
order to react on messages during the auto-tuning
sequence.
Enabling
, puts the frequency
converter into auto-tuning mode. The LCP then directs the
user with on-screen instructions.
The fan/pump is started by pressing [Auto On] and
applying a start signal. The speed is adjusted manually by
pressing [
▲
] or [
▼
] to a level where the feedback is around
the system set-point.
NOTE
It is not possible to run the motor at maximum or
minimum speed, when manually adjusting the motor
speed due to the need of giving the motor a step in the
speed during auto-tuning.
PID auto-tuning functions by introducing step changes
whilst operating at a steady state and then monitoring the
feedback. From the feedback response, the required values
for
and
are calculated.
20-95 PID Differentiation Time
is set to value
0 (zero).
20-81 PID Normal/ Inverse Control
is determined
during tuning process.
These calculated values are presented on the LCP and the
user can decide whether to accept or reject them. Once
accepted, the values are written to the relevant parameters
and auto-tuning mode is disabled in
.
Depending on the system being controlled the time
required to carry out auto-tuning could be several minutes.
It is advised to set the ramp times in
or
and
according to
the load inertia before carrying out PID autotuning. If PID
autotuning is carried out with slow ramp times, the auto-
tuned parameters will typically result in very slow control.
Excessive feedback sensor noise should be removed using
the input filter (parameter groups 6-**, 5-5* and 26-**,
Terminal 53/54 Filter Time Constant/Pulse Filter Time
Constant #29/33) before activating PID autotuning. In order
to obtain the most accurate controller parameters, it is
advised to carry out PID autotuning, when the application
is running in typical operation, i.e. with a typical load.
Parameter Description
VLT
®
Refrigeration Drive Programming Guide
MG16H102 - VLT
®
is a registered Danfoss trademark
117
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