Operating instructions

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
).
3.18.4 20-6* Sensorless
Parameters for Sensorless. See also par. 20-00 Feedback 1
Source, par. 18-50 Sensorless Readout [unit], par. 16-26 Power
Filtered [kW] and par. 16-27 Power Filtered [hp].
NOTE
Sensorless unit and Sensorless Information requires set
up by MCT10 with sensorless specific plug in.
20-60 Sensorless Unit
Option: Function:
Select the unit to be used with par. 18-50 Sensorless
Readout [unit].
[20] l/s
[21] l/min
[22] l/h
[23] m/s
[24] m/min
[25] m/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] ft/s
[126] ft/min
[127] ft/h
[170] psi
[171] lb/in
[172] in WG
[173] ft WG
[174] in Hg
20-69 Sensorless Information
Range: Function:
0 * [0 - 0 ]
3.18.5 20-7* PID autotuning
The frequency converter PID Closed Loop controller (parame-
ters 20-**, FCDrive Closed Loop) can be auto-tuned, simplify-
ing and saving time during commissioning, whilst ensuring
accurate PID control adjustment. To use auto-tuning it is
necessary for the frequency converter to be configured for
closed loop in par. 1-00 Configuration Mode.
A Graphical Local Control Panel (LCP) must be used in order to
react on messages during the auto-tuning sequence.
Enabling par. 20-79 PID Autotuning, 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] button on the
LCP and applying a start signal. The speed is adjusted manual-
ly by pressing the [
▲
] or [
▼
] navigation keys on the LCP 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
par. 20-93 PID Proportional Gain and par. 20-94 PID Integral
Time are calculated. Par. 20-95 PID Differentiation Time is set to
value 0 (zero). Par. 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 par. 20-79 PID Autotuning. Depend-
ing 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 par. 3-41 Ramp 1 Ramp Up
Time, par. 3-42 Ramp 1 Ramp Down Time or par. 3-51 Ramp 2
Ramp Up Time and par. 3-52 Ramp 2 Ramp Down Time accord-
ing 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
®
HVAC Drive Programming Guide
128 MG.11.CA.02 - VLT
®
is a registered Danfoss trademark
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