Main Menu - Extended Closed-Loop - Group - Danfoss VLT FC 100 Series Programming Manual

Parameter Description

3.19 Main Menu - Extended Closed-loop - Group 21

The FC 102 offers 3 extended closed-loop PID controllers in
addition to the PID controller. These can be configured
independently to control either external servos (valves,
dampers, etc.) or be used together with the internal PID
controller to improve the dynamic responses to setpoint
changes or load disturbances.
The extended closed-loop PID controllers may be intercon-
nected or connected to the PID closed-loop controller to
form a dual loop configuration.
In order to control a modulating device (e.g., a valve
motor), this device must be a positioning servo motor with
built-in electronics accepting either a 0–10 V (signal from
Analog I/O card MCB 109) or a 0/4–20 mA (signal from
control card and/or General Purpose I/O card MCB 101)
control signal.
The output function can be programmed in the following
parameters:
•
Control Card, terminal 42: 6-50 Terminal 42 Output
(setting [113]...[115] or [149]...[151], Ext. Closed-
loop 1/2/3
•
General Purpose I/O card MCB 101, terminal
X30/8: 6-60 Terminal X30/8 Output, (setting [113]...
[115] or [149]...[151], Ext. Closed-loop 1/2/3
•
Analog I/O card MCB 109, terminal X42/7...11:
26-40 Terminal X42/7 Output, 26-50 Terminal X42/9
Output, 26-60 Terminal X42/11 Output (setting
[113]...[115], Ext. Closed-loop 1/2/3
General Purpose I/O card and Analog I/O card are optional
cards.
3.19.1 21-0* Extended CL autotuning
The extended PID Closed-loop PID controllers can each be
auto-tuned, simplifying and saving time during commis-
sioning, while ensuring accurate PID control adjustment.
To use PID autotuning it is necessary for the relevant
extended PID controller to have been configured for the
application.
A graphical Local Control Panel (LCP) must be used in
order to react on messages during the autotuning
sequence.
Enabling autotuning 21-09 PID Autotuning puts the relevant
PID controller into PID autotuning mode. The LCP then
directs the user with on-screen instructions.
®
VLT HVAC Drive Programming Guide
PID autotuning functions by introducing step changes and
then monitoring the feedback. From the feedback
response, the required values for PID Proportional Gain,
21-21 Ext. 1 Proportional Gain for EXT CL 1, 21-41 Ext. 2
Proportional Gain for EXT CL 2 and 21-61 Ext. 3 Proportional
Gain for EXT CL 3 and Integral Time, 21-22 Ext. 1 Integral
Time for EXT CL 1, 21-42 Ext. 2 Integral Time for EXT CL 2
and 21-62 Ext. 3 Integral Time for EXT CL 3 are calculated.
PID Differentiation Time, 21-23 Ext. 1 Differentation Time for
EXT CL 1, 21-43 Ext. 2 Differentation Time for EXT CL 2 and
21-63 Ext. 3 Differentation Time for EXT CL 3 are set to
value 0 (zero). Normal / Inverse, 21-20 Ext. 1 Normal/Inverse
Control for EXT CL 1, 21-40 Ext. 2 Normal/Inverse Control for
EXT CL 2 and 21-60 Ext. 3 Normal/Inverse Control for EXT CL
3 are determined during the 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 PID autotuning mode is disabled in 21-09 PID
Autotuning. Depending on the system being controlled the
time required to carry out PID autotuning could be several
minutes.
Excessive feedback sensor noise should be removed using
the input filter (parameter groups 5-5*, 6-**, and 26-**,
Terminal 53/54 Filter Time Constant/Pulse Filter Time
Constant #29/33) before activating PID autotuning.
21-00 Closed-loop Type
Option:
[0]
[1]
[2]
[3]
[4]
MG11CD22 - VLT ® is a registered Danfoss trademark
Function:
This parameter defines the application
response. The default mode should be
sufficient for most applications. If the
relative application speed is known, it
can be selected here. This will decrease
the time needed for carrying out PID
autotuning. The setting has no impact
on the value of the tuned parameters
and is used only for the PID autotuning
sequence.
Auto
*
Fast Pressure
Slow Pressure
Fast Temperature
Slow Temperature
3 3
3-123