Danfoss VLT HVAC Series, Programming Manual, Page: 206 / 338

3.19 Main Menu - Extended Closed-loop - FC 100 - Group 21
3.19.1 21-** Ext. Closed-loop
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 dis-
turbances.
The extended closed-loop PID controllers may be interconnected 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: par.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: par.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: par.26-40 Terminal X42/7 Output , par.26-50 Terminal X42/9 Output , par.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.
3.19.2 21-0* Extended CL autotuning
The extended PID closed-loop PID controllers ( par. 21-**, Ext. Closed-loop ) can each be autotuned, simplifying and saving time during commissioning,
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 par.21-09 PID Auto Tuning puts the relevant PID controller into PID autotuning mode. The LCP then directs the user with on-screen
instructions.
PID autotuning functions by introducing step changes and then monitoring the feedback. From the feedback response, the required values for PID
Proportional Gain, par.21-21
Ext. 1 Proportional Gain
for EXT CL 1, par.21-41
Ext. 2 Proportional Gain
for EXT CL 2 and par.21-61
Ext. 3 Proportional
Gain
for EXT CL 3 and Integral Time, par.21-22
Ext. 1 Integral Time
for EXT CL 1, par.21-42
Ext. 2 Integral Time
for EXT CL 2 and par.21-62
Ext. 3
Integral Time
for EXT CL 3 are calculated. PID Differentiation Time, par.21-23
Ext. 1 Differentation Time
for EXT CL 1, par.21-43
Ext. 2 Differentation
Time
for EXT CL 2 and par.21-63
Ext. 3 Differentation Time
for EXT CL 3 are set to value 0 (zero). Normal / Inverse, par.21-20
Ext. 1 Normal/Inverse
Control
for EXT CL 1, par.21-40
Ext. 2 Normal/Inverse Control
for EXT CL 2 and par.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 par.21-09
PID Auto Tuning
. 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 6-**,5-5* and 26-**, Terminal 53/54 Filter Time Constant/
Pulse Filter Time Constant #29/33) before activating PID autotuning.
3 Parameter Description VLT ® HVAC Drive Programming Guide
3-182
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