3.19. Main Menu - Extended Closed Loop - FC 100 - Group 21
3.19.1. 21-** Ext. Closed Loop
The FC102 offers 3 Extended Closed Loop PID controllers in addition to the PID Controller. These can be configured independently to control either
external actuators (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 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
0-10V (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 (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, (setting [113]...[115] or [149]...[151], Ext. Closed Loop 1/2/3
•
Analog I/O card MCB 109, terminal X42/7...11:Par. 26-40/50/60 (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 auto-tuned, simplifying and saving time during commissioning,
whilst 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 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 for EXT CL 1, par 21-41 for EXT CL 2 and par 21-61 for EXT CL 3 and Integral Time, par 21-22 for EXT CL 1, par 21-42 for
EXT CL 2 and par 21-62 for EXT CL 3 are calculated. PID Differentiation Time, Par 21-23 for EXT CL 1, par 21-43 for EXT CL 2 and par 21-63 for EXT CL
3 are set to value 0 (zero). Normal / Inverse, par 21-20 for EXT CL 1, par 21-40 for EXT CL 2 and par 21-60 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. 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.
21-00 Closed Loop Type
Option:
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 auto-tuning sequence.
[0]
*
Auto
[1]
Fast Pressure
VLT
®
HVAC Drive Programming Guide
3. Parameter Description
MG.11.C5.02 - VLT
®
is a registered Danfoss trademark
165
3