Samson TROVIS 6400 - Adaption (Self-Tuning)

6.3 Adaption (self-tuning)
For optimum configuration of control loops, the characteristic values of the controlled system
must be known. Self-tuning is an automized function used to record and optimize the dynamic
system characteristics.
Self-tuning of
TROVIS 6494
involves evaluation of the measured transfer function from which
the ideal control parameters are calculated.
Before conducting the adaption, the control loop should assume a calm state for five minutes,
with an controller output value under 80%.
The desired control mode (
PI
or
PID
response) must be selected prior to conducting the adap-
tion. PI control mode is selected with the control parameters
P
,
I
>
0
(for I (integral)-action com-
ponent) and
dP
=
0
;
PID
control mode implies use of control parameters
P
,
I
>
0
and
dP
>
0
(for I
(integral)-action component and D (derivative)-action component). Select the operating direc-
tion and the controller output prior to proceeding with the adaption.
The adaption option is selected in the configuration level with configuration block
AdP
. Con-
figuration switch
AdP
=
1
is used to set an adaption for optimum behaviour when the disturb-
ance z is instabile. After exiting the configuration level, the controller assumes MANUAL oper-
ation. Controlled variable x can be viewed in the top display; output variable y can be viewed in
the bottom display. Now, the adaption is ready to be started by means of the MANUAL/AUTO-
MATIC key (6). If not desired, de-select in the configuration level with configuration switch
AdP
=
0
using the yellow ENTER key (8).
Running the adaption procedure is accomplished by actuating the MANUAL/AUTOMATIC key.
If the current controller output value is less than 80 %, no adaption is initiated. As soon as the
adaption has been started, all keys except the MANUAL/AUTOMATIC key are locked until the
adaption has completed.
By starting the adaption routine, a 20 % step change of output variable y is controller output in a
positive direction, which informs the controller of a step response which it uses to calculate the
ideal control parameters.
The LED in the MANUAL/AUTOMATIC key continues to flash until the control parameters are
calculated and stored.
If necessary, the adaption procedure can be aborted at any time using the MANUAL/AUTO-
MATIC key.
After the adaption is finished, the controller assumes MANUAL operation. All control par-
ameters determined by the adaption are stored and in non-volatile and memory protected
against power loss. Their values can be changed as desired in the parameterization level.
Restraint:
The controller output option of the self-tuning function is to be selected so small that the system
excitation does not assume a critical value for the process.
The adaption procedure implemented in
TROVIS 6494
is intended for controlled systems where
recovery action and dead time are crucial factors which must be dealt with.
Code number for servicing 1732
33