Series1000 Operators Manual
13
FASt
This type results in a Zeigler/Nicholls type response with large
overshoots and undershoots. Settling time however will be fast.
WARNING
During tuning the tuner will, at times, apply 100% power to the plant .This is likely
to cause large swings in the process variable. DO NOT use the tuner if 100%
power or large swings may cause damage to your plant.
5.2
Starting the tuner
For the tuner to work correctly and produce meaningful results it is necessary that
the measured value is close to the normal working value of the process and that
the process is stable when the tuner is engaged. If the process is not stable then it
may be made so by one of the following methods:-
•
Setting the controller to manual mode so that the output power is fixed and
waiting until the measured value settles. Remember to return the controller to
auto mode when the tuner is started.
•
In Auto, turn off integral and derivative actions, set prop band to a large value
and wait for the measured value to settle.
In order to operate the tuner the following conditions must be satisfied:-
1. The auxiliary fixed outputs must not be selected. These are manually set levels
of output which may be configured so that they are applied whenever the
correct digital input is made.
2. The password requirements are satisfied. If a password has been set for the
tuner then the correct password must be used when entering the long scroll.
3. The controller must be configured as a heat only, heat/cool or motorised valve
instrument.
4. The profiler must be in its ready mode.
When the tuner is started the controller will switch to ON/OFF control mode. This
will cause oscillations in the measured variable around setpoint. When the
measured variable has crossed the setpoint five times the tuning is complete and
new values for P, I, D and possibly Rel will be calculated and applied immediately.
The Tuner will abort its tune operation under any of the following conditions:-
•
A mains interruption has occurred
•
An auxiliary output is selected
•
The tuner is switched off.
•
More than one hour has elapsed since the tuner was started.
