Brainchild C21 User Manual page 38

You can use the
set the appropriate values for PB, TI & TD according to the historical
records for the repeated systems. If the control behavior is still
inadequate, then use
section 3-12 section 3-12 for manual tuning.
CPB Programming : The cooling proportional band is measured by % CPB Programming :
of PB with range 50~300. Initially set 100% for CPB and examine the
cooling effect. If cooling action should be enhanced then decrease
CPB, if cooling action is too strong then increase CPB. The value of
CPB is related to PB and its value remains unchanged throughout the
auto-tuning procedures.
Adjustment of CPB is related to the cooling media used. For air is
used as cooling media, adjust CPB at 100(%).For oil is used as
cooling media, adjust CPB at 125(%). For water is used as cooling
media, adjust CPB at 250(%).
DB Programming: Adjustment of DB is dependent on the system DB Programming:
requirements. If more positive value of DB ( greater dead band ) is
used, an unwanted cooling action can be avoided but an excessive
overshoot over the set point will occur. If more negative value of DB (
greater overlap ) is used, an excessive overshoot over the set point
can be minimized but an unwanted cooling action will occur. It is
adjustable in the range -36.0% to 36.0 % of PB. A negative DB value
shows an overlap area over which both outputs are active. A positive
DB value shows a dead band area over which neither output is active.
Output 2 ON-OFF Control ( Alarm function ): Output 2 ON-OFF Control ( Alarm function ):
configured as alarm function. There are 6 kinds of alarm functions can
be selected for output 2, these are:
DE.LO DE.LO (deviation low alarm ),
), DB.LO DB.LO (deviation band in band alarm),
and PV.LO PV.LO ( process low alarm ). Refer to
the description of deviation alarm and process alarm with normal
alarm mode ( NORM is set for ALMD ).
37
auto-tuning auto-tuning program for the new process or directly
manual tuning manual tuning
DB.HI DB.HI
UM0C911A
to improve the control. See
The output 2 can also be
DE.HI DE.HI (deviation high alarm ),
(deviation band out of band alarm
PV.HI PV.HI (process high alarm )
Figure 3.3 Figure 3.3 and Figure 3.4 Figure 3.4 for