Self-Tune Diagnostic Messages - ABB C300 Operating Manual

...6 TUNING LEVEL

6.3 Self-tune Diagnostic Messages

Message
Flashing
S–tUNE
with
CAUtN
Flashing
S–tUNE
with
FAIL
20
Explanation
The self-tune process has
Pb–INt
selected a proportional band or
integral action time above the
HI–LMt
high limits of these parameters
so the high limit has been used.
or
With
'Start-up'
SP tOO
the control set point was >10%
CLOSE
of the display range above the
process variable, it may still be
too close to allow the self-tune
facility to determine the process
characteristics accurately.
or
With
'At Set Point'
INCrSE
ratio of process oscillation to
StEP
hysteresis value is too small for
best results.
The process is too slow for the
SLO
self-tuning to work correctly.
PrCESS
or
The process variable signal is
NOISY
excessively 'noisy'.
PrCESS
or
With
'Start-up'
SP tOO
process variable is <10% of the
CLOSE
display range, below the control
set point.
or
The input failure level has been
INPUt
exceeded, possibly due to a
broken sensors or the process
LIMItS
has exceeded one of the self-
tune limits.
Table 6.1 Self-tune Error/Diagnostic Messages
Action
B e c a u s e o f t h e p r o c e s s
characteristics, re-trying the self-
tuning process is unlikley to
improve the calculated control
parameters.
If desired, allow the process
tuning, although
variable to move further below the
control set point (by changing the
control output in the manual
control mode) before re-trying
'Start-up'
use the
facility.
tuning, the Restart self-tune with a larger
output step size or a smaller
hysteresis value.
must be at least equal to and
preferably greater than process
noise.
If possible, use a larger output
step value.
Check input wiring to try and find
the source of the problem. If the
process is changing rapidly then
allow it to settle before re-trying
the self-tuning process.
tuning, the Allow the process variable to
move further below the control
set point before re-trying the
'Start-up'
Alternatively, use the
Point'
Check input wiring to find the
cause of the failure or restart self-
tuning with a smaller output step
size.
self-tuning. Alternatively,
self-tune
'At Set Point'
Hysteresis
self-tuning facility.
'At Set
self-tune facility.