Checkout Time Measurement Variable And Correction Variable; Checkout Time Control - ProMinent DULCOMETER Assembly And Operating Instructions Manual

8.6

Checkout time measurement variable and correction variable

Error text
LIMIT ERR
TLIMITERR
If upon elapsing of the checkout time, the valid measuring range is not reached, then the
DULCOMETER ® Compact Controller exhibits the following behaviour:
LIMIT ERR: The control is switched off. A fault current is output, provided the output
n
is configured as a measured variable output
TLIMITERR: The control is switched off. A fault current is output, provided the output
n
is configured as a correction variable or a measured variable output
Initially the limit transgression is only a limit value transgression. This leads to a
'WARNING' . Switching on of the checkout time 'TIMELIM' (> 0 minutes) converts the
limit value transgression to an alarm. The alarm switches the control to basic load.
8.7

Checkout time control

Monitoring of the control path
The checkout time monitors the con‐
trol path. The checkout time mecha‐
nism permits detection of possible
defective sensors.
Dead time determination
Each control path has a dead time. The
dead time is the time, which the control
path requires to detect a change or addi‐
tion of metered chemicals using its own
instrumentation.
You must select the checkout time so that
it is greater than the dead time. You can
determine the dead time, by operating the
metering pump in manual mode and, for
example, dosing acid.
Control parameters and functions
Description
Checkout time of the measured variable
Checkout time of the correction variable
NOTICE!
Dead time determination
You should only determine the dead
time if the current process cannot be
negatively influenced by the manual
metering.
You must determine the time, which the
control path (i.e. the entirety of controllers,
sensors, measurement water, flow
gauges, etc.) requires to detect a first
change in the measured value starting
from the beginning of dosing. This time is
'dead time' . A safety margin, e.g.
the
25%, must be added to this dead time.
You must allocate an appropriate safety
margin for your own particular process.
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