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

Control parameters and functions
9.6

Checkout time for measured variable and correction variable

Error text
LIMIT ERR
TLIMITERR
If upon the expiry of the checkout time, the valid measuring range is not reached, then
the DULCOMETER
LIMIT ERR: The control is switched off. An error current is emitted, provided the
n
output is configured as a measured variable output
TLIMITERR: The control is switched off. An error current is emitted, provided the
n
output is configured as a correction variable output or a measured variable output
Initially the transgression of a limit is only a limit value transgression. This leads to a
'WARNING' . Switching on the control time 'TIMELIM' (> 0 minutes), creates an alarm
from the limit value transgression. In the event of a
[STOP] .
to
9.7

Checkout time control

Monitoring of the control path
The checkout time monitors the
control path. The checkout time
mechanism 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.
72
® Compact Controller exhibits the following behaviour:
Description
Checkout time of the measured variable
Checkout time of the correction variable
[TLIMITERR] a, the control switches
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.