Burster 9180, Руководство пользователя

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Model 9180
burster
Digital Panelmeter
Page 4-14
2. Logically combined alarms
The switching points
SET2
and
SET4
can be combined by means of programming with the
corresponding switching points SET1 and SET3 . This kind of alarm is not triggered by
comparison of the previously programmed display value, but by the comparison to the value
used to trigger the combined alarm.
When programming this alarm, the value of the first switching point is set (for example
SET1 = 200 ) and the interval ( Offset ) determined between this and the second alarm (for
example
TRACK2 = 50
). Even if the value of
SET1
changes,
alarm 2
is always triggered
50 points above
SET1
. If a negative value is programmed (-50),
alarm 2
is activated 50
points under
SET1
. Fig. 6.8.2d shows an example for a positive (
TRACK2
) and a negative
(
TRACK4
) logic combination.
3. Correction of excess volumes
Due to mechanical factors and assembly, for certain measurements, particularly for
weighing and dosing, it is not possible to stop an operation precisely at a certain point
(reaction time, "
weight in fly "- effect).
The "
weight in fly
"- effect arises when filling vessels. In this process a flow inlet valve is
closed via an alarm upon reaching a programmed value. However, as there can still be
residual material in the pipe or in the air when the alarm is triggered, the desired filling level
is exceeded in the vessel.
The function
AUTO TRAC
is particularly designed to correct these excess volumes. This
function is based on controlling the volume which exceeds the programmed amount or
measure. To obtain the desired end value, the alarm is triggered with the excess amount
taken into account.
Only the
SET2
alarm is equipped with an "
AUTO TRAC
" function. Here SET1 is the set
alarm.
To perform the "
AUTO TRAC
" function the desired switching point value is programmed in
SET1
.
SET2
is automatically programmed as the logically combined alarm (initially it had
the same value as
SET1
).
SET1 = desired switching point value
SET2 = AUTO TRAC
If the value of
SET1
is reached, output 1 interrupts the process, but the filling volume rises
to a value which is registered as the maximum value.
The measured maximum value is compared to the set value and the difference between the
two is saved as the
TRAC
value and deducted from
SET2
. The value of
SET2
is thus
somewhat smaller than that of
SET1
. During the next measurement
SET2
interrupts the
process so that the effective end volume approximately corresponds to the programmed
value in
SET1
.
This process is updated in the following measurements.