Chemtrac SCC3500XRD, Руководство по эксплуатации, Страница: 22 / 58

Chemtrac Systems, Inc. Page 21
3.2.2 SCM2500XRD Setup Menu (1)
From the MAIN screen, press SETUP function key, the SETUP screen will display.
Within the SETUP screen menu, the
GAIN , OFFSET , and SCV ALARMS settings can
be modified.
u
v
w
x
y
z {
“
Definitions
u
Sensor Gain: Signal amplification factor, adjustable from 1X to 20X . The gain
should be adjusted so that a regular change in dosage results in a noticeable
deviation (e.g. 20 to 30 units). To select the proper gain setting let the reading
stabilize for 10 minutes and record the reading. Make a normal dosage change
and then allow another 5 to 10 minutes for the reading to fully stabilize. If the
reading did not change noticeably, simply increase the gain setting and repeat
testing. If the reading changed, but did so by more than 50 units, it is suggested
to decrease the gain setting. Ideal change in Streaming Current for a normal
dosage change is anywhere between 20 to 50 units. If the reading seems
unstable when flow, dosage, NTU, and PH are stable, then check to ensure the
probe is clean and that the sensor is getting a well mixed sample.
v
Offset Mode: Offset mode can be changed to IN or OUT . Changing the Offset
mode to from “OUT” to “IN” will automatically zero or null the current Streaming
Current reading. For example, if the current reading was –150 and the Zero
Offset was changed to “IN”, then the adjusted Streaming Current value is
displayed on the Main Screen would be zero. The reading will not stay exactly at
zero since the reading is always slightly changing as a result of slight changes in
charge. The Offset value will display at the line below. On the Main Display, the
raw Streaming Current value (with offset) will be displayed to the right of the
Zero Offset: IN. The different between the Streaming Current value and the raw
is the offset value. To disengage the Offset, simply change the Offset mode to
“OUT” and the true Streaming Current Reading will be displayed.
w
Offset Value: The Offset value indicates the amount of offset that has been
applied to the reading in order to offset the reading to zero. So that, at any time
the operator can see what the offset value is and if anyone has changed it from a
previous offset. To disengage the offset, simply change the Offset Mode to
“OUT” and the true Streaming Current Reading will be displayed. This is also
the method used to re-zero the reading if the current offset no longer
corresponds to optimum coagulant feed. To re-zero the reading when Offset
mode is “IN”, increased or decreased the Offset Value then press
Enter to
SAVE .