Servomex NanoTrace DF-760E, Инструкция по эксплуатации

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User Interface DF-760E 101
small positive offset is added to the analyzer O2 readings (display and output) to
compensate for the long term downward trending in the readings during cleanup. The
Active Zero Offset provides an automatic addition of offset that occurs in miniscule steps,
and within set guidelines, corresponding to the predictable behavior of a typical system
during cleanup.
When Active Zero Offset is enabled through the Diagnostics Menu, the User Zero Offset
feature is disabled and vice versa. While the User Zero Offset feature requires the user to
enter a fixed positive offset value to accommodate the baseline cleanup, the Active Zero
Offset does so automatically, and only when necessary.
The current Active Zero Offset value is shown in the CHECK/ADJUST ZERO menu. It
starts at a value of 0.00 ppb when the analyzer is first turned on, and then increments
automatically as the analyzer applies offset to the readings. After each User Zero
Calibration, the Active Zero Offset value is reset to 0.00 ppb and then automatically
increments again as needed.
The Active Zero Offset is designed to operate when the zero baseline is falling at a rate
less than 0.1 ppb/hr as would be the case after 1-2 weeks of initial operation. If user
calibrations are performed sooner, the O
2
readings may be decreasing too rapidly for the
Active Zero Offset feature to operate properly and negative O
2
readings may result.
If the Active Zero Offset value reaches 3 ppb a warning message CAL ZERO will flash in
the system status block on the display instructing the user that a zero calibration should be
performed. The maximum amount of offset that can be applied by this feature is 3 ppb.
Any further downward trend (baseline cleanup) exceeding –0.3ppb will result in negative
readings until the next user calibration is performed resetting the Active Zero Offset value
to zero.
If the Active Zero Offset feature is turned off, the User Zero Offset value will appear in its’
place in the CHECK/ADJUST ZERO menu. The previous user Zero Offset value (if any)
will reappear and immediately be applied to the live display readings. Likewise, if the
Active Zero Offset feature is on, then its’ value (if any) will appear and immediately be
applied to the live readings.
7.7
System Menu
The System menu controls operation of systems outside of the specific sensors, and allows
higher level user options to be implemented.