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Instruction Manual
245364-V
May 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Operation 3-3
Model 755A
NOTE:
The Zero and Span adjustments on the
analyzer door are used only for the
calibration of the digital readout for 0
to 100% oxygen.
The suppressed recorder ranges may
only be set up after the digital readout
has been calibrated. When setting up
a suppressed recorder range, use only
R41, R104 (setpoint) and R88 (Span)
for adjustments. DO NOT RE-ADJUST
THE ZERO AND SPAN CONTROLS ON
THE ANALYZER DOOR.
Example 2, Selection of a Zero-
Suppressed Recorder Oxygen Range.
•
Desired oxygen range for recorder
output: 90% to 100%.
•
Required span of 10% oxygen (100%
- 90%) is selected when Recorder
Oxygen Span Jumper is placed in the
10X gain position.
•
Required zero suppression is 90%
oxygen, thus Recorder Zero
Suppression Jumper, is placed in
80% position, the highest setting
below the zero suppression level, and
R41, Recorder Zero Suppression
Coarse Adjustment, and R104,
Recorder Zero Suppression Fine
Adjustment, are adjusted for the
additional 10% required to reach the
desired zero suppression level (90%
desired level - 80% zero suppression
Jumper).
b. Readout of Applied Zero-Suppression
Voltage on Digital Display
In order to establish the precise zero
suppression required for the desired
recorder oxygen range, the actual applied
zero suppression voltage may be read on
the digital display.
Procedure:
1. Verify that Recorder Voltage Output
Jumper is in the position appropriate
to the recorder: 10 mV, 100 mV, 1 V
or 5 VDC.
2. Place the front panel TEST switch in
position 4, thus disconnecting the
signal input to permit display of the
zero-suppression voltage only.
3. Temporarily place Recorder Oxygen
Span Jumper in 100% oxygen (i.e.,
1X gain) position. The digital display
will now read the applied zero
suppression voltage in the range of
0.00 volt (equivalent to 0% oxygen) to
10.00 volts (equivalent to 100%
oxygen).
4. Obtain the required zero suppression
by appropriate combination of settings
on the Recorder Zero Suppression
Jumper and Recorder Zero
Suppression Adjustments R41 and
R104, as indicated by an exactly
correct reading on the digital display.
5. Return the Recorder Oxygen Span
Jumper to the normal operating
position for the selected range.
6. Set the front panel TEST switch to
position 1.
Example: With a highly expanded scale
such as the 99% to 100% oxygen range
of this example, a slight readjustment of
R104 may be required to set the recorder
pen at the precisely correct position on
the chart.