Model 755A

Instruction Manual

245364-V May 2002

SECTION 3

OPERATION

3-1 OVERVIEW

Preparatory to startup and calibration, the operator should study Figure 3-1 (page 3-2), Figure 3-2 (page 3-7) and Table 3-1 (page 3- 5). Together they give locations and summarized descriptions of operating controls and adjustments of the Model 755A.

3-2 SELECTION OF RECORDER OXYGEN RANGE

The digital display provides readout over the full range of 0.00% to 100.00% oxygen, eliminating the requirement for expanded- scale operation. With a recorder, however, resolution is normally limited to approximately 1% of fullscale. Thus, if the recorder output is to be the important display medium for the particular application, expanded-scale operation may be necessary to obtain the desired readout accuracy. Such operation is obtained by an appropriate combination of scale expansion and zero suppression.

a.Recorder Oxygen Range Selection Procedure

3.Select the required zero suppression by appropriate settings of the following:

a.Set Recorder Zero Suppression Jumper for fixed value of 0%, 20%, 40%, 60% or 80% oxygen.

b.Set Recorder Zero Suppression Coarse Adjustment R41 for appropriate value in the range of 05 to 25% oxygen.

NOTE:

The actual applied zero suppression may be measured and established via readout on the digital display per the procedure of Section 3-2b (page 3-3).

Example 1, Selection of a Zero-Based Recorder Output Range:

•Desired oxygen range for recorder output: 0 to 100%.

Refer to Table 3-1 (page 3-5) and Figure 3-2 (page 3-7).

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 Recorder Oxygen Span Jumper in the position appropriate to the desired span. Note that on the circuit board switch positions are marked according to the amplifier gain.

•Required span of 100% oxygen is selected when Recorder Oxygen Span Jumper is in the 1X position.

•Required Zero Suppression is 0%, thus Recorder Zero Suppression Jumper, is removed, and R41, Recorder Zero Suppression Coarse Adjustment, and R104, Recorder Zero Suppression Fine Adjustment, are adjusted for 0% oxygen.

Desired Oxygen

Amplifier Gain

Span for Recorder

Marking on Board

100%

1X

20%

5X

10%

10X

5%

20X

2%

50X

1%

100X

Rosemount Analytical Inc. A Division of Emerson Process Management

Operation 3-1