ABB AX411, User Manual, Page: 41 / 56

39
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Notes.
• The analyzer is calibrated by the Company prior to dispatch and routine recalibration is not necessary. High stability
components are used in the analyzer's input circuitry and, once calibrated, the Analog to Digital converter chip self-
compensates for zero and span drift. It is therefore unlikely that the calibration will change over time. It is not advisable to
attempt recalibration unless the input board has been replaced or the calibration tampered with.
• Prior to attempting recalibration, test the analyzer's accuracy using suitably calibrated test equipment – see Sections 7.2 and
7.3.
7.1 Equipment Required
a) Decade resistance box (conductivity cell input simulator): 0 to 10k (in incr ements of 0.1 ), accuracy ±0.1%.
b) Decade resistance box (Pt100/Pt1000 temperature input simulator): 0 to 1k (in incr ements of 0.01 ), accuracy ±0.1%.
c) Digital milliammeter (current output measurement): 0 to 20mA.
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Note. Resistance boxes have an inherent residual resistance which may range from a few m up to 1 . This value must
be taken into account when simulating input levels, as should the overall tolerance of the resistors within the boxes.
7.2 Preparation
a) Switch off the supply and disconnect the conductivity cell(s), temperature compensator(s) and current output(s) from the
analyzer's terminal blocks.
b) Sensor A:
1) Link terminals B9 and B10.
2) Link terminal B12 to the Case Earth Stud – see Fig. 6.8.
3) Connect the 0 to 10k decade r esistance box to terminals B13 and B14 to simulate the conductivity cell. Connect the decade
box earth to the Case Earth Stud.
4) Connect the 0 to 1k decade r esistance box to terminals B11 and B9 to simulate the Pt100/Pt1000 .
Sensor B (dual input conductivity only):
1) Link terminals B1 and B2.
2) Link terminal B4 to the Case Earth Stud – see Fig. 6.8.
3) Connect the 0 to 10k decade r esistance box to terminals B5 and B6 to simulate the conductivity cell. Connect the decade
box earth to the Case Earth Stud.
4) Connect the 0 to 1k decade r esistance box to terminals B3 and B1 to simulate the Pt100/Pt1000 .
c) Connect the milliammeter to the analog output terminals.
d) Switch on the supply and allow ten minutes for the circuits to stabilize.
d) Select the
FACTORY SETTINGS
page and carry out Section 7.3.
Fig. 7.1 Analyzer Terminal Links and Decade Resistance Box Connections
Terminal link
Decade Resistance Box Connections
Conductivity
Cell Simulator
Temperature
Simulator
Earth
B10 B11 B12 B13 B14
B9
Sensor A Terminal Numbers
Sensor B Terminal Numbers
B2 B3 B4 B5 B6 B1
7 CALIBRATION