Metrohm 746 VA Trace Analyzer - Manual (Page 554)

7.6 Diagnosis
746 VA Trace Analyzer / 747 VA Stand
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• Attach electrode cable WE to clamping screw WE-D.
•
2 diagrams are printed out and must be assessed as follows:
Segment WE-L (DCTMODE):
− In principle, the plotted diagonal must be straight. Small deviations
are partly due to the resolution of the printer.
− Current at voltage – 200 mV: – 1.6 µ A ... – 2.4 µ A*
− Current at voltage +200 mV: +1.6 µ A ... +2.4 µ A*
* These tolerance values refer to illustrative scatters, that is to the differences
between individual instruments. The value determined for a specific instrument
shows less scatter. The deviation depends mainly on the temperature and should
be around 10%.
Segment WE-D (AC1MODE):
− A symmetrical, gaussian-shaped peak should be plotted. The
evaluation must provide a result for the peak voltage U and the peak
current I, which are printed out at the end of the curve.
− Peak voltage U : – 450 mV ... – 550 mV