YSI 3100 - Manual (Page 32)

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Cable Series Resistance and Shunt Capacitance
YSI 3200 series cells utilize a 4-wire connection virtually eliminating errors due to cable
resistance.
The short cables provided as a part of regular cell assemblies will introduce negligible error in
most measurements. However, if longer cables are required or if extraordinary accuracy is
necessary, special precautions may be prudent.
When using the YSI 3232 cell adapter and a 2-wire cell (such as the YSI 3400 series cells) with
solutions having very high conductivity values, a high cable resistance will become a major
source of error unless accounted for. When working with solutions having very low conductivity
values and long cables with large capacitance, such as might be used with a flow-through cells at
remote locations, the large cable capacitance will become a major source of error.
Galvanic and Miscellaneous Effects
In addition to the error sources described above, there is another class of contributors that can be
ignored for all but the most meticulous of laboratory measurements. These errors are always
small and are generally completely masked by the error budget for cell-constant calibration,
instrument accuracy, etc. Examples range from parasitic reactances associated with the solution
container and its proximity to external objects to the minor galvanic effects resulting from oxide
formation or deposition on electrodes. Only trial and error in the actual measurement
environment can be suggested as an approach to reduce such errors. If the reading does not
change as the setup is adjusted, errors due to such factors can be considered too small to see.