eDAQ Picostat, Руководство пользователя

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28 eDAQ Potentiostats
The Overload Indicator
Located on the left–hand side of the front panel is the Overload
indicator,
Figure 3–1 . When lit, this indicates that the Picostat has gone
out of compliance, which usually occurs because of an open circuit
(such as an unconnected or faulty electrode) or the resistance is too
high in the electrochemical cell. Higher resistances can be often be
encountered when electrodes are fouled by the products of electrolysis
reactions. The Picostat tries to compensate by increasing the
compliance potential (that is, the potential between the auxiliary and
working electrodes). If the compliance voltage exceeds specification,
about 13 V, potential control of the cell is lost and drifting, or
oscillation, of the signal can be seen. Any data collected during this
period is unreliable and should be discarded.
The Picostat Overload indicator will remain lit once an overload has
occurred — it will be reset once the scan has finished.
If the indicator comes on repeatedly, and your connections are good,
then try bringing your electrodes closer together, and/or increasing
electrolyte concentration, and/or modifying your experimental
conditions to avoid fouling of the electrodes. Redesigning you
electrochemical cell may be necessary. Normally electrochemical cells
are designed to keep the reference and working electrodes very close
together, however, when a potential overload occurs, you also need to
consider the distance between the auxiliary and working electrodes.
NOTE: A potential overload is quite different from a current overload
condition. A current overload is caused when the current signal
exceeds the full scale limits of the sensitivity setting of the current
channel. This is, in turn, due to a low resistance between the electrodes.