eDAQ e-corder, Manual

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24 eDAQ Potentiostats
The Status Indicator
When software (such as EChem, Chart or Scope) has located and
initialised the Dual Picostat the Status Indicator will turn on. If the light
does not go on when the software is run, check that the Dual Picostat is
properly connected. If there is still a problem, please refer to
Appendix B
Troubleshooting, page 85 .
The Overload Indicator
Located below and slightly to the left of the electrode cable connectors,
the Overload indicators,
Figure 3–1 will light continuously when an
‘out-of-compliance’ situation occurs, usually because of an open circuit
condition (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 Dual 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 12 V, potential control of the sample 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 Overload indicator will remain lit, and an alarm beep will sound
once an overload has occurred, even if the overload condition
subsequently goes away — 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 to minimise inter-electrode
resistances. 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 due to a low resistance between the auxiliary and
Status
Power
Trigger
Overload