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•
The control amplifier has lost control of the cell. The absolute value of the cell current may be trying to
exceed 5 A, or the absolute value of the counter electrode voltage may be trying to exceed 8 V.
Either condition is a Control Overload.
•
The absolute value of the cell current has exceeded full scale on the current range presently in use.
This condition is an I Overload.
Transient (temporary) overloads during an experiment in which the cell voltage or current is being stepped or
swept are often normal. In most cases, they do not indicate a system or instrument malfunction.
Consider the case of an infinitely-fast voltage step into a perfect capacitor. In theory, charging a perfect
capacitor requires an infinite current. The current spike seen at each step in a stepped voltage waveform can
easily illuminate the Overload LED. The current spike normally decays to near zero before the actual current
and voltage readings are taken.
Overload indications when the cell is being connected or disconnected are common and usually do not
indicate a problem. Overloads can also be seen when one of the cell leads is disconnected from the other cell
leads, even though the cell is off. Again, this does not indicate a problem.
A steadily glowing Overload LED during an experiment most likely indicates a problem is occurring. Possible
causes include:
•
One of the cell leads is disconnected (this is the most common cause),
•
A gas bubble in the cell is blocking one of the electrodes,
•
The potentiostat could be oscillating.
A glowing red Overload LED does not necessarily indicate a system malfunction. The
Overload LED can illuminate when one or more cell leads are disconnected, without indicating a problem
with the system. The Overload LED can often illuminate momentarily during a swept or stepped
experiment. The only Overload LED indication that definitely points towards a problem is a continuously
glowing Overload LED during an experiment.
Personalization Label Area
The left side of the Interface 5000 front panel has a transparent area in its plastic overlay. A paper label behind
this area allows a custom appearance. This is especially important when the instrument is in a multiple-
potentiostat system.
Panel Indicators and Connectors
49
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