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Chapter 3 -- Cell Cable Connections -- ZRA Mode Cell Connections
ZRA Mode Cell Connections
The PC4 can function as a precision Zero Resistance Ammeter (ZRA). It maintains two metal samples at the
same potential and measures the current flow between the samples. It can also measure the potential of the
samples versus a reference electrode.
The cell cable connections for ZRA mode are shown in Table 3-2. Note that the connections are very similar to
those for the potentiostat and galvanostat modes. A second working electrode is substituted for the counter
electrode and the orange counter sense lead must be connected.
Color
Type
Blue
Banana Plug
Green
Banana Plug
White
Pin Jack
Red
Banana Plug
Orange
Banana Plug
Long Black
Banana Plug
Short Black
Banana Plug
The counter sense and the working sense lead are each connected to different metal samples. In the ZRA
mode the PCI4 is programmed to maintain zero volts between these leads. It therefore maintains the two metal
samples at the same voltage.
The white pin jack on the cell cable is normally connected to a reference electrode. The potential between
this lead and the working sense lead is reported as the cell potential.
In ZRA mode, if you don't have a reference electrode in your cell, we recommend that you connect the white
reference lead to the working electrode. In theory, the measured potential will be exactly zero when this is
done. In practice, A/D noise and offset will create a small, almost noiseless signal very close to zero.
Membrane Cell Connections
The PCI4 can be used with membrane cells. In this type of cell, a membrane separates two electrolyte
solutions. Two reference electrodes are used - one in each electrolyte. Each electrolyte also contains a counter
electrode. The PCI4 controls the potential across the membrane. Table 3-3 shows the cell connections used
with a membrane type cell.
Table 3-2
Cell Cable Connections for ZRA Mode
Name
Working Sense
Working Electrode
Reference
Counter Electrode
Counter Sense
Floating Ground
Chassis Ground
3-3
Normal Connection
Connect to metal sample #1
Connect to metal sample #1
Connect to a reference electrode
Connect to metal sample #2
Connect to metal sample #2
Leave open or connect to a Faraday shield
Connect to Faraday Shield to reduce EMI
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