Most of the Princeton Applied Research systems (PARSTATs, 263A, 283, VS II) can be configured into a ZRA.  In this configuration, no potential or current waveform is applied to the sample, so this is considered an “open-circuit” technique.  For this special configuration, the electrochemical cell will be connected to the cable leads of the potentiostat in a different manner:

Working electrode (green) is connected to one of the samples

If the sense lead (gray) is available, connect it to the same sample as the working electrode

Ground lead (black) is connected to the other sample

Reference lead (white) is connected to the reference electrode

Counter electrode (red) is not used

This configuration is used for such techniques as Galvanic Corrosion (current characteristics of two dissimilar metals immersed in a solution and measured as a function of time) or Electrochemical Noise (current and potential characteristics for two samples of the same composition measured as a function of time).

Note:   Models 273 and 273A cannot be configured as an open-circuit ZRA in this manner.