Instruction Manual

3.3 Potentiostat
797 VA Computrace – Software
59
Notes:
• The CPVS measurement mode can only be used with RDE elec-
trodes.
• The measurement time
t (i) is defined as follows:
Interval time ≥ 100 ms → t (i) = 20/16.67 ms (power frequency
50/60 Hz)
Interval time < 100 ms → t (i) = Interval time / 4
3.3 Potentiostat
The potentiostat built-in in the 797 VA Computrace stand normally
works with full sensitivity for current measurements from 5 pA to
80 mA. Depending on the measured current, the current range will
be selected automatically between the lowest and the highest cur-
rent range. For fast measurements with CV, CVS, SqW or DC is
helpful to limit the highest and/or lowest current range in order to
avoid disturbing current leaps.
Highest current range [ 10 nA, 1/10/100 μA, 1/10 mA ; 10 mA ]
Limitation of the highest current range.
Lowest current range [ 10 nA, 1/10/100 μA, 1/10 mA ; 100 nA ]
Limitation of the lowest current range.
Note: If you work with the SqW mode, you should define a fixed
current range to avoid detecting problems caused by quick swee-
ping and high current. Put Highest current range and Lowest cur-
rent range
in the POTENTIOSTAT window on the same level (see
section 9.6 SqW Problems).
Because of the limited bandwidth of some current ranges, it is not
possible to freely select any Voltage step time or Frequency for a
distinct current range on the Voltammetric tab of the EDIT WOR-
KING METHOD PARAMETERS
window.
The following table shows the possible values for the modes DP,
SqW**, AC, NP, DC, CV*, CVS*: