Metrohm 797 VA Computrace - Manual (Page 59)

3.2 VA measurement modes
797 VA Computrace – Software
47
Sweep parameters:
Hydrodynamic (measurement) [ on, off ; off ]
Enable/disable stirring of the RDE/SSE during the sweep.
Start potential (V) [ -5...+5 V ; -0.9 V ]
Start voltage for the voltage sweep.
End potential (V) [ -5...+5 V ; -0.1 V ]
Final voltage for the voltage sweep.
Base potential (V) [ -5...+5 V ; -0.9 V ]
Base voltage for voltage sweep.
Pulse time (s) [ ≥ 500 μs ; 0.04 s ]
Time interval during which an increasing voltage pulse is su-
perimposed on the base voltage.
Voltage step (V) [ > 0 V ; 0.006 V ]
Voltage step for direct voltage ramp.
Voltage step time (s) [ > 0 s ; 0.4 s ]
Time interval after which the voltage in the sweep is in-
creased or decreased by the amount
Voltage step .
Sweep rate (V/s) [ read only ]
Ramp slope calculated as Voltage step / Voltage step time .
Notes:
•
The NP measurement mode can be used with all types of elec-
trodes (but only in the exploratory mode!).
• The following conditions apply to the definition of the
Voltage
step time :
Voltage step time > Pulse time + 10 ms (HMDE/RDE)
Voltage step time > Pulse time + 220 ms (DME)
Voltage step time > Pulse time + Drop size × 40 ms + 200 ms
(SMDE)
• The measurement time
t (i) is defined as follows:
Pulse time ≥ 40 ms → t (i) = 20/16.67 ms ( power frequency
50/60 Hz )
Pulse time < 40 ms → t (i) = 0.5 × Pulse time