Metrohm 732 IC Detector - Manual (Page 112)

4.6 Triggering of functions
732 IC Detector / 733 IC Separation Center
105
4.6.3 key
ZERO
The key is used to trigger the auto-zero function. "Auto-zero"
is the name used for the automatic electronic background compensa-
tion, i.e. the current measured conductivity value is set to zero and
hence lies in the middle of the selected full-scale range. The diagram
below shows the operating principle of the auto-zero function. Before
the auto-zero function is activated for the first time or after it has been
switched off, the measuring signal lies outside the full-scale range (FS);
it is automatically set to 0 µ S/cm each time the key is
pressed.
0
+ FS
– FS
+ 1.5 FS
+ 1.8 FS
– 1.5 FS
– 1.8 FS
ZERO ZERO
ZERO OFF
4
The auto-zero function can be triggered at any time using the
key – also in the edit mode or when a program is running. Lighting up
of green LED 66 in the key shows that the electronic back-
ground compensation is active.
The auto-zero function works properly only when the measured value
remains relatively stable (e.g. not during the appearance of the injec-
tion peak at the start of the chromatogram).
Lighting up of the red overload display 88 shows that the measured
value lies outside ± 150% of the selected full-scale range. If the meas-
ured value is outside ± 180% of the selected full-scale range, the over-
load display 88 starts to flash and the display shows the absolute con-
ductivity (see also section 4.5.1).
Conductivity
Time
Overload
flashes
Overload
flashes
Overload
lit up
Overload
flashes