Instruction Manual
ExTox Control Unit ET-1D Series
Page 9 of 17
Menu text
Selection
Function
Hyst.
0 % to 10 %
Fixes the alarm hysteresis in percent of the measuring
range. A non-latching alarm lapses only if it is the
value of hysteresis below the alarm level. By means of
this permanent repetition of alarm triggering due to
slight fluctuation of measuring values near the alarm
level are avoided. Example: Measuring range 100
ppm, Hysteresis 3 %, Alarm level 10 ppm. Alarm will
deactivated when the measuring value is below 7 ppm.
Standard setting: 0 %
Attention: Combination of low alarm levels with great
hysteresis may involve that alarms will be deactivated
never or very late.
NPC
0 to 5 %
Zero point attenuation can be adjusted. The range of
values from 0 to + NPC of measuring range is indi-
cated as zero. In the subsequent range up to + 2·NPC
of measuring range a fluent approach to a linear curve
takes place.
This function enables the suppression of small indica-
tion changes in the display without affecting the indi-
cation behaviour around the alarm levels. But alarm
levels shall not
Standard setting: 0 %, that means, deactivated.
I
ist
: The actual unevaluated value of the transmitter
output current which rests at the input of the control
unit is displayed.
The two last menu items serve for the adjustment of the control unit without any work to be
necessary at the transmitter.
Adjustment is done in two steps:
1.
When applying zero gas first the zero point (NP) is as long changed as the value indi-
cated on the display is ISTWERT 0. Please note that negative values are described as "<
0". If the adjustment is done correctly the preset "<" disappears and exactly 0 is de-
scribed.
2.
Then when applying test gas GAIN is adjusted until the actual value indicated on the
display corresponds to the nominal value.
Zero
2.000 to 6.000 State of the zero point. In case of value 4.000 [mA]
there is no correction done.
ACTVALUE: the measured value corrected in ZERO and
eventually GAIN is displayed.
Gain
0.500 to 2.000 Correction value for the gain. For explication please
see text above. In case of value 1.000 there is no cor-
rection done.
ACTVALUE: the measured value corrected in ZERO and
eventually GAIN is displayed.
Remarks for calibration/ adjustment at the control unit
The ET-1D is usually used with transmitter which dispose of a 4-20 mA output with linear
curve, that means an input current of 4 mA is interpreted as zero point and an input current
of 20 mA is interpreted as end value of measuring range. In between conversion is done
linearly according to the following formula:
