KROHNE ACM 500 EN - Manual (Page 12)

ACM 500 02/2013 12
4 Maintenance / Error handling
4.1 Error displays
The measuring device is self-monitoring for errors and plausibility. The indication in the display
supplies information about possible error conditions. The current outputs, too, are controlled in the
event of an error.
4.1.1 Overranging of the conductivity measuring range
Up to 21.6 mA, the current output follows linearly to the measured value (overrange). Therefore, if
the measured conductivity exceeds the set measuring range by more than 10%, the current output
remains within the limits.
This can be remedied by selecting a larger measuring range. Please also note that at
temperatures below 25°C the temperature compensation will always calculate larger conductivity
values.
^ 231.6 mS
1
25.4 °C
Measured conductivity
Measured temperature
00
Current output: overranging of conductivity
4.1.2 Overranging of ADC conductivity
At high temperatures and a high temperature coefficient it is possible that the ADC will overrange,
in which case the current output will output an error value of 21.6 mA.
In such a case, select a measuring range from the next-higher decade.
^^^^.^ mS
1
25.4 °C
Measured conductivity
Measured temperature
00
Overranging of conductivity
4.1.3 Error in conductivity measurement
At temperatures above 130°C, the device may in certain circumstances not be able to measure
conductivity any more. The current output then goes to the error value of 2.4 mA. Should this
condition occur at lower temperatures, this means that the device has an internal defect.
vvv.v mS
1
25.4 °C
Measured conductivity
Measured temperature
00
Conductivity error