Weidmuller CNDR - Universal galvanically isolated signal converter - Handbuch (Seite 14)

1
en CND/R
•Operation
General
The CND/R measures conductivity using conductance cell and Pt100
for temperature compensation. It displays the conductivity at the
reference temperature and has two alarm channels.
Conductance(Ω -1 ),Conductivity(Ω -1 cm -1 )andProbefactors
The conductance measurement is the inverse of the resistance
between the two probes. This depends on properties of the probe like
the distance between them. The probe factor P
f
gives the relationship
between measured conductance M
c
and the actual conductivity C
measurement, so that
C = M
c
x P
f
Normally electrical conductivity is measured at 25 °C. Since the
relationship to temperature is frequently non­linear, the CND/R allows
you to enter four additional points for linearisation. The points are
entered as temperature (T) and the ratio (R) of the conductivity at that
temperature (C
T
) to the conductivity at reference temperature (C
25 °C
).
So that
R = C
T
/ C
25 °C
Viewingthecelltemperature
Press the
ì key to display the cell temperature. If the display shows
Ovr , then the RTD is not connected correctly.
Over-rangedisplay
When the input signal is outside the programmed input range the
display will show Ovr for over­range or -Ovr for under­range.