West Control Solutions TB 45 Temperature Monitor - Manual (Page 24)

a
For using the pre-defined scaling with thermocouples and resistance thermometers (Pt100), the settings for
InL and OuL as well as for InH and OuH must correspond with each other.
+
For resetting the input scaling, the settings for InL and OuL as well as InH and OuH must
correspond.
6.3.1 Input error detection
For life zero detection of connected input signals, variable adjustment of the response value for FAIL detection is possi-
ble according to formula:
Fail response value In.L - 0,125 * (In.H - In.L)
Example 1: In.L = 4 mA, In.H = 20 mA
Fail response value 2 mA
Example 2: In.L = 2 V, In.H = 6 V
Fail response value 1,5 V
6.3.2 Two-wire measurement
Normally, resistance and resistance thermometer measurement is in three-wire connection, whereby the resistance of
all leads is equal.
Measurement in four-wire connection is also possible for input I. With this method, the lead resistance is determined
by means of reference measurement.
With two-wire measurement, the lead resistance is included directly as a falsification in the measurement result. How-
ever, determination of the lead resistances by means of is possible.
g
Besides the connection of the both leads of the RTD / R sensor the 3rd
connector has to be short-circuited.
Procedure with Pt100, Pt1000
Connect a Pt100 simulator or a resistance decade instead of the sensor a t the test
point so that the lead resistance is included and calibrate the values by means of
2-point correction.
+
By means of measurement value correction the resulting temperature
value will be corrected, but not the resistance input value. In this case the
linearization error can increase.
Procedure with resistance measurement
Measure the lead resistance with an ohmmeter and subtract it from the measured
value via the scaling.
Functions
24 Input scaling TB 45
INP2
INP1
8 7 6
3 2 1
5
3 4
1
2