Temp. (°C)
Pt 100 (
Ω
Ω
)
0
100.0
10
103.9
20
107.8
25
109.7
30
111.7
40
115.5
50
119.4
60
123.2
70
127.1
80
130.9
85
132.8
90
134.7
100
138.5
MODEL SOLU COMP II
SECTION 8.0
TROUBLESHOOTING
8.6 SIMULATING TEMPERATURE
8.6.1 General.
The Solu Comp II accepts a Pt100 RTD. The Pt100
RTD is in a three-wire configuration. See Figure 8-2.
8.6.2 Simulating temperature
To simulate the temperature input, wire a decade box to
the analyzer or junction box as shown in Figure 8-3.
To check the accuracy of the temperature measure-
ment, set the resistor simulating the RTD to the values
indicated in the table and note the temperature read-
ings. The measured temperature might not agree with
the value in the table. During sensor calibration an offset
might have been applied to make the measured tem-
perature agree with a standard thermometer. The offset
is also applied to the simulated resistance. The Solu
Comp II is measuring temperature correctly if the differ-
ence between measured temperatures equals the differ-
ence between the values in the table to within ±0.1°C.
For example, start with a simulated resistance of 103.9
Ω
, which corresponds to 10.0°C. Assume the offset from
the sensor calibration was -0.3
Ω
. Because of the offset,
the analyzer calculates temperature using 103.6
Ω
. The
result is 9.2°C. Now change the resistance to 107.8
Ω
,
which corresponds to 20.0°C. The analyzer uses 107.5
Ω
to calculate the temperature, so the display reads
19.2°C. Because the difference between the displayed
temperatures (10.0°C) is the same as the difference
between the simulated temperatures, the analyzer is
working correctly.
FIGURE 8-2. Three-Wire RTD Configuration.
Although only two wires are required to connect
the RTD to the analyzer, using a third (and some-
times fourth) wire allows the analyzer to correct
for the resistance of the lead wires and for
changes in the lead wire resistance with tempera-
ture.
FIGURE 8-3. Simulating RTD Inputs.
47
