M&C TechGroup EC-30_FD Operator's manual - Manual (Page 29)

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Gas sampling and gas conditioning technology 3-4.20-ME
Figure 12 shows the voltage characteristics in relation to temperature. If the measured voltage is
inside the shaded area, the sensor is defective and has to be replaced.
°C
V
-3
-2
-1
0
1
2
3
4
-30 -20 -10 0 10 20 30 40
Figure 12 Voltage in relation to the temperature of the cooling stage
Resistance method
In this case the sensor must be disconnected from pins 1 and 2 at the EC automatic control board
(Fig. 9) and removed from the cooling block. When measuring the resistance of the PT100 element,
this must be proportional to the ambient temperature. The resistance-temperature characteristics are
shown in Figure 13 below.
°C
Ohm
95
97
99
101
103
105
107
109
111
113
115
117
-10 0 10 20 30 40
Figure 13 Resistance-temperature characteristics of the PT100 temperature sensor
19.2 CHECKING THE TEMPERATURE SENSOR OF THE DEEP COOLING STAGE
In order to check the sensors for the low-temperature stages  and , the voltage at the EC30 control
board should be measured between pins 27 and 28 (fig. 15) for channel 1 and between pins 33 and
34 for channel 2. Figure 14 allocates a corresponding voltage value for a given temperature value.
This should be compared with the measured voltage value.