Specifications

Section 3. CR3000 Measurement Details
Panel Temperature error summary
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-55 -35 -15 5 25 45 65 85
Sum of Worst Case Errors
Thermistor Tolorance
CR1000 Measurement
Completion Resistor Error
S&H Err
FIGURE 3.4-1. Panel Temperature Errors
With an external driving gradient, the temperature gradients on the input panel
can be much worse. For example, the CR3000 was placed in a controlled
temperature chamber. Thermocouples in channels at the ends and middle of
each analog terminal strip measured the temperature of an insulated aluminum
bar outside the chamber. The temperature of this bar was also measured by
another datalogger. Differences between the temperature measured by one of
the thermocouples and the actual temperature of the bar are due to the
temperature difference between the terminals the thermocouple is connected to
and the thermistor reference (the figures have been corrected for thermistor
errors). Figure 3.4-2 shows the errors when the chamber was changed from
-65 to 70°C in approximately 90 minutes. Figure 3.4-3 shows the results when
going from 75 to 25°C. During these rapid changes in temperature, the
temperature of panel thermistor will tend to lag behind the terminals because it
is buried a bit deeper in the CR3000. Under these conditions, terminals closest
to the panel thermistor had the least error while terminals farthest from the
thermistor showed the most error in temperature measurements. A second set
of tests run with thermocouples connected to channels 8 through 14 showed a
similar pattern of temperature measurement errors.
3-10