Campbell Scientific CS547A-L Conductivity/Temperature Probe and A547A Interface - Manual (Page 23)

CS547A Conductivity and Temperature Probe and A547 Interface
8.2 Temperature Measurement Error
The overall probe accuracy is a combination of the thermistor's
interchangeability specification, the precision of the bridge resistors, and the
polynomial error. In a "worst case" all errors add to an accuracy of ±0.4
°C
over the range of -24 ° to 48°C and ±0.9°C over the range of -38°C to 53°C.
The major error component is the interchangeability specification of the
thermistor, tabulated in Table 8.2-1. For the range of 0
° to 50°C the
interchangeability error is predominantly offset and can be determined with a
single point calibration. Compensation can then be done with an offset entered
in the measurement instruction. The bridge resistors are 0.1% tolerance with a
10 ppm temperature coefficient. Polynomial errors are tabulated in Table 8.2-2
and plotted in Figure 8.2-1.
TABLE 8.2-1. Thermistor
Interchangeability Specification
Temperature
Temperature ( °C) Tolerance ( ±°C)
−40 0.40
−30 0.40
−20 0.32
−10 0.25
0 to +50 0.20
TABLE 8.2-2. Polynomial Error
-40 to +56 < ±1.0°C
-38 to +53 < ±0.5°C
-24 to +48 < ±0.1°C
FIGURE 8.2-1. Error produced by polynomial fit to published values
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