Campbell-scientific CS547 Conductivity and Temperature Probe and A547 Bedienungsanleitung PDF herunterladen (Seite 18)

CS547 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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Campbell-scientific CS547 Conductivity and Temperature Probe and A547 Bedienungsanleitung Seite 18