Campbell-scientific 110PV Surface Temperature Probe Manual de usuario descargar pdf (Pagina 9)

110PV Surface Temperature Probe

2. Accuracy

The overall probe accuracy is a combination of the thermistor's

interchangeability specification and the accuracy of the bridge resistor. The

Steinhart-Hart equation used to calculate temperature has a negligible error

(Figure 2-1). In a "worst case" the errors add to an accuracy of ±0.2°C over

the range of -40° to 70°C; ±0.5°C over the range of 71°C to 105°C; and ±1°C

from 106°C to 135°C. The major error component is the interchangeability

specification (tolerance) of the thermistor. The bridge resistor has a 0.1%

tolerance with a 10 ppm temperature coefficient. Figures 2-2 to 2-7 show the

possible worst case probe and measurement errors.

FIGURE 2-1. Steinhart-Hart Error

1 2 3 4 5 6 7 8 9 10 11 12 13 14 ... 31 32

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Campbell-scientific 110PV Surface Temperature Probe Manual de usuario Pagina 9