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100

101

Section 8. Operation

314

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Error Calculations with Input Reversal = True

µVerror=gainterm+offsetterm

=(830.7µV*0.07%)+(1.5*0.67µV+1.0µV)

=0.581µV+2.01µV

=2.59µV(=0.061°C)

Error Calculations with Input Reversal = False

µVError=gainterm+offsetterm

=(830.7µV*0.07%)+(3*0.

67µV+2.0µV)

=0.581µV+4.01µV

=4.59µV(=0.11°C)

Input Error Examples: Type K Thermocouple @ 1300°C

Error in the temperature due to inaccuracy in the measurement of the

thermocouple voltage increases at temperature extremes, particularly when the

temperature and thermocouple type require using the ±200|250 mV range. For

example, assume type K (chromel-alumel) thermocouples are used to measure

temperatures around 1300°C.

These examples demonstrate that at temperature extremes, input offset error is

much less than input gain error because the use of a larger input range is required.

Conditions

CR3000moduletemperature,‐25to50°C

Temperature=1300°C

Referencetemperature=25°C

DeltaT(temperaturedifference)=1275°C

Thermocoupleoutputmultiplierat1300°C=34.9µV°C

‐1



Thermocoupleoutput=1275°C*34.9µV°C

‐1

=44500µV

Inputrange=±200mV

Error Calculations with Input Reversal = True

µVerror=gainterm+offsetterm

=(44500µV*0.07%)+(1.5*6.67µV+1.0µV)

=31.2µV+11.0µV

=42.2µV(=1.21°C)

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Campbell-scientific CR3000 Micrologger Manuale Utente Pagina 314

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