Agilent-technologies U2802A Uživatelský manuál stáhnout pdf (Strana 56)

4 Product Specifications

46 Agilent U2802A 31-Channel Thermocouple Input User’s Guide

Calculating System Accuracy

The overall measurement system comprises of three major components:

1 DAQ (U2355A or U2356A)

2 Signal Conditioner (U2802A), which includes CJ Sensor error

3 Sensor (Thermocouples)

Errors introduced by each of the above components has to be accounted

for when calculating the total system accuracy. Since errors from each

component are not correlated with each other, the total system error will

be the root- sum- square (RSS) of all the errors:

TOTAL

= E

DAQ

+ E

SIG_COND

+ E

THERMOCOUPLE

Example:

Assume the following conditions:

• DAQ: Agilent U2355A

• Signal Conditioning: Agilent U2802A

• Ambient temperature: 23 °C

• Thermocouple type: J- type, standard limits of error

• Temperature to measure: 600 °C

Assume the following error specifications:

• U2355A: Gain error = 0.02% of reading

• Offset error = 1 mV

• U2802A gain = 97.673

• Gain error = 0.06% of reading

• Offset error = 15 µV (with respect to input)

• Zeroing error = 6 µV (with respect to input)

• CJ measurement accuracy = 1 °C

• Thermocouple = greater than 2.2 °C or 0.75% error

• Noise error has been omitted to simplify the example

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Agilent-technologies U2802A Uživatelský manuál Strana 56