PXIe-4310 and TB-4310 (10V)/TB-4310 (600V)
|
© National Instruments
|
19
AI Typical Accuracy Equation
Accuracy
=
Reading
* (
GainError
) +
Range
* (
Offset Error
) +
Self Heating
+
Noise Uncertainty
Gain Error
=
Residual Gain Error
+
Gain Tempco
* (
TempChangeFromLastInternalCal
) +
Reference Tempco
* (
TempChangeFromLastExternalCal
)
Offset Error
=
Residual Offset Error
+
Offset Tempco
*
(
TempChangeFromLastInternalCal
) +
INL_Error
Self Heating
= If Reading > 120 V,
Self-Heating
* (
Reading
- 120 V), otherwise 0.
Noise Uncertainty
=
for a coverage factor of 3 σ
and averaging 10000 points.
Typical Accuracy Example
Accuracy at full scale is determined using the following assumptions:
•
TempChangeFromLastExternalCal
= 10 °C
•
TempChangeFromLastInternalCal
= 1°C
•
Number_of_readings
= 10000
•
CoverageFactor
= 3 σ
For example, on the 600 V range, the accuracy at full scale is as follows:
Gain Error
= 335 ppm + 15 ppm * 1 °C + 5 ppm * 10 °C = 400 ppm
Offset Error
= 16 ppm + 9 ppm * 1 °C + 51 ppm = 76 ppm
Self Heating
= 26 µV/V * (600 V - 120 V) = 12.48 mV
Noise Uncertainty
=
= 309 µV
Typical Accuracy
= 600 V * (
Gain Error
) + 600 V * (
Offset Error
) +
Self Heating
+
Noise Uncertainty
= 298 mV
Random Noise
* 3
10000
--------------------------------------------
10.3 mV * 3
10000
-------------------------------
