Example of three simulated values with their measurement errors/uncertainties attached.
Measurement instruments typically have errors.
These errors are detailed in their ISO 17025 calibration certificates along with their estimated calibration measurement uncertainties.
But this information, from the calibration certificate, is often used only to verify if such instruments are qualified or not to be used in the process measurement.
The LAquis SCADA system allows utilizing this information attached to the values read from the equipment in real time.
When the obtained values are compared to the process tolerance limits, these errors and uncertainties are taken into account.
That ensures better quality and knowledge of the measurement and also ensures that every instrument, even with more significant errors, is being used guaranteedly within the process tolerance margin.
The calibration certificate data is finally being used in practice automatically.
Each value, depending on the range or calibration measurements, has an estimated maximum total error attached to it. This error is associated with the SCADA tag value. Example: 10 ± 1.1 where 10 is the current value, and 1.1 is the maximum estimated total error in that point.
The measurement uncertainty can be generated by the uncertainty calculator.
The database with the stored values from the SCADA also keeps the error information attached to them.
The ISO 17025 based instrument calibration certificate is imported by LAquis SCADA using a XML format.
Reference here: XML generic calibration certificate.
<calibrations <calibration> <id>Multimeter1</id> <name>MULTIMETER</name> <number>16231531</number> <issuer>METETECHE</issuer> <user>Phillip Smith</user> <responsible>Phillip Smith</responsible> <calibrationdate>06/07/2017 19:59:21</calibrationdate> <validuntil>07/2018</validuntil> <ranges> <range> <name>ELECTRICAL VOLTAGE - VDC</name> <rangefrom>-400m</rangefrom> <rangeto>400m</rangeto> <resolution>0.1m</resolution> <unit>V</unit> <referencetype>STANDARD</referencetype> <measurements> <measurement> <reference>75.000m</reference> <bias>0.000000</bias> <uncertainty>0.004000</uncertainty> <veff/> <totalerror>0.004000</totalerror> <standard>FLUKE#VDC</standard> </measurement> <measurement> <reference>200.00m</reference> <bias>-0.000001</bias> <uncertainty>0.000058</uncertainty> <veff/> <totalerror>0.000059</totalerror> <standard>FLUKE#VDC</standard> </measurement> <measurement> <reference>350.00m</reference> <bias>-0.000100</bias> <uncertainty>0.004000</uncertainty> <veff/> <totalerror>0.004100</totalerror> <standard>FLUKE#VDC</standard> </measurement> </measurements> </range> </ranges> <sources> <source> <id>FLUKE#</id> <name>Multimeter</name> <number>131431131</number> <issuer>Mecatecape</issuer> <calibrationdate>3/2018</calibrationdate> <validuntil>3/2018</validuntil> </source> </sources> </calibration> </calibrations>