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14 MagCheck
3.2.2 Explanation of the automatic verification run (verified data)
Converter data Data indicated and stored
Measurement of the field current Calibrated and actual value [mA]
Measurement of field frequency Act frequency [Hz]
ADC linearity and accuracy test at 25% of full scale
1)
ADC linearity and accuracy test at 50% of full scale
1)
ADC linearity and accuracy test at 75% of full scale
1)
ADC linearity and accuracy test at 100 % of full scale
1)
Output of input amplifier and
analogue to digital converter: True
and act. value [% of full scale]
Testing of the 1st calibration point P04 for current output
2)
Testing of the 2nd calibration point P20 for current output
2)
Calibrated and actual value [mA]
Testing of the 1st pulse output with f = 500 Hz
3)
True and actual value [Hz] for
f100% = 1000Hz
If flowhead is tested as well
Measurement of field coil resistance Coil resistance (Ohms)
Measurement of resistance of electrode 1
4)
Measurement of resistance of electrode 2
4)
Measurement of isolation resistance of field coils
Resistance values are measured.
Display of subsequent voltage
levels and resistance values
Following the measurement, the measured data are stored in the MagCheck.
1) ADC test verifies accuracy of input amplifier and analogue to digital conversion of flow signal
During this test the GK of the converter is temporarily set to factory test conditions GK = 2.500.
At end of verification the GK will be reprogrammed automatically by MagCheck to original data.
2) mA output tests verify compliance of mA output with factory calibration settings
Time constant T settings via IMoCom is reduced by MagCheck to allow for sufficiently fast
settling of mA output and pulse output. At the end of the verification, the time constant will be
reprogrammed automatically by MagCheck to original data.
3) For test of frequency / pulse output setting of this output will be temporarily programmed by
MagCheck to 1000 Hz at full scale flow. At end of verification frequency / pulse output will be
reprogrammed automatically by MagCheck to original data.
4) If mode "Empty pipe" has been selected under MagCheck Function 1.1 electrode insulation
data are measured, displayed and stored.
In case of power interruption during flow meter verification e.g. by interruption of wiring, field current
supply etc. the setting of GK, pulse output and time constant must be checked and eventually
reprogrammed manually. Such an interruption is indicated by MagCheck after its restart with the
warning message: Last meter not re-programmed.
3.3 MagCheck as manual flow signal calibrator
3.3.1 Menu for manual calibration with IMoCom connection to IMoCom converters
MagCheck IMoCom connector must be connected to the IMoCom connector of the converter.
Note down all data settings and readings in a paper print of the Excel spreadsheet
“MagCheck_Verification_Listing.XLS” (see Appendix 1). After transfer of these data into this file,
error calculations and a protocol will be created automatically. Main menus must be selected
manually.