XITRON 2000I, Руководство пользователя

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54
2000I & 2000M User Guide, Rev B
Note: The 2000I and 2000M instruments do not have intrinsic safety
certification for process control systems.
Using the Adjust Mode to Check Calibration
For this application the “Adjust” mode of operation is used to measure the
error of the equipment being tested. To test, simply set the calibrator to the
required output level and then adjust the output level until the equipment
being calibrated reads the correct value. The display of the calibrator will
then show the actual error of the unit. When one unit has been calibrated,
remove the calibrator from the “Adjust” mode. The output level will then
revert to the nominal output level in readiness for calibration of the next unit.
Calibrating Transducer Systems:
Connect the 2000 instrument in parallel with a 4 – 20mA or a 1 – 5V
transducer output to modify the transducer’s indicated output.
Adjusting Calibration of Multiple Units
The drive capabilities of the 2000 instruments are sufficient to adjust the
calibration of multiple units of equipment simultaneously. In voltage mode
this is achieved by connecting all the units to be calibrated in parallel. 10 to
20 units can be adjusted simultaneously at voltages above 220mV. At
voltages below 220mV the 50
Ω
output impedance of the 2000 instruments
becomes significant.
If the units being adjusted have 10m
Ω
(or lower) input impedance then a
correction has to be made for the output impedance of the 2000 instrument.
•
The output impedance of the 220mV range is
45.048
Ω Ω
• 0.1%
•
The output impedance of the 22mV range is
49.998
Ω Ω
•
0.1%
.
•
Thus the correction required to allow for the input impedance of the units
being adjusted is:
Correction = (Z
O
+ Z
IN
) / Z
IN
ü
Where the required output voltage should be multiplied by
Correction.
ü
ZO
is the actual output impedance of the 2000I or 2000M
instrument.