VEGA VEGAFLEX 81 4 … 20 mA_HART two-wire Coax probe With SIL qualification - Manual (Page 31)

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6 Functional safety (SIL)
VEGAFLEX 81 • 4 … 20 mA/HART two-wire
44216-EN-130823
Measure the current output and compare the value with the calcu-
lated current value.
You have to determine the permissible deviation of the values
yourself. This deviation depends on the the accuracy requirements of
your measurement loop. Determine the permissible tolerance for the
deviation.
Mode "Range monitoring"
If both levels are important for the safety function, you have to pro-
ceed according to the mode "Range monitoring".
1. Move the level to at least three points within the range limits.
Keep a holding time of 1 minute for each level before you com-
pare the measured value.
2. Move the level to a point directly above and directly below the
range limits.
Keep a holding time of 1 minute for each level before you com-
pare the measured value.
Result
In all cases the output current must correspond to the respective level.
For this purpose, you have to measure for all levels the current output
and compare the values with the calculated current values.
You have to determine the permissible deviation of the values
yourself. This deviation depends on the the accuracy requirements of
your measurement loop. Determine the permissible tolerance for the
deviation.
After setup, the modified parameters must be verified. To do this, you
first have to enter the current PIN. The adjustment is then locked au-
tomatically. Then you carry out a comparison of two character strings.
You must confirm that the character strings are identical. This is used
to check the character presentation.
Then you confirm that the serial number of your instrument has been
carried over correctly. This is used to check device communication.
Then, all modified parameters that have to be confirmed are listed. Af-
ter this process is terminated, the safety function is again guaranteed.
Verify parameters/Lock
adjustment