Fault Diagnostic Time Interval; Proof Test; Purpose Of Proof Testing; Expected Outcome Of Proof Testing - Honeywell XNX Safety Manual

XNX Universal Transmitter

4 Fault Diagnostic Time Interval

XNX conducts approximately 30 diagnostics total on the main board
and personality board. These diagnostics occur at different time
intervals, with the longest interval at 24 hours. But when a fault is
detected, it is reported within 3 seconds. Refer to the XNX Technical
Manual for more information on diagnostics.
Fault Diagnostic Time Interval

5 Proof Test

5.1 Purpose of Proof Testing

A proof test is a periodic test to detect failures in the system so that,
if necessary, the system can be restored to an "as new" condition or
as close as practical to this condition.

5.2 Expected Outcome of Proof Testing

The following features are checked and adjusted if required
• current output at different levels (4.0 mA and 20.0 mA)
• verifying zero gas and span gas calibration current output
• verifying current output of warnings and faults
• simulating warnings and faults
• validation of the current output of zero gas and/or span gas
calibration (required if the current output of zero gas and/or
span gas calibration had to be changed)

5.3 Tolerance of Output Current Levels

The tolerance for the output current levels is ± 0.1 mA.
Example: If the procedure requires the current output to be 4.0 mA,
the actual current reading at the controller end can range from 3.9 mA
to 4.1 mA.
6 Purpose of Proof Testing