Emerson Rosemount 6888A, Reference Manual

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4.3 Alarm indications
The first indication of a problem at the O
2
measuring system usually comes from the
operators running the process. Critical alarms that render the O
2
measurement unusable
will force the 4-20 mA analog output signal representing O
2
to go to a default condition, as
follows:
4-20 mA signal alarm level Transmitter condition
0 mA Transmitter unpowered or completely failed
3.5 mA Critical alarm - transmitter reading unusable (factory de-
fault)
3.8 mA Reading under range (Example - you set range to 2-10%.
Current reading is 1.9%.)
4 to 20 mA Normal operation
20.5 mA Reading over range (Example - range is 0-10%. Current
reading is 12%.)
>21 mA Critical alarm - transmitter reading is unusable (you can
choose this alarm level instead of the factory default level
of 3.5 to 3.6 mA).
NOTICE
To ensure correct operation, you should make sure that the Digital Control System is
configured to interpret these signal levels correctly.
Once an alarm condition is identified, the Rosemount 6888A offers a number of
diagnostics to interpret the specific alarm.
Alarm indications are available via the optional Rosemount 6888Xi or the 375/475 Field
Communicator and Rosemount's Asset Management software. When the error is
corrected and/or power is cycled, the diagnostic alarms will clear or the next error on the
priority list will appear.
Troubleshooting
90 Rosemount 6888A