Rosemount OCX 8800, Instruction Manual

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Instruction Manual
IM-106-880, Rev 2.1
April 2017
OCX 8800
7-7
Mapping of PWA
Description of the PlantWeb Alerts that are supported by the OCX 8800
Fieldbus Output Board are listed in Table 7-3.
Figure 7-3. Description of PlantWeb Alerts
.
Alerts Alarms
AMS
Tab What does the
alert indicate?
Recommended
Action Description
Sensor Transducer Sensor This alert is Check sensor wires 1) The oxygen cell interface is designed to
Malfunction Block: Alerts active when for loose or broken indicate a very high output if the cell becomes
the sensor is connection or disconnected from the electronics. It is
1) O
2
Cell Open indicating a
very high or replace the cell. possible that a wire connection to the cell,
either in the probe tip or at the electronics, is
2) Comb Cell unexpected loose or broken. The cell may also be
Error output. damaged from mechanical stress. In extreme
cases, a very low oxygen concentration in the
process may cause this alarm. Diagnosis must
be done at the analyzer. Refer to Section 8:
Troubleshooting for details.
Sensor Degraded Transducer
Block:
O
2
Cell
Impedance High
Sensor
Alerts This alert is
active when the
oxygen sensor
impedance
indicates that the
cell is beyond its
useful life. Replace the oxygen
cell.
2) This problem could be caused by a mechanical
failure in the sensor housing or at the
electronics. An open circuit in the combustible
sensor could also cause this alarm. Refer to
Section 8: Troubleshooting for details.
Oxygen cells will degrade over time due to aging
and corrosion. An increasing cell resistance is a
good indicator of reduced cell performance. As
the cell impedance increases, the cell output falls
off and response time increases. Calibrating the
instrument will compensate for the increased cell
resistance up to several hundred ohms, beyond
which the cell is no longer functional. Diagnosis
must be done at the analyzer. Refer to Section 8:
Troubleshooting for details.
Thermo-
couple
Malfunction Transducer
Block:
1) O
2
T/C Open
2) O
2
T/C
Shorted
3) O
2
T/C
Reversed
4) Comb T/C
Open
5) Comb T/C
Shorted
6) Comb T/C
Reversed
7) SB T/C Open
8) SB T/C
Shorted
9) SB T/C
Reversed
T/C Heater
Alerts This alert
indicates a
miswired or faulty
thermocouple. Check the
thermocouple wires
for loose or broken
connections, short
circuit condition,
reverse wire
condition. When the heater thermocouple alarms are
initiated, they diagnose one of three states:
1) Open
2) Shorted
3) Reversed
The problem could be caused by a mechanical
failure in the probe tip or at the electronics. Power
to the device must be cycled to resume operation.
Diagnosis must be done at the analyzer. Refer to
Section 8: Troubleshooting for details.