Rosemount OCX 8800, Instruction Manual

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Instruction Manual
IM-106-880, Rev 2.1
April 2017
OCX 8800
7-8
Alerts Alarms
AMS
Tab What does the
alert indicate?
Recommended
Action Description
Sensor Heater Transducer Block
1) O
2
Heater
Failure
2) Comb Heater
Failure
3) SB Heater
Failure
4) O
2
Heater
Ramp Rate
Exceeded
5) Comb Heater
Ramp Rate
Exceeded
6) SB Heater
Ramp Rate
Exceeded
7) Heater Relay
Failed
T/C Heater This alert Check heater circuit Mechanical or thermal stress may eventually
Malfunction Alerts indicates that no for lose or broken cause the sensor heater to fail. The resistance of
measurable heat connections, check a properly functioning cell heater will measure
energy is being thermocouple wiring, less than 100 ohms. A failed heater will generally
detected at the test or replace the measure as an open circuit. Diagnosis must be
oxygen sensor or heater. done at the analyzer. Refer to Section 8:
that the heater Troubleshooting for details.
temperature is
rising too fast. The Heater Ramp Rate Exceeded problem is
usually caused by the inability of the device to
limit power to the heater. This could be caused by
a shorted triac component on the power supply in
the electronics stack. Diagnosis must be done at
the analyzer. Refer to Section 8: Troubleshooting
for details.
Sensor Heater
Over Temp-
erature
Sensor Heater
Temp-
erature Variance
Transducer
Block:
1) O
2
Cell Temp.
Very High
2) Comb Temp.
Very High
3) SB Temp Very
High
Transducer
Block:
1) O
2
Cell Temp.
Low
2) O
2
Cell Temp.
High
3) Comb Temp.
Low
4) Comb Temp.
High
5) SB Temp.
Low
6) SB Temp.
High
TC Heater
Alerts
T/C Heater
Alerts
This alert
indicates a very
high heater
temperature;
temperature is
rising too fast.
This alert
indicates a
sensor heater
temperature that
is too high or too
low.
Check heater wiring,
check thermocouple
wiring or replace the
electronics stack.
Allow instrument
several minutes to
reach proper
temperature or
check power supply.
A heater over-temperature/out of control problem
would generally be caused by the inability of the
device to limit power to the heater. This could be
caused by a shorted triac on the power supply in
the electronics stack.
Cell temperature control may become erratic for
the following reasons:
1) Temperature is settling during startup.
2) Large variations in process temperature or
flow.
3) Fluctuations or noise in the power supplied to
the instrument.
Calibration Error Transducer
Block:
1) O
2
Calibration
Failed
2) Comb
Calibration
Failed
3) Calibration
Warning
Calib-
ration
Alerts This alert
indicates that the
slope and
constant values
determined from
the calibration did
not fall within an
acceptable
range. Check the
calibration gas
supplies and
connections. Make sure the oxygen concentrations of the
calibration gases match the concentration values
in the device. If the calibration has been
performed correctly this alarm may indicate that
the sensor requires replacement. Refer to
Section 8: Troubleshooting for details.
Calibration Transducer
Recommended Block:
Calib-
ration
Alerts This alert Check instrument
Calibration
Recommended
indicates that the accuracy and/or
sensor resistance calibrate.
has changed by a
predetermined
amount since the
last calibration.
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. If using the device with an IMPS or
SPS calibration sequencer, increased cell
impedance can automatically trigger a calibration.