Emerson 3081FG - Manual (Page 63)

Instruction Manual
IB-106-3081 Rev. 1.5
September 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 6-5
Model 3081FG
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26020026
Figure 6-7. Fault 3, Shorted Thermocouple
c. Fault 3, Shorted Thermocouple
The thermocouple connections are shorted.
The fault displays as shown in Figure 6-7.
1. Allow adequate time for the oxygen
probe to reach operating temperatures.
Probe temperatures below approxi-
mately 500
°C (932°F) may result in this
fault.
2. Refer to Figure 6-4. Using a multime-
ter, measure between terminals 8(-)
and 10(+).
3. If the multimeter reading, in voltage
mode, is between -0.5 and +0.5 mV,
the thermocouple is shorted.
4. If the thermocouple is shorted, replace
the oxygen probe per paragraph 5-2.
5. If the thermocouple is not shorted, then
replace the PC board stack assembly
per paragraph 5-1.
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26020027
Figure 6-8. Fault 4, High Probe Temperature
d. Fault 4, High Probe Temperature
The probe’s temperature has exceeded the
maximum cell temperature setpoint. The
fault displays as shown in Figure 6-8.
1. If the probe temperature exceeds the
maximum cell temperature setpoint,
the 4-20 mA signal output will become
invalid and go to the default value.
2. Verify that the upper cell temperature
setpoint is configured as desired under
the PROGRAM MENU (see Section 3,
STARTUP AND OPERATION).
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