Emerson 5081FG instruction manual Fault 3, Shorted Thermocouple

Model 5081FG

Instruction Manual

IB-106-5081, Rev. 1.0 May 2005

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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 faulty analog or CPU board per paragraph 5-1.

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 6

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).

Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 6-5