Emerson Rosemount OCX8800A - Page 123

Sensor Heater Over Temperature
The T/C Heater Alerts tab displays one of the following alarms:
1. O
2
Cell Temp. Very High
2. Comb. Temp Very High
3. SB Temp. Very High
This alert indicates a very high heater temperature; temperature is rising too fast.
Potential cause
A heater over-temperature/out of control problem is generally caused by the
inability of the transmitter to limit power to the heater. This could be caused by a
shorted triac on the power supply in the electronics stack.
Recommended actions
1. Check heater wiring.
2. Check thermocouple wiring.
3. Replace the electronics stack.
Sensor Heater Temperature Variance
The following alarms may display on the T/C Heater Alerts tab:
1. O2 Cell Temp. Low
2. O2 Cell Temp. High
3. Comb. Temp. Low
4. Comb. Temp. High
5. SB Temp. Low
6. SB. Temp. High
This alert indicates a sensor heater temperature that is too high or too low.
Potential causes
Cell temperature may become erratic for the following reasons:
1. Temperature is settling during start-up.
2. There are large variations in process temperature or flow.
3. There are fluctuations or noise in the power supplied to the transmitter.
Recommended actions
1. Allow the transmitter several minutes to reach proper temperature.
2. Check power supply.
Calibration Error
The Calibration Alerts tab may display the following alarms:
Manual
FOUNDATION
™
Fieldbus
00809-0500-4880 December 2022
Rosemount OCX8800A 123