Emerson Rosemount OCX 8800 Reference Manual page 115

Table 7-3: Descriptions of PlantWeb Alerts
Alerts Alarms
Sensor Heater Transducer block:
Malfunction 1. O
2
ure
2. Comb Heater
Failure
3. SB Heater Fail-
ure
4. O
2
Ramp Rate Ex-
ceeded
5. Comb Heater
Ramp Rate Ex-
ceeded
6. SB Heater
Ramp Rate Ex-
ceeded
7. Heater Relay
Failed
Reference Manual
(continued)
AMS tab
T/C Heater Alerts
Heater Fail-
Heater
What does the Recommended
alert indicate? action
This alert indi- Check heater cir-
cates that no cuit for loose or
measureable heat broken connec-
energy is being tions; check ther-
detected at the mocouple wiring;
oxygen sensor or test or replace the
that the heater heater.
temperature is ris-
ing too fast.
Foundation Fieldbus
Description
Mechanical or
thermal stress
may eventually
cause the sensor
heater to fail. The
resistance of a
properly function-
ing cell heater
measures less
than 100 ohms. A
failed heater gen-
erally measures as
an open circuit.
Do the diagnosis
at the analyzer.
Refer to
Section 8.2 for de-
tails.
The Heater
Ramp Rate Ex-
ceeded 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. Do the di-
agnosis at the an-
alyzer. Refer to
Section 8.2 for de-
tails.
105