Figure 8-10. Fault 8, Low Heater Temp - Emerson Oxymitter 4000 Instruction Manual

Instruction Manual
IB-106-340 Rev. 3.0
December 2003
DIAGNOSTIC
ALARMS
CALIBRATION RECOMMENDED
TEST
POINTS
INC INC
HIGH LOW
GAS GAS
DEC DEC
KEYPAD
Alarms
O2 Temp Low

Figure 8-10. Fault 8, Low Heater Temp

8-12 Troubleshooting
HEATER T/C
HEATER
SW2
O2 CELL
CALIBRATION
O2 CELL mV +
TP1
O2 CELL mv -
TP2
HEATER T/C +
TP3
HEATER T/C -
TP4
CAL
TEST GAS + TP5
PROCESS -
TP6
% O2
LOI
37260026
h. Fault 8, Low Heater Temp
Figure 8-10 shows the electronic assembly
for an Oxymitter 4000 with a membrane
keypad (upper view) and an Oxymitter 4000
with an LOI (lower view).
Membrane Keypad. When Fault 8 is de-
tected, the HEATER LED flashes four times,
J1
pauses for three seconds, and repeats.
1. The low heater temperature alarm is
2. If the thermocouple reading continues
3. Power down the electronics. Remove
4. If the heater is good, the reading will be
LOI. When Fault 8 is detected, the LOI dis-
plays the "O2 Temp Low" message. Refer
to the comments and procedures in para-
graphs 1 through 4 above.
Rosemount Analytical Inc.
Oxymitter 4000
active when the thermocouple reading
has dropped below 28.6 mV.
to ramp downward for one minute and
does not return to the temperature set
point of approximately 29.3 mV, then
an Open Heater fault will be displayed.
the electronic assembly per paragraph
9-4d, Electronic Assembly Replace-
ment. Using a multimeter, measure
across the heater connector, J8.
approximately 70 ohms. If the heater is
open, see paragraph 9-4h, Heater Strut
Replacement.
A Division of Emerson Process Management