Emerson Process Management OXYMITTER 4000 IM-106-340 - Manual (Page 106)

8-14
Instruction Manual
IM-106-340, Rev. 4.0
May 2006
Oxymitter 4000
Figure 8-10. Fault 8, Low Heater Temp
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 detected, the HEATER LED
flashes four times, pauses for three seconds,
and repeats.
1. The low heater temperature alarm is active
when the thermocouple reading has
dropped below 28.6 mV.
2. If the thermocouple reading continues 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.
3. Power down the electronics. Remove the
electronic assembly per "Electronic
Assembly Replacement" in Section 9:
Maintenance and Service. Using a
multimeter, measure the resistance across
the terminals of heater connector, J8.
4. If the heater is good, the reading will be
approximately 70 ohms. If the heater is
open, see "Heater Strut Replacement" in
Section 9: Maintenance and Service.
LOI
When Fault 8 is detected, the LOI displays the
"O2 Temp Low" message. Refer to the
comments and procedures in paragraphs 1
through 4 above.
37260026
LOI
KEYPAD
Alarms
O2 Temp Low
DIAGNOSTIC
ALARMS
TEST
POINTS
HEATER T/C
HEATER
O2 CELL
CALIBRATION
CALIBRATION RECOMMENDED
O2 CELL mV +
O2 CELL mv -
HEATER T/C +
HEATER T/C -
INC INC
DEC DEC
HIGH
GAS
LOW
GAS
CAL
TEST GAS +
PROCESS -
% O2
SW2
TP1
J1
TP2
TP3
RED YEL GRN ORG
TP4
TP5
TP6
ON