Emerson Process Management IM-106-340 Alarms O2 Cell Open, Fault 10, High Cell mV

Oxymitter 4000

Figure 8-12. Fault 10, High Cell mV

	HEATER T/C
DIAGNOSTIC	HEATER	SW2
ALARMS	O2 CELL	ON
	CALIBRATION

CALIBRATION RECOMMENDED

Instruction Manual

IM-106-340, Rev. 4.0

May 2006

Fault 10, High Cell mV

Figure 8-12shows the electronic assembly for an Oxymitter 4000 with a membrane keypad (upper view) and an Oxymitter 4000 with an LOI (lower view). The upper view also shows J1 and test points TP1 through TP6, located on the microprocessor board, below the membrane keypad or the LOI module.

Membrane Keypad

TEST

POINTS

INC INC

HIGH LOW GAS GAS

DEC DEC

O2 CELL mV +

O2 CELL mv - HEATER T/C + HEATER T/C -

CAL

TEST GAS + PROCESS - % O2

TP1 TP2 TP3 TP4

TP5

TP6

J1 RED YEL GRN ORG

When Fault 10 is detected, the O2 CELL flashes once, pauses for three seconds, and repeats.

1. Using a multimeter, measure across TP1+

to TP2-. If you measure 204 mV to 1 volt

DC, the cell reading is due to high

combustibles. This is a self-clearing alarm,

once the combustible conditions go away.

If you measure 1.2 VDC, the cell wires,

either orange or green, have become

detached from the input.

2. One possible cause is connector J1. The

orange or green wire has come loose from

KEYPAD

Alarms

O2 Cell Open

LOI 37260028

the crimped connection.

3. The platinum pad could also be at fault.

The pad could have broken free from the

back of the cell.

4. Replace heater strut per "Heater Strut

Replacement" in Section 9: Maintenance

and Service. If necessary, replace the cell

and flange assembly per "Cell Replace-

ment" in Section 9: Maintenance and Ser-

vice.

LOI

When Fault 10 is detected, the LOI displays the "O2 Cell Open" message.

1.Remove power. Unscrew and remove the LOI module from the electronic assembly.

2.Reconnect power to the Oxymitter 4000.

3.Perform the diagnostic steps 1 through 4 shown for the membrane keypad.

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