Emerson Process Management IM-106-340 Alarms O2 Temp Low, Fault 8, Low Heater Temp

Oxymitter 4000

Figure 8-10. Fault 8, Low Heater Temp

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

CALIBRATION RECOMMENDED

Instruction Manual

IM-106-340, Rev. 4.0

May 2006

Fault 8, Low Heater Temp

Figure 8-10shows 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.

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

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:

KEYPAD

Alarms

O2 Temp Low

LOI 37260026

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.

8-14