Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 215)

IM 11M12D01-01E 12-5
12. Troubleshooting
2) Error 2: Heater Temperature Failure
Possible causes of heater temperature failure
This error occurs if the detector heater temperature does not rise during warm-up, falls
below 730
؇C after warm-up, or exceeds 780؇C. When Error 2 occurs, Alarm 5 (cold
junction temperature alarm) may be generated at the same time. Be sure to touch the
error icon to get the error description and confirm whether or not this alarm is being
generated simultaneously.
If Alarm 5 is generated simultaneously, a failure in the cold junction system on the
detector terminal block is suspected. In this case follow the procedure according to
troubleshooting for Alarm 5 in Subsection 12.2.3.5.
The following are possible causes of Error 2 when it occurs independently.
1) Fuse for the heater on the power supply unit has brown.
2) Failure in wiring between the averaging converter and the detector. (e.g., loose
connection at terminals, wire breakage, short-circuit.)
3) Faulty cold junction compensation sensor on the detector terminal block. (loose
connection at terminals)
4) Faulty thermocouple in the detector (wire breakage, short-circuit in internal wiring).
5) Faulty heater in the detector (wire breakage, etc.).
6) Failure in electrical circuits inside the averaging converter.
<Locating cause of failure, and countermeasures>
1) Turn off power to the channel with error by how swap function or to the averaging
converter.
2) Remove the cable from terminals 7 and 8 of the detector and measure the resistance
between these terminals. The heater unit is normal if the resistance is lower than
about 90
⍀. If the resistance value is higher, failure of the heater unit is suspected. In
this case, replace the heater unit (refer to Subsection 11.2.3, "Replacement of the
Heater Unit"). In addition, check that the two-way wiring resistance between the
converter and the detector is 10
⍀ or less.
3) Remove the wiring from terminals 3 and 4 of the detector and measure the resistance
between these terminals. The thermocouple is considered normal if the resistance
value is 5
⍀ or less. If the value is higher than 5 ⍀, it may indicate that the thermo-
couple wire has broken or is about to break. In this case, replace the heater unit
(refer to Subsection 11.2.3, "Replacement of the Heater Unit"). Also, check that the
wiring resistance between the converter and the detector is 10
⍀ or less.
CAUTION
Measure the thermocouple resistance value after the temperature difference between the
detector tip and the ambient atmosphere has decreased to 50
Њ C or less. If the thermo-
couple voltage is large, accurate measurement cannot be achieved.