Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 179)

<12. Troubleshooting>
12-9
IM 11M12A01-02E
(3) A failure of the cold junction temperature sensor located at the detector terminal block
occurred.
(4) A failure of the electrical circuits inside the converter occurred.
If “C.J.temperature” exceeds 150 °C or falls below -20 °C, the following can be considered.
• The temperature of the detector terminal block is out of the operating temperature range
(-20 °C to 150 °C).
• A failure of the cold junction temperature sensor located at the detector terminal block
occurred.
• A failure of the electrical circuits inside the converter occurred.
<Locating cause of failure and countermeasures>
Before proceeding to the following troubleshooting procedure, examine whether or not the
temperature of the detector terminal block is out of the operating temperature range.
The operating temperature range varies with the type of detector. If the detector terminal block
is out of its operating temperature range, take the measure to lower the temperature, such as
situating it so that it is not subjected to radiant heat.
The case where the Model ZR22 Detector is used:
(1) Stop the power to the converter.
(2) Remove the wiring from terminals 5 and 6 of the detector and measure the resistance
between these terminals. If the resistance value is out of the range of 1 to 1.6 kΩ, the cold
junction temperature sensor is considered to be faulty. Replace that temperature sensor
with a new one.
(3) If the resistance value is within the above range, the cold junction temperature sensor
seems to be normal. Check whether or not the cable is broken or shorted out, and whether
the cable is securely connected to the terminals. Also, check that the resistance of the wiring
between the converter and detector is 10 Ω or less.
(4) If there is no failure in the wiring, the electrical circuits inside the converter may possibly fail.
Contact the service personnel at Yokogawa.
The case where the Model ZO21D Detector is used:
(1) Without stopping the power to the converter, remove the wiring from terminals 5 and 6 of
the detector and measure the voltage between these terminals. If the voltage between the
terminals is out of the range of 0.4 to 0.7 V, the cold junction temperature sensor seems to
be faulty. Replace the cold junction temperature sensor.
(2) If the voltage between the terminals is within the above range, the cold junction temperature
sensor seems to be normal. Check whether or not the cable is broken or shorted out, and
whether the cable is securely connected to the terminals. Also, check that the resistance of
the wiring between the converter and detector is 10 Ω or less.
(3) If there is no failure in the wiring, the electrical circuits inside the converter may possibly fail.
Contact the service personnel at Yokogawa.
CAUTION
• The operating temperature range of the Model ZO21D Detector is -10 °C to 80 °C (except
for the high temperature detector ZO21D-H). Since a cold junction temperature alarm for
this analyzer is not generated until the temperature exceeds 155 °C, if the Model ZO21D
Detector is used, be careful in controlling the ambient temperature of the terminal block.
8th Edition : Jan.13,2012-00