Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 162)

IM 11M13A01-04E 12-8
12.2.2.6 Alarm 11: Thermocouple Voltage Alarm
This alarm is generated when the emf (voltage) of the thermocouple falls below -5 mV
(about -170
؇ C) or exceeds 42.1 mV (about 1020؇ C). Whenever Alarm 11 is generated,
Error-2 (heater temperature failure) occurs.
(1) Breakage of the heater thermocouple signal wire between the converter and the
detector occurred, or the cable is not securely connected to the connecting terminals.
(2) The positive and negative poles of the heater thermocouple signal wiring are shorted
out in the wiring extension or at the connection terminals.
(3) A failure of the thermocouple at the detector heater assembly occurred.
(4) A failure of the electrical circuits inside the converter occurred.
<Locating cause of failure, and countermeasures>
(1) Stop the power to the converter.
(2) Remove the wiring from terminals 3 and 4 of the detector and measure the resistance
between these terminals. If the resistance value is 5
⍀ or less, the thermocouple
seems to be normal. If it is higher than 5
⍀, it may indicate the possibility that the
thermocouple has broken or is about to break. In this case, replace the heater unit
(refer to Section 11.1.3, “Replacement of the Heater Unit”).
CAUTION
• Measure the thermocouple resistance value after the difference between the detector
tip temperature and ambient temperature falls to 50
؇ C or less. If the thermocouple
voltage is large, accurate measurement cannot be achieved.
(3) If the thermocouple is normal, check whether or not the wiring cable is broken or
shorted out, and also whether the wiring cable is securely connected to the terminals.
Also check that the wiring resistance between the converter and the detector is 10
⍀
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 Electric Corporation.
12.2.2.7 Alarm 13: Battery Low Alarm
An internal battery is used as backup for the clock. After this alarm occurs, removing
power from the instrument may cause the clock to stop but should not affect stored
parameters. The internal clock is used for blowback scheduling; if you use this then after
a battery alarm occurs (unitl the battery is replaced) be sure to check/correct the date and
time every time you turn on the power.
<Corrective action>
When the battery low alarm occurs, remember that the battery cannot be replaced by the
user. Contact your Yokogawa service representative.
Note
Battery life varies with environmental conditions.
• If power is applied to the instrument continuously, then the battery should not run
down, and life is typically about ten years. However the battery will be used during
the time interval between shipment from the factory and installation.
• If power is not applied to the instrument, at normal room temperatures of 20 to 25
؇ C
then battery life is typically 5 years, and outside this range but within the range -30 to
+70
؇ C then battery life is typically 1 year.