YOKOGAWA RC400G, User Manual

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<9. Troubleshooting>
9-9
IM 12F4A1-01E
Table 9.3 Causes and Corrective Actions for Operation Failures in Measurement
Symptoms Possible Causes Corrective Actions
Measured
value is
abnormal.
1. Reagent is not mixed with sample water.
a. No reagent in the reagent tank.
1. a. Supply reagent to the reagent tank.
b. Reagent metering pump failure 1. b. Check delivery flow rate. If flow rate is not
in specified range, adjust it.
Replace defective "Bellofram" or valve
sheet, if there is any damage.
2. The indicator electrode is not rotating.
a. The drive belt of the electrode drive is
not turning.
2. a. Tighten the set screw.
b. The cell motor does not turn. 2. b. Replace the motor with a new one.
3. The indicator electrode is worn and
damaged.
3. Replace the electrode with a new one.
4. Electric resistance between the rotating
shaft and the rotating contact is high.
4 Replace the rotating contact.(See 8.10.1)
5. Failure of the temperature sensor in the
counter electrode.
5. Replace the counter electrode. (Checking
method: Measure resistance between the
conductors T1 and T2 of the electrode cord. It
should be about 1078 Ω at 20°C. If resistance
value changes with temperature, it is normal.)
Measurement
error is large.
1. The electrodes, especially the indicator
electrode, is contaminated.
1. Polish the indicator electrode referring to
subsection 4.3.10, and clean glass beads
referring to subsection 8.4. (If not cleanable,
replace them.)
2. Zero point and span are not properly
calibrated.
2. Calibrate zero point and span.
3. Sand adsorbs chlorine (when filter sand
in the sand filter has been replaced).
3. Clean sand repeatedly before performing
measurement. (total cleaning time: About 20
minutes)
No response,
Slow
response
1. The pump does not feed sample water. 1. Replace "Bellofram" or valve sheet.
2. Deterioration of the filter capacity of the
sand filter.
2. Improve performance referring to subsection
8.9.
Measured
value
fluctuates
largely
1. The indicator electrode does not rotate
at a constant speed.
1. Check the set screw for loosening. Replace
the drive belt, driven shaft assembly etc. if
defective.
2. Incomplete conduction in the electrode
mechanism block.
2. Replace the rotating contact. (See 8.10.1)
Measured
value does
not vary
1. Out-of-sample in the measuring tank.
(detected by out-of-sample detection)
1. Restore detached tubing, abnormally of the
metering pump, etc. to the normal status.
2. Wire breakage between the electrodes. 2. Repair broken wiring. Replace electrode for
wire breakage in the electrode.
3. No voltage is applied between the
indicator and counter electrodes.
3. Repair the converter. (Checking method:
Measure voltage between connecting terminals
ME(+) and RE(-) of the 1 MΩ or more. A result
in the range of -0.40 ±0.02 V is normal.)
14th Edition : Jul. 15, 2020