YOKOGAWA DT450G Series, Руководство пользователя, Страница: 36 / 41

<6. Troubleshooting>
6-1
IM 11K01C01-01E
6. Troubleshooting
This chapter explains measures that should be taken when the output signal gives abnormal
readings. Note that not all anomalies are due to failure (disorder or malfunction) in the DT450G.
Some of them may be due to a change in the physical properties types of components, the flow
velocity, etc.) of the gas being measured. If such a change is likely, first check for the following.
Table 6.1 Causes of Failure and Corrective Actions
State of Failure Cause Corrective Action
The output signal
overshoots
toward the 20 mA
side.
• Air purge is not effective.
• Condensation occurs at the probe inlet.
• Check that the gap at the purge-air exit is
as specified. If the exit is contaminated with
dust, increase the purge pressure (remove
the dust on the exit).
• Take appropriate heat insulation measures.
The output signal
gives abnormal
readings.
• The purge-air exit is contaminated with
dust.
• The sensor probe is in a state of insulation
failure because of inappropriate purge air
(e.g., contains moisture).
• The gas under measurement has entered
the purge-air piping, causing an insulation
failure in the sensor probe.
• Clean the exit (see subsection 5.1.1).
• Use normal, dry purge air.
• Set the pressure relatively higher and
continue air purge for a while.
(If contaminants still remain in the piping,
contact Yokogawa Electric for assistance.)
The output
signal does not
stabilize.
• The flow velocity of the gas under
measurement is not constant.
• The humidity of the gas under
measurement changes.
• Change the measurement point to a
position in the straight portion of the duct
where the flow of gas is regular.
• If the change occurs constantly, check if
measuring the gas is practicable at all.
The output
signal becomes
disturbed
momentarily.
• The wiring is inappropriate and therefore
picks up noise.
• There is equipment nearby serving as a
source of noise.
• Check the states of grounding and wiring
and correct a problem if there is any.
• Take measures for protecting the DT450G
from the source of noise.
There is no
output signal.
• The fuse is blown or there is something
wrong with the wiring connections.
• There is something wrong with the electric
circuit components.
• Turn off the power switch temporarily if the
green indicator lamp is unlit.
Then, examine the wiring connections and
check if the fuse has blown.
Consult Yokogawa if the fuse has blown.
• Request repair to be carried out by
Yokogawa.
Table 6.2 Corrective Action against Errors at Automatic Setup
Display Description Corrective action
-E1 Input signal is too low Try Automatic Setup again
Manually set measurement range to Range 5
-E2 Input signal is too High Try Automatic Setup again
Manually set measurement range to Range 1