4 How to Use
4-3. Precautions
for system designing
- 12 -
Do not install the detector in a place where maintenance of the detector cannot be performed or where
handling the detector involves dangers.
Regular maintenance of the detector must be performed.
Do not install the detector in a place where the machinery must be stopped when maintenance is performed
in its inside, where parts of the machinery must be removed to perform maintenance, or where the detector
cannot be removed because tubes or racks prevent access to it. Do not install the detector in a place where
maintenance involves dangers, for example, near a high-voltage cable.
Do not install the detector in machinery which is not properly grounded.
Before installing the detector in machinery, the machinery must be grounded properly.
Do not install the detector in a place where interference gases exist around it.
The detector must not be installed in a place where interference gases exist around it.
4-3. Precautions for system designing
Using a stable power supply
The external output and alarm contact of the detector may be activated when the power is turned on, when
momentary blackout occurs, or while the system is being stabilized. In such cases, use a UPS
(uninterruptible power supply), or take appropriate actions on the receiving side.
The detector must be provided with the following power supply.
Power supply voltage 24 VDC±10%: Terminal voltage of the detector
Allowed time of
momentary blackout
Up to 10 milliseconds
(To recover from the momentary
blackout for 10 milliseconds or more,
restart the detector.)
Example of actions
To ensure continuous operation and
activation, install a UPS outside the
detector.
Others
Do not use it with a power supply of
large power load or high-frequency
noise.
Example of actions
Use a line filter to avoid the noise source
if necessary.
Introducing protective measures against lightning
If cables are installed outside the factory/plant, or if internal cables are installed in the same duct as the
cables coming from outside the factory/plant, "lightning" will cause problems. Because lightning acts as a
large emission source while cables act as a receiving antenna, devices connected to the cables may be
damaged.
Lightning cannot be prevented. Cables installed in a metal conduit or under the ground cannot be
completely protected from inductive lightning surge caused by lightning. Although complete elimination of
disasters caused by lightning is impossible, the following protective measures can be taken.
CAUTION
An unstable power supply and noise may cause malfunctions or false alarms.
The descriptions in this section must be reflected on the designing of a system using the detector.
WARNING
An oxygen detector is affected by pressure. If the detector is used at a pressure other than
atmospheric pressure, a calibration is required under that pressure. The maximum allowable
pressure is 110 KPa. The detector cannot be used under reduced pressure. Using the detector at a
pressure exceeding the allowable range may cause a trouble in the oxygen sensor performance.
Summary of Contents for PT2-177
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