Riken Keiki FI-915, Руководство по эксплуатации

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3 How to Install 3-3. How to Connect Wire
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2. Take a measure against noise according to the installation environment.
(1) Measure against lightning surge
"Lightning" is a problem for the devices installed outdoors at plants, etc. Because lightning acts as a
large emission source while cables act as a receiving antenna, devices connected to the cables
may be damaged. Cables installed in a metal conduit or under the ground cannot be completely
protected from inductive lightning surge caused by lightning. However, the following measure can
be taken. Take an appropriate measure before using FI-915.
<Provide protection by a lightning arrester (cable arrester)>
Although inductive lightning surge can be transmitted through the cable, it is prevented by installing
a lightning arrester before the field devices and central processing equipment. Insert lightning
arresters to the points where the cables enter the building from outside. A lightning arrester has a
circuit that removes a surge voltage to prevent field devices from being damaged.
(2) Measure against power line noise
The following measures can be taken to mitigate the influence of electromagnetic or electrostatic
induction noise from the power line. Take an appropriate measure before using FI-915.
<Keep away from power line>
Keep enough distance between the signal and power lines, avoiding parallel layout if possible. If
they need to intersect with each other, it should be done at a right angle.
<Install an electrostatic shield>
Use a shielded signal line and ground the shield. Also, take measures to make the electrical
isolation such as using an iron raceway for the power line, installing a grounded metal partition
plate between the lines and putting each line in an individual metal duct.
In addition to lightning, there are more sources of surge noise. To protect devices from these noise
sources, the devices must be grounded.
3-3-3. Protective grounding
For stable operation of FI-915 and safety, it must be connected to a grounding terminal. The grounding
wire should be thick and short as much as possible to minimize grounding resistance. Use the EARTH
terminal (terminal 3) of the external terminal plate to ground FI-915.
CAUTION

Be careful not to damage the internal electronic circuit when wiring.
CAUTION

The "b" contact (break contact) under de-energized state may be opened momentarily by a
physical shock, such as external force.

When the "b" contact is selected for the alarm contact, take appropriate actions to prepare for a
momentary activation, for example, add signal delay operation (approximately one second) to
the receiving side of the "b" contact.
WARNING

The grounding must be made as D type grounding (below 100 Ω of grounding resistance).

Do not connect the grounding wire to a gas tube.