Riken Keiki SD-1DRI, Operating Manual

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4 How to Use 4-3. Precautions for system designing
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Protection against
lightning
Take appropriate measures in accordance with the importance of the facilities
and the environment.

Provide protection by a lightning arrester (cable safety retainer).
(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. For information on how to use a lightning arrester,
please contact the manufacturer.)
Grounding
In addition to lightning, there are more sources of surge noise. To protect units
from these noise sources, the units must be grounded.
* The lightning arrester has a circuit to remove a surge voltage which damages field devices, so that
signals may be attenuated. Before installing a lightning arrester, verify that it works properly.