3-5
Section
Noise Precautions
39
Install surge suppressors on devices that generates noise, particularly devices
that have an inductive component such as motors, transformers, solenoids, and
magnetic coils.
Surge suppressor
(Installed next to device)
DC input type
Device
(such as a motor)
AC input type
Surge suppressor
(Installed next to device)
Device
(such as a motor)
If a surge suppressor does not fit on the device, installing a ferrite core directly
next to the device’s contactors, such as a contactor may be effective.
Ferrite core 0443-1641151
Nisshin Electric Co, Ltd.
Device
(such as a motor)
Because noise currents flow through metallic equipment (such as casings), the
communications cables should be placed as far away from metallic equipment
as possible.
Ground the shielding wire on the communications cable at one point. If the same
ground is used for the communications cable and communications power sup-
ply, there is a possibility that noise may be transmitted through the ground line to
the communications line. In order to avoid this, be sure that the power line
ground and the grounds for the communications cables and the communica-
tions power supply are located as far from each other as possible.
Insert a line filter on the primary side of the communications power supply.
When there are two or more communications power supplies, the communica-
tions power cables can be grounded by simply connecting a single Power Sup-
ply Tap near the center of the communications cable. Do not ground shielding
wire at more than one place.
Master
T-branch Tap or Power Supply Tap
or Communications Connector
Slave
Ground at only one point
When there is only one power supply
When there are two or more power supplies
PS
PS
PS
PS
Master
Slave
Slave
Slave
Power Supply Tap
Power Supply Tap
PS: Communications
power supply
PS: Communications
power supply
