Omron NA5-12W series Hardware User Manual page 78

3 Installation and Wiring
NA Unit
(a) One-point grounding:
Acceptable
 Precautions when Grounding
• If the same ground is used for both the signal lines and the enclosure, isolate the channel base (a
grounded metal plate inside a control panel) with an insulating material.
• To prevent influence from leakage current from other electrical devices, electrically isolate the panel
in which the NA Unit is housed from other devices.
• If high-frequency equipment is present, then ground not only the high-frequency equipment but also
the panel itself in which the NA Unit is housed.
 NA Unit Functional Ground Terminal
The NA Unit has the following ground terminal.
Functional ground terminal: Connected to a neutral point in the noise filter to provide a ground when
When the functional ground terminal is correctly grounded, it is generally effective in suppressing power
supply common noise. Occasionally, however, grounding this terminal will result in picking up more
noise, so be careful when using it.
External power
NA Unit side
supply side
Connections When Using an External Noise Filter
3 - 20
NA Unit
Other
Other
device
device
(b) Common ground:
Incorrect
The NA Units are designed to be
mounted so that they are isolated
(separated) from the mounting surface
to protect them from the effects of noise
in the installation environment (e.g., the
environment in which the control panel
is mounted).
Insulating material
Channel base
power supply noise causes malfunctioning.
NA Unit
Other
device
Ground of
100 Ω or
less
(c) Independent grounds:
Incorrect
NA-series Programmable Terminal Hardware User's Manual (V117)