Omron NX1P2 series User Manual page 216

5 Installation and Wiring
 Star Earthing
If the earthing method used for the building is not equipotential bonding or the earthing system is
unknown, choose a) from among the earthing methods given below.
a) Connecting devices and noise sources to separate earth electrodes
This is an earthing method to separately ground an earth electrode of the device that is con-
nected with a communications cable or other devices and an earth electrode of a high-power
device that could be a noise source, such as a motor or inverter.
Each earth electrode must be ground to 100 Ω or less.
Connect the ground lines of the device that is connected with a communications cable and other
devices as a bundle to a single earth electrode. Be sure that the earth electrode is separated by
a minimum of 10 m from any other earth electrode of a device that could be a noise source.
NX-series CPU Unit
Control panel
b) Connecting devices and noise sources to a common earth electrode
This is an earthing method to connect the device that is connected with a communications cable,
other devices, and a device that could be a noise source, to a common earth electrode.
This earthing method is not recommended because the device that could be a noise source may
interfere electromagnetically with other devices.
NX-series CPU Unit
Control panel
5 - 84
NX-series NX1P2 CPU Unit
Other device
NX-AUX01
Hub
10 m min.
NX-series NX1P2 CPU Unit
Other device
NX-AUX01
Hub
A device that could be
a noise source
A device that could be
a noise source
NX-series NX1P2 CPU Unit Hardware User's Manual (W578)