Omron OMNUC G User Manual page 210

4-3 Wiring Conforming to EMC Directives
If no-fuse breakers are installed at the top and the power supply line is wired from the lower duct,
use metal tubes for wiring or make sure that there is adequate distance between the input lines
and the internal wiring. If input and output lines are wired together, noise resistance will decrease.
Wire the noise filter as shown at the left in the following illustration. The noise filter must be
installed as close as possible to the entrance of the control box.
Correct: Separate input and output
AC input
4
Ground
Use twisted-pair cables for the power supply cables, or bind the cables.
Correct: Properly twisted
Separate power supply cables and signal cables when wiring.
Control Panel Structure
Openings in the control panel, such as holes for cables, operating panel mounting holes, and gaps
around the door, may allow electromagnetic waves into the panel. To prevent this, observe the
recommendations described below when designing or selecting a control panel.
Case Structure
Use a metal control panel with welded joints at the top, bottom, and sides so that the surfaces will
be electrically conductive.
If assembly is required, strip the paint off the joint areas (or mask them during painting), to make
them electrically conductive.
The panel may warp and gaps may appear when screws are tightened. Be sure that no gaps
appear when tightening screws.
Do not leave any conductive part unconnected.
Ground all Units within the case to the case itself.
Door Structure
Use a metal door.
Use a water-draining structure where the door and case fit together, and leave no gaps. (Refer to
the diagrams on the next page.)
Use a conductive gasket between the door and the case. (Refer to the diagrams on the next page.)
Strip the paint off the sections of the door and case that will be in contact with the conductive
gasket (or mask them during painting), so that they will be electrically conductive.
The panel may warp and gaps may appear when screws are tightened. Be sure that no gaps
appear when tightening screws.
4-29
AC output
1 4
NF
2 5
3 6
E
Servo Drive
L1C
L2C
Wrong: Noise not filtered effectively
AC input
1 4
NF
2 5
3 6
E
Ground
AC output
Correct: Cables are bound.
Servo Drive
Binding
L1
L2
L3