4-20
4-3 Wiring Conforming to EMC Directives
4
System Design
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.
Use twisted-pair cables for the power supply cables, or bind the cables.
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 from
occurring, observe the items 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.
If gaps appear in the control box case when screws are tightened, make adjustments to prevent
this from occurring.
Do not leave any conductive part unconnected.
Ground all Units within the case to the case itself.
Correct: Separate input and output
Wrong: Noise not filtered effectively
NF
1
2
3
4
5
6
E
NF
1
2
3
4
5
6
E
AC input
AC input
Ground
Ground
AC output
AC output
Correct: Properly twisted
Correct: Cables are bound.
Servo Drive
Servo Drive
L1
L1
L2
L3
L3
Binding
