Cables - Mitsubishi Electric QS001CPU User Manual

9
EMC, LOW VOLTAGE, AND MACHINERY DIRECTIVES

9.1.3 Cables

The cables pulled out from the control panel contain a high frequency noise component.
On the outside of the control panel, therefore, they serve as antennas to emit noise.
To prevent noise emission, use shielded cables when pulling out the cables which are
connected to intelligent function module and CC-Link Safety remote I/O module and using
them outside of the control panel.
The use of shielded cables also increases noise immunity.
For signal lines (including common line) of intelligent function module and CC-Link Safety
remote I/O module, the noise immunity satisfies the standard value on the condition that
the shielded cables are used for grounding.
If shielded cables are not used or not grounded correctly, the noise immunity does not
meet the specified requirements.
(1) Shield grounding processing of shielded cables
• Provide a grounding point on the shielded cable as near the module as possible
so that the wiring between the module and grounding point is not induced
electromagnetically by the other parts of wiring on the cable.
• Take appropriate measures so that the exposed shield part of the shielded cable,
where the cable jacket was partly removed, is grounded to the control panel on
the widest contact surface.
A clamp may also be used as shown in Figure 9.2.
In this case, however, a mask painting is required for the inner wall of the control
panel which comes into contact with the clamp.
Shield part
Figure 9.1 Part to be exposed
Note) If a wire is soldered onto the shield part of the shielded cable for grounding
as shown below, the high-frequency impedance rises, resulting in a loss of
shield effect.
Figure 9.3 Shield grounding (Bad example)
9.1 Requirements for Conformance to EMC Directive
Mask painting
Figure 9.2 Shield grounding (Good example)
Shield cable
Wire
Solderless terminal
9.1.3 Cables
9
10
11
12
Screw
Clamp
Shield cable
9
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