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14. EMC AND LOW VOLTAGE DIRECTIVES
(4) Cables
The cables extracted 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 for the cables extracted to the outside of the control panel.
The use of a shielded cable also increases noise resistance.
(a) Grounding of shield section of shield cable
1) When the grounded cables and the not yet grounded cables are bundled in grounding point of
shielded cable back, the cables might be induced to electromagnetic and generated high frequency
noise outside of the control panel.
2) Ground the exposed shield section to spacious area on the control panel. A clamp can be used as
shown in Figure 14.2.
In this case, mask the inner wall surface when coating the control panel, and contact the exposed
shield section with the clamp at the exposed bare metal surface.
Shield section
Screw
Clamp fitting
Shield cable
Exposed bare
metal surface
Figure 14.1 Part to be exposed Figure 14.2 Shield grounding (Correct example)
Shield cable
Wire
Solderless terminal, crimp contact
Figure 14.3 Shield grounding (Incorrect example)
Note. The method of grounding with a vinyl-coated wire soldered onto the shielded section of the shielded cable as in shown Figure
14.3 is not recommended. Doing so will raise the high frequency impedance, resulting in loss of the shielding effect.
(5) Precautions relevant to the electrostatic discharge
Before touching the position board, always touch grounded metal, etc. to discharge static electricity from
human body. Failure to do so may cause the position board to fail or malfunction.
Do not directly touch the conductive parts of position board and electronic components. Touching them
could cause an operation failure or damage the position board.