Mitsubishi MELSEC L Series User Manual page 387

(2) Installation in a control panel
Programmable controller is an open type device and must be installed inside a control panel.
This ensures safety as well as effective shielding of programmable controller-emitted electromagnetic noise.
*1 Modules on the remote station in each network must be also installed inside the control panel. However, the waterproof
type remote station can be installed outside the control panel.
(a) Control panel
• Use a conductive control panel.
• Mask off the area used for grounding when securing the top or bottom plate to the control panel using
bolts.
• To ensure electrical contact between the inner plate and the control panel, mask off the bolt installation
areas of an inner plate so that conductivity can be ensured in the largest possible area.
• Ground the control panel with a thick ground cable so that low impedance can be ensured even at high
frequencies.
• Keep the diameter of the holes on the control panel to 10cm or less. If the diameter is larger than 10cm,
electromagnetic wave may be emitted. In addition, because electromagnetic wave leaks through a
clearance between the control panel and its door, reduce the clearance as much as possible. Use of EMI
gaskets (sealing the clearance) can suppress undesired radiated emissions.
The tests by Mitsubishi were conducted using a control panel having the damping characteristics of 37dB
(maximum) and 30dB (average) (measured at 3m distance, 30 to 300MHz).
(b) Wiring power cables
• Provide a ground point to the control panel near the power supply module. Ground the LG and FG
terminals of the power supply module to the ground point with the thickest and shortest ground cable
possible (30cm or shorter).
APPENDICES
*1
A
385