Mitsubishi Electric Q80BD-J61BT11N, User Manual

Page: 349 / 362

App - 87 App - 87
MELSEC
APPENDIX
(2) Installing devices in the control panel
Installing devices in the control panel has a considerable effect, not only securing
safety but also shielding the noise generated from the personal computer in the
control panel.
: Also, each network remote station needs to be 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 and ground cables
The power supply cable and ground cable for a personal computer should
be laid out as follows:

Provide a ground point to the control panel near the power supply module.
Ground the FG terminal of the personal computer and the SLD terminal
of the CC-Link Ver.2 board to the ground point with the thickest and
shortest ground cable possible (30cm or shorter).

Twist the ground cable leading to the ground point with the power supply
cable. By twisting it with the ground cable, the noise leaking from the
power supply cable may be grounded at a higher rate. However, twisting
the power supply cable with the ground cable may not be necessary if a
noise filter is installed on the power supply cable.