Installation Instructions For Emc Directive - Mitsubishi Q01CPU User Manual

9
EMC AND LOW VOLTAGE DIRECTIVES

9.1.2 Installation instructions for EMC Directive

Programmable controller is an open type device and must be installed inside a control
panel for use.*
This not only ensures safety but also ensures effective shielding of programmable
controller-generated electromagnetic noise.
(1) Control panel
(2) Connection of power line and ground wire
Gound wire and power supply cable for the programmable controller system must be
connected as described below.
* : 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.
• Use a conductive control panel.
• When attaching the control panel's top plate or base plate, mask painting and
weld so that good surface contact can be made between the panel and plate.
• To ensure good electrical contact with the control panel, mask the paint on the
installation bolts of the inner plate in the control panel so that contact between
surfaces can be ensured over the widest possible area.
• Ground the control panel with a thick wire so that a low impedance connection to
ground can be ensured even at high frequencies.
• Holes made in the control panel must be 10 cm (3.94 inch) diameter or less. If
the holes are 10 cm (3.94 inch) or larger, radio frequency noise may be emitted.
In addition, because radio waves leak through a clearance between the control
panel door and the main unit, reduce the clearance as much as practicable.
The leakage of radio waves can be suppressed by the direct application of an
EMI gasket on the paint surface.
Our tests have been carried out on a panel having the damping characteristics of
37 dB max. and 30 dB mean (measured by 3 m method with 30 to 300 MHz).
• Provide an grounding point near the power supply module. Ground the power
supply's LG and FG terminals (LG : Line Ground, FG : Frame Ground) with the
thickest and shortest wire possible. (The wire length must be 30 cm (11.81 inch)
or shorter.) The LG and FG terminals function is to pass the noise generated in
the programmable controller system to the ground, so an impedance that is as
low as possible must be ensured. As the wires are used to relieve the noise, the
wire itself carries a large noise content and thus short wiring means that the wire
is prevented from acting as an antenna.
• The ground wire led from the grounding point must be twisted with the power
supply wires. By twisting with the ground wire, noise flowing from the power
supply wires can be relieved to the ground. However, if a filter is installed on the
power supply wires, the wires and the ground wire may not need to be twisted.
9.1 Requirements for Conformance to EMC Directive
9.1.2 Installation instructions for EMC Directive
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