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5.1 Requirements to Meet EMC Directive
5.1.2 Control panel
5.1.2
Control panel
The GOT is an open type device (device installed to another device) and must be installed in a conductive
control panel.
It not only assure the safety but also has a large effect to shut down the noise generated from GOT, on the
control panel.
(1) Control panel
(a) The control panel must be conductive.
(b) When fixing a top or bottom plate of the control panel with bolts, do not coat the plate and bolt
surfaces so that they will come into contact.
And connect the door and box using a thick grounding cable in order to ensure the low
impedance under high frequency.
(c) When using an inner plate to ensure electric conductivity with the control panel, do not coat the
fixing bolt area of the inner plate and control panel to ensure conductivity in the largest area as
possible.
(d) Ground the control panel using a thick grounding cable in order to ensure the low impedance
under high frequency.
(e) The diameter of cable holes in the control panel must be 10cm (3.94in.). In order to reduce the
chance of radio waves leaking out, ensure that the space between the control panel and its
door is small as possible.
Attach some EMI gaskets to fill up the space and suppress the leakage of radio waves.
Out test have been carried out on a panel having the damping characteristics of 37dB max.
and 30dB mean (measured by 3m method with 30 to 300MHz).
(2) Connection of power and ground wires
Ground and power supply wires for the GOT must be connected as described below.
(a) Provide a grounding point near the GOT. Short-circuit the LG and FG terminals of the GOT
(LG: line ground, FG: frame ground) and ground them with the thickest and shortest wire
possible (The wire length must be 30cm (11.18in.) or shorter.) The LG and FG terminals
function is to pass the noise generated in the PC 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.
Note) A long conductor will become a more efficient antenna at high frequency.
(b) The earth wire led from the earthing point must be twisted with the power supply wires. By
twisting with the earthing wire, noise flowing from the power supply wires can be relieved to the
earthing. However, if a filter is installed on the power supply wires, the wires and the earthing
wire may not need to be twisted.
