Mitsubishi Electric LCPU-U-HW Safety Manuallines page 58

(15) Other measures
(a) Ferrite core
Ferrite core is effective for reducing radiated noise in the
30MHz to 100MHz frequency band.
It is recommended to install a ferrite core if a shield cable
extended out of the control panel does not provide sufficient
shielding effects.
Install a ferrite core to the cable in the position immediately
before the cable is extended out of the control panel. If the
installation position is not appropriate, the ferrite core will not
produce any effect.
Install a ferrite core to each power cable as shown below.
(Ferrite core used for the tests conducted by Mitsubishi: NEC
TOKIN ESD-SR-250)
Example
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