Hvis EMC er et problem, så har jeg mer tro på ferritter på kabelen.
EMC området er fra - til hvilke frekvenser ? og ferritter er effektive i område?
Det er jeg neimen ikke sikker på. Fra noen hundre kHz og oppover?
Og korrekt betegnelse er vel EMI eller RFI, hvis jeg ikke tar helt feil.
Du virker da skråsikker mtp både ferritter og skjerm så kan vel dine utsagn kalles..
EMC standaren dekker området 9KHz - 400GHz.
Standaren definerer målemetode 9KHz - 1GHz.
Ferritter er mest effektive i området 0,5 - 1GHz.
Nettstøy filtre - EMI/RFI filtre i område 50KHz - 50MHz
Cable shielding is a very effective measure to improve susceptibility
and reduce emission. However, incorrect installation can reduce
the effectiveness or even completely destroy the effect of shielding.
The enclosure has to
be grounded plainly, because ungrounded enclosures will provide
only minimum shielding attenuation. The paint of enclosures often
neutralizes the shielding effect of the enclosure.
If shielded cables are used, the ends of the shield have to be connected
to ground. If none of the ends is connected, the shield
becomes ineffective. Induced fields cannot be diverted; ground currents
cannot be reduced. If shields are connected on only one side,
they become effective against electric fields. However, once the resonance
frequency of the shield is reached, the shield becomes ineffective
and even amplification can occur. If both ends of the shield are
connected to ground, the shield has the best effect.
The most common problem with the connection of shields is the
use of “pigtails”,
The shield is twisted to one tail and then connected to ground on only one point.
This increases the coupling resistance of the shield and reduces its
performance. The best connection of a shield is a 360° connection at
both ends as shown on the right side.