EMI shielding

[bigalow]

We have some machinery using old Phillips Scales and pulse conditioners. Problem is the pulse conditioners are very susceptible to noise interferance. Contactors chattering. Solonoids energizing ect...
What are some shielding tricks that I could try. I found these iron core donuts that I slid over the feedback cable. This seems to help. What is the theory behinfd the iron donuts. These were on the feedback cables from another machine from Europe

[vger]

Those donuts help eliminate high frequencies from the wire they are around. Without going into detail, they lower the maximum slew rate of the current passing through them by impeding the change in magnetic flux around the wire.

Try to keep the susceptible wire away from wires that have high current switched loads if possible. You can also put the same "donuts" around the output and input leads on the contactors to keep the pulse noise from propagating down the wires where it can radiate out.

Steve

[Al_The_Man]

The best thing is to try and kill it at source, for AC solendoids etc, use an RC snubber and for DC use a reverse EMF diode, across the coil in each case.
Snubber link http://www.cnczone.com/forums/showth...hlight=snubber
Al.