Ferrite Beads

[Paddymagee]

Hi,

I have just received a "product update" from a supplier advising that we fit the ferrite beads (see link) to the supply of control PCBs.

http://www.kemtron.co.uk/buyferrites.html

We have to fit 3 in total, L,N & Earth by loping the cable a single time through the bead.

My guess is that this is going to look a bit unprofessional so im wondering if there is a neater solution out there?
Are there any encapsulated modules out there that will do the job?

Supply voltage = 110VAC
Supply current = <100mA

Thanks in advance

 

[Skogsgurra]

Why do you need to use three cores? The whole idea is to keep HF on the load side and not let it propagate common-mode to the mains.

Using one core, which is the standard way of doing it, will keep common-mode impedance high. Using separate cores will need more core material so that the normal mode current doesnt saturate the cores. Saturated cores have a much lower impedance and will not work very well in most instances.

Is there some misunderstanding? Or does your supplier want to sell three times more cores to you?

Gunnar Englund

http://www.gke.org

 

[MacGyverS2000]

My question is "Why is a supplier (and not the customer or your engineers) dictating what you put on your equipment?"

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Paddymagee]

Sorry I was unclear - the "supplier" is the producer of the equipment that we are fitting the supply to.
Although we have had no problems apparently other distributers have found a problen and these beads sort it out.
We have not yet bought or fitted any ferrites.

Thanks for the advice on how to connect the ferrite. Thats stopped me looking a bit silly!

 

[itsmoked]

To add; the first four are pretty standard and should look "high techie" and will be fine. You'll note most computer monitors have these in their signal cables these days.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[DanEE]

I have used black 3:1 ratio (high contraction) adhesive heat shrink over these types of beads to dress up their appearance.

It also keeps the ferrite bead from easily sliding down the cord in the cases where it's not a tight fit...

 

[qassure]

Ferrite beads are used to prevent the Electro-Magnetic Interference (EMI). Most of the power supply modules / PCBs have these ferrite beads in the input lines. These beads can be put along with the input connector (i.e. at the backside of the connector pins)instead of PCBs. presently coloured ferrite beads are available in the market.

 

[kontiki99]

An EMC testing/certification lab may have recommended adding the beads while emissions testing the final assembly.

It may have been the only way they got the final assy to comply to FCC, CE or whatever requirements.