Ferrite rings?

[murphy625]

I'm thinking that it couldnt hurt to put ferrite rings on the inputs to my servo drive power wires.. (3ph 480 volts)

How do I go about determining how big, thick, etc of a ring I should use?

I know little about them other than that they absorb energy.. (maybe that's what the F117 Stealth fighter is coated with ?)

Anyhow.. any tips on sizing these?

Thanks,
Murphy

[High Seas]

Ferrite "chokes" are often used on Ham radio rigs to kill RFI - maybe check a local HAM - or the Radio "snack" guys to get the right size. Cheers - Jim

[Al_The_Man]

Aerotech recommend one toroid right at the motor, they use ECZ280 with 10 turns of each motor lead through the toroid, so it has to be quite large, I picked a qty up on ebay, they were 1.5"OD .75"ID and 5/8"w but you should not go any smaller than this.
Al.

[murphy625]

So would I be correct in saying that the size of the ring does not matter so long as its big enough ???

Oversize not a problem on this??? What about the physical shape??

Thanks everyone!
Murphy

[Al_The_Man]

I usually use whatever is available, some have a higher frequency composition rating like
http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW
But I imagine they should work.
Al.

[sendkeys]

Would somthing in the lines of this work? Or does it really need to have 10+- loops? (there is ton of them at my local surplus store)
Also would adding one to the encoder wires help? Reason i ask this is i seen small cables use them, like usb camera cords .