ferrite bead for surge suppression of power circuits 1

[electricpete]

Just thinking out loud....

Ferrite beads apparently filter surges based on frequency-selective behavior:

http://en.wikipedia.org/wiki/Ferrite_bead

Could such a device be used as surge protector for power devices like motors?

It would have the advantage of introducing no additional failure modes (unlike capacitors or MOV's) which physically connect to the power system)

This approach is not used as far as I know. Is there some technical challenge or is it a cost challenge? Any thoughts?

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[electricpete]

One correction on last equation of slide 2 attached.
(There are no other corrections coming, I'm going to bed)

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[electricpete]

OK, I lied. One correction on my conclusions. I said the slope is not significantly changed in any of these variations... I meant to say the "rise time" of the terminal end voltage is not significantly changed. (the magnitude changes, so the slope changes).

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[electricpete]

The equation at bottom of 2nd slide still wasn't right in powerpoint (but was right in Maple).

Attached incorporates all the corrections discussed above.

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[electricpete]

FYI - I posted a question about applicability to TL theory for short elements such as this in the Microwave and Electromagnetic forum, using the same attachment as my example.
thread239-293269

Since it's sort of a double post, let's keep any responses related to transmission line theory in that other thread.


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