Noise supression in long wires

A

AirPix

Member
I've always been conscious of electrical noise in RC systems, especially electric powered planes. I've been known to put "torroids" (magnetic rings) on long ESC leads.

In a noisy, multi-motor system like Multirotors, this seems like a good idea. In fact, the other day at my LHS I saw a crashed Blade 350 with torroids installed on each ESC leads back to the "power distribution board" (battery) and to the Flight Controller. Three wraps for the power leads, three wraps for the ESC lead.

But I got to thinking (always dangerous), I can see noise supression on the ESC lead. But on the power wires ( = and - )? Which are likely to be noisy, fine. But I wonder if noisy power lead might not try to make the torroid act like a simple transformer and try to induce noise into the ESC leads? I think that the ferrite torroid might not behave at all like transformer laminations, so this might be a moot point...

Has anyone used magnetic rings like this on your ESC leads?

--Bill
 

E

Electro 2

Member
AirPix said:
But I wonder if noisy power lead might not try to make the torroid act like a simple transformer and try to induce noise into the ESC leads? I think that the ferrite torroid might not behave at all like transformer laminations, so this might be a moot point...

Has anyone used magnetic rings like this on your ESC leads?
Click to expand...

The/a toroid only supresses common mode signals when *both* send and return wires of an individual circuit are passed through it. Think if it as a "buck" model, it resists common mode signals that are common to both wires. Whether this magnetic device consists of a laminated silicon steel core or a cast iron-ferrite core, depends on the peak rejection *frequency* one is trying to reject. Ferrites are prefered for RF frequncies, silicon steel laminate for lower frequencies, within the audio range. Has to do with magnetic domain sizes and orientation within the core material. And the answer is yes, and yes again. In a perfect world *all* the wires from/to an ESC would be choked off. Any of these cables conductors could act as a conduit for EMI into other parts of the system.
 


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