> Ruben J=F6nsson wrote:
> > Another difference is that I don't use CAT5 cables but standard industr=
ial 2
> > twisted pair with shield. Cable area at least 0.5mm2. The shield is cla=
mped
> > directly to the groundplane on the circuit board, no isolated transceiv=
ers but
> > good transient protection on the RS485 lines.
> >   =

> =

> I wonder if the 2 pair data shielded would offer any more protection
> against transients. We have used that cable for other RS485
> installations (mainly data only, not power as well). When we did use it
> for power, it was only 10 - 15 metres and just between two devices.
> =

> The cheap 2 pair shielded data cable is 0.22 sq mm per conductor.
> Standard CAT5E seems to be slightly smaller (0.20 sq mm), but I can
> parallel two or three pairs for much lower voltage drop.
> David...
> =


It is depending on where the transients come in. If you can keep them in th=
e =

shield, nothing will happen with this setup - if you have a good groundplan=
e. I =

could also abuse this setup with high levels of all kind of disturbances =

(radiated and conducted RF, fast transients/bursts, surge and esd) in the E=
MC =

lab without so much as affecting even one bit of the communication.


/Ruben
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D

-- =

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