RE: Electric Fences (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 28 Oct 2003 11:52:32 -0500
From: "Mccauley, Daniel H" <daniel.h.mccauley@xxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: RE: Electric Fences (fwd)



Its much easier to supply your low voltage power and use multiple hv
units at the locations you need them at.

Dan



> > Some "applied HV" questions for you today.
> >
> > 1) I need to feed power to an electric fence through an underground
> > cable.  The solid core, triple-insulated cable sold for the purpose
> > seems to have a very short lifespan, with the insulation
> splitting after
> > very little time.  I am planning to route the cable through
> water pipe
> > to prevent penetration by stones, etc., but was wondering
> what would be
> > the best cable to use.  Moisture in the pipe would probably cause
> > ordinary mains cable to pinhole with the HV pulses.  How
> about some sort
> > of coax?
>
> I think the capacitance of the cable would seriously distort the
> pulses reducing the voltage.
>
> > [Solid-core polypropylene coax (NOT the foam core) is great
> for HV, but it
> > has a fair amount of capacitance so I'm not sure how well
> it would work
> > with pulsed or high-frequency HV.  You could always change
> your driver
> > circuit and just charge your fence up with straight high
> voltage DC ;-)
> > As a side note, you can even use coax cable as a
> high-voltage capacitor.
> > SRR]
>
> If the capacitance is high enough it might also push the discharge
> energy outside that permitted by regulation for electric fences.
>
> > 2) I would like to measure the voltage on the fence at
> various points,
> > to calculate losses and trace faults.  (I use a traditional Megger
> > tester at the moment for fault-finding.)  Since the HV is coming in
> > pulses, what is the best way to measure?  I was thinking
> along the lines
> > of a divider network with the A to D convertor of an AVR
> microcontroller
> > sampling at about 1kHz to catch the pulses. Any thoughts?
>
> Sound pretty complex and the sample rate is probably nowhere near
> high enough to catch transients. I'd use a good old compensated
> divider and analog scope.
>
> Malcolm
>
>
>
> > [You could probably wire up a cap and resistor with a long
> enough time
> > constant so you wouldn't have to worry about catching pulses.  SRR]
> >
> > Cheers
> >
> > M
> >
> > --
> > Matthew Smith
> > Kadina Business Consultancy
> > South Australia
> > http://www.kbc.net.au
> >
> >
> >
>
>
>
>