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#14251 - 09/18/02 12:04 AM Electric Fence Induction Problem
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
I am on the horns of a real dilemma, guys, I wonder if you fella's could give me some advice as to what I can do, to correct a problem, that is becoming more and more common, now days.
We have a burgeoning Dairy Industry, over here, with this comes Electric Fences, all running at 16,000V, this would not be a problem, but all of the telecoms lines are run overhead and owing to induced voltages,
the pulsed output of the Energisers, ends up on the telephone lines.
This would not have been a problem, 10 years ago, but now all of the people out in the rural areas want high-speed Internet access and you can imagine what induced voltages like this will do to a Modem made in China.
What I am looking for advice on, guys is wether or not this problem can be remedied at the computer terminal end of things, with something like a filtering network, that will take out the voltage pulses,(some of which, can be up to 15-30V, depending upon the parallel length of circuit), but will not upset the normal operation of the phone-line/Internet access.
This is a big call people, I hope that you can help.

[This message has been edited by Trumpy (edited 09-20-2002).]
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#14252 - 09/18/02 02:57 AM Re: Electric Fence Induction Problem
George Corron Offline
Member

Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Induced voltages on phone lines can usually be dispensed with by properly bonding the utilities. ie: each junction point, and to the electric service bond at the customer service point.

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#14253 - 09/18/02 03:35 AM Re: Electric Fence Induction Problem
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
Ahh, that reminds me...

When I was young and had no sense
I peed on near an electric fence
It shocked my pecker, and stung my balls
And made me sh-t in my coveralls

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#14254 - 09/18/02 03:55 PM Re: Electric Fence Induction Problem
Currently Offline
Member

Registered: 04/21/02
Posts: 54
Loc: TN
Redsy,

Ruefully speaking from experience, that ain't what happens!
It's more like:

5 minutes on the ground
grunting and moaning
and rolling all around!

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#14255 - 09/18/02 04:54 PM Re: Electric Fence Induction Problem
Chris Rudolph Offline
Member

Registered: 05/01/01
Posts: 160
Loc: Winter Park,Fl USA
Some modems have operational amplifiers that have balanced inputs that offer a fair amount of iterference rejection also called common mode rejection.This is expressed in dB,the higher the dB level the better rejection.
Another way is to shield the data/telephone line for example, use external/outside Cat 5 cable near the electric fence.
Let us know what works.
Chris

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#14256 - 09/18/02 07:12 PM Re: Electric Fence Induction Problem
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
Redsy,

I almost fell out of my chair laughing when I read your post. I was working on a farm here in NJ many years ago, when I was checking out a barn and how I was going to run an outside feeder, I backed into an electric fence. I was just a helper then working for my old boss, it sure taught me to repect electricity.

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#14257 - 09/19/02 03:59 AM Re: Electric Fence Induction Problem
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
We've had a constant problem with my buddy's music studio on a beef unit. Induction to the power lines or something.

Amps going:

Pop...Pop...Pop...Pop...Pop...Pop...Pop...ad infinitum...

Swears up and down there aren't any E-fences on in his place...
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Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#14258 - 09/19/02 09:21 AM Re: Electric Fence Induction Problem
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Redsy! — You have discovered the secret second verse to the poem:
Here I sit all broken-hearted,
Spent a dime and only...

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#14259 - 09/19/02 09:31 AM Re: Electric Fence Induction Problem
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Uhm, one thing about electric fencers and RFI is that if there is any flashover from wire-to-ground {say, at insulators on metal posts} the "signal" will be a lot more 'penetrating.' Run the fenceline at night and you may see and hear the problem.

Now, if you give cows there own internet access, {wcw.bovimania.cow is good} you can unplug the fencer for a couple of hours and the cows never notice!

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#14260 - 09/19/02 08:27 PM Re: Electric Fence Induction Problem
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Bjarney,

Infinitely worse scenario:

Here I sit, soiled and committed...
'Cause I thought I'd f*rt,
But, I didn't. I s___ed!




*senses mods impending doom*
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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