graze-l May 2006: [SPAM] - Re: [SPAM] - Re: [Graze-l]
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On 15/5/06 10:19 AM, "KV9U" <mrfarm@mwt.net> wrote:
> Hi Charles,
>
> Stray voltage is not easy to detect, even for professional engineers
> working on this problem.
Experts have little problem.
>We have several in our state who work with
> government and power companies to try and determine the cause. Even
> measuring mV (millivolts or 1/1000th of a volt) is not always going to
> help you. Some of these transients are fleeting and can come from miles
> away from factories, businesses and schools with inductive loads and
> square wave generation.
Sometimes because of the pathetically small earth pegs close to building
under eves.
> One way to accurately measure stray voltage is to use a storage
> oscilloscope which can hold the waveform with its attendent voltage and
> rise and fall times. This can give you some indication of the source.
> This type of equipment is very expensive and only a few troubleshooters
> seem to have it. If the leakage is constant, you could then measure the
> voltage with low cost equipment since most DVM's (Digital Volt Meters)
> can see a few millivolts on their most sensitive settings. The other
> issue is what do you measure across? The standard approach is to measure
> between a cow drinking location and a point where the hind feet would be
> and measure this across a 500 ohm resistor to simulate a livestock
> equivalent. They usually use some hydraulic pressure on the floor probe
> to match the weight of the livestock. The state folks claim that you
> would need over a 0.5 volt differential to be of concern.
They are wrong. Much less can affect a cow on four feet without gumboots and
with milking machines on tender teats.
In some US rural areas the electricity supply is a disaster, but the
suppliers will not admit it.
> Rick W.
>
>
> Charles Ritch wrote:
>
>> Rick,
>>
>> You wrote: This can help to reduce any chance of stray voltage.
>>
>> How would one check for "stray voltage". I am told the
standard volts
>> meters, ever thought they measure in mV, are not accurate for
>> measuring stray voltage. I call my electrical supply house and they
>> wanted over $700 for a meter that could accurately measure mV.
>>
>> Thanks,
>>
>> Charles Ritch
>> Goose Pond Farm
>> ritch@hiwaay.net
>
>
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Best wishes,
Vaughan Jones
Hamilton
New Zealand
