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Posted by Don Foreman on April 26, 2008, 7:10 pm
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On Sat, 26 Apr 2008 14:32:13 -0400, "Michael A. Terrell"
>
>Don Foreman wrote:
>>
>> I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
>> so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
>> VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
>> load end. The regulator costs about a dollar. It'll need a bit of
>> heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
>> as desired to fit in a space.
>
>
> Don't forget the bypass capacitors for that regulator, or it will be
>very unstable. Also, you need to protect it from lightning induced
>surges. Transfomers at both ends would help, mut make sure they are
>rated for 2500 VAC insulation. Split bobbin transformers would be a
>good choice. They can be found as surplus, or salvaged from junk
>equipment.
Yes, an 0.1 to 1.0 uF 50-volt bypass cap is a good idea. 30-volt TVS
(transient voltage suppressors) would handle about all induced
lightning surges.
Example: 1.5KE30
http://www.microsemi.com/datasheets/SA4-15.PDF
About 90 cents each.
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Posted by on April 26, 2008, 10:59 pm
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On Sat, 26 Apr 2008 18:10:39 -0500, Don Foreman
>On Sat, 26 Apr 2008 14:32:13 -0400, "Michael A. Terrell"
>
>>
>>Don Foreman wrote:
>>>
>>> I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
>>> so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
>>> VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
>>> load end. The regulator costs about a dollar. It'll need a bit of
>>> heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
>>> as desired to fit in a space.
>>
>>
>> Don't forget the bypass capacitors for that regulator, or it will be
>>very unstable. Also, you need to protect it from lightning induced
>>surges. Transfomers at both ends would help, mut make sure they are
>>rated for 2500 VAC insulation. Split bobbin transformers would be a
>>good choice. They can be found as surplus, or salvaged from junk
>>equipment.
>
>Yes, an 0.1 to 1.0 uF 50-volt bypass cap is a good idea. 30-volt TVS
>(transient voltage suppressors) would handle about all induced
>lightning surges.
>Example: 1.5KE30
>http://www.microsemi.com/datasheets/SA4-15.PDF
>
>About 90 cents each.
I have not been following the calculations closely - but if he has 6
strands, and the resistance is 7.7 ohms per 1000 feet on single strand
- if he parallels the wires into 2 conductors of 3 seperated strands
each, the total resistance is only 7.7/3=2.56 ohms per 1000 feet.
** Posted from http://www.teranews.com **
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Posted by Don Foreman on April 27, 2008, 1:04 am
Please log in for more thread options On Sat, 26 Apr 2008 22:59:32 -0400, clare at snyder dot ontario dot
canada wrote:
>On Sat, 26 Apr 2008 18:10:39 -0500, Don Foreman
>
>>On Sat, 26 Apr 2008 14:32:13 -0400, "Michael A. Terrell"
>>
>>>
>>>Don Foreman wrote:
>>>>
>>>> I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
>>>> so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
>>>> VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
>>>> load end. The regulator costs about a dollar. It'll need a bit of
>>>> heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
>>>> as desired to fit in a space.
>>>
>>>
>>> Don't forget the bypass capacitors for that regulator, or it will be
>>>very unstable. Also, you need to protect it from lightning induced
>>>surges. Transfomers at both ends would help, mut make sure they are
>>>rated for 2500 VAC insulation. Split bobbin transformers would be a
>>>good choice. They can be found as surplus, or salvaged from junk
>>>equipment.
>>
>>Yes, an 0.1 to 1.0 uF 50-volt bypass cap is a good idea. 30-volt TVS
>>(transient voltage suppressors) would handle about all induced
>>lightning surges.
>>Example: 1.5KE30
>>http://www.microsemi.com/datasheets/SA4-15.PDF
>>
>>About 90 cents each.
>
>
>I have not been following the calculations closely - but if he has 6
>strands, and the resistance is 7.7 ohms per 1000 feet on single strand
>- if he parallels the wires into 2 conductors of 3 seperated strands
>each, the total resistance is only 7.7/3=2.56 ohms per 1000 feet.
>** Posted from http://www.teranews.com **
It's 1000 meters (round trip) rather than feet ... but you're
certainly correct that loop resistance will drop if he uses more
wires.
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Posted by Gunner Asch on April 26, 2008, 4:33 pm
Please log in for more thread options wrote:
>
>> On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
>>
>>>grumpyoldhori writes:
>>>
>>>> Is it feasible to use two of these wires to carry twelve
>>>> volts that distance ?
>>>
>>>No.
>>
>> I'd say yes.
>
>Probably need to start with 24 volts to get 12 at the top. It will have
>about 15+ ohms total resistance (~3000 feet of wire). Is the load constant?
>Like a lamp or such?
>
>Is the wire insulated from the wood post? He could use 24 volts AC to a
>transformer at the top and convert to DC at the end.
>
>Tom
>
Indeed. AC up, convert to dc to avoid the losses
Gunner
Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.
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Posted by Ted Frater on April 26, 2008, 1:27 am
Please log in for more thread options grumpyoldhori wrote:
> Could I have some advice please.
> I need to get a twelve volt, 1/2 amp supply five
> hundred metres up a hill.
> I do have a fence a metre high made from wooden posts and
> seven runs of Num eight (4 mil) galvanised steel
> wire.
> Is it feasible to use two of these wires to carry twelve
> volts that distance ?
> Thank you.
>
>
If it was me, I run some trials.
Id get a 12 volt car battery ,connect the positive to one of your
galvanised wires then at the 500 meter point conect this wire to one say
2 strands down,come back to the battery and put a volt meter between the
retun wire and the battery negative.
this will show you the voltage losss/drop over the 1000m length.
what ever this is, lets say for example 12 volts, youll then have to
add another 6 volt battery to make the input voltage 18 to get
12 volts at the 500 meter point.
Run the trialand let us all know what the values are.
Even tho its up hill that shouldnt make much difference to what you get out.
To replace or run a copper line 1000meters is a much better way to go.
tho the cost wold be high.
Depends where you are.
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>Don Foreman wrote: