Re: [TCML] Consensus on HV cable

[David Sharpe <sparktron01@xxxxxxxxx>]

Joe

The calculation process you outlined is correct, however even
Golka's monster Magnifier would not have needed cables as large
as this...  Your power feeder could handle significantly more
then 400kVAR of load at 14.4kV and much more at say
34.5-40kVAC input.

RG8 from a conductor ampacity perspective is fine.  I've used as
small as #18 at 5kVA input without issues.  I would recommend
the use of SOLID PE dielectric RG8 however; the foam
polyethylene with air inclusions has a much lower ultimate
dielectric strength then the solid PE.

Of course, if you really wanted to impress someone, use EDPM
15kV jumper power conductors (#6 is smallest size commercially available
however).  X-Ray cable as previously mentioned is a suitable
bragging rights alternative   ;^D

Regards

On Tue, Sep 14, 2010 at 1:51 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx> wrote:
>
> Not to pile on here, but just to do some of the calculations for the
> original question:
>
>  - For a Pole Pig of 14400V output, and 1.0uf tank cap, 60Hz  Ichg=
> 377*1x10^-6*14400 = 5.43A
>
>  - NEC Table 310-16 suggests ampacity for 10Ga AWG between 30 -40A depending
> on temp, 60-90 C.
>
> - Inner conductor diameter of RG8/U coax is, depending on type, is between
> 0.103" to  0.108" copper, stranded or solid, with insulating material of
> foam polyethylene or teflon.
>
> - Diameter of solid 10Ga AWG copper is 0.102"
>
> - Therefore, using the center conductor only of a length of RG8/U is
> feasible for a 1uf Tank primary + 14400V pole pig , taking only current into
> account.
>
> Am I missing something in that brief analysis?
>
> However, I wonder if the group could comment - does it matter if the core
> insulating material is foam-polyethylene,  or teflon?  Should one consider
> shorting the shield to the center conductor to avoid creating some sort of
> distributed capacitive transmission line (though at 60hz, probably not so
> much of an issue)?
>
> Has anyone actually done this?
>
> Thanks in advance,
>
> Joe
>
>
>
>
> On 9/14/2010 5:46 AM, David Sharpe wrote:
>>
>> David
>>
>> What is output voltage of pole pig?
>> What is size of tank capacitor?
>>
>> Ichg ~ w * C * E  (w= 2*pi*f; 377);  C farads, E volts, Ichg amps
>> Ichg is approximate steady state VAR current
>>
>>  Would size wire to support minimum 2X that value
>>  (see NEC table 310-16 for typical conductor
>>   ampacities).
>>
>> Typical #16 is good for 7.5A continuous which at
>> 12kV is nearly 90kVA delivery to load; insulation
>> to support applied voltage.
>>
>> Regards
>>
>> On Mon, Sep 13, 2010 at 11:49 PM, David Speck<Dave@xxxxxxxxxxxxxxxx>
>>  wrote:
>>>
>>>  Esteemed list:
>>>
>>> Is there any consensus on the optimum gauge and insulation of the cable
>>> that
>>> goes from the HV output terminals of a 10 KVA pole pig to the RSG and
>>> tank
>>> cap of a 12" x 48" Coil?
>>>
>>> I seem to recall that the inner conductor of RG-8 coax with solid
>>> polyethylene jacket and without the shield was the preferred material.
>>>
>>> Anyone found anything better?
>>>
>>> Thanks,
>>> Dave
>>> _______________________________________________
>>> Tesla mailing list
>>> Tesla@xxxxxxxxxx
>>> http://www.pupman.com/mailman/listinfo/tesla
>>>
>>
>>
>
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>



-- 
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
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