[BC] Air-Dielectric Sections

[Cowboy]

On Thursday 08 March 2007 11:08 pm, Andrew Skotdal wrote:
>   We intend
> to bury 3" air line (heliax?) at least three feet deep (not rigid line),
> in 6 inch conduit, with lots of sand around the conduit (42 inch deep
> trench, 6 inches of sand, conduit, and 6 additional inches of sand
> on-top of the conduit with warning tape and dirt backfill over that).  

 May I suggest THREE warning tapes ?
 RED one foot above the line.
 ORANGE two feet above, and
 YELLOW just ( 1 foot ) below grade.

 I might also suggest less critical lines ( such as AC power ) above the
 critical stuff, so that an errant back-hoe will hit something less fatal
 to operation *first.*

 ( sparks from AC are less fatal than sparks from RF to the operation,
 but both will usually get the hoe operator's attention )

>  I hadn't considered that. I'd probably
> cause the phasor designer to have a heart-attack over changing the size
> of transmission line and thus the velocity factor.

 I doubt it.
 It will change the phase budget slightly in a DA, thereby causing a slightly
 different length spec in a DA, but you mentioned a Non-D application, in
 which case it would only make a difference if also part of a DA, or if you're
 talking a significant additional length such that additional loss becomes
 a factor.

-- 
Cowboy