On Thu, 06 Oct 2011 14:51:14 -0500, Ignoramus15921
wrote:

On 2011-10-06, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Jon Elson fired this volley in
:

There is also no radiation or ground heating from DC.

Jon

Jon, that's not right (not completely). ANY conductor carrying a current
induces a magnetic flux around itself, the strength of which is entirely
dependent upon current, not voltage.

But the flux is constant and thus, does not induce any electromagnetc
waves or current in the ground.

Although AC transmission produces a moving (alternating) magnetic field
that can induce currents in still objects (like the ground, yes), the
magnetic field around a DC conductor can still induce currents in moving
objects (like people, vehicles, etc.).

Good point.

So it's not right to say a DC conductor doesn't "radiate", because it
does radiate a magnetic field. It just happens to be a static field, so
long as the current remains constant. Vary the current, and you have a
varying field with similar (if reduced) effects like those of an AC
transmission line.

Very good clarification.

The only fly in that ointment is...

While it's DC on the transmission lines and should therefore be a nice
steady current, it's being rectified from 60-Hz AC at one end and
turned back into 60-Hz AC at the other end, and as we've noted the
frequencies and phase rotations at either end are most likely
different.

So even with plenty of capacitance at both of the converter stations
and the inherent capacitance of the transmission lines themselves,
that's got to introduce some AC Ripple into the DC. It won't be -
can't be - pure DC. ("Close Enough" will work for the transmission
line itself.)

You can never get the Capacitance and inductance of the tuned
circuits dialed in perfectly - and the minute you do, the loads will
change again. There's a reason they build the entire converter
station inside a steel building and it's switchgear enclosed in a huge
outdoor Faraday Cage, to try and keep the RF noise it will generate
inside the cage.

(That the big cages keep birds and other critters out of the converter
stations is just a convenient side effect.)

-- Bruce --