On Thu, 7 Jul 2005 18:46:36 -0400, "Walter Maxwell"
wrote:


Well, Owen, if you believe the expressions I presented in Reflections 2 are
approximate, then why do I get the correct answers?

It seems to me that the method requires that rho is not greater than
one (otherwise the denominator (1-rho2**2) becomes negative, which is
a nonsense). This hints that it does not apply in the general case
where rho *can* be greater than 1, and is therefore probably limited
to cases of distorionless line (Xo=0).

To avoid publishing "ugly" maths here, I have put a page up at
http://www.vk1od.net/temp/reflection.htm with a bunch of expressions
for conditions on the modelled line, including functions for power
flow at an arbitrary point, Loss calculated from powerflow at two
points and loss based on your loss formula + matched line loss.

The graphs show the loss from point x to the load, x is 0 at the load
and negative toward the source.

The algorithms produce quite different results. If I ignore Xo (ie
force Zo to be real), then both algorithms produce the same results.

Have I made a mistake in the maths, or in modelling the scenario?

Owen
--