How Transmission Lines Transposition could affect Protection systems?

[Luichip]

I would like to know if Transposition on Transmission Lines could affect the basis and the way the power system is evaluated to set up the protection for the Transmission line? as compared to the non-transposed Transmission Lines.

Thanks in advance,

Regards,

 

[sophiecentaur]

Are you referring to the fact that an open circuited quarter wave line will present a short circuit at the input? (etc.) It's enough of a problem to make it worth while using DC for long distance power transmission.

 

[Luichip]

I'm Talking about Long AC Transmission Lines, not DC in this case. Thanks.

Transposition is done regularly in long AC transmission lines as a means of balancing transmission line frequency impedance and admittance in a long line, and that contribute to unbalance voltages. This is usually done in double circuit AC long transmission lines...

 

[ZunairaMaryam]

I want to why TEM waves are not supported by transmission lines? and where is the point of difference in using waveguides and transmission lines?
Thanx in Advance.

 

[Bob S]

I want to why TEM waves are not supported by transmission lines? and where is the point of difference in using waveguides and transmission lines?

They do. See http://en.wikipedia.org/wiki/Transmission_line
This is why RG-8 has a characteristic impedance of Z=50 ohms, for example.

Bob S

 

[Bob S]

Transposition of individual conductors in a long AC transmission lines can minimize the inductive coupling to proximal lines. See refs 23-25 by Firestone and (Barney) Oliver on page 553 in

http://astro.berkeley.edu/~greg/isnumber=24903&prod=JNL&arnumber=1126050&arSt=+544&ared=+558&arAuthor=+Cristal%252C+E.G.%253B++Young%252C+L.pdf

If the lines are not transposed, loss of current in one line will inductively couple to the other lines.

Bob S