HV DC transmission design / theory
HV DC transmission design / theory
(OP)
I'm curious about the design of this apparently HV DC transmission circuit. What is the theory behind the third conductor suspended in the "V" ? It's insulated very differently than the 2 primary conductor bundles, so I'm pretty sure this is not multiphase AC. This circuit is located near Littleton, MA. Sorry the pic is not a bit clearer. Thanks !






RE: HV DC transmission design / theory
>There are 6 HV lines suspended from the long insulators current-carrying
>There are 2 lightning protection lines that have no insulators, non-current carrying, since they are way thinner than all the others
>There is a single line suspended from short insulators, current-carrying.
TTFN
RE: HV DC transmission design / theory
The first HVDC lines used only one conductor and used ground for return. They were built to bridge waters (Gotland, Pas de Calais, Sicily etc). Environmentalists then made this arrangement more or less impossible. The wide DC current loop also disturbed magnetic compasses on ships. So later on one plus conductor and one minus conductor was used. The middle point (you could call it Neutral or Zero) was tied to ground. In this installation, it looks like the "neutral" has been brought all the way from source to sink - at least, that's how I interpret the thin low voltage (maybe 20 - 40 kV) insulated top conductor.
Gunnar Englund
www.gke.org
RE: HV DC transmission design / theory
RE: HV DC transmission design / theory
I have read on artical where the "earth" terminals on HVDC line caused water to the break down of ground water into hydrogen and oxygen. Lots of interesting research and papers written on the subject. The geological formations where the "ground" is connected is significant.
RE: HV DC transmission design / theory
Thanks,
dave
RE: HV DC transmission design / theory
RE: HV DC transmission design / theory
The transmitting and the receiving terminals are identical. They are both mains-commutated, which means that the 50 (or 60) Hz mains does the commutation. No islanding possible - there must be a rather stiff grid to connect to at both ends.
I shall try and dig out some diagrams that show this more clearly.
Gunnar Englund
www.gke.org
RE: HV DC transmission design / theory
http://www
Gunnar Englund
www.gke.org
RE: HV DC transmission design / theory
Thanks Gunnar
Respectfully
RE: HV DC transmission design / theory
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: HV DC transmission design / theory
Thank you also for your graphic.
Respectfully
RE: HV DC transmission design / theory
However, there are several undesirable side effects. One of these effects is stray current corrosion of underground metallic structures such as pipelines. Other environmental concern may be the chlorite generation in HVDC submarine cable.
RE: HV DC transmission design / theory
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: HV DC transmission design / theory
I hope this is considered a related side issue rather than cross posting.
I hope for a wider response by posting a specific question rather than posting a link to this thread.
respectfully.
RE: HV DC transmission design / theory
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: HV DC transmission design / theory
I had thought that Tesla & Westinghouse had shown that HV AC was better than Edison's DC for transmitting power.
Does this mean that newer equipment such as ABB's vindicate Edison in this respect???
RE: HV DC transmission design / theory
The HVDC system became advantageous over to the AC system in a large amount of power transmitted in long distance. During Edison and Westinhouse time only limited amount of power and relative short distances was required. Also the power electronic technology to support the HVDC, apperars meny years leter after Edison and Westinhouse.
RE: HV DC transmission design / theory
The idea of DC being safer is curious: anyone who has seen a major fault on a DC system will know how tough it is on the switchgear. Once a powerful DC arc is established it is not a trivial task to interrupt it. I treat all electricity as dangerous, but I'm especially wary of big DC systems.
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Sometimes I only open my mouth to swap feet...
RE: HV DC transmission design / theory
Perhaps you are thinking in current interruption of DC vs. AC. However, comparing the DC with AC at industrial power frequency of 60 or 50 Hz there are many evidence to conclude that T. Edison was right from the safety point of view.
I took the liberty to plot the physiological effect of electric current in human body based on the Charles Deziel experiment in human body that confirming that the AC current at power frequency of 60 Hz require of a fraction as low as 15% of the DC current to produce a painful electric shock with muscular control loss by 0.5%.
Another interesting data shows that AC current at high frequency such as 10,000 Hz is less dangerous than the DC counterpart.
For illustration of the physiological effect on human body, see the enclose link.
http:/
."Edison spent a great deal of time dealing with lawyer-suing other companies for stealing his patents, getting sued in turn for stealing theirs".