A/C Current in Power Lines
A/C Current in Power Lines
(OP)
Hello all,
I currently work for a electric utility and I am trying to delve a little more into the transmission process. I recently was trying to reason through how alternating current works and it makes sensse in to me within a circuit, but I am at a loss for how alternating current behaves in distribution lines. A/C current reverses dicrection as it is goes into negative region on a current vs time graph. How does this apply in a conductive element such as a distribution line.
Thanks in advance
I currently work for a electric utility and I am trying to delve a little more into the transmission process. I recently was trying to reason through how alternating current works and it makes sensse in to me within a circuit, but I am at a loss for how alternating current behaves in distribution lines. A/C current reverses dicrection as it is goes into negative region on a current vs time graph. How does this apply in a conductive element such as a distribution line.
Thanks in advance






RE: A/C Current in Power Lines
RE: A/C Current in Power Lines
RE: A/C Current in Power Lines
Another analogy is to think of a line of that old "clacking balls" desk toy (aka Newtons Cradle) you used to see all over, where a row of steel balls hung from a frame on strings. If you pull back the end ball and release it, the energy of your pull gets expressed on the ball at the other end, but all the balls in between don't really move much. Then the energy in that opposite end ball swings back into the lineup and transfers back, making the first ball move out.
The transmission line, or really ANY conductor, is essentially that row of balls. It doesn't create or use the energy, it just transmits it.
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: A/C Current in Power Lines
RE: A/C Current in Power Lines
English - Russian technical translator and DTP specialist. One of top EN-RUS technical translators in Russia and Ukraine according to proz.com. Full compliance with DIN 2345 standard.
RE: A/C Current in Power Lines
Keith Cress
kcress - http://www.flaminsystems.com
RE: A/C Current in Power Lines
English - Russian technical translator and DTP specialist. Full compliance with DIN 2345 standard. http://engrutra.com
RE: A/C Current in Power Lines
RE: A/C Current in Power Lines
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: A/C Current in Power Lines
Thanks for that rule of thumb Gunnar.
Bill
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"Why not the best?"
Jimmy Carter
RE: A/C Current in Power Lines
RE: A/C Current in Power Lines
(My puter has started to put capital letters in the beginning of certain Words. How does one change that?)
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: A/C Current in Power Lines
A question Gunnar. I understand the TDR measures the time to the fault and back. Would Keith's figure of 1/3 be the one way time and your figure of 2/3 be the two way time?
Thanks
Bill
Bill
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"Why not the best?"
Jimmy Carter
RE: A/C Current in Power Lines
Many of the simplified explanations for electricity come with build-in misconceptions. This website has several good analogies and points out some of the more common misconceptions:
http://amasci.com/miscon/eleca.html#light
By circuit vs distribution line, do you mean a source and resistance in a single loop versus 3 wires on a utility pole? In the simple single phase circuit, all electrons synchronize their wiggles, meaning that energy stops flowing when the electrons momentarily pause to change direction. In a balanced 3 phase distribution system, electron wiggles are offset by 1/3 of a cycle. This allows energy to continue flowing, even when the electrons in any one wire stop to change directions.
RE: A/C Current in Power Lines
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: A/C Current in Power Lines
Keith Cress
kcress - http://www.flaminsystems.com
RE: A/C Current in Power Lines
Gunnar what is TDR? Can you explain how you arrived at 100 metre figure? In transformer impulse testing we use 1.2/50 microsecond surge.When a failure occurs in test, there will be distortion in voltage and neutral current oscillogram wave shape.To locate fault in winding, we take a surge speed of 150 metres per micro second and the time from start to distortion in oscillogram.All these years, I never knew from where this 150 metres came. David now cleared my doubt.
RE: A/C Current in Power Lines
You inject a pulse into a wire, transmission line, free-space, fluid-filled pipeline, even a closed space. You then accurately time how long it takes to reach the "end" and return. Divide it by 2 and you have the one way distance.
The same thing works whenever there is an anomaly in a transmission system of any kind. Say you have a coax cable that has a squirrel gnawed shield somewhere. A piece of the 'pulse' will unexpectedly come back (reflect) from even that. This allows one to pinpoint where an issue is.
I used it to find tiny breaks in petrochemical pipelines.
Keith Cress
kcress - http://www.flaminsystems.com