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niaziel
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High Voltage Transmission Lines

02/01/2015 6:35 AM

What will happens? If high voltage sustains for a long time on transmission line??

Is there any possibility to open SF6 breakers on both side??
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JohnDG
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#1

Re: High voltage transmission lines

02/01/2015 7:47 AM

If a high voltage transmission line does not sustain a high voltage for a long time, it hasn't been designed, built or maintained correctly, and a lot of the electicity supplier's customers will get very cross.

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#2
In reply to #1

Re: High voltage transmission lines

02/01/2015 9:18 AM

True, but if the OP designed this transmission line then there is a strong possibility that any and all circuit breakers will frequently trip open.

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Ali18
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#3

Re: High voltage transmission lines

02/01/2015 12:51 PM

The problems related to HV transmission lines mostly result from the magnitude of amperage (for overcurrent protection) and its direction (for directional protection)... While the OverVoltage phenomena comes from problems in the power transformer or busbars.

For the problem "Is there any possibility to open SF6 breakers on both side??", it all depends on the whole protection plan (in terms of both components & calculations) applied in the system in question.

I hope this helps.

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jack of all trades
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#4

Re: High voltage transmission lines

02/01/2015 1:46 PM

How long are we talking here because electricity is pretty fast and once you disconnect the power to the long line it really does stop pretty quickly?

Why do you think you need to open both sides of a really long transmission line? Aren't you taking the "electricity is kind of like water" analogy a little to far?

The electricity will stop flowing long before any communication signal (including light)reaches the protection on the far end of the transmission line and trips it to open it up as well.

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redfred
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#6
In reply to #4

Re: High voltage transmission lines

02/01/2015 4:22 PM

This is a transmission line, not a line cord or extension cord. Depending on the load factors happening on the grid the power can easily flow either direction through this transmission line.

I forgot to mention my usual caveat. Only authorized people should work on transmission lines. They are complicated and unforgiving devices. Many lives besides the unauthorized bozo on the line can be critically effected by a misstep.

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tcmtech
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#5

Re: High voltage transmission lines

02/01/2015 2:19 PM

I'n going with 57 amps on this one.

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IdeaSmith
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#7
In reply to #5

Re: High voltage transmission lines

02/01/2015 7:33 PM

Why not 42?

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raghun
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#8

Re: High Voltage Transmission Lines

02/02/2015 12:28 AM

High voltage can cause the

  • arcing horns to flashover and some times
  • line insulators to flashover. It can even be that the
  • surge arresters at the line ends start conducting.

If any of the above cases, the protection will see it as a fault and trip breakers at either end.

It all depends on

  • what is the voltage and the duration that we are talking,
  • what are the protections for the transmission lines and
  • the specification of line insulators, arcing horns as well as the surge arresters.
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cristle
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#9
In reply to #8

Re: High Voltage Transmission Lines

02/02/2015 1:22 AM

The protection scheme , characteristics of the line and characteristics of the protection equipment will interact in ways were it is possible for both relays to operate and trip. For example, if there was slow reacting circuit breakers on the far end, faster reacting circuit breakers at the supply end of the line, and no communications between the relays, then the first relay would look through the second and still see the fault present. Causing it to trip as well as the second relay. You could fix this by having differential protection that comes with a good protection engineer.
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#10

Re: High Voltage Transmission Lines

02/02/2015 9:33 AM

Note, this is not a reply to the OP's question, but a response to this whole 'category' of questions)

This requires more resources that we mere users have (at least without resorting to unethical/illegal means of data extraction), so this job, would need to fall to the forum admins:

  1. We need to collect the information on 'country of origin' for all the questions like these, ESPECIALLY when it's the first post of a new user.
  2. After annonomizing the data, we do a statistical analysis to determine which areas of the world have high concentrations of unqualified people trying to do Electrical Engineering.
  3. Once we know where the problem areas are, we start a system of 'humanitarian aid,' sending volunteer EE out to help these countries so they can enter the early-mid 20th century safely. (Yes, I know we're a decade into the 21st already, but too much change too fast can be harmful.)
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#11

Re: High Voltage Transmission Lines

02/02/2015 1:48 PM

Since this thread is getting off-topic due to lack of initial information in your question and subjective guess-work on our part, Niaziel can you post a more detailed explanation on what you actually want?

More details please!

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