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  1. Replies
    27$$
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    909

    The local substations: 1) West 50th st has...

    The local substations:


    1) West 50th st has Five 138kv-13.8kv transformers each 65 MVA. This station supplies the Hudson network.

    2) Astor has Five 138kv-13.8kv transformers each rated 65MVA....
  2. Replies
    27$$
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    909

    Transformers- I know you were asking about them....

    Transformers- I know you were asking about them.


    West 49th st has Five 345kv-138kv auto transformers, each rated 420 MVA.

    There is room for two more if seven total are ever needed.

    The...
  3. Replies
    27$$
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    909

    Thank you for sharing this! This is why I post...

    Thank you for sharing this! This is why I post here.

    Could be a coincidence, could be related.

    I can't see a 13.8kv fault pulling the voltage down all the way to Pittsburgh, but if it somehow...
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    27$$
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    909

    The 4 substations supplied by West 49th st:

    The 4 substations supplied by West 49th st:
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    27$$
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    909

    Here is the public supporting data: ...

    Here is the public supporting data:


    https://res.cloudinary.com/engineering-com/image/upload/v1563230166/tips/49th_St_Sub_Outage_kotvei.jpg




    Page 15:
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    27$$
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    909

    Here is the West 49st substation. It is a bulk...

    Here is the West 49st substation. It is a bulk substation.

    It takes in Five 345kv feeders and steps down 345kv to 138kv via 5 auto-transformers.


    It puts out 11 138kv feeders which supply...
  7. Replies
    27$$
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    909

    A "network" can handle the loss of any medium...

    A "network" can handle the loss of any medium voltage feeder cable without customer outages, or in the case of Con Edison two feeder cables can simultaneously fail without customers loosing power.
    ...
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    27$$
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    909

    Part 2:

    Part 2:
  9. Replies
    27$$
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    909

    Con Ed released a report after the Washington...

    Con Ed released a report after the Washington Heights network outage in 1999.


    The appendix lists the typical yearly medium voltage cable failures for various networks in a given year:
  10. Replies
    27$$
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    909

    Keep in mind the media tosses the term...

    Keep in mind the media tosses the term "transformer explosion" around to describe everything electrical to which everyone follows leading to the perception thats what actually happened.



    From...
  11. Replies
    27$$
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    909

    So what happens when a 12.47kv distribution...

    So what happens when a 12.47kv distribution feeder with 2,000 smaller distribution transformers trips from a tree in the line?


    Way off. I'm stunned you would say something like this.
  12. Replies
    9$$
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    457

    Auto reclosing. And in some cases rewiring...

    Auto reclosing.


    And in some cases rewiring of the system after lockout (reclose attempts made and none of them held):


    https://www.youtube.com/watch?v=2VGs7FdrSIE
  13. Replies
    15$$
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    549

    Just don't tell certain folks, it will give them...

    Just don't tell certain folks, it will give them ideas :lol::rant:
  14. Replies
    15$$
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    549

    Would it even have a waveform?

    Would it even have a waveform?
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    15$$
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    549

    The question IMHO is- was that parallel arc more...

    The question IMHO is- was that parallel arc more than 75 amps or as a series arc greater then 5 amps?
  16. Replies
    112$$
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    4,100

    This being what determines the two being bonded...

    This being what determines the two being bonded together vs not bonded together:

    .
  17. Replies
    112$$
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    4,100

    What neutral switching scheme :? I'm asking...

    What neutral switching scheme :?


    I'm asking you to use this chart on a 5 cycle clearing MGN system:

    ...
  18. Replies
    112$$
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    4,100

    Remember, I just said you can show me the results...

    Remember, I just said you can show me the results at 5 cycles. Lets first determine if 5 cycles is ok or not ok.



    I have always been taught to take BF into account. I normally bite my tongue,...
  19. Replies
    112$$
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    4,100

    Page 4: ...

    Page 4:

    https://www.scientificbulletin.upb.ro/rev_docs_arhiva/full628_442581.pdf

    We have a voltage of 2.4kv

    5 cycles 10 cycles 15 cycles.

    Where do the values land on the physiology graph?
  20. Replies
    15$$
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    549

    I agree, great replies thanks guys :)

    I agree, great replies thanks guys :)
  21. Replies
    15$$
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    549

    Would an arc fault trip on this?

    Keyless lamp holder with an actual arc fault. Not from a loose connection but it appears some yellow water got inside of it. Would this lead to a fire? Or trip a regular AFCI?


    ...
  22. Replies
    112$$
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    4,100

    Prove to me that even with functioning equipment...

    Prove to me that even with functioning equipment 5 cycles of 2.4kv will not hurt someone. Calculate the body resistance, the current that will flow and check in relation to the IEC graph.




    ...
  23. Replies
    20$$
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    1,058

    Not code complaint, but may be necessary. ...

    Not code complaint, but may be necessary.


    Before you pull them permanently see if the circuit holds with a regular GFCI.
  24. Replies
    112$$
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    4,100

    This is good, but its difficult to do with tens...

    This is good, but its difficult to do with tens of thousands of breakers every few years. Especially when for some you need to schedule an outage (straight bus).



    With multiple reclosers in...
  25. Replies
    29$$
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    1,555

    I think you are right. Its probably the max frame...

    I think you are right. Its probably the max frame size for 63 amps.


    Keep in mind off brand Chinese products are 1 part translation fail 1 part playing by their own rules.
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