Transmission Tower Collapse and Resulting New Orleans Power Outage

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I love the (quite sensible) note-
"For safety grounding/purposes, the available fault current is above 40KA"
(I should hope it is.)

Which typically means two 4/0 (or greater) grounding jumpers. Some stations only top out at 10,000 to 20,000 amps. 40 to 63ka is typical for generating and large interconnecting substation. New Jersey has upwards for 80-90ka on their 230kv stations o_O

I'm thinking switching 765 transmission and 345kv sub transmission is in order.
 
210901-0841 EDT

In my town, Ann arbor, MI, the main campus of the University of Michigan has its own power plant. This alone is not sufficient to supply all U of M facilities.

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Is said power plant there to supply majority of power to the campus or is it there more for relief of demand charges when necessary from the utility? Another benefit can be providing a certain level of emergency standby.
 
Duke lost a transmission tower near Aurora, NC during either Irene or Sandy, I forgot which. A huge lightning strike literally blew the pole apart. Based on what their engineers said and estimated the lightning strike was extremely large and very rare. It is unusual for 230 kV lines to be affected.
 
210904-1339bEDT

kwired:

The U of M main power plant was constructed a long time ago, and probably powered a large part of the main campus. There was no North Campus at that time.

Some details are:

The CPP is a combined cycle cogeneration power plant which includes seven steam boilers totaling 1,000,000 pounds of steaming capacity and 46 megawatts of electric generation capacity. The CPP team operates and maintains the facility to ensure we are compliant with the federal, state and local Environmental & Safety regulations. We are a proactive team who strive for continuous improvement by applying the Facilities and Operations principles of being Respectful, Collaborative, Solutions-Based and Proactive into our daily work.



I would say the U of M main campus power plant is for base load, as is the Parke-Davis North Campus power plant. and that DTE supplies peaking power. But in some buildings DTE is going to be base power.

.And there are a lot of emergency generation units that are not generally powered. Probably not even for peaking.

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For example, see page 9 where the CT government disclosed a single line breaker diagram for the state of Connecticut for a project effecting the public and its interest:



And the ISO for that state releasing generator diagrams for open phase detection as part of a major project effecting the state:

https://www.iso-ne.com/static-asset...otection_system_ppa_withdrawal_dem_16_t01.zip

Technically any time tax money is involved information must be disclosed otherwise it will be in villoation of several laws including the US Constitution.
This came up before and is incorrect. Where I worked for a local govt, we had homeland security do a security review, the results were classified as protected critical infrastructure information and not subject to public disclosure. But bid docs are considered public,
 
Looks like they are tearing down the other tower?
Maybe a dumb question, but I was taught never to not ask them...

In the video posted by mbrooke (post #25) they indicate dynamite was used to bring down the lines that fell into the river. Not blowing up the tower, but the actual current carrying cables that were laying in the water. Why dynamite I wonder? I realize that you are not going up in a basket with a pair of 6" side cutters - but why use explosives to separate the lines? I wonder if it's because they are so heavy and tight (in tension) you don't want to be anywhere near them when they are parted because they will fly apart fast? I assume they are no longer energized by this point? So it's likely not an electrical safety thing, but some mechanical safety aspect?
 
Maybe a dumb question, but I was taught never to not ask them...

In the video posted by mbrooke (post #25) they indicate dynamite was used to bring down the lines that fell into the river. Not blowing up the tower, but the actual current carrying cables that were laying in the water. Why dynamite I wonder? I realize that you are not going up in a basket with a pair of 6" side cutters - but why use explosives to separate the lines? I wonder if it's because they are so heavy and tight (in tension) you don't want to be anywhere near them when they are parted because they will fly apart fast? I assume they are no longer energized by this point? So it's likely not an electrical safety thing, but some mechanical safety aspect?
If I had to guess, they did not use "dynamite". This is lazy journalists at work. Most likely, they used JetCord (linear shaped charge), or multiple wraps of det cord to cut the cables.

 
Looking at the "outage" map this morning and they still have a long way to go especially in the outlying areas,
 
If I had to guess, they did not use "dynamite". This is lazy journalists at work. Most likely, they used JetCord (linear shaped charge), or multiple wraps of det cord to cut the cables.

Yes -agreed - and I almost used "air quotes" around my mention of dynamite from that TV report.

One advantage that came to mind for using explosives to bring the cables down would be they would drop all at the same time. As opposed to a crew in a basket (using some kind of cutter) that would take some time to get up and around all the locations they'd want to part. So if there were logistics of safety and space clearing underneath the cables (and there obviously would be) maybe it would be easier (and quicker) to have them all come down at once?
 
210904-1339bEDT

kwired:

The U of M main power plant was constructed a long time ago, and probably powered a large part of the main campus. There was no North Campus at that time.

Some details are:

The CPP is a combined cycle cogeneration power plant which includes seven steam boilers totaling 1,000,000 pounds of steaming capacity and 46 megawatts of electric generation capacity. The CPP team operates and maintains the facility to ensure we are compliant with the federal, state and local Environmental & Safety regulations. We are a proactive team who strive for continuous improvement by applying the Facilities and Operations principles of being Respectful, Collaborative, Solutions-Based and Proactive into our daily work.



I would say the U of M main campus power plant is for base load, as is the Parke-Davis North Campus power plant. and that DTE supplies peaking power. But in some buildings DTE is going to be base power.

.And there are a lot of emergency generation units that are not generally powered. Probably not even for peaking.

.
Sounds like maybe just the opposite of what I was thinking then. Instead of reducing peak from utility they maybe sending excess to the utility pretty much at all times?
 
Yes -agreed - and I almost used "air quotes" around my mention of dynamite from that TV report.

One advantage that came to mind for using explosives to bring the cables down would be they would drop all at the same time. As opposed to a crew in a basket (using some kind of cutter) that would take some time to get up and around all the locations they'd want to part. So if there were logistics of safety and space clearing underneath the cables (and there obviously would be) maybe it would be easier (and quicker) to have them all come down at once?
Those cables are under a lot of tension, when they give they are going to be moving like a bat out of hell, in both directions, or in whatever directions the resultant force vectors are pointing. No one in their right mind wants to be in a basket cutting through the final strand that makes everything go "Pop!" The springback force on the tower is going to be non-trivial too, I would think.
 
Yes -agreed - and I almost used "air quotes" around my mention of dynamite from that TV report.

One advantage that came to mind for using explosives to bring the cables down would be they would drop all at the same time. As opposed to a crew in a basket (using some kind of cutter) that would take some time to get up and around all the locations they'd want to part. So if there were logistics of safety and space clearing underneath the cables (and there obviously would be) maybe it would be easier (and quicker) to have them all come down at once?
New 345kV line was run near where I live not so many years ago. IIRC they pulled them all at same time when tensioning them, probably for good reason. I think I recall seeing them pull all the conductors at same time even on some local distribution line construction though, maybe not needed so much for strain related issues but rather is just quicker and easier to do so.
 
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