NYC power outage

[mbrooke]

And oh- I meant to say DTT, not DDT. :ashamed1:


DTT= Direct Transfer Trip


Basically you tell the remote breakers to open and stay open.

 

[mbrooke]

Somewhat redundant- but for reference/citation.

Before Con Ed brought up the relaying failure at 65th they did tell reporters about the transmission bus at West 49th.


https://www.dailymail.co.uk/news/ar...rday-nights-five-hour-Manhattan-blackout.html

The company's president, Tim Cawley, told reporters Sunday a malfunctioning transmission bus in a substation on the western end of W. 49th St. was the root of the calamity.

 

[mbrooke]

Two papers that may help shed more light and provide more info in this information vacuum.


Page 20 (actual page 7):


https://www.researchgate.net/profil...-infrastructure.pdf?origin=publication_detail


https://www.bnl.gov/isd/documents/26662.pdf

 

[mbrooke]

The N-2 redundancy is confirmed:


(to point out I seriously doubt that long sideways S in the 138kv cable is a fuse)

 

[mbrooke]

From what I'm reading there is no over current protection for the transformers. The low side breaker should, but then again it may not.

 

[mbrooke]

There is also a good chance that the primary and secondary feeder relaying was changed with microprocessor relaying.


Con Ed has for a while expressed desire to upgrade old EM relays.


After Hurricane Sandy Con Ed has undertaking major IEC-61850 projects in the name of moderniation and flood resiliency.


http://digitalsubstation.com/wp-con...850-Europe-2017-Manuel-Pimenta_-ConEdison.pdf


And I applaud SEL for saying it


http://prorelay.tamu.edu/wp-content/uploads/sites/3/2017/04/3-IfYouCannot_6778_AA_3160_20170308.pdf

 

[romex jockey]

It's hard to imagine a blackout occurring ,given all this apparent redundant protection ? This then must make any forensic investigation much more a chore.....~RJ~

 

[mbrooke]

It's hard to imagine a blackout occurring ,given all this apparent redundant protection ? This then must make any forensic investigation much more a chore.....~RJ~

It is, especially one that "spreads" when no generation instability, voltage depression or supply equipment overloads are present.

 

[mbrooke]

And speaking of the above, it appears that 65th st should already have a circuit switcher.


Page 158 of 232:

http://158.57.189.31/2016-rate-fili...electric/08-eiop-exhibits-eiop-01-eiop-14.pdf

 

[mbrooke]

Con Ed has had concerns of uncleared 13.8kv faults, and I would imagine that involves implementing over current on the transformers such that an uncleared 13.8kv secondary fault does not solely rely on zones of differential protection but also backup 50/51 elements that cause the transformer's protection to trip the circuit switcher only.


Failure of both primary and backup 13.8kv feeder relaying is the equivalent of having an uncleared bus fault that is not detected by buss differential protection.


Con Ed has specifically been doing this in part to prevent the shutdown of an entire substation. In 1990 there was a sustained fault induced fire at the Sea Port Substation which ended clearing all 5 138kv cables from Farragut which also ended up cutting power to the WTC substation (4 more networks) in addition to a 5th network fed by Seaport.


https://www.nytimes.com/1990/08/14/...12041E190BA54A1A45&gwt=pay&assetType=REGIWALL

https://www.nytimes.com/1990/08/14/...B80735937ED6CBE003&gwt=pay&assetType=REGIWALL

 

[mbrooke]

Circuit switcher should have been in place and functioning at the time of the event:

 

[romex jockey]

Circuit switcher should have been in place and functioning at the time of the event:

Are those maintenance outages TBA....?

~RJ~

 

[mbrooke]

Are those maintenance outages TBA....?

~RJ~

Yes- they must be scheduled ahead of time. Perhaps they were never approved now that you ask. But I am inclined to doubt it.

 

[mbrooke]

FWIW, looking at other stations listed as "Beyond 2018" seem to have been equipped with a circuit switcher in the past year.



Bruckner:

 

[mbrooke]

Other side of Bruckner:

 

[mbrooke]

Hell Gate:

 

[mbrooke]

Jamaica:

 

[mbrooke]

Approximate single line breaker diagram of West 65st:

 

[mbrooke]

Drawing ended up being big so I had to shrink it and split it into two.

 

[mbrooke]

If anyone is curious is how MV is typically distributed and used in a network.


Small buildings are directly fed from the 208 volt mesh where as large buildings take 4 or more 13.8kv cables and have spot networks inside the building. Typically roughly every 10 floors will require a spot network- not uncommon for Manhattan buildings to have one or two in the basement, one or two on the middle mechanical equipment room and one or two on the roof.


Again the loss of two 13.8kv cables should not trigger equipment over load or an outage- even 3 cables is usually no issue outside of high load periods. Loss of 3 or 4 13.8kv cables supplying the 208 volt street mesh is typically not a problem outside the most hottest days.


Typically the secondary 208 volt cables are 500MCM phase and 4/0 neutral.