Con Edison Substation explosion NYC

kwired

Electron manager
Location
NE Nebraska
Did something actually explode or was this just a major arc flash incident?

All we see in the video is the flash, and have no idea what actually happened.

An arc flash is an explosive event, but many will incorrectly say that a transformer exploded, when it did not.
 

fmtjfw

Senior Member
I wonder what caused the explosion?

I didn't see any dimming before it happened. And of course the usual why didn't the OCPDs keep the sub station from blowing up?
Pure conjecture:

Maybe the station battery got shorted out before the HV/MV equipment was shorted. The station battery would normally be close to the floor in the relay hut and could have been flooded early. HV/MV could be higher in the air, especially if it is bus bars. The OCPDs are typically operated by relaying equipment that detects over currents, reverse currents, a whole myriad things not detected by LV circuit breakers. The breakers are tripped by currents from the station battery through the relays. They are not tripped directly by the overload currents themselves.
 
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jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Engineer
An arc flash is an explosive event, but many will incorrectly say that a transformer exploded, when it did not.
Utility transformers usually contain oil. Oil usually starts a fire and burns for an extended time, when transformers truly explode.

The bright flash of light and then nothing, is more indicative of the conductors feeding the transformer 'exploding' as they are shorted.
 

kwired

Electron manager
Location
NE Nebraska
Utility transformers usually contain oil. Oil usually starts a fire and burns for an extended time, when transformers truly explode.

The bright flash of light and then nothing, is more indicative of the conductors feeding the transformer 'exploding' as they are shorted.
I didn't think about the oil. Just how often does a transformer get hot enough to burn the oil? Don't they generally provide overcurrent protection making this somewhat unlikely?
 

cornbread

Senior Member
In my many years of working I've had the opportunity to see a couple of substation Xfmrs blow their tops and catch fire..... The couple of failures I witnessed... there were no bright flashes just a mushroom cloud of fire and smoke....very impressive. If it were not for the fence aroud the substaion I would still be running.
 

zog

Senior Member
Location
Charlotte, NC
I didn't think about the oil. Just how often does a transformer get hot enough to burn the oil? Don't they generally provide overcurrent protection making this somewhat unlikely?
Usually a transformer like this will have differential relays to protect from an issue like this. It is very difficult for the oil to burn but if the heat gets high enough to expand the oil so the sudden pressure relief lifts you will have ionized oil spraying out which can catch fire. Just lke this (You can see the relief lift right before the explosion). http://www.youtube.com/watch?v=fzbQjd_Oo4Q
 

ron

Senior Member
It was underwater. Water is a relatively good conductor.

John Miksad, Con Ed?s senior vice president of electric operations, sat down with The Wall Street Journal on Tuesday WSJ:

What is the single most challenging logistical task facing Con Ed?


The biggest single issue is the equipment explosion?and the resulting problem
that affected our 13th Street substation. We are in there now. We?re pumping
water out of there. And that is a common theme in a lot of this.

All of that is going to start with getting water out of our system. It?s not
only in the way of our access ? it?s also submerged some of our equipment.

We?ve got ? whatever it is ? two, four, six, eight feet of water that?s
sitting there with our equipment under it?We have folks pumping water and then
trying to get in. I think they may even have rowboats in there.

WSJ Do we have a better sense of what caused the
substation explosion?


We do not. We could not get access last night because of the water?.I think
it?s probably most likely flying debris.
 

fmtjfw

Senior Member
More conjecture about reason for failure:

WSJ: Why did the explosion knock out so many neighborhoods?

John Miksad: It?s a combination of that failure, which resulted in a short-circuit, and ? again conjecture ? the belief is that the control wiring, the wiring that protects that equipment, was saturated and mis-operated, resulting in a larger outage.

It?s like the circuit breaker panel in your house being under water.
 

mbrooke

Senior Member
Location
United States
Did something actually explode or was this just a major arc flash incident?

All we see in the video is the flash, and have no idea what actually happened.

An arc flash is an explosive event, but many will incorrectly say that a transformer exploded, when it did not.
The news media seems to call every electrical equipment faluire a transformer explosion. During the coverage of Sandy a tree branch shorted across 2 phases on a utlity pole near a reporter. The reporter stated "a transformer just exploded" Live shots during the storm were showing bright blue flashes in the horizion one after the other in variuos states, the anchor man's explanation was that those were transformers exploding all over the towns because they had enough from the storm:lol:

Looks like we need millions of pole top units and substation transformers. Nothing like media "experts" spreading disinformation. And everyone trusts these people to give the truth.:rant:
 
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kwired

Electron manager
Location
NE Nebraska
The news media seems to call every electrical equipment faluire a transformer explosion. During the coverage of Sandy a tree branch shorted across 2 phases on a utlity pole near a reporter. The reporter stated "a transformer just exploded" Live shots during the storm were showing bright blue flashes in the horizion one after the other in variuos states, the anchor man's explanation was that those were transformers exploding all over the towns because they had enough from the storm:lol:

Looks like we need millions of pole top units and substation transformers. Nothing like media "experts" spreading disinformation. And everyone trusts these people to give the truth.:rant:
Exactly why I asked. I can only assume that the video was a substation incident, as I can not tell what it is from the distance in that video.
 

mbrooke

Senior Member
Location
United States
Exactly why I asked. I can only assume that the video was a substation incident, as I can not tell what it is from the distance in that video.
Based on what I saw Im willing to guess that a part of the 115kv or 23kv (or which ever volage is used) buss or switchgear shorted out. It doesnt look like a transformer explosion because there would be smoke and fire from the oil in the vault transformer. I dont know anything about Con-eds system so I can only guess what failed and why.

I know United Illuminating had to shut down 3 substations in bridgeport ( 2 on Congress street and one in the poquonock section) at the height of the storm due to flooding concerns. CL&P had to build a concrete barrier around a Stamford substation at the south end in 90mph gusts.

If a substation gets flooded while energized the loses are much higher than when de-energized and unfortunetly Con-eds was energized.
 

kwired

Electron manager
Location
NE Nebraska
Based on what I saw Im willing to guess that a part of the 115kv or 23kv (or which ever volage is used) buss or switchgear shorted out. It doesnt look like a transformer explosion because there would be smoke and fire from the oil in the vault transformer. I dont know anything about Con-eds system so I can only guess what failed and why.

I know United Illuminating had to shut down 3 substations in bridgeport ( 2 on Congress street and one in the poquonock section) at the height of the storm due to flooding concerns. CL&P had to build a concrete barrier around a Stamford substation at the south end in 90mph gusts.

If a substation gets flooded while energized the loses are much higher than when de-energized and unfortunetly Con-eds was energized.
My first guess was potentially some flying debris got caught in the bus or something of that nature. I guess I wasn't really thinking of flooding, but would flooding present much problem with typical substation transformers unless they become submerged to near the level of terminals? Other than the exposed terminals they are a sealed container otherwise the oil would leak out.
 

mbrooke

Senior Member
Location
United States
I just read that it had something to do with a circuit breaker getting wet. Im wondering why its taking so long to energize, unless there multiple breakers wet and relay control eqipment got damaged to. Either way they will have a hefty bill at the end.
 

fmtjfw

Senior Member
The substation is fed by at least 2 345 or 375KV underground, oil-filled cables. They could probably supply enough energy to do significant damage. As I understand it it served 250,000 customers. They were flooded several feet above their design depth. Which would make me think that bushings were partially submerged and probably arced over. With the control wiring flooded out (and breakers not opening), it could be damaged transformers.
 

mbrooke

Senior Member
Location
United States
The substation is fed by at least 2 345 or 375KV underground, oil-filled cables. They could probably supply enough energy to do significant damage. As I understand it it served 250,000 customers. They were flooded several feet above their design depth. Which would make me think that bushings were partially submerged and probably arced over. With the control wiring flooded out (and breakers not opening), it could be damaged transformers.

To my surprise if you look closley at the videos none of the HID street lamps dim or extinguish on the neighboring islands or upper manhattan during the 2 flash overs which leads me to think that the fault did not occur on the 345kv bushings but somewhere after a transformer. Either that the area is fed by a large and diverse number of transmission sources. Its something wonder about.


As for restoration there could be damaged transformers. If any of them had on board tap changers they are probably toasted.

In cases like these being able to transfer load and having reserve capacity in neighboring substations is king. If not the case here it is something that really needs to be considered.
 
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