New York Times
August 16, 2003

Experts Asking Why Problems Spread So Far
By MATTHEW L. WALD, RICHARD PERÉZ-PEÑA and NEELA BANERJEE

The power collapse that stilled a large swath of North America
Thursday apparently began with a failure in the Midwest that cascaded
into Canada, and from there into New York, power industry officials
said yesterday. They said they were trying to determine why it spread
so far.

An enormous, instantaneous reversal of the power flow - huge amounts
of electricity that had been moving east over the Great Lakes and was
suddenly sucked back - overloaded one or more power lines, which
quickly took themselves out of service.

In seconds, parallel lines were overloaded as well and shut themselves
down, and then generating stations disconnected themselves.
Ultimately, dozens of lines and about 100 power plants, with a
staggering 61,800 megawatts of generation, had shut down - apparently
before any human being could react. The series of major failures began
about 4:08 p.m., and was over within roughly five minutes. The
failures were triggered by a few seconds of tremendous instability in
energy flows.

"This whole event was essentially a 9-second event, maybe 10," said
Michehl R. Gent, president and chief executive of the North American
Electric Reliability Council, describing how the problem started. His
organization was founded after the 1965 blackout to establish rules
and procedures to prevent repetitions.

Mr. Gent and other officials could offer no explanation for the
failure of a series of systems that are supposed to isolate such
problems, keeping a blackout in one region from dragging its neighbors
into darkness, as happened Thursday. Some of those systems worked,
notably in northern New Jersey and Pennsylvania, preventing the
failure from spreading southward, and in Connecticut, protecting New
England. But others clearly did not.

And so, as some government officials squabbled over what went wrong
first, experts and energy officials were urgently trying to answer the
more serious question of what, in effect, went wrong second - the
inability of the system's computers and human operators over the next
few minutes to isolate and limit the trouble.

"If we've designed the system for this not to happen, how did it
happen?" Mr. Gent said. "I can't answer that question." He added, "I
am embarrassed."

After the 1965 blackout, the transmission system that carries power
from one area to another was modified specifically to avoid such a
domino-effect collapse, although the state of the nation's intricately
connected electrical grid has been widely derided as antiquated and
vulnerable to catastrophe. The next major blackout, in 1977, was
limited to a much smaller area, primarily New York City.

As for the first event that set the disaster in motion, no one is sure
yet what it was. Engineers said they believed the first event was a
loss of generation, but it happened so fast that, a day later,
officials were still gathering computer logs to try to establish the
sequence.

But records show that, in the two hours before the full collapse,
there was a series of problems on transmission lines in Ohio. Records
kept by SoftSwitching Technologies, a company hired by the power
industry to monitor the grid, show episodes of voltage sagging too low
on those lines - at 2:24 p.m., twice at 3:17 p.m. and most seriously,
twice again at 3:43 p.m. The more serious problems might have involved
a transmission line in Cleveland that investigators were focusing on.

The last two incidents, unlike the previous ones, did not correct
themselves after a few seconds, and voltage remained low. By 4:09, a
problem surfaced in Michigan, and the calamity was fully underway.

The problems in Ohio raise questions about whether officials there
were struggling to solve a crisis, and whether proper measures were
taken to prevent its spread. Officials of First Energy, which serves
Cleveland and other parts of the state, would not comment last night,
other than to say they were trying to repair their system.

Officials were able, though, to rule out a number of theories spun
Thursday about the root causes of the problem, including high demand
due to heat, lightning strikes in the Niagara Falls area, or a fire at
a power plant.

As well, after New York State officials said they believed it was a
problem at the Perry nuclear reactor near Cleveland, the operators of
that plant disputed that, and said that several transmission lines in
Michigan had tripped out of service first.

Either way, officials at both the New York Independent System
Operator, the consortium that manages the state's grid, and the
reliability council, said it appeared that the problem began in the
Midwest, crossed into the Canadian province of Ontario near Detroit
and then passed into New York at Niagara Falls and perhaps other
points, as well. The blackout, the largest in the nation's history,
ultimately extended to Connecticut and parts of New Jersey, as well.

In summertime, power produced in the Midwest is often sold to
consumers in the Northeast, but the current does not always take the
most direct route; instead, it often takes a loop around Lake Erie and
through Ontario. In fact, even sales from Pennsylvania to New York can
take the Canadian route.

Mr. Gent said 300 to 500 megawatts, enough to electrify a small city,
were moving west to east, from Michigan to New York through Ontario,
when the problem - either the failure of some power plants or of some
transmission lines - struck. Suddenly, he said, the flow of electrons
reversed direction, pulling 500 megawatts from east to west, out of
New York - a swing, in the space of a few seconds, of as much as 1,000
megawatts, the output of a large power plant.

Officials at the New York Independent System Operator said the swing
might have been much greater, as much as 3,000 megawatts or more.

The problem is that the power grid is like a game of tug of war, which
works as long as neither side - the generating stations and the load
centers - wins. If one side falters, and the rope moves too far,
everyone on the other side will fall down.

In this case, the power swing, no matter what its precise size,
sharply destabilized the flow of power, and eventually produced some
first, specific failure.

In a system with hundreds of critical components, the top priority of
each is not to keep the lights on, but to protect itself from
overload. Power lines are guarded by automatic devices that "isolate"
them, or take them out of service, when the tug-of-war rope moves too
far. In electrical terms, this means that the voltage (which is
somewhat like pressure in a pipe) is too high, or that the frequency
is out of whack.

When transmission lines or power plants shut themselves down, the
system is designed to "shed load," or turn off power supply to some
areas to balance the amount of power being generated and the amount
being used. Parts of the nation's electrical grid are laced with
equipment, like relays, that detect when and where there is an
abnormality on the line and then automatically break the circuit so
that the problem does not move through and disable more of the system.

A top engineer with a Northeast utility said there were three or four
geographic points in New York State where that cutoff could have
occurred on Thursday, preventing a large problem from spreading east
and south. But with a swing of that magnitude and suddenness, that
preventive function did not take hold fast enough.

Cautioning that only a thorough investigation would reveal what went
wrong, Phillip G. Harris, chief executive of PJM Interconnection,
which manages the transmission grid for all or part of seven Eastern
states and the District of Columbia, said any number of things might
account for a failure of the relays meant to halt a progressive
failure.

Mr. Harris said that if a relay in the system did fail to break a
circuit, it could stem from a lack of maintenance or "something
falling apart like it would in your car." But the impact is
potentially disastrous, he explained.

"When a relay fails, the next one has to catch the problem, and the
fault is even bigger then," he said. "It builds up a momentum, like
something running downhill."

But one expert said the problem on Thursday might have been something
fairly simple and easily corrected.

If power plants in an area are producing less electricity than
consumers are demanding, the system falls below 60 cycles per second
(the frequency at which electrons in the wires reverse directions) and
damage can be done to the equipment. When that happens, the plants are
quick to shut down.

But plants are more likely to tolerate frequencies above 60, when they
are pumping out slightly more electricity than consumers are using.

But a surplus of energy could have caused a transmission line to fail,
said Robert Blohm, an energy consultant who serves on a committee
advising the reliability council. That, in turn, would have worsened
the imbalance in the regional grid, possibly leading to a wider system
failure and blackout.

Elected officials complained yesterday of an antiquated transmission
system and called for major new investment in the grid. But Mr. Blohm
cautioned that the chain of events might have been set off by bad
rules governing the electric grid, which led to a transmission line
shutting when what was needed was for a generator to shut down. That
could have made the problems worse.

Mr. Gent, the chief executive of the reliability council, said that
the problem on Thursday might have been somebody breaking a rule or
might indeed have been because the rules did not anticipate the
physical circumstances of the system. The rules govern companies that
generate, transmit or distribute electricity, and are highly technical
in nature.

Engineers say the people who manage the transmission system set limits
on how much power can be pumped through a particular line based on
having the system survive a single failure, not an unexpected
combination of failures. That appears to have happened on Thursday and
produced extraordinary results.

The manager of the New York Power Authority's giant Niagara
hydroelectric plant, Ronald W. Ciamaga, said he was standing in the
control room watching a meter that confirms that the electric system
is keeping to its 60-cycle pace. Fluctuations are usually measured in
the hundredths or tenths of a cycle, but as generation and consumption
fell out of balance Thursday, the rate dropped to 57 cycles.

"I was up there in the control room, seeing frequency variations like
I've never seen," said Mr. Ciamaga, who has been with the Power
Authority for 30 years.

The Niagara Project stayed in operation, because hydroelectric plants
are less fragile than other kinds of generating stations. Plants
powered by coal, natural gas and uranium all tripped off line.

Mr. Gent said that weather was not a factor. It was hot, but not
unseasonably so, across the East and Midwest, he said. "There was an
abundance of generating power available," he said.

In New York, demand at the time of the blackout was about 28,500
megawatts, comfortably below the record high of more than 31,000
megawatts.

Officials were warning a decade ago of weakness in the grid that moves
power around the country, and the challenges have grown with
deregulation. Under the old system, a local utility monopoly built and
owned both the power plants and the wires in a region.

Under deregulation, the plants have been sold to other companies that
often sell their power to utilities hundreds of miles away, increasing
traffic on the grid. To meet rising demand for power, new plants have
been built, in some cases further straining the transmission system.
Meanwhile, obtaining environmental permits to build power lines has
gotten harder.

--------------------------------------------------------------------------------

August 16, 2003
THE TECHNOLOGY
Restoring Lost Voltage Takes Time, and a Complex Choreography
By ERIC LIPTON

If only it were as simple as flipping the switch.

In an era when electricity that powers a blow dryer in Queens may have
been generated at a hydroelectric dam in Canada, restarting the juice
after a colossal power failure is a painfully complicated affair.

Where is the electricity turned back on first? How quickly can it be
restarted? How stable is it after the power is flowing again? Each
question is decided not by a single group of engineers at a utility
headquarters. Rather, it is a dance that must be perfectly
choreographed among often-distant power generators, wholesale
distributors of this power, local utilities like Consolidated Edison
or the Long Island Power Authority, and their armies of electricians,
who, after being sent out to hundreds of local substations, finally,
and ever so thankfully, throw that switch.

At every step along the way, there are opportunities for slip-ups that
will send the local system, or perhaps even the region, back into the
black.

"It is like matching the speed of two race cars where the nose of the
car is at exactly the same place at the same time," said Thomas Spatz,
the director of electric service at KeySpan, which operates the system
for Long Island Power Authority.

In New York City, the nerve center for this recovery is Con Edison's
emergency command post at 4 Irving Place, the utility's headquarters
in Gramercy Park. A 19th-floor auditorium is filled with tables around
which engineers and executives spent day and night over the last two
days fielding calls from electricity-routing centers in each of the
five boroughs. Power plants not owned by Con Edison must send
electricity through these routing centers to the power-hungry city.
Last evening, Katherine Boden, working out of 4 Irving Plaza, had her
eyes trained on the Con Edison transmission grid, a four-foot long,
foot-wide diagram spread out before her that resembles a computer
circuit board.

"It is so overwhelming when you are starting from scratch," said Ms.
Boden, chief distribution engineer for Con Ed. "It means pushing the
voltage and the power from one end of this chart to the other."

It is the modern-day arrangement, where Con Edison does not own its
own power-generating plants and 25 percent of the power consumed in
the city must be imported from outside, that so complicates the
process of turning the lights back on.

Con Edison's engineers must await word from the New York Independent
System Operator, a four-year-old not-for-profit corporation based in
Albany that administers the state's wholesale energy markets, before
it restores power for even small swaths of the city. For example, on
Thursday evening a call from the I.S.O., as it is known, indicated
that it had identified 900 megawatts of power from northern New Jersey
it could send to northern Westchester, which Con Edison also serves.

The utility's operators monitored the movement of this power on
electronic boards at its Upper West Side control center. Then, with
the click of a computer mouse, they closed a switch that completed a
circuit and allowed the electricity to flow from one state to the
other, which is part of the reason power was restored to parts of
Westchester before New York City.

Con Edison did have some limited ability to direct where power would
be restarted first, said a company spokesman, Michael Clendenin. The
utility directed power to a section of the city that has a major
hospital and where there are power plants that needed a shot of
electricity to actually start making power again. But for the most
part, the system's mechanics - how much power was available, where it
was coming from and whether the available supply matched demand in a
particular area - determined who got the fastest relief, he said.

The second major piece of the restoration effort involved restarting
the local power plants, then methodically rebuilding the regional and
national networks of these plants, known as grids.

The system is designed so that when a regional grid is up and running,
any surge in demand from a particular city is like pulling a bucket of
water out of an ocean. But in the early phases of a restoration,
before a stable and power-rich network is established, the independent
pieces of this grid are much more vulnerable to breakdown. For this
reason, the plants are started up very slowly and in isolation.

A plant that can generate 400 megawatts - New York City on a hot day
can consume 11,000 megawatts - will start up first by simply
generating 2 or 3, sending out this bit of power to area substations
where it can be released to customers in even smaller quantities. Send
it out to too many customers at once and the system could be
overloaded, as devices typically consume much more energy as they are
first turning on, like a computer that is being rebooted.

Not until an individual plant, step by step, reaches 20 percent to 50
percent of its capacity can it be connected to other plants in the
immediate network. And the power from two plants can only be brought
together once the electricity they are producing levels out at 60
cycles or wave forms per second, or more simply 60 hertz. It is a slow
building process from the An individual plant links to other area
plants and then into the regional network and then the Northeastern
and Midwestern grid.

Over the last two days, a fair amount of improvisation was used in an
effort to get more electricity running into the New York region in the
early stages of the startup. To get more power to Long Island, for
example, the United States Department of Energy authorized the use of
an electric cable that connects New York with Connecticut under the
Long Island Sound. A regulatory battle has prevented use of this cable
during nonemergency times, but as of Friday afternoon it was providing
about 100 megawatts, or 3 percent, of Long Island's power, Mr. Spatz
said.

"Every megawatt is about 300 customers," he said.

So those thousands of Long Island residents who suddenly had
air-conditioning and refrigerators running again can thank the Cross
Sound Cable, a power line that many never knew existed and that will
soon be retired again when a full complement of power is flowing
through the routine connections from Connecticut and New York State.

For New York City, the slow restoration is a result of the fact that
it needs two things - its local plants operating, and the tie lines
from outside the region delivering power - to get that blow dryer
running again.

The return of power was spotty in New York City, starting Thursday
night and becoming complete at 9:03 p.m. Friday.

--------------------------------------

I know the REAL reason why the power outage happened.

It looks like SOMEBODY plugged in a Santa Claus like christmas
decoration in the middle of the summer.

D'oh!

(KJS) wrote in message ...
New York Times
August 16, 2003

Experts Asking Why Problems Spread So Far
By MATTHEW L. WALD, RICHARD PERÉZ-PEÑA and NEELA BANERJEE

The power collapse that stilled a large swath of North America
Thursday apparently began with a failure in the Midwest that cascaded
into Canada, and from there into New York, power industry officials
said yesterday. They said they were trying to determine why it spread
so far.

An enormous, instantaneous reversal of the power flow - huge amounts
of electricity that had been moving east over the Great Lakes and was
suddenly sucked back - overloaded one or more power lines, which
quickly took themselves out of service.

In seconds, parallel lines were overloaded as well and shut themselves
down, and then generating stations disconnected themselves.
Ultimately, dozens of lines and about 100 power plants, with a
staggering 61,800 megawatts of generation, had shut down - apparently
before any human being could react. The series of major failures began
about 4:08 p.m., and was over within roughly five minutes. The
failures were triggered by a few seconds of tremendous instability in
energy flows.

"This whole event was essentially a 9-second event, maybe 10," said
Michehl R. Gent, president and chief executive of the North American
Electric Reliability Council, describing how the problem started. His
organization was founded after the 1965 blackout to establish rules
and procedures to prevent repetitions.

Mr. Gent and other officials could offer no explanation for the
failure of a series of systems that are supposed to isolate such
problems, keeping a blackout in one region from dragging its neighbors
into darkness, as happened Thursday. Some of those systems worked,
notably in northern New Jersey and Pennsylvania, preventing the
failure from spreading southward, and in Connecticut, protecting New
England. But others clearly did not.

And so, as some government officials squabbled over what went wrong
first, experts and energy officials were urgently trying to answer the
more serious question of what, in effect, went wrong second - the
inability of the system's computers and human operators over the next
few minutes to isolate and limit the trouble.

"If we've designed the system for this not to happen, how did it
happen?" Mr. Gent said. "I can't answer that question." He added, "I
am embarrassed."

After the 1965 blackout, the transmission system that carries power
from one area to another was modified specifically to avoid such a
domino-effect collapse, although the state of the nation's intricately
connected electrical grid has been widely derided as antiquated and
vulnerable to catastrophe. The next major blackout, in 1977, was
limited to a much smaller area, primarily New York City.

As for the first event that set the disaster in motion, no one is sure
yet what it was. Engineers said they believed the first event was a
loss of generation, but it happened so fast that, a day later,
officials were still gathering computer logs to try to establish the
sequence.

But records show that, in the two hours before the full collapse,
there was a series of problems on transmission lines in Ohio. Records
kept by SoftSwitching Technologies, a company hired by the power
industry to monitor the grid, show episodes of voltage sagging too low
on those lines - at 2:24 p.m., twice at 3:17 p.m. and most seriously,
twice again at 3:43 p.m. The more serious problems might have involved
a transmission line in Cleveland that investigators were focusing on.

The last two incidents, unlike the previous ones, did not correct
themselves after a few seconds, and voltage remained low. By 4:09, a
problem surfaced in Michigan, and the calamity was fully underway.

The problems in Ohio raise questions about whether officials there
were struggling to solve a crisis, and whether proper measures were
taken to prevent its spread. Officials of First Energy, which serves
Cleveland and other parts of the state, would not comment last night,
other than to say they were trying to repair their system.

Officials were able, though, to rule out a number of theories spun
Thursday about the root causes of the problem, including high demand
due to heat, lightning strikes in the Niagara Falls area, or a fire at
a power plant.

As well, after New York State officials said they believed it was a
problem at the Perry nuclear reactor near Cleveland, the operators of
that plant disputed that, and said that several transmission lines in
Michigan had tripped out of service first.

Either way, officials at both the New York Independent System
Operator, the consortium that manages the state's grid, and the
reliability council, said it appeared that the problem began in the
Midwest, crossed into the Canadian province of Ontario near Detroit
and then passed into New York at Niagara Falls and perhaps other
points, as well. The blackout, the largest in the nation's history,
ultimately extended to Connecticut and parts of New Jersey, as well.

In summertime, power produced in the Midwest is often sold to
consumers in the Northeast, but the current does not always take the
most direct route; instead, it often takes a loop around Lake Erie and
through Ontario. In fact, even sales from Pennsylvania to New York can
take the Canadian route.

Mr. Gent said 300 to 500 megawatts, enough to electrify a small city,
were moving west to east, from Michigan to New York through Ontario,
when the problem - either the failure of some power plants or of some
transmission lines - struck. Suddenly, he said, the flow of electrons
reversed direction, pulling 500 megawatts from east to west, out of
New York - a swing, in the space of a few seconds, of as much as 1,000
megawatts, the output of a large power plant.

Officials at the New York Independent System Operator said the swing
might have been much greater, as much as 3,000 megawatts or more.

The problem is that the power grid is like a game of tug of war, which
works as long as neither side - the generating stations and the load
centers - wins. If one side falters, and the rope moves too far,
everyone on the other side will fall down.

In this case, the power swing, no matter what its precise size,
sharply destabilized the flow of power, and eventually produced some
first, specific failure.

In a system with hundreds of critical components, the top priority of
each is not to keep the lights on, but to protect itself from
overload. Power lines are guarded by automatic devices that "isolate"
them, or take them out of service, when the tug-of-war rope moves too
far. In electrical terms, this means that the voltage (which is
somewhat like pressure in a pipe) is too high, or that the frequency
is out of whack.

When transmission lines or power plants shut themselves down, the
system is designed to "shed load," or turn off power supply to some
areas to balance the amount of power being generated and the amount
being used. Parts of the nation's electrical grid are laced with
equipment, like relays, that detect when and where there is an
abnormality on the line and then automatically break the circuit so
that the problem does not move through and disable more of the system.

A top engineer with a Northeast utility said there were three or four
geographic points in New York State where that cutoff could have
occurred on Thursday, preventing a large problem from spreading east
and south. But with a swing of that magnitude and suddenness, that
preventive function did not take hold fast enough.

Cautioning that only a thorough investigation would reveal what went
wrong, Phillip G. Harris, chief executive of PJM Interconnection,
which manages the transmission grid for all or part of seven Eastern
states and the District of Columbia, said any number of things might
account for a failure of the relays meant to halt a progressive
failure.

Mr. Harris said that if a relay in the system did fail to break a
circuit, it could stem from a lack of maintenance or "something
falling apart like it would in your car." But the impact is
potentially disastrous, he explained.

"When a relay fails, the next one has to catch the problem, and the
fault is even bigger then," he said. "It builds up a momentum, like
something running downhill."

But one expert said the problem on Thursday might have been something
fairly simple and easily corrected.

If power plants in an area are producing less electricity than
consumers are demanding, the system falls below 60 cycles per second
(the frequency at which electrons in the wires reverse directions) and
damage can be done to the equipment. When that happens, the plants are
quick to shut down.

But plants are more likely to tolerate frequencies above 60, when they
are pumping out slightly more electricity than consumers are using.

But a surplus of energy could have caused a transmission line to fail,
said Robert Blohm, an energy consultant who serves on a committee
advising the reliability council. That, in turn, would have worsened
the imbalance in the regional grid, possibly leading to a wider system
failure and blackout.

Elected officials complained yesterday of an antiquated transmission
system and called for major new investment in the grid. But Mr. Blohm
cautioned that the chain of events might have been set off by bad
rules governing the electric grid, which led to a transmission line
shutting when what was needed was for a generator to shut down. That
could have made the problems worse.

Mr. Gent, the chief executive of the reliability council, said that
the problem on Thursday might have been somebody breaking a rule or
might indeed have been because the rules did not anticipate the
physical circumstances of the system. The rules govern companies that
generate, transmit or distribute electricity, and are highly technical
in nature.

Engineers say the people who manage the transmission system set limits
on how much power can be pumped through a particular line based on
having the system survive a single failure, not an unexpected
combination of failures. That appears to have happened on Thursday and
produced extraordinary results.

The manager of the New York Power Authority's giant Niagara
hydroelectric plant, Ronald W. Ciamaga, said he was standing in the
control room watching a meter that confirms that the electric system
is keeping to its 60-cycle pace. Fluctuations are usually measured in
the hundredths or tenths of a cycle, but as generation and consumption
fell out of balance Thursday, the rate dropped to 57 cycles.

"I was up there in the control room, seeing frequency variations like
I've never seen," said Mr. Ciamaga, who has been with the Power
Authority for 30 years.

The Niagara Project stayed in operation, because hydroelectric plants
are less fragile than other kinds of generating stations. Plants
powered by coal, natural gas and uranium all tripped off line.

Mr. Gent said that weather was not a factor. It was hot, but not
unseasonably so, across the East and Midwest, he said. "There was an
abundance of generating power available," he said.

In New York, demand at the time of the blackout was about 28,500
megawatts, comfortably below the record high of more than 31,000
megawatts.

Officials were warning a decade ago of weakness in the grid that moves
power around the country, and the challenges have grown with
deregulation. Under the old system, a local utility monopoly built and
owned both the power plants and the wires in a region.

Under deregulation, the plants have been sold to other companies that
often sell their power to utilities hundreds of miles away, increasing
traffic on the grid. To meet rising demand for power, new plants have
been built, in some cases further straining the transmission system.
Meanwhile, obtaining environmental permits to build power lines has
gotten harder.

--------------------------------------------------------------------------------

August 16, 2003
THE TECHNOLOGY
Restoring Lost Voltage Takes Time, and a Complex Choreography
By ERIC LIPTON

If only it were as simple as flipping the switch.

In an era when electricity that powers a blow dryer in Queens may have
been generated at a hydroelectric dam in Canada, restarting the juice
after a colossal power failure is a painfully complicated affair.

Where is the electricity turned back on first? How quickly can it be
restarted? How stable is it after the power is flowing again? Each
question is decided not by a single group of engineers at a utility
headquarters. Rather, it is a dance that must be perfectly
choreographed among often-distant power generators, wholesale
distributors of this power, local utilities like Consolidated Edison
or the Long Island Power Authority, and their armies of electricians,
who, after being sent out to hundreds of local substations, finally,
and ever so thankfully, throw that switch.

At every step along the way, there are opportunities for slip-ups that
will send the local system, or perhaps even the region, back into the
black.

"It is like matching the speed of two race cars where the nose of the
car is at exactly the same place at the same time," said Thomas Spatz,
the director of electric service at KeySpan, which operates the system
for Long Island Power Authority.

In New York City, the nerve center for this recovery is Con Edison's
emergency command post at 4 Irving Place, the utility's headquarters
in Gramercy Park. A 19th-floor auditorium is filled with tables around
which engineers and executives spent day and night over the last two
days fielding calls from electricity-routing centers in each of the
five boroughs. Power plants not owned by Con Edison must send
electricity through these routing centers to the power-hungry city.
Last evening, Katherine Boden, working out of 4 Irving Plaza, had her
eyes trained on the Con Edison transmission grid, a four-foot long,
foot-wide diagram spread out before her that resembles a computer
circuit board.

"It is so overwhelming when you are starting from scratch," said Ms.
Boden, chief distribution engineer for Con Ed. "It means pushing the
voltage and the power from one end of this chart to the other."

It is the modern-day arrangement, where Con Edison does not own its
own power-generating plants and 25 percent of the power consumed in
the city must be imported from outside, that so complicates the
process of turning the lights back on.

Con Edison's engineers must await word from the New York Independent
System Operator, a four-year-old not-for-profit corporation based in
Albany that administers the state's wholesale energy markets, before
it restores power for even small swaths of the city. For example, on
Thursday evening a call from the I.S.O., as it is known, indicated
that it had identified 900 megawatts of power from northern New Jersey
it could send to northern Westchester, which Con Edison also serves.

The utility's operators monitored the movement of this power on
electronic boards at its Upper West Side control center. Then, with
the click of a computer mouse, they closed a switch that completed a
circuit and allowed the electricity to flow from one state to the
other, which is part of the reason power was restored to parts of
Westchester before New York City.

Con Edison did have some limited ability to direct where power would
be restarted first, said a company spokesman, Michael Clendenin. The
utility directed power to a section of the city that has a major
hospital and where there are power plants that needed a shot of
electricity to actually start making power again. But for the most
part, the system's mechanics - how much power was available, where it
was coming from and whether the available supply matched demand in a
particular area - determined who got the fastest relief, he said.

The second major piece of the restoration effort involved restarting
the local power plants, then methodically rebuilding the regional and
national networks of these plants, known as grids.

The system is designed so that when a regional grid is up and running,
any surge in demand from a particular city is like pulling a bucket of
water out of an ocean. But in the early phases of a restoration,
before a stable and power-rich network is established, the independent
pieces of this grid are much more vulnerable to breakdown. For this
reason, the plants are started up very slowly and in isolation.

A plant that can generate 400 megawatts - New York City on a hot day
can consume 11,000 megawatts - will start up first by simply
generating 2 or 3, sending out this bit of power to area substations
where it can be released to customers in even smaller quantities. Send
it out to too many customers at once and the system could be
overloaded, as devices typically consume much more energy as they are
first turning on, like a computer that is being rebooted.

Not until an individual plant, step by step, reaches 20 percent to 50
percent of its capacity can it be connected to other plants in the
immediate network. And the power from two plants can only be brought
together once the electricity they are producing levels out at 60
cycles or wave forms per second, or more simply 60 hertz. It is a slow
building process from the An individual plant links to other area
plants and then into the regional network and then the Northeastern
and Midwestern grid.

Over the last two days, a fair amount of improvisation was used in an
effort to get more electricity running into the New York region in the
early stages of the startup. To get more power to Long Island, for
example, the United States Department of Energy authorized the use of
an electric cable that connects New York with Connecticut under the
Long Island Sound. A regulatory battle has prevented use of this cable
during nonemergency times, but as of Friday afternoon it was providing
about 100 megawatts, or 3 percent, of Long Island's power, Mr. Spatz
said.

"Every megawatt is about 300 customers," he said.

So those thousands of Long Island residents who suddenly had
air-conditioning and refrigerators running again can thank the Cross
Sound Cable, a power line that many never knew existed and that will
soon be retired again when a full complement of power is flowing
through the routine connections from Connecticut and New York State.

For New York City, the slow restoration is a result of the fact that
it needs two things - its local plants operating, and the tie lines
from outside the region delivering power - to get that blow dryer
running again.

The return of power was spotty in New York City, starting Thursday
night and becoming complete at 9:03 p.m. Friday.

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(...Starblade Riven Darksquall...)