# East Coast outage?

>Then run parts at 105-110% and it gets really hard.

The power industry designs a grid that runs so close to capacity that if^W
when something big fails, the whole grid shuts down in a cascade. They
know it:

Rubbish again.

professor what does

E1 = E2

in context of yesterdays events.

That's not really answering the question, and it's also not
entirely right.

For one, even if we naively accept sum(Eproduced) = sum(Econsumed),
that says nothing about the amperage which can safely traverse
parts of the grid intertie wiring, switching facilities, etc.
If *those* are running at or slightly over capacity, and in
particular of all those facilities don't have at least N+1
and preferably N+M redundant actual capacity, then a single
point failure will produce a fatal cascading failure in the
system. That appears to be what happened.

For two, most of the things that consume power are not in
fact consuming exactly a fixed amount of power. Light bulbs
go dimmer if you reduce voltage; electrical motors will produce
less power (torque X rpm) if voltage drops, etc. Minor blips
are happening all the time in major grids, and the voltage is
continuously varying up and down slightly. If we had to keep
voltage exactly constant, a real AC power system would be
nigh-on impossible to build.

Our concerns with electrical capacity in terms of the interchange
grids having N+1 or N+M capacity, and having systems with enough
robustness and graceful failure modes, and having systems with
enough reserve generation capacity are all legitimate. A lot of
other people are looking at that now, too.

But you *can't* just simplify this to Ein = Eout.

-george william herbert
gherbert@retro.com

For two, most of the things that consume power are not in
fact consuming exactly a fixed amount of power. Light bulbs
go dimmer if you reduce voltage; electrical motors will produce
less power (torque X rpm) if voltage drops, etc. Minor blips
are happening all the time in major grids, and the voltage is
continuously varying up and down slightly. If we had to keep
voltage exactly constant, a real AC power system would be
nigh-on impossible to build.

Part of the problem is that an increasing fraction of the grid will
actually draw more power as the voltage decreases. Switching power supplies
will maintain a constant output power provided their input voltage remains
in a reasonable window. Their efficiency is generally the highest at their
design nominal volatage. So a decrease in volage will require them to draw
more current both because more is needed for the same power and they'll need
more power.

As more and more of the load becomes 'smart', the resiliency starts to go
out of the system. To some extent, the same is true of things like cooling
systems. As the voltage drops, their duty cycle will increase, though this
problem manifests itself over a slightly longer term.

And, of course, you can't keep the voltage constant. It's the differences
in voltage that make the current flow.

DS

>> >Then run parts at 105-110% and it gets really hard.
>>
>> The power industry designs a grid that runs so close to capacity that if^W
>> when something big fails, the whole grid shuts down in a cascade. They
>> know it:
>
>Rubbish again.
>
>professor what does
>
> E1 = E2
>
>in context of yesterdays events.

That's not really answering the question, and it's also not
entirely right.

[skip]

But you *can't* just simplify this to Ein = Eout.

No, it is spinning physics that does not work - physics *is* simple as long
as one does not skip the linkage between different things:

Econsumed = Econsumed_productive + Qreleased + Wreqired

Econsumed_productive is what you actually used
Qreleased is the energy released in a form of a increase/decrease heat
Wrequired is the work required to get Econsumed.

Alex