AC-line supplies - under 1% loss

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qlgoki01v2l@drn.newsguy.com:

legg wrote...

I've heard of transmission system losses
nearing 20% (2009). Perhaps that was a
worst-case scenario for places that
don't generate much of their own.

A number like that isn't surprising, for
the entire system input-to-output. It's
individual elements, xfmr, etc., that are
under 1%, have to be I guess, to allow a
bit more for long transmission lines and
still keep the total loss to under 20%.

I have seen some new local distribution HV lines and poles get
placed recently, and the new hardware I saw made me think that
America could get back about ten of those percentage points by
upgrading our grid infrastructure.

Because I have also seen lines that were so leaky that one could
ride under them at 4:30 in the morning and smell the heavy Ozone
laden air falling down off the leaky as hell insulators at this one
pole in San Diego. That area has a LOT of noticeably leaky nodes. I
am aghast that their power system works at all.
 
whit3rd <whit3rd@gmail.com> wrote in
news:22d7df42-8820-40a5-a293-f835cd847a67@googlegroups.com:

Is it possible that residential metering is so good that the power
companies can pinpoint these losses by data analysis?

Seems unlikely when I used to make IR thermometers with rifle
scopes on them so they could go around pointing them at the
insulators and transformers looking for heat, that telltale indicator
of leakage (insulators) or failed operation (xfmrs).

I am sure metering and such is much better now too. Less inductive
loads than back in the hang a shitload of caps on the line days.
Also I have seen way better capacitors and seen them in really well
designed substations and such, so they likely are very good at seeing
"which legg" of a system is sporting the most losses, or a greater
than usually tolerated number indicating a more intensive leak
condition or such.

One would think they could though. Although TDR type stuff used in
Ethernet, etc. so they can pinpoint to the foot on pretty long runs,
where a failure point is.

With power, a TDR type system would likely be too noisey to give an
accurate 'picture' of a grid segment. Also all while the thing is up
and capable of roasting one to a crisp in a heartbeat or two.

It seems that boots on the ground is very likely the best, most
cost efficient way, since facts get recorded and repairs get
scheduled or done, and lines have to be looked at periodically
anyway, one step at a time.

The monitoring gear to get that fancy is probably not a priority
(obviously) since they allow so much loss now.

Since they privatized, the American public likely took a hit in
quality of service as the bean counters and greed set in.

Bridges fall, and they call it a crisis, and I say the crisis is
city management that squanders funds earmarked for infrastructure
maintainence.

A lot of folks got real fat on this great nation and they all have
nice houses and real Cherry furniture yada yada while the standard of
living for the rest of the nation melted away to nothing.
 
On Friday, September 13, 2019 at 6:23:02 PM UTC-7, DecadentLinux...@decadence.org wrote:
Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qlgoki01v2l@drn.newsguy.com:

legg wrote...

I've heard of transmission system losses
nearing 20% (2009).

A number like that isn't surprising, for
the entire system input-to-output. It's
individual elements, xfmr, etc.,

The most expensive distribution transformers (with oriented crystal
iron cores) go in rural locations, because the quiescent current
for high-L is less of an (unbillable) energy drain for the
power company.

I have seen some new local distribution HV lines and poles get
placed recently...I have also seen lines that were so leaky that one could
ride under them at 4:30 in the morning and smell the heavy Ozone

Never smelled ozone, but one HV tree used to have a continuous buzz/hiss (probably corona,
but never saw the glow); then a month ago, a crew showed up, redid the works, and
now... it's much less alarming walking down that sidewalk.

Is it possible that residential metering is so good that the power companies can
pinpoint these losses by data analysis?
 
On Fri, 13 Sep 2019 14:49:27 -0400, legg <legg@nospam.magma.ca> wrote:

On 12 Sep 2019 14:03:11 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

Winfield Hill wrote...

klaus.kragelund@gmail.com wrote...

Active rectifiers for mains bridge replacement is easy

What is hard is to construct one that handles 4kV
surge and burst and keeping a price point not orders
of magnitude higher than a standard bridge

A standard bridge is dirt cheap, so a few orders
of magnitude higher isn't so bad. I have no
experience with MOSFETs as bridges, but the PFC
guys don't seem worried by it. It's not very
hard to protect the gates, and these big MOSFETs
can handle a lot of energy while in avalanche.

I've studied avalanche breakdown in many types of
silicon devices, read papers, and have made many
measurements of MOSFET avalanche breakdown, and
would like to assert that it's not intrinsically
more vulnerable than a rectifier diode.

Anyway, the central idea here is that if the HV
power-transmission guys can keep their losses well
under 1%, right up to our property boundary, why
can't we try to do the same in our consumption?

Where'd you get that number?

I've heard of transmission system losses nearing 20% (2009).
Perhaps that was a worst-case scenario for places that
don't generate much of their own.

That 20 % sounds a lot and is for the whole network from generator to
user load, not th losses for a single component, such as a
transformer. In addition that sounds for peak load conditions, not
daily or annual averages.

In areas with large peak to average ratio the conductor I˛R losses
can be significant. If the daily peak period is short, the lost energy
doesn't economically justify the line upgrade.

Of course, you should avoid loading the line so much that there are
going to be brownouts during peak hours.
 
On Fri, 13 Sep 2019 19:37:33 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

klaus.kragelund@gmail.com> wrote in message
news:4d0dfae5-1c8b-4b18-aef6-61ebcd1c9d63@googlegroups.com...
I would not expact 5nS to pass the mains filter L C.
That is 200 MHz.

At 200MHz and saturated current, the CM inductor is nothing but a
capacitor. But you are somewhat right, might not be as bad as I wrote, but
something to dig deeper into


More important is that the pulse is tall enough to saturate CMCs. It won't
be saturated due to mains current, because that's still balanced.

Diff mode, the 50 ohm transient just bounces off the input X1 cap. What's
left isn't all that much, and the CMC will not be saturated in leakage mode
(for obvious reasons).

Unless the pulse source is very close, the mains wiring inductance (in
the order of 1 uH/m) together with the X capacitor capacitance will
extend the pulse rise and fall times.
 
On 13 Sep 2019 11:54:10 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

legg wrote...

I've heard of transmission system losses
nearing 20% (2009). Perhaps that was a
worst-case scenario for places that
don't generate much of their own.

A number like that isn't surprising, for
the entire system input-to-output. It's
individual elements, xfmr, etc., that are
under 1%, have to be I guess, to allow a
bit more for long transmission lines and
still keep the total loss to under 20%.

There's too little common collected/applied knowledge re energy,
carbon, man-hour and capital inputs to our individual and
collective maintenance. Claiming 1% conversion loss in any
process doesn't help.

You should re-check your transformer number, too.

Ashes to ashes - has an efficiency with many zeros ofter the
decimal point; but there's no 'point' in thinking like that.

RL
 
legg wrote...
There's too little common collected/applied knowledge
re energy, carbon, man-hour and capital inputs to our
individual and collective maintenance. Claiming 1%
conversion loss in any process doesn't help.

You should re-check your transformer number, too.

Probably these numbers come from best cases. A story
about London's underground cable tunnels shocked me:
"A typical 1.8-km tunnel stretch between ventilation
shafts produces 400 kilowatts of heat". Forget 1%.

https://spectrum.ieee.org/energywise/energy/environment/londons-hidden-cable-tunnels-could-warm-thousands-of-homes

Ashes to ashes - has an efficiency with many zeros
ofter the decimal point; but there's no 'point' in
thinking like that.

Mother nature gets its efficiencies where it can.


--
Thanks,
- Win
 
On 14 Sep 2019 08:58:40 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

legg wrote...

There's too little common collected/applied knowledge
re energy, carbon, man-hour and capital inputs to our
individual and collective maintenance. Claiming 1%
conversion loss in any process doesn't help.

You should re-check your transformer number, too.

Probably these numbers come from best cases. A story
about London's underground cable tunnels shocked me:
"A typical 1.8-km tunnel stretch between ventilation
shafts produces 400 kilowatts of heat". Forget 1%.

https://spectrum.ieee.org/energywise/energy/environment/londons-hidden-cable-tunnels-could-warm-thousands-of-homes

With a 10 km tunnel, the heat lost would be 2.5 MW. If that represents
1 % of transferred power, the transferred power would be 250 MW.

No big deal for a 400 kV line, but as far as I know, there are no 400
kVac cables available, but that power would just be with 100-200 kV
line capacity, especially if the tunnels are less than 10 km long.
 

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