Wind/Solar Electrics ???

On Tue, 20 Dec 2005 10:29:12 -0800, "RST Engineering \(jw\)"
wrote:

It seems as though we are trying to build a cathedral foundation to hold an
outhouse. It isn't like I'm LIVING in the hangar, nor am I there working
all day every day. Sure, lights when you are elbow deep inside an engine
are nice, but hardly bleeding edge solar design. What? Ten fluorescent
fixtures with 80 watts of bulbs each? A drop cord with another 20 watt
fluorescent bulb? Perhaps a hand drill twice a day WHEN you are working in
the hangar?

It's not a matter of building a cathedral foundation, but rather trying to
design the least expensive foundation.

But I guess if you're going to light 35 hangars with ten fluorescent
fixtures that are on for a few minutes each day, you won't need much.


As to the compressor, drill press, grinder etc., a gas generator for the few
times a month you need them is quite in order and certainly less expensive
in both the short and long term than gearing up for 100% solar for the
peaks.

Very reasonable, and what I would suggest depending on how much the surge
is. Of course, that means you'll have to have wiring so that those items
will plug directly into the generator, rather than going through the
inverter.


And, if you design the system correctly, letting the gas generator
run for an hour every time you fire up and letting the batteries take a full
charge from an inexpensive battery charger can add to the output of the
solar system.

It is extremely inefficient to bring the batteries up to full charge using
the gas generator. Batteries charge more slowly as they approach full
charge. Better get a reliable generator, then.



I've done a little digging and it seems that Great Plains has the best
pricing on solar panels. Harbor Freight has a little better pricing, but I
need something that I can reliably get month in and month out (I'm the
guinea pig for about 50 hangars) and I can never rely on Harbor Freight to
have what I need when I need it.

My best guess after doing a little educated digging is that I can come up
with a system I can live with for a little over 1 AMU.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

"philkryder" wrote in message
oups.com...
Steve - How many equal "steps" are necessary for the MSW inverter to be
a sufficiently close approximation to a "rotary" sine wave?


Careful. Even true 'rotary' generators don't always put out a true sine
wave.

Even the very, very large commercial generators used in power plants, don't
put out a 'pure' sine wave. The number of stator slots and rotor geometry
cause a small amount of harmonics. The exact connections of windings is
often used to help improve the fundamental and minimize some of the higher
harmonics (6th, 9th and 11th are some of the more troubling ones).

After it passes through several transformers, getting to the substation,
most of the harmonics have been filtered out by the characteristics of the
transformers.

So the question, as usual, boils down to 'how good, is good enough?'

daestrom

I've heard that a boat is a hole in the water lined with wood, into
which one pours money. ;-)

Do airplane people have a similar saying?

An Airplane is a large mobile fan into which the owner is obliged to
throw handfuls of money (to watch it blow away).

David Johnson

Modified Semantic Wave is correct.

"George Ghio" wrote in message
...


wmbjk wrote:

I take that to mean that you won't be providing any
examples of sine
wave inverters with stepless waveforms. What a
shocker.

Wayne

Take it to mean that you can't prove that true sine
wave inverters don't
exist.

Modified Square Wave inverters = True

Modified Sine Wave inverters = False

We previously went through this crap with CD players.
The sampling frequency was chosen to be 44.1 kHz, well
beyond the range of human hearing. No filtering would
be needed.

Except for one thing...when they played the CD back
unfiltered, people would find their tweeters melting
for some weird reason....44.1kHz! at huge powers!

Out came the drawing board and complex analogue (and
expensive) filters were designed until one day some
smart engineer discovered they could double the freq.
in a computer and put out 88.2 kHz sampling noise and
use a less efficient and less expensive filter.

Well, the audio hype that came out then was "2 times
oversampling" followed by 4x, 8x, 16x & 32x
"oversampling". Shister and ignorant marketing people
explained this as "reading the CD 16 times repeatedly
and eliminating the digital errors" "You can eliminate
scratches with this"

In reality the "oversampling" technique was the
development of a digital filter that made the analogue
filter into a simple capacitor to eliminate the
sampling noise.

Any square wave can be filtered enough to produce a
pure sine wave. The trick is the cost. Huge core
inductors and capacitors to handle and smooth out big
quantities of power cost money to design and money to
produce. Not to mention the sheer weight of the beasts.

Multistep waveforms can be filtered much easier. This
is analogous the "oversampling" technique used in CD
players of years past. Digital filtering is much easier
and cheaper than the equivalent analogue filtering.
It's not like an inverter, these days, doesn't have a
computer chip inside then anyway.

How little distortion do you need anyway? Most of it
can be accomplished inside the computer and then just
amplified to useful power levels. At a cost, of course,
and a marketing tool for more money...always.


"daestrom" wrote in
message
...

"philkryder" wrote in message

oups.com...
Steve - How many equal "steps" are necessary for
the MSW inverter to be
a sufficiently close approximation to a "rotary"
sine wave?


Careful. Even true 'rotary' generators don't always
put out a true sine
wave.

Even the very, very large commercial generators used
in power plants, don't
put out a 'pure' sine wave. The number of stator
slots and rotor geometry
cause a small amount of harmonics. The exact
connections of windings is
often used to help improve the fundamental and
minimize some of the higher
harmonics (6th, 9th and 11th are some of the more
troubling ones).

After it passes through several transformers, getting
to the substation,
most of the harmonics have been filtered out by the
characteristics of the
transformers.

So the question, as usual, boils down to 'how good,
is good enough?'

daestrom

Tell us why anyone would modify a sine wave.

SolarFlare wrote:
Modified Semantic Wave is correct.

"George Ghio" wrote in message
...


wmbjk wrote:


I take that to mean that you won't be providing any

examples of sine

wave inverters with stepless waveforms. What a

shocker.

Wayne

Take it to mean that you can't prove that true sine

wave inverters don't

exist.

Modified Square Wave inverters = True

Modified Sine Wave inverters = False

"....We have a touch lamp that will not change
state on MSW, but will on generator"

Do you know if these new smaller Inverter style generators are a close
enough approximation for things like the laser printer?

Just how good are the "sine" like waves on them?

I thought someone was going to put a 'scope on one...

"....It depends how you count "steps"."

Indeed.

I suppose something like "the number of distinct voltage changes per
cycle" might be a good first approximation of something to call steps
and to count.

In your example I would count something like "3" or maybe "2" or "4" -
I always have trouble with boundary conditions...

In any case, it seems that the device you had was effective.
And the only thing I could imagine as having fewer steps would be a
similar device that didn't have the pause at zero...

And yet it was effective -
I wonder if it would have worked with the light dimmer mentioned
above...

Steve Spence wrote:
philkryder wrote:
Steve - How many equal "steps" are necessary for the MSW inverter to be
a sufficiently close approximation to a "rotary" sine wave?


That depends on what you are driving. A laser printer requires closer
representation than a computer. The manufacturer of a particular load
could tell you that information. The old test of whether something was
sine or some version of square was a lamp dimmer. On a square wave unit
the light goes full bright. We have a touch lamp that will not change
state on MSW, but will on generator.

A lot of ac loads are quite happy on dc. Almost anything that rectifies
the mains waveform will run fine on dc of V_mains x 1.414.

NT

philkryder wrote:
"....We have a touch lamp that will not change
state on MSW, but will on generator"

Do you know if these new smaller Inverter style generators are a close
enough approximation for things like the laser printer?

Just how good are the "sine" like waves on them?

I thought someone was going to put a 'scope on one...

What are those Phil?

NT