Home sized generators??????????

[Johnny]

Just looking around to see if there are any biomass generators for home use.
Looking into the costs, etc.

 

[The Alien]

Just looking around to see if there are any biomass generators for home use.
Looking into the costs, etc.

I'd like to expand your question and ask how to size up a generator
for the home?


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[JoeSP]

..

--
Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous
for general use." Thomas Alva Edison

He tried to prove it by employing a certain Dr. Brown, who was fond of
electrocuting household pets in public to "prove" how dangerous AC current
was. He selected the cutest and most adorable dogs and cats for the maximum
psychological effect. At one point he electrocuted an adult elephant in
public.

He was also the first to facilitate using AC current to electrocute
condemned criminals. By all accounts by the witnesses present, this first
attempt was like slow-roasting a person to death. He was still alive,
half-burnt and writhing in agony after 20 minutes. Edison is said to have
been pleased with the results, perhaps proving once and for all that AC
current was a dangerous and undesirable form of power, compared to his own
commercial product, DC power.

 

[The Alien]

X-No-archive: yes On Sun, 11 Dec 2005 18:57:00 GMT, "Tom Horne,

X-No-archive: yes On Sun, 11 Dec 2005 11:22:30 -0500, "Johnny" <.com>
used recycled pixels to say:

Just looking around to see if there are any biomass generators for home use.
Looking into the costs, etc.

I'd like to expand your question and ask how to size up a generator
for the home?


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You need to take an inventory of the loads that the generator will need
to carry. Add up the number of watts that each thing needs to run.
Were the label does not give watts you must multiply the voltage times
the amps to get watts. Take the largest motor load you wish to run and
multiply by three prior to adding it into the total. That is the
smallest wattage generator that will run those loads based on it's
continuous output wattage. A generator twice that size will last a lot
longer.

Thank you!


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[William P.N. Smith]

I'd like to expand your question and ask how to size up a generator
for the home?

In general, somewhere between 5 and 10 KW will run most homes, though
there will always be exceptions. Unless you've got a giant or tiny
house, or {all,no}-electric appliances, anything in the 7.5-10KW range
is probably fine.

You probably want to invest in a clamp-on ammeter, so you can measure
the actual load in your actual home. Nameplate numbers tend to be
higher than actual, and you don't want to run everything at the same
time, and starting loads aren't always specified or easily calculated.

For instance, my 8.2KW generator can't start my _smallest_ AC unit,
though it starts and runs the other two just fine.

You will want to do some manual load management while running on your
generator anyway, for instance don't run the clothes dryer while using
the electric stove, turn off the AC while microwaving dinner, etc.

 

[JoeSP]

In general, somewhere between 5 and 10 KW will run most homes, though
there will always be exceptions. Unless you've got a giant or tiny
house, or {all,no}-electric appliances, anything in the 7.5-10KW range
is probably fine.

You probably want to invest in a clamp-on ammeter, so you can measure
the actual load in your actual home. Nameplate numbers tend to be
higher than actual, and you don't want to run everything at the same
time, and starting loads aren't always specified or easily calculated.

For instance, my 8.2KW generator can't start my _smallest_ AC unit,
though it starts and runs the other two just fine.

You will want to do some manual load management while running on your
generator anyway, for instance don't run the clothes dryer while using
the electric stove, turn off the AC while microwaving dinner, etc.

All these years I have been relying on voltage drop and engine sound to
determine load. I guess I was wrong.

 

[JoeSP]

Honda and others have sites for figuring loads, but best is your own
audit. Motors take 2.5-9x times Surge and need to be figured in run load
of gen. Not Surge load. So a 300w motor easily needs 1000 watts, but
old equipment can need much more. Also dont strain the unit running
25-50% power will give many times longer life. Just because a gen is
rated 5000w doesnt with cheap units mean it gives 5000w. Consumer Repots
tested a Generac 4000Exl a 900$ unit that failed load tests.

About 20 years ago, our camp was having trouble with our water pump causing
the generator to trip out every time it started up. I fixed the problem by
taking the centrifugal switch apart in the pump motor. I stretched the coil
springs so that the centrifugal weights on the starter circuit switched off
the started circuit much sooner and at a lower speed while starting up.
This had no negative effect because the pump was a centrifugal type and
started under virtually no load anyway. It worked perfectly after that.

 

[William P.N. Smith]

All these years I have been relying on voltage drop and engine sound to
determine load. I guess I was wrong.

Why, what's wrong with that? The initial sizing might want to be a
bit more scientific, or just a swag at 7.5-10KW, but for load
management that's fine. I can't hear my generator most of the time,
but I can watch the lights dim...

 

[[email protected]]

...Motors take 2.5-9x times Surge and need to be figured in run load
of gen. Not Surge load. So a 300w motor easily needs 1000 watts...

.... for a few seconds, but I've read that should be in the surge vs run load,
that we only need to handle the run load plus the largest single surge load.

Nick

 

[m Ransley]

No Nick you read wrong because there is then over loading potential ,
and possible damage to the gen if continued. Manufactures of cheap home
units specify this, even Honda. Commercial equipment may be different,
it made better

 

[[email protected]]

No Nick you read wrong...

Nonono. YOU are wrong!

... there is then over loading potential and possible damage to the gen
if continued. Manufactures of cheap home units specify this, even Honda.

.... who recommend the sizing method I suggested, with a 1600 W continuous
load, derated from 2 kW for 30 minutes, for an EU2000.

Nick

 

[m Ransley]

Your an idiot nick ol senile ol boy, a baffoon. Talk of Honda, go read
their site since you refer to Honda , you moron.

 

[JohnH]

Your an idiot nick ol senile ol boy, a baffoon. Talk of Honda, go read
their site since you refer to Honda , you moron.

Sorry man - Nick is spot on.

 

[Dave Hinz]

Sorry man - Nick is spot on.

Yeah, he usually is.

 

[Steve Spence]

Yeah, he usually is.

Usually, anyone who disagrees with Nick fell asleep during science class.

 

[[email protected]]

Could one of you provide a link to the Honda page that states the
method to use?

Sure.

http://www.hondapowerequipment.com/genwat.asp

You’ll also need to consider the maximum and rated power...
This is important depending on what items you want to run off of your
generator. Items such as toaster, lamps, and coffee makers are resistive, or
constant loads and their total load can be calculated at amps x 1. Items
such as saws and drills are reactive loads and while the running load may be
small, the starting load should be calculated at running amps x 3. Remember,
after the intial start less power is required for actual operation.

Always remember that simple power management will allow a smaller generator
to do a big job. Very seldom are all tools or appliances operating
simultaneously. When calculating power requirements, consider the starting
requirements are only for the initial start and then additional tools may be
operated in addition.

~~~
As an industry, we should find some way to come together -- not simply to
talk, but to act -- working together toward new solutions for our planet.

Honda President Nobuhiko Kawamoto

Nick

 

[Derek Broughton]

Usually, anyone who disagrees with Nick fell asleep during science class.

yeah, but Nick may have been teaching the class. Once I work it out, he's
usually right, but getting there can be tedious.

 

[Me]

Sorry man - Nick is spot on.

Nick usually is, but then again consider the source of the critisism
here.... WebTv isn't really where the Scientifically Compitant hang
out......


Me

 

[[email protected]]

Nick thank you.

You are welcome.

As I interpret it, Honda is using 3x for starting "reactive" loads.

I recall fuzzy language like that, but I'd go by their table. Unlike
motors, reactive loads don't neceessarily need long surge currents.

As I interpret your guidance, one should find the largest reactive
load, multiply it by 3 and add it to the base load.

I'd use the Honda site table.

... it assumes that only ONE load will be starting at a time.

That's why they mentioned "simple power management." With random startups,
you might add up all the surge currents and make sure that's less than
the surge load or the rated load. Or use a fraction of that based on the
Gaussian distribution and the square root of the sum of the surge minus
load currents squared and the probability of blowing a breaker, like
adjusted worst-case propagation delays in computer hardware design. As the
number of independent items increases, the load approaches the average
vs the worst-case sum of surge loads.

Is there any form of protection we can apply to prevent overload if we
have the "perfect storm" of multiple, simultaneous reactive load starts?

You might work out an X-10 micro-load management system that senses start
requests at wall sockets and delays application of power to individual
sockets based on a priority scheme. Turn off the electric oven or the
fridge while the well pump runs for a few seconds, and so on.

I'll try not to sleep through the answer.

That's best, to avoid ruler-whacks.

Nick

 

[daestrom]

yeah, but Nick may have been teaching the class. Once I work it out, he's
usually right, but getting there can be tedious.
--

(if only he didn't leave out all the units from all his numbers, and maybe
take a few extra seconds to type in where they sometimes come from ;-)

daestrom