Genset overprovisioning...

[Don Y]

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

 

[Dean Hoffman]

On Friday, April 21, 2023 at 10:31:14 PM UTC-5, Don Y wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

This is related to farm irrigation engines so take it with the old grain of salt. The engines were
generally sized to power the pump plus a 10 or 15 kw. 480 volt three phase generator to power the center pivot. The overall load would be somewhere in the 60 to 75 horsepower range. We naturally didn\'t want to get wet while fixing the pivots so we\'d throw the clutch to disconnect the well.
Diesel engines worked fine because they all had governors for engine speed. There might be a second long umph if I changed direction of the pivot and all of the pivot motors started.
Natural gas and propane engines were a nuisance. It took a few minutes for them to reach operating temperature. Speed would vary according to load.. The best we could hope for is a happy medium when we set the throttle. I never saw one with an engine governor though.
The set ups would look something like this.
<https://propane.com/propane-products/irrigation-engines/>
Center pivot dealers usually have some sort of portable power unit with a generator to test the new pivots before the rest of the set up is completed. There is usually a smaller diesel engine, the three phase generator, plus a fuel tank on a cart.
Is fuel consumption an issue?

 

[Don Y]

On 4/22/2023 4:45 AM, Dean Hoffman wrote:

On Friday, April 21, 2023 at 10:31:14 PM UTC-5, Don Y wrote:
I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house has a ~25KW feed --
and we likely never approach that!)

However, I\'m wondering if the (relatively) small load would make the
genset\'s \"control\" tougher to keep on mark?

This is related to farm irrigation engines so take it with the old grain of
salt. The engines were generally sized to power the pump plus a 10 or 15
kw. 480 volt three phase generator to power the center pivot. The overall
load would be somewhere in the 60 to 75 horsepower range.

So, ~50KW load plus another ~15KW headroom? The units I\'m looking at are
about twice that, but...

We naturally didn\'t want to get wet while fixing the pivots so we\'d throw
the clutch to disconnect the well.

Is that reflected in the above figure?

Diesel engines worked fine because they
all had governors for engine speed. There might be a second long umph if I
changed direction of the pivot and all of the pivot motors started.

But, the diesel was sized \"roughly\" to the load. Imagine it being
several times the load (or, your load being considerably smaller).

And, I would assume that (reflected mechanical) load was relatively
constant (save for the direction changes)?

Natural
gas and propane engines were a nuisance. It took a few minutes for them to
reach operating temperature. Speed would vary according to load.

The smaller, dual/tri-fuel gensets seem to use an electro-mechanical
governor to maintain RPMs as load varies. I\'m not sure how
well that would respond to sudden load changes as \"flipping a switch\"
doesn\'t give the genset any forewarning. And, the control seems
to work by dicking with the (mechanical) throttle... I can\'t imagine
that having a quick response.

The best
we could hope for is a happy medium when we set the throttle. I never saw
one with an engine governor though. The set ups would look something like
this. <https://propane.com/propane-products/irrigation-engines/> Center

Ah, OK. So, the mechanical link to the pump is what you were
talking about, above. The engine drove that \"mechanically\"
and the \"wheel motors\" electrically?

pivot dealers usually have some sort of portable power unit with a generator
to test the new pivots before the rest of the set up is completed. There
is usually a smaller diesel engine, the three phase generator, plus a fuel
tank on a cart. Is fuel consumption an issue?

This is one of those \"buy-it-so-we-never-need-it\" purchases.
So, in practical terms, I expect fuel use to be zero! :>

*Noise* may be a problem... not sure how loud these are as
they aren\'t really intended for residential deployments.
OTOH, as long as it\'s not brutally loud, it\'s no worse
than a neighbor hiring a landscaping service that uses
those frigging gasoline powered trimmers and blowers
for an hour *each* month.

The fact that we don\'t have any other use for diesel
(to justify keeping any amount of it on-hand and \"fresh\")
may be a problem. A gas genset you can consume any \"on-hand\"
fuel in a vehicle, periodically (and refill the storage tank).
Ditto for propane (BBQ).

In a time of need, getting additional fuel RSN might prove
to be an issue/hassle depending on the source and magnitude
of the outage.

What about reliability/availability? In your example, I
would imagine they are used *regularly*. So, a problem
manifests \"soon\" (good and bad to that... could be more
frequent problems but, also, better opportunity to
react to a problem given that you can probably defer
irrigation for a day while making repairs or shuffling
equipment).

I can\'t imagine diesel gensets having *short* lifespans
(most big gensets have hours-of-use meters) but can
assume gas/propane/lng would suffer from more issues.

 

[Jasen Betts]

On 2023-04-22, Don Y <blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

Are you asking if a motor with a load that varies from 0 to 25%
would have more trouble dealing with that than say a smaller
motor with a load that varies from 0 to 75%?



--
Jasen.
🇺🇦 Слава Україні

 

[Fred Bloggs]

On Saturday, April 22, 2023 at 9:30:45 AM UTC-4, Jasen Betts wrote:

Are you asking if a motor with a load that varies from 0 to 25%
would have more trouble dealing with that than say a smaller
motor with a load that varies from 0 to 75%?

Underloading any kind of generator to less than 50% rated causes all kinds of problems.

Considering price per gal diesel in Arizona is about $4.60, the generator will cost $12/ hr just to idle, and that easily doubles with any kind kW loading, tripling at maximum load. That\'s a lot of money considering the average home is drawing less than 0.5kW for the vast majority of time.

https://www.cat.com/en_US/by-industry/electric-power/Articles/White-papers/the-impact-of-generator-set-underloading.html

--
Jasen.
🇺🇦 Слава Україні

 

[Dean Hoffman]

On Saturday, April 22, 2023 at 8:17:04 AM UTC-5, Don Y wrote:

On 4/22/2023 4:45 AM, Dean Hoffman wrote:
On Friday, April 21, 2023 at 10:31:14 PM UTC-5, Don Y wrote:
I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house has a ~25KW feed --
and we likely never approach that!)

However, I\'m wondering if the (relatively) small load would make the
genset\'s \"control\" tougher to keep on mark?

This is related to farm irrigation engines so take it with the old grain of
salt. The engines were generally sized to power the pump plus a 10 or 15
kw. 480 volt three phase generator to power the center pivot. The overall
load would be somewhere in the 60 to 75 horsepower range.
So, ~50KW load plus another ~15KW headroom? The units I\'m looking at are
about twice that, but...
We naturally didn\'t want to get wet while fixing the pivots so we\'d throw
the clutch to disconnect the well.
Is that reflected in the above figure?
Diesel engines worked fine because they
all had governors for engine speed. There might be a second long umph if I
changed direction of the pivot and all of the pivot motors started.
But, the diesel was sized \"roughly\" to the load. Imagine it being
several times the load (or, your load being considerably smaller).

And, I would assume that (reflected mechanical) load was relatively
constant (save for the direction changes)?
Natural
gas and propane engines were a nuisance. It took a few minutes for them to
reach operating temperature. Speed would vary according to load.
The smaller, dual/tri-fuel gensets seem to use an electro-mechanical
governor to maintain RPMs as load varies. I\'m not sure how
well that would respond to sudden load changes as \"flipping a switch\"
doesn\'t give the genset any forewarning. And, the control seems
to work by dicking with the (mechanical) throttle... I can\'t imagine
that having a quick response.
The best
we could hope for is a happy medium when we set the throttle. I never saw
one with an engine governor though. The set ups would look something like
this. <https://propane.com/propane-products/irrigation-engines/> Center
Ah, OK. So, the mechanical link to the pump is what you were
talking about, above. The engine drove that \"mechanically\"
and the \"wheel motors\" electrically?

Yes. The generators for the 3 phase power to run the pivots are belt driven from a pulley on
the front of the engine. The actual irrigation well is mechanically driven from the back of the engine.
I should have said disengage the clutch to stop the well. It is the big majority of the load. It smooths out
the effect of the pivot\'s varying load on the generator. That part doesn\'t matter regardless of the type of fuel.

pivot dealers usually have some sort of portable power unit with a generator
to test the new pivots before the rest of the set up is completed. There
is usually a smaller diesel engine, the three phase generator, plus a fuel
tank on a cart. Is fuel consumption an issue?
This is one of those \"buy-it-so-we-never-need-it\" purchases.
So, in practical terms, I expect fuel use to be zero! :

*Noise* may be a problem... not sure how loud these are as
they aren\'t really intended for residential deployments.
OTOH, as long as it\'s not brutally loud, it\'s no worse
than a neighbor hiring a landscaping service that uses
those frigging gasoline powered trimmers and blowers
for an hour *each* month.

Maybe a couple mufflers in series would keep the neighbors calm. Point the exhaust
up. I don\'t really know how effective these flappers are but they\'re common in my world.
<https://www.amazon.com/Tractor-Exhaust-Silencer-Weather-Muffler/dp/B07YYVYP6Z/ref=sr_1_2?keywords=exhaust+flapper&qid=1682175106&sr=8-2>

The fact that we don\'t have any other use for diesel
(to justify keeping any amount of it on-hand and \"fresh\")
may be a problem. A gas genset you can consume any \"on-hand\"
fuel in a vehicle, periodically (and refill the storage tank).
Ditto for propane (BBQ).

In a time of need, getting additional fuel RSN might prove
to be an issue/hassle depending on the source and magnitude
of the outage.

What about reliability/availability? In your example, I
would imagine they are used *regularly*. So, a problem
manifests \"soon\" (good and bad to that... could be more
frequent problems but, also, better opportunity to
react to a problem given that you can probably defer
irrigation for a day while making repairs or shuffling
equipment).

The engines last for years despite sitting outside. Some farmers do have something resembling a carport over them. They will sit for maybe 4 months during the
winter from maybe December through March depending on the weather. Farmers will run them just
to move the center pivots so they can do their field work. That doesn\'t normally take more than a couple hours.
Irritation season might start in June and end in late August. That\'s more or less continuous use with everything running. ey

I can\'t imagine diesel gensets having *short* lifespans
(most big gensets have hours-of-use meters) but can
assume gas/propane/lng would suffer from more issues.

Well, I learned two somethings again. I\'ve been around irrigation related things all of my life. I know what they\'re called. Search engines don\'t necessarily like my terms.
The second thing is how cheap used portable military gensets can be.

 

[Don Y]

On 4/22/2023 8:05 AM, Dean Hoffman wrote:

The best we could hope for is a happy medium when we set the throttle. I
never saw one with an engine governor though. The set ups would look
something like this.
https://propane.com/propane-products/irrigation-engines/> Center
Ah, OK. So, the mechanical link to the pump is what you were talking
about, above. The engine drove that \"mechanically\" and the \"wheel motors\"
electrically?

Yes. The generators for the 3 phase power to run the pivots are belt driven
from a pulley on the front of the engine. The actual irrigation well is
mechanically driven from the back of the engine. I should have said
disengage the clutch to stop the well. It is the big majority of the load.

Ah! So, you\'re NOT really a 50KW+ load in this operating condition?

It smooths out the effect of the pivot\'s varying load on the generator.
That part doesn\'t matter regardless of the type of fuel.

The only real \"need\" for us to have a larger-than-portable genset
is to handle the ACbrrr. I think that\'s about a 12KW load plus
the load for the blower. That\'s going to govern the actual load.

And, with that much available power, we\'d likely not trim any
of the other \"idle\" loads in the house (automation system is ~2KW
and other semi-static loads of about 1KW).

[So, a 100KW genset sees a load alternating between ~2KW and
15KW when it likely was designed expecting a load that\'s
significantly larger]

With a smaller genset, that big cooling load falls out of the
equation (we\'d possibly buy a small portable ACbrrr and opt to
keep *a* room cool) so the load is more constant (refrigerator
and freezer being the only things that might \"cycle\"). And,
the smaller genset likely operating at something closer to its
\"sweet spot\".

pivot dealers usually have some sort of portable power unit with a
generator to test the new pivots before the rest of the set up is
completed. There is usually a smaller diesel engine, the three phase
generator, plus a fuel tank on a cart. Is fuel consumption an issue?
This is one of those \"buy-it-so-we-never-need-it\" purchases. So, in
practical terms, I expect fuel use to be zero! :

*Noise* may be a problem... not sure how loud these are as they aren\'t
really intended for residential deployments. OTOH, as long as it\'s not
brutally loud, it\'s no worse than a neighbor hiring a landscaping service
that uses those frigging gasoline powered trimmers and blowers for an hour
*each* month.

Maybe a couple mufflers in series would keep the neighbors calm. Point the
exhaust up. I don\'t really know how effective these flappers are but
they\'re common in my world.
https://www.amazon.com/Tractor-Exhaust-Silencer-Weather-Muffler/dp/B07YYVYP6Z/ref=sr_1_2?keywords=exhaust+flapper&qid=1682175106&sr=8-2

Or, throw a cable over the fence and let them suck off some of that
surplus power as a \"neighborly\" act.

\"Oh, the noise is bothering you? Sure, I can shut down YOUR power...\"

In a time of need, getting additional fuel RSN might prove to be an
issue/hassle depending on the source and magnitude of the outage.

What about reliability/availability? In your example, I would imagine they
are used *regularly*. So, a problem manifests \"soon\" (good and bad to
that... could be more frequent problems but, also, better opportunity to
react to a problem given that you can probably defer irrigation for a day
while making repairs or shuffling equipment).

The engines last for years despite sitting outside. Some farmers do have
something resembling a carport over them. They will sit for maybe 4 months
during the winter from maybe December through March depending on the

Ah, winter! I forgot places still have that! :> Here, the
risk would be from UV exposure (hoses?). But, most units are
\"housed\" in enclosures (which would also help a little with
noise).

The smaller \"portable\" gensets tend to want to be kept away
from that sort of exposure. They\'re also made for less
durable use.

weather. Farmers will run them just to move the center pivots so they can
do their field work. That doesn\'t normally take more than a couple hours.
Irritation season might start in June and end in late August. That\'s more
or less continuous use with everything running. ey

So, tanks are big? But, they\'d likely have diesel on-hand for
other pieces of equipment.

Propane would be the most practical, for us (use it as an
emergency cooking fuel, as well). But, then you\'re back to
a more \"consumerish\" product.

I can\'t imagine diesel gensets having *short* lifespans (most big gensets
have hours-of-use meters) but can assume gas/propane/lng would suffer from
more issues.

Well, I learned two somethings again. I\'ve been around irrigation related
things all of my life. I know what they\'re called. Search engines don\'t
necessarily like my terms. The second thing is how cheap used portable
military gensets can be.

Gensets, in general, are pretty inexpensive (if not \"brand new\").
There are different types of users. E.g., there are places, here,
that *live* off their gensets (slowly switching over to solar).
You want to avoid these as they tend to be consumerish and
tend to have high hours.

Larger \"industrial\" units (100-250KW) are often purchased to
bridge what are typically short outages. So, a genset may see
10 hours of use in a year!

The other issue is that folks who own/operate larger gensets likely
are more religious about maintenance. Small consumer units probably
not as much (small units have frequent maintenance schedules... like
50 hours of use!).

And, smaller units tend not to have hour meters. (So, how is the
\"responsible owner\" to know when maintenance is due? Keep a written
log book???)

Biggest downside to the industrial units is size. You have to
decide if you want one mounted on wheels (\"tow behind\") or
stationary (and a service to site it for you -- unless you
know a friend with a forklift! :> )

And, once you get above the power levels of the little portable units,
you\'re gonna have to tap someone to do the electrical install,
transfer switch and inspection (a couple of $K).

 

[boB]

On Fri, 21 Apr 2023 20:30:57 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

What kind of generator is it ?

boB

 

[server]

On Fri, 21 Apr 2023 20:30:57 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

Do you have multiple motor loads ? A motor can take up to six times
starting current compared to normal running current. This can cause
problems to the genset.

Modern motors use some kind of soft starter or the traditional
wye/delta (277/480 V) starter can be used to reduce the starting
current. With multiple motors, some adjustable delay can be added to
stagger the starting sequence of multiple motors to reduce the stress
on the genset even further.

 

[Dean Hoffman]

On Saturday, April 22, 2023 at 11:23:25 AM UTC-5, Don Y wrote:

On 4/22/2023 8:05 AM, Dean Hoffman wrote:
The best we could hope for is a happy medium when we set the throttle.. I
never saw one with an engine governor though. The set ups would look
something like this.
https://propane.com/propane-products/irrigation-engines/> Center
Ah, OK. So, the mechanical link to the pump is what you were talking
about, above. The engine drove that \"mechanically\" and the \"wheel motors\"
electrically?

Yes. The generators for the 3 phase power to run the pivots are belt driven
from a pulley on the front of the engine. The actual irrigation well is
mechanically driven from the back of the engine. I should have said
disengage the clutch to stop the well. It is the big majority of the load.
Ah! So, you\'re NOT really a 50KW+ load in this operating condition?

No. The load on the power unit was just the generator supplying electricity to the
center pivot. That was small but varied. We\'d start everything up as soon as we had the
problem fixed. That got the irrigation going ASAP. The main advantage to us was the farmer
wasn\'t standing there waiting to start up. He wasn\'t there \"helping\" or telling how to do something
we\'d done a hundred times before. Usually, anyhow.

It smooths out the effect of the pivot\'s varying load on the generator.
That part doesn\'t matter regardless of the type of fuel.
The only real \"need\" for us to have a larger-than-portable genset
is to handle the ACbrrr. I think that\'s about a 12KW load plus
the load for the blower. That\'s going to govern the actual load.

And, with that much available power, we\'d likely not trim any
of the other \"idle\" loads in the house (automation system is ~2KW
and other semi-static loads of about 1KW).

[So, a 100KW genset sees a load alternating between ~2KW and
15KW when it likely was designed expecting a load that\'s
significantly larger]

With a smaller genset, that big cooling load falls out of the
equation (we\'d possibly buy a small portable ACbrrr and opt to
keep *a* room cool) so the load is more constant (refrigerator
and freezer being the only things that might \"cycle\"). And,
the smaller genset likely operating at something closer to its
\"sweet spot\".
pivot dealers usually have some sort of portable power unit with a
generator to test the new pivots before the rest of the set up is
completed. There is usually a smaller diesel engine, the three phase
generator, plus a fuel tank on a cart. Is fuel consumption an issue?
This is one of those \"buy-it-so-we-never-need-it\" purchases. So, in
practical terms, I expect fuel use to be zero! :

*Noise* may be a problem... not sure how loud these are as they aren\'t
really intended for residential deployments. OTOH, as long as it\'s not
brutally loud, it\'s no worse than a neighbor hiring a landscaping service
that uses those frigging gasoline powered trimmers and blowers for an hour
*each* month.

The little generators for center pivot power could run off a couple V belts. We had to size the
pulley on the generator to make it run the proper speed. Trehe power units didn\'t use the same sized
pulley necessarily.
Is the engine on your possible unit directly coupled to the generator? Would it be practical to change the
gearing to let the engine run at a fast idle while maintaining generator speed? I\'m guessing the engine would
have plenty of horsepower to do that. You wouldn\'t happen to have an old car transmission out in the trees?
That should lessen noise.

Maybe a couple mufflers in series would keep the neighbors calm. Point the
exhaust up. I don\'t really know how effective these flappers are but
they\'re common in my world.
https://www.amazon.com/Tractor-Exhaust-Silencer-Weather-Muffler/dp/B07YYVYP6Z/ref=sr_1_2?keywords=exhaust+flapper&qid=1682175106&sr=8-2
Or, throw a cable over the fence and let them suck off some of that
surplus power as a \"neighborly\" act.

\"Oh, the noise is bothering you? Sure, I can shut down YOUR power...\"
In a time of need, getting additional fuel RSN might prove to be an
issue/hassle depending on the source and magnitude of the outage.

What about reliability/availability? In your example, I would imagine they
are used *regularly*. So, a problem manifests \"soon\" (good and bad to
that... could be more frequent problems but, also, better opportunity to
react to a problem given that you can probably defer irrigation for a day
while making repairs or shuffling equipment).

The engines last for years despite sitting outside. Some farmers do have
something resembling a carport over them. They will sit for maybe 4 months
during the winter from maybe December through March depending on the
Ah, winter! I forgot places still have that! :> Here, the
risk would be from UV exposure (hoses?). But, most units are
\"housed\" in enclosures (which would also help a little with
noise).

My dad\'s first irrigation engine was a four cylinder Hercules taken off an old combine.
Crank start. It burned gasoline. The gas tank for it was on stilts and painted aluminum. I think
it had some sort of filter.
His farm tractors burned gasoline. They had sediment bowls at the bottom of the tanks.
One rule we had was to fill them as soon as we were done with the field work. Those old tractors
sat outside. Condensation was an issue. Oh, he was environmentally friendly (frugal) before city people caught on. The exhaust pipes usually pointed straight up. He\'d rescue an old bean or corn can out of the trash to cover the exhaust pipe instead of the flappers I mentioned earlier. The sediment bowls are still available. Mr. Google and I agree on the name for them..

The smaller \"portable\" gensets tend to want to be kept away
from that sort of exposure. They\'re also made for less
durable use.
weather. Farmers will run them just to move the center pivots so they can
do their field work. That doesn\'t normally take more than a couple hours.
Irritation season might start in June and end in late August. That\'s more
or less continuous use with everything running.
So, tanks are big? But, they\'d likely have diesel on-hand for
other pieces of equipment.

Yes, they do have fuel storage generally at their home places. They also have pumps to take fuel
out of the storage tanks at individual fields for the irrigation wells. These tanks are generally 1000 gallons or so.
The tanks usually have fuel filters right at the fuel exit. The power units themselves have filters also.

Propane would be the most practical, for us (use it as an
emergency cooking fuel, as well). But, then you\'re back to
a more \"consumerish\" product.

Propane sellers promote it as the clean fuel. It\'s more planet friendly than natural gas, they say.

I can\'t imagine diesel gensets having *short* lifespans (most big gensets
have hours-of-use meters) but can assume gas/propane/lng would suffer from
more issues.

Well, I learned two somethings again. I\'ve been around irrigation related
things all of my life. I know what they\'re called. Search engines don\'t
necessarily like my terms. The second thing is how cheap used portable
military gensets can be.
Gensets, in general, are pretty inexpensive (if not \"brand new\").
There are different types of users. E.g., there are places, here,
that *live* off their gensets (slowly switching over to solar).
You want to avoid these as they tend to be consumerish and
tend to have high hours.

Larger \"industrial\" units (100-250KW) are often purchased to
bridge what are typically short outages. So, a genset may see
10 hours of use in a year!

The other issue is that folks who own/operate larger gensets likely
are more religious about maintenance. Small consumer units probably
not as much (small units have frequent maintenance schedules... like
50 hours of use!).

And, smaller units tend not to have hour meters. (So, how is the
\"responsible owner\" to know when maintenance is due? Keep a written
log book???)

Biggest downside to the industrial units is size. You have to
decide if you want one mounted on wheels (\"tow behind\") or
stationary (and a service to site it for you -- unless you
know a friend with a forklift! :> )

Irrigation power units in my area are usually on trailers made specifically for that.
The trailers also have brackets for the generators. Lima is the brand of choice.

And, once you get above the power levels of the little portable units,
you\'re gonna have to tap someone to do the electrical install,
transfer switch and inspection (a couple of $K).

 

[Don Y]

On 4/22/2023 2:00 PM, upsidedown@downunder.com wrote:

On Fri, 21 Apr 2023 20:30:57 -0700, Don Y
blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

Do you have multiple motor loads ? A motor can take up to six times
starting current compared to normal running current. This can cause
problems to the genset.

It\'s a house. The motors one would typically encounter are
in the various compressors -- freezer, refrigerator and
ACbrrr compressor -- and the blower motors in the furnace and
evap cooler. Motors in the washer and dryer are tiny,
by comparison.

By far, the ACbrrr dominates the peak load. (which is why
we wouldn\'t bother powering it with a smaller genset)

Modern motors use some kind of soft starter or the traditional
wye/delta (277/480 V) starter can be used to reduce the starting
current. With multiple motors, some adjustable delay can be added to
stagger the starting sequence of multiple motors to reduce the stress
on the genset even further.

That\'s not practical in most homes -- without additional controls
(e.g., I can reprogram the thermostat to notice the total household
load before closing the contacts that call for cooling -- from
ACbrrr or evap or blower motor). The refrigerator already has (factory)
hooks for demand control but I\'ve not figured out how to masquerade
as the electric utility -- yet.

The washer and dryer would similarly require reprogramming.
E.g., the washer already knows not to demand water in certain
circumstances.

The oven/stove is a potential big load -- but purely resistive.

I think wiring also has an effect on how the load is perceived
at the power source. E.g., the ACbrrr compressor is at the
far end of ~75ft of \"service entrance\" cable.

 

[Tabby]

On Saturday, 22 April 2023 at 14:17:04 UTC+1, Don Y wrote:

On 4/22/2023 4:45 AM, Dean Hoffman wrote:
On Friday, April 21, 2023 at 10:31:14 PM UTC-5, Don Y wrote:
I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house has a ~25KW feed --
and we likely never approach that!)

However, I\'m wondering if the (relatively) small load would make the
genset\'s \"control\" tougher to keep on mark?

This is related to farm irrigation engines so take it with the old grain of
salt. The engines were generally sized to power the pump plus a 10 or 15
kw. 480 volt three phase generator to power the center pivot. The overall
load would be somewhere in the 60 to 75 horsepower range.
So, ~50KW load plus another ~15KW headroom? The units I\'m looking at are
about twice that, but...
We naturally didn\'t want to get wet while fixing the pivots so we\'d throw
the clutch to disconnect the well.
Is that reflected in the above figure?
Diesel engines worked fine because they
all had governors for engine speed. There might be a second long umph if I
changed direction of the pivot and all of the pivot motors started.
But, the diesel was sized \"roughly\" to the load. Imagine it being
several times the load (or, your load being considerably smaller).

And, I would assume that (reflected mechanical) load was relatively
constant (save for the direction changes)?
Natural
gas and propane engines were a nuisance. It took a few minutes for them to
reach operating temperature. Speed would vary according to load.
The smaller, dual/tri-fuel gensets seem to use an electro-mechanical
governor to maintain RPMs as load varies. I\'m not sure how
well that would respond to sudden load changes as \"flipping a switch\"
doesn\'t give the genset any forewarning. And, the control seems
to work by dicking with the (mechanical) throttle... I can\'t imagine
that having a quick response.
The best
we could hope for is a happy medium when we set the throttle. I never saw
one with an engine governor though. The set ups would look something like
this. <https://propane.com/propane-products/irrigation-engines/> Center
Ah, OK. So, the mechanical link to the pump is what you were
talking about, above. The engine drove that \"mechanically\"
and the \"wheel motors\" electrically?
pivot dealers usually have some sort of portable power unit with a generator
to test the new pivots before the rest of the set up is completed. There
is usually a smaller diesel engine, the three phase generator, plus a fuel
tank on a cart. Is fuel consumption an issue?
This is one of those \"buy-it-so-we-never-need-it\" purchases.
So, in practical terms, I expect fuel use to be zero! :

*Noise* may be a problem... not sure how loud these are as
they aren\'t really intended for residential deployments.
OTOH, as long as it\'s not brutally loud, it\'s no worse
than a neighbor hiring a landscaping service that uses
those frigging gasoline powered trimmers and blowers
for an hour *each* month.

The fact that we don\'t have any other use for diesel
(to justify keeping any amount of it on-hand and \"fresh\")
may be a problem. A gas genset you can consume any \"on-hand\"
fuel in a vehicle, periodically (and refill the storage tank).
Ditto for propane (BBQ).

In a time of need, getting additional fuel RSN might prove
to be an issue/hassle depending on the source and magnitude
of the outage.

What about reliability/availability? In your example, I
would imagine they are used *regularly*. So, a problem
manifests \"soon\" (good and bad to that... could be more
frequent problems but, also, better opportunity to
react to a problem given that you can probably defer
irrigation for a day while making repairs or shuffling
equipment).

I can\'t imagine diesel gensets having *short* lifespans
(most big gensets have hours-of-use meters) but can
assume gas/propane/lng would suffer from more issues.

Underloaded diesels get inefficient. 7kW is hand crankable, 100kW definitely not, creating an added reliability issue. Lead acids don\'t last well. Many but not all diesels are happy to burn all sorts of rubbish. Diesel fuel keeps happily for many years, as long as it doesn\'t get diesel bug.

Gas/petrol goes off in a year, making such backup gens less reliable.
Small portable gens often only have a life expectancy of 60 hours.

 

[Don Y]

On 4/22/2023 1:24 PM, boB wrote:

On Fri, 21 Apr 2023 20:30:57 -0700, Don Y
blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

What kind of generator is it ?

I\'m not sure I understand what you\'re after...
make/model? fuel source? somethingelse?

 

[Don Y]

On 4/22/2023 3:17 PM, Dean Hoffman wrote:

Yes. The generators for the 3 phase power to run the pivots are belt
driven from a pulley on the front of the engine. The actual irrigation
well is mechanically driven from the back of the engine. I should have
said disengage the clutch to stop the well. It is the big majority of
the load.

Ah! So, you\'re NOT really a 50KW+ load in this operating condition?

No. The load on the power unit was just the generator supplying electricity
to the center pivot. That was small but varied.

So, wrt the ~65hp, how much of a load was the generator?
I.e., was the engine as oversized for *that* load as the
example I\'m giving?

We\'d start everything up
as soon as we had the problem fixed. That got the irrigation going ASAP.
The main advantage to us was the farmer wasn\'t standing there waiting to
start up. He wasn\'t there \"helping\" or telling how to do something we\'d
done a hundred times before. Usually, anyhow.

*Noise* may be a problem... not sure how loud these are as they
aren\'t really intended for residential deployments. OTOH, as long as
it\'s not brutally loud, it\'s no worse than a neighbor hiring a
landscaping service that uses those frigging gasoline powered trimmers
and blowers for an hour *each* month.

The little generators for center pivot power could run off a couple V belts.
We had to size the pulley on the generator to make it run the proper speed.

I suspect that wouldn\'t be practical for 100KW loads.

Trehe power units didn\'t use the same sized pulley necessarily. Is the
engine on your possible unit directly coupled to the generator?

I would imagine so. Likely a (fixed) gearbox so the engine can
run at a \"convenient\" speed and ensure the proper frequency
(and load handling) for the generator. You\'d not want the engine
to run out of power at higher loads. Nor drift off frequency
(as this is a true generator; not an inverter generator)

Would it be
practical to change the gearing to let the engine run at a fast idle while
maintaining generator speed?

You mean, find a *better* \"sweet spot\" given my reduced load?

I\'m guessing the engine would have plenty of
horsepower to do that. You wouldn\'t happen to have an old car transmission
out in the trees? That should lessen noise.

Ha! No \"trees\" here. And, I\'m not keen on turning this
into a major project. I wouldn\'t mind having to do some rewiring
(e.g., in case packrats had a feast) or a \"tune up\". But, not
keen on spending time/money doing a \"redesign\" and always nervous
about what might go wrong in that effort.

Ah, winter! I forgot places still have that! :> Here, the risk would be
from UV exposure (hoses?). But, most units are \"housed\" in enclosures
(which would also help a little with noise).

My dad\'s first irrigation engine was a four cylinder Hercules taken off an
old combine. Crank start. It burned gasoline.

From the photo previously cited, that seems like it would be
a possible DIYer solution; link the PTO to the pump and hack
together a drive for the (small) genset.

I\'m not sure I\'m qualified to piece together a \"random\" diesel and
\"random\" generator. And, any controls to ensure it performs as
intended.

[Does the diesel just have a fixed governor that you tweek for
the desired generator RPM? How sensitive *your* (his) loads to
frequency variation?]

The gas tank for it was on
stilts and painted aluminum. I think it had some sort of filter. His farm
tractors burned gasoline. They had sediment bowls at the bottom of the
tanks. One rule we had was to fill them as soon as we were done with the
field work. Those old tractors sat outside. Condensation was an issue.

Yeah, from my years \"north\", it was a standing rule: just as easy to
keep the TOP half of the tank full as it is to keep the BOTTOM!

And, I remember some funky \"putty\" that you could glob onto the end of
a stick/probe and lower into the tank to check for moisture in the
fuel.

[It wasn\'t uncommon to have a batch of \"bad gas\" during the winter months,
esp if the station wasn\'t properly maintaining their tanks]

Oh,
he was environmentally friendly (frugal) before city people caught on. The
exhaust pipes usually pointed straight up. He\'d rescue an old bean or corn
can out of the trash to cover the exhaust pipe instead of the flappers I
mentioned earlier. The sediment bowls are still available. Mr. Google and I
agree on the name for them.

The (heating) oil tank in the house had a similar arrangement.
Bad batch of fuel and it would get all gunked up and slimey.
Operate *without* said filter if you don\'t mind having to have
the jets cleaned on the furnace! (NOT!)

The smaller \"portable\" gensets tend to want to be kept away from that sort
of exposure. They\'re also made for less durable use.
weather. Farmers will run them just to move the center pivots so they
can do their field work. That doesn\'t normally take more than a couple
hours. Irritation season might start in June and end in late August.
That\'s more or less continuous use with everything running.
So, tanks are big? But, they\'d likely have diesel on-hand for other pieces
of equipment.

Yes, they do have fuel storage generally at their home places. They also
have pumps to take fuel out of the storage tanks at individual fields for
the irrigation wells. These tanks are generally 1000 gallons or so. The
tanks usually have fuel filters right at the fuel exit. The power units
themselves have filters also.

A neighbor had a 10KG tank buried on his property. I suspect it wasn\'t
disclosed to the \"new buyers\" as I\'m sure it was an environmental hazzard
by that time.

Propane would be the most practical, for us (use it as an emergency
cooking fuel, as well). But, then you\'re back to a more \"consumerish\"
product.

Propane sellers promote it as the clean fuel. It\'s more planet friendly
than natural gas, they say.

<shrug> In the quantities *I\'d* be using, it likely wouldn\'t make
much of a difference. The upside of natural gas is that it\'s
already piped to the house (though I\'m not sure if the feed line
is large enough; don\'t know what the upstream pressure is like
to make that calculus).

Downside is you\'re dependant on the natural gas supply. We\'ve had
one occasion where the supply to the town wasn\'t sufficient to
heat all the homes (high demand in an unusually cold spell) and
most furnaces would simply refuse to run due to insufficient
heat from the available fuel.

[They had to shed much of the load in order for anyone to be able
to heat their homes]

Propane puts the issue back in our control. But, also makes
us responsible for its availability! Not keen on having a
*big* propane tank on the property. I learned from propane powered
fork lift that propane explosions are often \"spectacular\".

Biggest downside to the industrial units is size. You have to decide if
you want one mounted on wheels (\"tow behind\") or stationary (and a service
to site it for you -- unless you know a friend with a forklift! :> )

Irrigation power units in my area are usually on trailers made specifically
for that. The trailers also have brackets for the generators. Lima is the
brand of choice.

Yes, some of the gensets are on small two-wheel \"tow behind\" trailers.
I suspect for deployment at jobsites, etc.

Others are pad mounted (or, on stilts if you are in a flood plain).

The former is probably preferable in terms of getting it into place.
But, having to maintain tires on something that will forever
reside *in* that space is a downside.

And, it\'s unlikely you\'d bother trying to haul it out with you
if you had to bug-out. OTOH, a small (truly) portable unit might
merit some space in the back of a pickup.

[If that was the case, I\'d opt for something with a Honda gas engine
as they have been remarkably robust, IME. But, such products are
incredibly pricey -- *if* your hope is never to need them!]

And, once you get above the power levels of the little portable units,
you\'re gonna have to tap someone to do the electrical install, transfer
switch and inspection (a couple of $K).

 

[Ralph Mowery]

In article <u211lm$3bc1r$2@dont-email.me>, blockedofcourse@foo.invalid
says...

Gensets, in general, are pretty inexpensive (if not \"brand new\").
There are different types of users. E.g., there are places, here,
that *live* off their gensets (slowly switching over to solar).
You want to avoid these as they tend to be consumerish and
tend to have high hours.

The generators are cheap when compaired to the cost of the fuel. With
fuel going from $ 3.00 up per gallon it will not take long for a 10 kw
and up to cost more than the generator.

 

[Don Y]

On 4/23/2023 8:23 AM, Don Y wrote:

At ~$10K, you can buy a lot of fuel at $4/gallon (2500 gallons).

If you plumb it to your natural gas supply, then a fair bit less.
E.g., a 20KW propane generator at full load burns about 3G of fuel
per hour (20KWH).  That\'s about the amount of power we use in an
average (winter) day (25KWH).

25KWH is closer to 4G/Hr. So, $10/Hr (one day\'s consumption) vs.
$4.50/day for utility power. So, a premium of ~$6/day. Brings
the period over which (surplus) fuel costs will exceed genset cost
down to about 5 years.

Current rates put the propane at ~$8 ($2.60/G).  We pay $4.50 for
that amount of power delivered by the electric utility.

So, in practical terms, it costs a premium of about $4 per *day* of
power from a genset.  After about 8 *years* of (continuous) running
(2800 days) the added fuel cost would exceed the cost of the (installed)
genset cost.

 

[Don Y]

On 4/23/2023 7:30 AM, Ralph Mowery wrote:

In article <u211lm$3bc1r$2@dont-email.me>, blockedofcourse@foo.invalid
says...

Gensets, in general, are pretty inexpensive (if not \"brand new\").
There are different types of users. E.g., there are places, here,
that *live* off their gensets (slowly switching over to solar).
You want to avoid these as they tend to be consumerish and
tend to have high hours.

The generators are cheap when compaired to the cost of the fuel. With
fuel going from $ 3.00 up per gallon it will not take long for a 10 kw
and up to cost more than the generator.

If you don\'t have electricity -- and the things that go with it -- then
the cost of fuel is not important.

Small \"whole house\" (laughable) gensets are in the $3K ballpark -- plus
another 2K for labor and accessories. These are barely larger than a modest
\"portable\" unit.

When you start getting up to the 15KW (which would barely run our ACbrrr)
range, you\'re at $5K (plus the above install). A whole home (~25KW)
is closer to $7K (plus install).

At ~$10K, you can buy a lot of fuel at $4/gallon (2500 gallons).

If you plumb it to your natural gas supply, then a fair bit less.
E.g., a 20KW propane generator at full load burns about 3G of fuel
per hour (20KWH). That\'s about the amount of power we use in an
average (winter) day (25KWH).

Current rates put the propane at ~$8 ($2.60/G). We pay $4.50 for
that amount of power delivered by the electric utility.

So, in practical terms, it costs a premium of about $4 per *day* of
power from a genset. After about 8 *years* of (continuous) running
(2800 days) the added fuel cost would exceed the cost of the (installed)
genset cost.

 

[Dean Hoffman]

On Saturday, April 22, 2023 at 6:42:02 PM UTC-5, Don Y wrote:

On 4/22/2023 3:17 PM, Dean Hoffman wrote:
Yes. The generators for the 3 phase power to run the pivots are belt
driven from a pulley on the front of the engine. The actual irrigation
well is mechanically driven from the back of the engine. I should have
said disengage the clutch to stop the well. It is the big majority of
the load.

Ah! So, you\'re NOT really a 50KW+ load in this operating condition?

No. The load on the power unit was just the generator supplying electricity
to the center pivot. That was small but varied.
So, wrt the ~65hp, how much of a load was the generator?
I.e., was the engine as oversized for *that* load as the
example I\'m giving?

The load with the center pivot running dry at maximum speed would never be over 7 hp.even
on the older systems. It would probably drop to around 4 hp. at times. The towers start and stop to keep in line with the next one to the outside of the circle. Tower 1 runs 1/7th as much as tower 7 on a regular
pivot.

We\'d start everything up
as soon as we had the problem fixed. That got the irrigation going ASAP..
The main advantage to us was the farmer wasn\'t standing there waiting to
start up. He wasn\'t there \"helping\" or telling how to do something we\'d
done a hundred times before. Usually, anyhow.
*Noise* may be a problem... not sure how loud these are as they
aren\'t really intended for residential deployments. OTOH, as long as
it\'s not brutally loud, it\'s no worse than a neighbor hiring a
landscaping service that uses those frigging gasoline powered trimmers
and blowers for an hour *each* month.

The little generators for center pivot power could run off a couple V belts.
We had to size the pulley on the generator to make it run the proper speed.
I suspect that wouldn\'t be practical for 100KW loads.
Trehe power units didn\'t use the same sized pulley necessarily. Is the
engine on your possible unit directly coupled to the generator?
I would imagine so. Likely a (fixed) gearbox so the engine can
run at a \"convenient\" speed and ensure the proper frequency
(and load handling) for the generator. You\'d not want the engine
to run out of power at higher loads. Nor drift off frequency
(as this is a true generator; not an inverter generator)
Would it be
practical to change the gearing to let the engine run at a fast idle while
maintaining generator speed?
You mean, find a *better* \"sweet spot\" given my reduced load?
I\'m guessing the engine would have plenty of
horsepower to do that. You wouldn\'t happen to have an old car transmission
out in the trees? That should lessen noise.
Ha! No \"trees\" here. And, I\'m not keen on turning this
into a major project. I wouldn\'t mind having to do some rewiring
(e.g., in case packrats had a feast) or a \"tune up\". But, not
keen on spending time/money doing a \"redesign\" and always nervous
about what might go wrong in that effort.
Ah, winter! I forgot places still have that! :> Here, the risk would be
from UV exposure (hoses?). But, most units are \"housed\" in enclosures
(which would also help a little with noise).

My dad\'s first irrigation engine was a four cylinder Hercules taken off an
old combine. Crank start. It burned gasoline.
From the photo previously cited, that seems like it would be
a possible DIYer solution; link the PTO to the pump and hack
together a drive for the (small) genset.

I\'m not sure I\'m qualified to piece together a \"random\" diesel and
\"random\" generator. And, any controls to ensure it performs as
intended.

[Does the diesel just hayve a fixed governor that you tweek for
the desired generator RPM? How sensitive *your* (his) loads to
frequency variation?]

The diesel engines have throttles that one sets to desired speed. The governors
on the injection pumps keep the speed fairly constant after that. Pivots would run
ok from about 440 vac to maybe 510 vac or so. They aren\'t all that finicky..
Modern electronics on pivots have voltage monitors to shut them off if voltage drops too much.
Now a farmer can sit at his breakfast table to check his systems. They go check the ones
that have stopped unexpectedly to see what happened.

The gas tank for it was on
stilts and painted aluminum. I think it had some sort of filter. His farm
tractors burned gasoline. They had sediment bowls at the bottom of the
tanks. One rule we had was to fill them as soon as we were done with the
field work. Those old tractors sat outside. Condensation was an issue.
Yeah, from my years \"north\", it was a standing rule: just as easy to
keep the TOP half of the tank full as it is to keep the BOTTOM!

And, I remember some funky \"putty\" that you could glob onto the end of
a stick/probe and lower into the tank to check for moisture in the
fuel.

[It wasn\'t uncommon to have a batch of \"bad gas\" during the winter months,
esp if the station wasn\'t properly maintaining their tanks]
Oh,
he was environmentally friendly (frugal) before city people caught on. The
exhaust pipes usually pointed straight up. He\'d rescue an old bean or corn
can out of the trash to cover the exhaust pipe instead of the flappers I
mentioned earlier. The sediment bowls are still available. Mr. Google and I
agree on the name for them.
The (heating) oil tank in the house had a similar arrangement.
Bad batch of fuel and it would get all gunked up and slimey.
Operate *without* said filter if you don\'t mind having to have
the jets cleaned on the furnace! (NOT!)
The smaller \"portable\" gensets tend to want to be kept away from that sort
of exposure. They\'re also made for less durable use.
weather. Farmers will run them just to move the center pivots so they
can do their field work. That doesn\'t normally take more than a couple
hours. Irritation season might start in June and end in late August.
That\'s more or less continuous use with everything running.
So, tanks are big? But, they\'d likely have diesel on-hand for other pieces
of equipment.

Yes, they do have fuel storage generally at their home places. They also
have pumps to take fuel out of the storage tanks at individual fields for
the irrigation wells. These tanks are generally 1000 gallons or so. The
tanks usually have fuel filters right at the fuel exit. The power units
themselves have filters also.
A neighbor had a 10KG tank buried on his property. I suspect it wasn\'t
disclosed to the \"new buyers\" as I\'m sure it was an environmental hazzard
by that time.
Propane would be the most practical, for us (use it as an emergency
cooking fuel, as well). But, then you\'re back to a more \"consumerish\"
product.

Propane sellers promote it as the clean fuel. It\'s more planet friendly
than natural gas, they say.
shrug> In the quantities *I\'d* be using, it likely wouldn\'t make
much of a difference. The upside of natural gas is that it\'s
already piped to the house (though I\'m not sure if the feed line
is large enough; don\'t know what the upstream pressure is like
to make that calculus).

Downside is you\'re dependant on the natural gas supply. We\'ve had
one occasion where the supply to the town wasn\'t sufficient to
heat all the homes (high demand in an unusually cold spell) and
most furnaces would simply refuse to run due to insufficient
heat from the available fuel.

I read recently about some people not having gas heat because some of
the natural gas company\'s pumps would\'t work due to no electrical supply.

[They had to shed much of the load in order for anyone to be able
to heat their homes]

Propane puts the issue back in our control. But, also makes
us responsible for its availability! Not keen on having a
*big* propane tank on the property. I learned from propane powered
fork lift that propane explosions are often \"spectacular\".
Biggest downside to the industrial units is size. You have to decide if
you want one mounted on wheels (\"tow behind\") or stationary (and a service
to site it for you -- unless you know a friend with a forklift! :> )

Irrigation power units in my area are usually on trailers made specifically
for that. The trailers also have brackets for the generators. Lima is the
brand of choice.
Yes, some of the gensets are on small two-wheel \"tow behind\" trailers.
I suspect for deployment at jobsites, etc.

Others are pad mounted (or, on stilts if you are in a flood plain).

The former is probably preferable in terms of getting it into place.
But, having to maintain tires on something that will forever
reside *in* that space is a downside.

And, it\'s unlikely you\'d bother trying to haul it out with you
if you had to bug-out. OTOH, a small (truly) portable unit might
merit some space in the back of a pickup.

[If that was the case, I\'d opt for something with a Honda gas engine
as they have been remarkably robust, IME. But, such products are
incredibly pricey -- *if* your hope is never to need them!]
And, once you get above the power levels of the little portable units,
you\'re gonna have to tap someone to do the electrical install, transfer
switch and inspection (a couple of $K).

 

[Don Y]

On 4/23/2023 9:54 AM, Dean Hoffman wrote:

No. The load on the power unit was just the generator supplying
electricity to the center pivot. That was small but varied.
So, wrt the ~65hp, how much of a load was the generator? I.e., was the
engine as oversized for *that* load as the example I\'m giving?

The load with the center pivot running dry at maximum speed would never be
over 7 hp.even on the older systems. It would probably drop to around 4 hp.
at times. The towers start and stop to keep in line with the next one to
the outside of the circle. Tower 1 runs 1/7th as much as tower 7 on a
regular pivot.

Ah! So more like 3-5KW out of ~50KW (engine) capacity. That might be
comparable to the range of loads I\'m looking at (scaled by a factor).

[Does the diesel just have a fixed governor that you tweek for the desired
generator RPM? How sensitive *your* (his) loads to frequency variation?]

The diesel engines have throttles that one sets to desired speed. The
governors on the injection pumps keep the speed fairly constant after that.
Pivots would run ok from about 440 vac to maybe 510 vac or so. They aren\'t
all that finicky. Modern electronics on pivots have voltage monitors to
shut them off if voltage drops too much. Now a farmer can sit at his
breakfast table to check his systems. They go check the ones that have
stopped unexpectedly to see what happened.

But are they frequency insensitive? I\'d be concerned that a
change in engine speed would result in frequency disturbances.
Not sure how well \"home appliances\" would deal with that.

Downside is you\'re dependant on the natural gas supply. We\'ve had one
occasion where the supply to the town wasn\'t sufficient to heat all the
homes (high demand in an unusually cold spell) and most furnaces would
simply refuse to run due to insufficient heat from the available fuel.

I read recently about some people not having gas heat because some of the
natural gas company\'s pumps would\'t work due to no electrical supply.

Dunno. But, *gasoline* (and diesel) pumps would likely be \"out\" if a
widespread power outage. So, not a reliable fuel source

In our (natural gas) outage, there was gas. Just not at a high
enough distribution pressure to satisfy the safeties in the
appliances that used it. I\'d watch the furnace call for gas,
watch the igniter kick in, flame appear... then, the gas valve
shut down as the safeties didn\'t sense \"enough heat\" to convince
themselves that the fire was lit. Evacuate the fumes. Wait.
Repeat.

Plumbers had a field day from all the idiots who just thought
their furnace was \"broken\". Gotta wonder how the plumbers
could NOT just tell the callers \"check for flame; if none,
we\'ll come out. Otherwise, it\'s caused by a regional supply
outage\".

But, hey, why NOT screw over your (ignorant) customers? :>

 

[boB]

On Sat, 22 Apr 2023 16:09:30 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

On 4/22/2023 1:24 PM, boB wrote:
On Fri, 21 Apr 2023 20:30:57 -0700, Don Y
blockedofcourse@foo.invalid> wrote:

I\'m looking at a *big* genset (100KW++) -- great price.

But, my needs are nowhere near that (I think the house
has a ~25KW feed -- and we likely never approach that!)

However, I\'m wondering if the (relatively) small load
would make the genset\'s \"control\" tougher to keep
on mark?

What kind of generator is it ?

I\'m not sure I understand what you\'re after...
make/model? fuel source? somethingelse?

Generac ? Onan ? Etc ?