Genset voltage reg: capacitor vs. AVR

On Feb 17, 10:00*pm, jon_banquer > wrote:
> On Feb 17, 9:50*pm, jon_banquer > wrote:
>
> > On Feb 17, 9:40*am, "Existential Angst" > wrote:
>
> > > "jon_banquer" > wrote in message
>
> > ....
> > > On Feb 17, 8:23 am, "Existential Angst" > wrote:
>
> > > > > wrote in message
>
> > > ...
> > > > On Feb 17, 9:49 am, "Existential Angst" > wrote:
>
> > > > > "Pete S" > wrote in message
>
> > > > ...
>
> > > > > >I don't understand your question.
> > > > > > If you mean "capacitors" when you say "caps", I don't know how they
> > > > > > would
> > > > > > deal with output voltage regulation in any meaningful way.
>
> > > > > Ditto. ergo my Q. I guess they must in some fashion, just like you
> > > > > balance
> > > > > rpc's with caps.
>
> > > > > > What kind, model and serial number of genset do you have that
> > > > > > currently
> > > > > > has no voltage regulation built in to it?
>
> > > > >http://www.generatorsales.com/order/...Generator.asp?...
> > > > > modified for tri-fuel.
>
> > > > > It is regulated, just not to 1 or 2%, a swing of 230 to 250 V, from 50+
> > > > > amps
> > > > > down to zero amps.
> > > > > If you at mid-load it's 240 V, that's +/-10V, which is not terrible, but
> > > > > it's not 1% either.
>
> > > > > Assume no electrical-type regulation at all. There is something between
> > > > > the
> > > > > generator itself and the gas engine that ups fuel flow with load,
> > > > > maintaining a semi-constant voltage.
>
> > > > That would be the mechanical engine governor.
> > > > ================================================== ==
>
> > > > I sure would like to know the details on how those work.
>
> > > > An AVR sharpens this up.
>
> > > > Yes
>
> > > > > I don't quite understand how this works, and part of the intent of Q was
> > > > > to
> > > > > shed some light on this.
>
> > > > See my other post to a discussion.
>
> > > > > I also figgered that if the feedback between generator and engine was
> > > > > good
> > > > > enough, AVR wouldn't be needed.
> > > > > So basically I"m curious about the design of these things.
> > > > > --
> > > > > EA
>
> > > > Do you realize what you got for $2800? They take a Honda
> > > > engine and bolt it on to some generator made by someone
> > > > else. Perhaps you can shed light on to who that someone
> > > > else is, but given that it uses a cap for voltage regulation,
> > > > I would not be surprised that it's a cheap Chinese one.
> > > > Then they take pretty pictures of the thing with Honda showing
> > > > all over in the pretty pics and a lot of people make the
> > > > assumption that they are buying a Honda generator.
> > > > I don't believe that is the case.
> > > > ================================================== ===
>
> > > > McCaulte (sp?) makes the generator.
>
> > > > And yes, they mix'n'match.... but presumably they do it pretty well, altho
> > > > I got a li'l short-shrifted on the AVR deal....
> > > > I don't know that they are being misleading, as much as emphasizing the
> > > > Honda part.... LOL
> > > > Thin line, admittedly.
>
> > > > Further arousing suspicion is that they claim it's 15KW.
> > > > Then if you read the specs, it says it's rated at 13.5KW
> > > > continuous.
> > > > =============================================
>
> > > > This is typical. Generac does this.
>
> > > > Then they say it has a 50 amp main
> > > > breaker, which equates to 12KW, in my world.
> > > > ======================================
>
> > > > Yeah, I noticed that. And they trip fast, too!
> > > > I may put in my own 50 A slower-tripping or even 60 A breakers.
>
> > > > You with me so far? Further arrousing suspicion, they
> > > > quote fuel consumption in gallons, ie it's based on running
> > > > the engine on gas. So, next, let's look at the spec for
> > > > a Honda GX690. It says it produces 22hp running gasoline.
> > > > I'm no expert in conversions from gasoline to nat gas, but
> > > > AFAIK, when you run a gasoline engine on nat gas, you
> > > > have about 15% less energy output. Maybe someone has
> > > > the exact number. That means you really have about an
> > > > 18hp engine.
> > > > ===============================================
>
> > > > Again, par for the course. I simply went for the most watts. Those watts
> > > > will be similarly de-rated in most scenarios, so I just went with the
> > > > biggest number.
>
> > > > I've looked into generators a bit and what it takes to
> > > > power them. I don't think you can get 15KW out of an
> > > > 18hp engine. A Generac 12KW unit for example, uses
> > > > a 26hp engine.
> > > > ================================================
>
> > > > Oh, but I did get very nearly the full 13.5 continuous (on gasoline), and
> > > > proly could have gotten sig. more. I'll have to jump/replace the breaker,
> > > > tho. Already at near-full load, it started a 26 gal compressor, w/ nary a
> > > > hiccup.
>
> > > > A 26 hp engine for 12 kW is suspect as well, from two povs:
> > > > First, I suspect Generac hp is like Sears hp.
> > > > Second, if it IS 26 hp, yer just sipping lots more gas.... which was one
> > > > of
> > > > the things I was going to discuss in my upcoming Generator Manifesto.....
> > > > big-azz generators, in no-load conditions, are not economical.
>
> > > > I really couldn't find much better overall bang fer the buck, watt-wise.
> > > > The Honda motor is a plus, and the unit is VERY compact.
> > > > Generacs are big and complicated. OK, I spose, for the home-moaner who
> > > > justs likes to dial the telephone when sumpn goes wrong, and from what
> > > > I've
> > > > read about generac, they will be using their telephone fairly often..
>
> > > > Here's some of my take on this:
>
> > > > I would recommend the Sam's club 8,750 W blackmax, at $999, for most
> > > > people
> > > > with more than the basic needs. You can get it modified for tri-fuel, and
> > > > the link I provided sells a modified blackmax for $1600 -- about a
> > > > $200-$400
> > > > preimum over what you would pay if you did it yourself, but with a lot
> > > > less
> > > > headache, and somewhat of a guarantee. The blackmax also has AVR, iirc,
> > > > and
> > > > performed quite well, before it grew feet.
>
> > > > My unit does not come with a gas tank, but which is actually an advantage,
> > > > imo, because you just drop the genset's hose down any gas can (or your
> > > > car's
> > > > gas tank, if you can snake it in), and Wala, gasoline power.
>
> > > > I went for the 15 kW unit, in the second go-around, for many of the
> > > > reasons
> > > > you stated:
> > > > By the time you get done de-rating for whatever whatever reasons, you
> > > > have a lot less than when you started, so I figgered I'd just double the
> > > > size from the gitgo.
>
> > > > Really a lot of g-d work. The other bottom line to all this is that unless
> > > > you have a water-cooled 4 cylinder unit, you gotta simply build a separate
> > > > sound-proofed shed for these noise buckets.
> > > > A lot of my work so far went in to testing, given my cnc liabilities. So
> > > > far so good, but really a pita -- for sumpn I may NEVER use.
> > > > --
> > > > EA
>
> > > > Just some more things to think about.
>
> > > It seems it's often impossible to buy the right package for what
> > > someone wants.
> > > ============================================
>
> > > Amazing how that works.... in almost everything! *From vitamins to cars to
> > > cnc to real estate.....
> > > Canada here I come.....
>
> > > An example is an air compressor. I don't intend to run my air
> > > compressor day in and day out so I don't have the need for a very
> > > heavy duty dual stage air compressor pump like this one:
>
> > >http://www.northerntool.com/shop/too...ct_42535_42535
>
> > > I'd like this air compressor pump because it's got an 18 CFM rating at
> > > 90 PSI and it's got a decent price.
>
> > >http://www.northerntool.com/shop/too...7235_200387235
> > > ================================================== ======
>
> > > I'd be careful of Northern Tool. *They are not above shenannigans.
> > > I'd look at the displacement of the pistons, and try to guestimate the rpm,
> > > and match that to cfm claims of similar sized compressors. *Ahm no 'spert,
> > > but 18 cfm at 90 psi seems pretty substantial. I'da thought more like 5 or 8
> > > for that size.
> > > I'd check out comparable sized Quincy's, or other reputable brands, and see
> > > what they list.
>
> > > The husky compressor is surprisingly civilized.
>
> > > I'd like this motor:
>
> > >http://www.northerntool.com/shop/too...6765_200306765
>
> > > When I try an find a reasonably priced horizontal air tank I'm ****ed..
> > > Prices are insane. Looks like my only choice will be to buy a used
> > > horizontal air tank.
> > > ================================================== ==========
>
> > > Well, mixing/matching is not a bad idea, and proly a really good one. *Tanks
> > > are tanks, motors are motors, so really what you want are a nice (quiet)
> > > 'pressor head, and a good regulator, with separate set points for
> > > cut-in/cut-out, which bigbox stuff doesn't have.
>
> > > Also, recall from a previous discussion that a big tank will help compensate
> > > for smaller compressor size, and that instead of one big tank, a bunch of
> > > small ones are the same as one big one, and a lot more manageable. I have a
> > > bunch connected together, each one separately valved. *You don't even need
> > > the motor/'pressor mounted on a tank, per se.
> > > I've even got some BBQ propane tanks I want to hook in, but goddamm, do they
> > > make it difficult to remove dat stuff in the 3/4 neck. *Also, there's no
> > > drain, altho they are small enough you could put the drain on top, and just
> > > tilt it to drain it.
> > > --
> > > EA
>
> > I'm hearing almost all air compressor pumps are made in either China
> > or India. That includes Ingersoll Rand. Thinking that Northern Tool
> > may not be the way to go. Found this. Like the price and the specs:
>
> >http://www.eatoncompressor.com/catal...43/1320611.htm
>
> http://wiki.answers.com/Q/Are_Ingers...ade_in_the_USA


Spoke with Eaton compressor at length today. Person I spoke with was
very knowledgeable and no bull****. Their air compressor pumps have
been made in China for the last 12 years. They have dual suppliers in
China and the parts are interchangeable. They stock all the parts. I
like how the compressor pump I'm interested in runs at low RPM (850),
is 25 CFM (@90 PSI) and sells for $500. The also sell Lincoln electric
motors which are owned by Leeson. 7 1/2 HP Lincoln motor is $550. $65
for a pulley. Square D mag starter is $170. Pressure switch is $40.
Don't think I'm going to need multiple tanks. What do you see as the
benefit to multiple tanks if you have the right compressor to keep up
with your needs?

"jon_banquer" > wrote in message
...
On Feb 17, 10:00 pm, jon_banquer > wrote:
> On Feb 17, 9:50 pm, jon_banquer > wrote:
>
> > On Feb 17, 9:40 am, "Existential Angst" > wrote:
>
>
> > > Also, recall from a previous discussion that a big tank will help
> > > compensate
> > > for smaller compressor size, and that instead of one big tank, a bunch
> > > of
> > > small ones are the same as one big one, and a lot more manageable. I
> > > have a
> > > bunch connected together, each one separately valved. You don't even
> > > need
> > > the motor/'pressor mounted on a tank, per se.
> > > I've even got some BBQ propane tanks I want to hook in, but goddamm,
> > > do they
> > > make it difficult to remove dat stuff in the 3/4 neck. Also, there's
> > > no
> > > drain, altho they are small enough you could put the drain on top, and
> > > just
> > > tilt it to drain it.
> > > --
> > > EA
>
> > I'm hearing almost all air compressor pumps are made in either China
> > or India. That includes Ingersoll Rand. Thinking that Northern Tool
> > may not be the way to go. Found this. Like the price and the specs:
>
> >http://www.eatoncompressor.com/catal...43/1320611.htm
>
> http://wiki.answers.com/Q/Are_Ingers...ade_in_the_USA


Spoke with Eaton compressor at length today. Person I spoke with was
very knowledgeable and no bull****. Their air compressor pumps have
been made in China for the last 12 years. They have dual suppliers in
China and the parts are interchangeable. They stock all the parts. I
like how the compressor pump I'm interested in runs at low RPM (850),
is 25 CFM (@90 PSI) and sells for $500. The also sell Lincoln electric
motors which are owned by Leeson. 7 1/2 HP Lincoln motor is $550. $65
for a pulley. Square D mag starter is $170. Pressure switch is $40.
Don't think I'm going to need multiple tanks. What do you see as the
benefit to multiple tanks if you have the right compressor to keep up
with your needs?
================================================== ===========

True, a good compressor does not require my staged tank strategy, but imo,
increasing tank capacity will extend the usable cfm rating of any
compressor, AND reduce it's cycling.

This is more important if you are going on the cheap, or have limited power,
or space. I got my 26 gal Husky as a floor model for $160 at HD, and just
added extra tanks as I stumbled across them -- could even be tall welding
tanks!
Dat 7.5 hp motor is going to dim the lights!
You can also save on the contactor by just using a simple relay, with the
coil wired into the pressure switch.
For me, space is at a premium, portability is really helpful.
And even a 26 gal Husky (vertical) is heav-eeeeee!! Holy ****.....
Also make sure it's easy to drain the tanks. I run a long hose from the
bottom, with a small ball valve at the end of the hose (1/4" white stuff,
like for a fridge's ice-maker), and just empty it into a bucket.

If you are going to mix'n'match, $550 for a motor seems like a lot, I would
go to a motor re-winding place, and see what they have on their shelves, for
cheap. They often have *hundreds* of spare motors to choose from, I'll bet
you could find sumpn suitable for under $100, mebbe way under.

Finagling "small" has its advantages. For example, if you have limited
power, and are running cnc, you don't want big-azz motors causing transient
voltage drops every time the pressor kicks in. So a smaller motor/pressor
is less electrical strain, and larger tank volume creates less cycling,
jolts to the electrical service.
Which also becomes even more important during outtages, if running off a
generator.
And also ito moving **** around...

If none of this is a factor, then you can go big and heavy and strong, but
if it is a factor, finagling small stuff helps -- a kind of "modularity".
--
EA

"Leon Fisk" > wrote in message
...
> On Sun, 17 Feb 2013 11:23:27 -0500
> "Existential Angst" > wrote:
>
> <snip>
>>McCaulte (sp?) makes the generator.
>
> Website, instruction manuals he
>
> http://www.meccalte.com/index.php?s=52&page=0
>
> The model number off your unit would be really helpful
>
> Possibly the manual for your generator head:
>
> http://www.meccalte.com/send_file.ph...S20W%20manuale
>
> "S20W Series:
> 6kVA to 8.5kVA 3000rpm 50Hz or
> 7.2kVA to 10.2kVA 3600rpm 60Hz"
>
> or it might be this one:
>
> http://www.meccalte.com/send_file.ph...S20F%20manuale
>
> "S20F Series:
> 8.5kVA to 12kVA 3000rpm 50Hz or
> 10.5kVA to 14.4kVA 3600rpm 60Hz"
>
> Just guessing, using the output wattage you gave...

Yeah, I'm not sure either, I'll have poke around the generator -- oh,
actually, a booklet came with each component, I'll dig it up, post back.

Whatever it is, they'll be sending the AVR sized for that unit.
--
EA


>
> --
> Leon Fisk
> Grand Rapids MI/Zone 5b
> Remove no.spam for email
>

On Feb 19, 1:48*am, "Existential Angst" > wrote:
> "jon_banquer" > wrote in message
>
> ...
> On Feb 17, 10:00 pm, jon_banquer > wrote:
>
>
>
>
>
>
>
>
>
> > On Feb 17, 9:50 pm, jon_banquer > wrote:
>
> > > On Feb 17, 9:40 am, "Existential Angst" > wrote:
>
> > > > Also, recall from a previous discussion that a big tank will help
> > > > compensate
> > > > for smaller compressor size, and that instead of one big tank, a bunch
> > > > of
> > > > small ones are the same as one big one, and a lot more manageable. I
> > > > have a
> > > > bunch connected together, each one separately valved. You don't even
> > > > need
> > > > the motor/'pressor mounted on a tank, per se.
> > > > I've even got some BBQ propane tanks I want to hook in, but goddamm,
> > > > do they
> > > > make it difficult to remove dat stuff in the 3/4 neck. Also, there's
> > > > no
> > > > drain, altho they are small enough you could put the drain on top, and
> > > > just
> > > > tilt it to drain it.
> > > > --
> > > > EA
>
> > > I'm hearing almost all air compressor pumps are made in either China
> > > or India. That includes Ingersoll Rand. Thinking that Northern Tool
> > > may not be the way to go. Found this. Like the price and the specs:
>
> > >http://www.eatoncompressor.com/catal...43/1320611.htm
>
> >http://wiki.answers.com/Q/Are_Ingers...ade_in_the_USA
>
> Spoke with Eaton compressor at length today. Person I spoke with was
> very knowledgeable and no bull****. Their air compressor pumps have
> been made in China for the last 12 years. They have dual suppliers in
> China and the parts are interchangeable. They stock all the parts. I
> like how the compressor pump I'm interested in runs at low RPM (850),
> is 25 CFM (@90 PSI) and sells for $500. The also sell Lincoln electric
> motors which are owned by Leeson. 7 1/2 HP Lincoln motor is $550. $65
> for a pulley. Square D mag starter is $170. Pressure switch is $40.
> Don't think I'm going to need multiple tanks. What do you see as the
> benefit to multiple tanks if you have the right compressor to keep up
> with your needs?
> ================================================== ===========
>
> True, a good compressor does not require my staged tank strategy, but imo,
> increasing tank capacity will extend the usable cfm rating of any
> compressor, AND reduce it's cycling.
>
> This is more important if you are going on the cheap, or have limited power,
> or space. *I got my 26 gal Husky as a floor model for $160 at HD, and just
> added extra tanks as I stumbled across them -- could even be tall welding
> tanks!
> Dat 7.5 hp motor is going to dim the lights!
> You can also save on the contactor by just using a simple relay, with the
> coil wired into the pressure switch.
> For me, space is at a premium, portability is really helpful.
> And even a 26 gal Husky (vertical) is heav-eeeeee!! *Holy ****.....
> Also make sure it's easy to drain the tanks. *I run a long hose from the
> bottom, with a small ball valve at the end of the hose (1/4" white stuff,
> like for a fridge's ice-maker), and just empty it into a bucket.
>
> If you are going to mix'n'match, $550 for a motor seems like a lot, I would
> go to a motor re-winding place, and see what they have on their shelves, for
> cheap. *They often have *hundreds* of spare motors to choose from, I'll bet
> you could find sumpn suitable for under $100, mebbe way under.
>
> Finagling "small" has its advantages. *For example, if you have limited
> power, and are running cnc, you don't want big-azz motors causing transient
> voltage drops every time the pressor kicks in. *So a smaller motor/pressor
> is less electrical strain, and larger tank volume creates less cycling,
> jolts to the electrical service.
> Which also becomes even more important during outtages, if running off a
> generator.
> And also ito moving **** around...
>
> If none of this is a factor, then you can go big and heavy and strong, but
> if it is a factor, finagling small stuff helps -- a kind of "modularity".
> --
> EA

"True, a good compressor does not require my staged tank strategy, but
imo, increasing tank capacity will extend the usable cfm rating of any
compressor, AND reduce it's cycling."

The advantage I see in running a well designed air compressor pump is
lots more CFM, less space, less noise and a longer lasting pump
because it can be run at much lower RPM. Doing something like
pressurized sandblasting eats up a lot of CFM.

One thing I'm now sure of:

When you buy a big name like Ingersoll Rand you aren't getting high
quality like you use to get 20 years ago. All you are buying now is
the name.

Robert > wrote:
>
>Thanks for the link. From that thread, I determined that the
>keyphrase I needed to google was "alternator feedback
>capacitor".... That gave me the link to a paper called
>"Field Initiation Design Fundamentals for Pulsed Alternators"
>which has an abstract giving a short explanation of how
>the capacitor works. This was an IEEE paper.

I downloaded that paper, it's not actually using the capacitor as a
regulator at all. This is a trick for starting up a an air-core
alternator which doesn't have any residual magnetism to start current
in the armature when it's turned on, unlike a conventional steel-core
generator. I don't think any of this applies to the discussion at hand.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Jim Wilkins > wrote:
>
>How to regulate a permanent-magnet generator:
>http://www.google.com/patents/US4766362
>http://www.freepatentsonline.com/5625276.html (couldn't open)
>http://www.google.com/patents?id=A1E...page&q&f=false
>US 4,885,493

This is very cool and quite ingenious but also not relevant to the
discussion at hand.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

> wrote:
>On Feb 18, 11:12=A0am, (Scott Dorsey) wrote:
>> > wrote:

>> With a conventional AC generator, the speed of the engine governs the
>> output frequency. =A0The generator HAS to run at constant speed, usually
>> 1800 rpm, in order to get 60 Hz out of the generator. =A0Change the engin=
>e
>> speed, you change the line frequency.
>
>No **** sherlock and you also change the voltage.

Possibly for one fraction of a cycle, but as soon as there is any change, the
field coil voltage will be increased to compensate for it. The mechanical
feedback loop that controls the engine speed is very very slow, because it
is limited by the inertia of the engine an the rotor. The electrical feedback
loop that controls the field coil voltage is pretty fast; it is limited
mostly by the inductance of the field coil.

>> This is why conventional AC generators ALL have a device to regulate the
>> field coil voltage in order to get constant output voltage. =A0Some of th=
>ese
>> devices are better than others.
>
>That's true and why EA is asking about a cap versus
>a ture electronic voltage regulator.

And what does he mean by "a cap?" As I said earlier, you have two choices
for voltage regulation: a feedback loop controlled by a mechanical buzzer, or
a feedback loop controlled by a solid state device. What is this mysterious
"capacitor regulation" that he has come up with? Nobody in this thread has
yet explained it, described it, or given an example of it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Feb 19, 1:54*pm, (Scott Dorsey) wrote:
> > wrote:
> >On Feb 18, 11:12=A0am, (Scott Dorsey) wrote:
> >> > wrote:
> >> With a conventional AC generator, the speed of the engine governs the
> >> output frequency. =A0The generator HAS to run at constant speed, usually
> >> 1800 rpm, in order to get 60 Hz out of the generator. =A0Change the engin=
> >e
> >> speed, you change the line frequency.
>
> >No **** sherlock and you also change the voltage.
>
> Possibly for one fraction of a cycle, but as soon as there is any change, the
> field coil voltage will be increased to compensate for it.

But what you stated was:

"The engine governor has nothing to do with the output voltage
regulation,
really. "

Which would mean to me that you could run a generator with a bad or
incorrectly adjusted governor running at 3400 RPPM, or 4000 RPM
and the only thing that would change is that the frequency would not
be 60hz, ie the voltage stays the same. That isn't true, because the
voltage is directly proportional to the speed too. I agree that
adjusting
the field is how the voltage is adjusted without changing the engine
speed.



The mechanical
> feedback loop that controls the engine speed is very very slow, because it
> is limited by the inertia of the engine an the rotor. *The electrical feedback
> loop that controls the field coil voltage is pretty fast; it is limited
> mostly by the inductance of the field coil.
>
> >> This is why conventional AC generators ALL have a device to regulate the
> >> field coil voltage in order to get constant output voltage. =A0Some of th=
> >ese
> >> devices are better than others.
>
> >That's true and why EA is asking about a cap versus
> >a ture electronic voltage regulator.
>
> And what does he mean by "a cap?" *As I said earlier, you have two choices
> for voltage regulation: a feedback loop controlled by a mechanical buzzer, or
> a feedback loop controlled by a solid state device. *What is this mysterious
> "capacitor regulation" that he has come up with? *Nobody in this thread has
> yet explained it, described it, or given an example of it.
> --scott
>
> --

I posted a link to a discussion on the subject previously.
Apparently capacitors are used as a cheap voltage regulator.
Also, just google and you'll find info.

> wrote:
>
>Which would mean to me that you could run a generator with a bad or
>incorrectly adjusted governor running at 3400 RPPM, or 4000 RPM
>and the only thing that would change is that the frequency would not
>be 60hz, ie the voltage stays the same. That isn't true, because the
>voltage is directly proportional to the speed too. I agree that
>adjusting
>the field is how the voltage is adjusted without changing the engine
>speed.

But you CAN run the generator at some other speed and the output voltage
will be the same. Try it! That's the purpose of the feedback control of
the field coil. The faster you run the thing, the more the regulator
will drop the voltage of the field coil. It completely decouples the operating
speed from the output voltage.

>I posted a link to a discussion on the subject previously.
>Apparently capacitors are used as a cheap voltage regulator.
>Also, just google and you'll find info.

This is just handwaving. What is actually going on? The capacitor can
be used to shift the phase of a signal, it can be used as part of a resonant
tank. What is the capacitor _doing_ in this magic circuit?

I have googled and I have seen nothing particularly useful, unfortunately.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Feb 19, 1:54*pm, (Scott Dorsey) wrote:
> > wrote:
> >On Feb 18, 11:12=A0am, (Scott Dorsey) wrote:
> >> > wrote:
> >> With a conventional AC generator, the speed of the engine governs the
> >> output frequency. =A0The generator HAS to run at constant speed, usually
> >> 1800 rpm, in order to get 60 Hz out of the generator. =A0Change the engin=
> >e
> >> speed, you change the line frequency.
>
> >No **** sherlock and you also change the voltage.
>
> Possibly for one fraction of a cycle, but as soon as there is any change, the
> field coil voltage will be increased to compensate for it. *The mechanical
> feedback loop that controls the engine speed is very very slow, because it
> is limited by the inertia of the engine an the rotor. *The electrical feedback
> loop that controls the field coil voltage is pretty fast; it is limited
> mostly by the inductance of the field coil.
>
> >> This is why conventional AC generators ALL have a device to regulate the
> >> field coil voltage in order to get constant output voltage. =A0Some of th=
> >ese
> >> devices are better than others.
>
> >That's true and why EA is asking about a cap versus
> >a ture electronic voltage regulator.
>
> And what does he mean by "a cap?" *As I said earlier, you have two choices
> for voltage regulation: a feedback loop controlled by a mechanical buzzer, or
>a feedback loop controlled by a solid state device. * What is this
mysterious
> "capacitor regulation" that he has come up with?

A cap is a given as a capacitor. You regulate voltage, raising it
means you lower its current. Increasing the current means you can run
something faster, like a fan, but you lower the voltage, so you are
regulating it in that sense. But the power is what always remains the
same (assuming reaction in the circuit isn't a factor).