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Generators & Electric Motors General Discussion

Adding AVR to Capacitor Alternator?


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  #11  
Old 10-21-2018, 05:27:08 PM
Newoldstock Newoldstock is offline
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Default Re: Adding AVR to capacitor alternator?

Quote:
Originally Posted by Jim McIntyre View Post
Huh.

I'm sort of familiar with the 'capacitor-regulated' generator the OP describes (more here: http://www.freepatentsonline.com/4786853.pdf and here: https://patentimages.storage.googlea.../US4296368.pdf)

And I'm sort of familiar with some of the Chinese generators that have a 'harmonic winding', but they have brushes.

So, can you provide any link to a reference that says more about 'harmonic excitement' in a brushless generator?
The rotor is picking up all kinds of magnetic flux and rectifying it.
The caps have no issues with the harmonics and let the flow ( scope an small gen like this and you can even see the slots in stator reflected in the weave forms you can see a lot of whats going on ).

AS the load in creases there is armature reaction and all kinds of stray flux leakage.
Some of this including harmonics are rectified to increase the field strength.

The danger and downfall is there is no real regulation its just rectified noise and this is fine as long as you are not using switching power supplies or inductive/capacities loads.
Then your voltage regulation goes to hell.
It does not compensate for this.

Some other manufactures have also done things this crudely.
Leroy Somers was famous for just running a loop through rectified and into a series coil to add flux as Stator current rose.
Yup it worked as long as power factor was good.

Cheap and simple and good enough for most people.
This was before sensitive electronics mind you.

Quote:
Originally Posted by armandh View Post
there are brush-less systems traditionally regulated.
these have a primary alternator with a stationary field, and rotating rectification of the field current for the main alternator.

this is very much different than the cap regulation.
This is called a Pilot and main exciter.

Quote:
Originally Posted by Jim McIntyre View Post
Huh.

I'm sort of familiar with the 'capacitor-regulated' generator the OP describes (more here: http://www.freepatentsonline.com/4786853.pdf and here: https://patentimages.storage.googlea.../US4296368.pdf)

And I'm sort of familiar with some of the Chinese generators that have a 'harmonic winding', but they have brushes.

So, can you provide any link to a reference that says more about 'harmonic excitement' in a brushless generator?
ST heads.
Mostly the same thing but the coils that pick up the action of rising and falling stator current plus the constant excitation are separate and feed a bridge then on to the slip rings.
The Brushless ST heads work the same way as the before mentioned system with diodes, caps and stabistors on the rotor.

I wont pretend to have all the answers, but I have included a link to show some of the reactions happening inside any electrical machine that rotates.
The vector diagrams are the best to look at and simply consider....

Basically if you have a machine with no regulator and can tap some of these things with passive parts like simply a cap and a diode you can increase and decrease your field excitation as load increases.

It has no feedback but it does work and it works.
Consider for a moment how an over compound DC generator increases flux to compensate for IR losses as the armature current increases.
These systems that tap the harmonics and changes in core flux of a cheapo bruhsless machine are kind of doing the same thing.

http://machineryequipmentonline.com/...s-notes-part2/
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  #12  
Old 10-21-2018, 11:30:49 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Adding AVR to capacitor alternator?

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Originally Posted by Newoldstock View Post
...but I have included a link to show some of the reactions happening inside any electrical machine that rotates...
Yeah, but like my electric machine texts, no mention of harmonic current whatsoever in that link that I could find...
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  #13  
Old 10-25-2018, 06:04:59 AM
armandh armandh is offline
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Default Re: Adding AVR to Capacitor Alternator?

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Originally Posted by Jim McIntyre View Post
^ Yes, well aware of that.

I'm curious about thaumatuge's brushless, harmonic-excited machine...
like lipstick on a pig
cap regulated is the essence of cheap

mostly if the speed is right and the cap/diodes good the voltage will be right
but the speed has to be right and steady first.
working to get the engine to develop enough HP to keep the speed steady
will likely yield better results than trying to fit an incompatible regulator
[IMHO YMMV]
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Old 10-25-2018, 07:54:36 AM
cjjmw cjjmw is offline
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Default Re: Adding AVR to Capacitor Alternator?

So,

Regarding lipstick on a pig.....

We also have two Kohler 20RES generators laying here, 1000CC each. Might be RESA, I can't remember.

These look like they use the control board to control the exciter via brushes and also control the throttle electronically.

Are these any good, or junk also? They seem much more complicated than the capacitor unit.
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Old 10-26-2018, 06:52:34 AM
armandh armandh is offline
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Default Re: Adding AVR to Capacitor Alternator?

all depends on whats broke, parts cost, availability, etc
and lots of knowledge to determine what is worth the time and effort.

the first concern is two broken ones

I have no professional HVAC experience but...
I avoided an expensive do-everything board replacement
adding in a generic white-rodgers ignition control module
Safe but not OEM and it passed inspection for operation at time of sale
[parts needed, fully disclosed to new owner]

no telling what a handy person could do with the generators

in another hobby
I am putting a working collection of Seeburg parts into a case built by my daughter's SO.
the parts span a 20 year range of different models including tube and transistor sections.
[but not any computer controlled devices]
it would leave any knowledgeable Seeburg techs scratching their heads.

this last sort of stuff is not commercial, just for fun.
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Last edited by armandh; 10-26-2018 at 07:16:19 AM.
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Old 10-26-2018, 08:33:41 AM
cjjmw cjjmw is offline
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Default Re: Adding AVR to Capacitor Alternator?

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Originally Posted by armandh View Post
all depends on whats broke, parts cost, availability, etc
and lots of knowledge to determine what is worth the time and effort.

the first concern is two broken ones

I have no professional HVAC experience but...
I avoided an expensive do-everything board replacement
adding in a generic white-rodgers ignition control module
Safe but not OEM and it passed inspection for operation at time of sale
[parts needed, fully disclosed to new owner]

no telling what a handy person could do with the generators

in another hobby
I am putting a working collection of Seeburg parts into a case built by my daughter's SO.
the parts span a 20 year range of different models including tube and transistor sections.
[but not any computer controlled devices]
it would leave any knowledgeable Seeburg techs scratching their heads.

this last sort of stuff is not commercial, just for fun.
Oh, I know why they're here.
I just meant when they are working, are they considered decent units (like Onan) or junk?
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  #17  
Old 10-26-2018, 08:49:38 AM
Thaumaturge Thaumaturge is online now
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Default Re: Adding AVR to capacitor alternator?

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Originally Posted by Jim McIntyre View Post
Yeah, but like my electric machine texts, no mention of harmonic current whatsoever in that link that I could find...
Don't much feel like arguing this into the ground, but this link explains my use of term "harmonic excitation". Read carefully where it states second wave at twice frequency (or second harmonic) travels reverse direction around rotor. http://machineryequipmentonline.com/...ss-excitation/

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  #18  
Old 10-26-2018, 09:28:14 PM
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Default Re: Adding AVR to Capacitor Alternator?

^Thanks! That looks like the same scheme in the patents I linked to, neither of which mentioned the 2nd harmonic current, at least that I saw...

It looks like this is the original source of this description:
https://books.google.com/books?id=M5...tor%22&f=false
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Old 10-27-2018, 09:23:37 AM
Wayne 440 Wayne 440 is offline
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Default Re: Adding AVR to Capacitor Alternator?

I'm not entirely convinced. But the effort required to prove or disprove the statement would be lots of work for little practical gain.
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Old 10-28-2018, 07:22:06 PM
Newoldstock Newoldstock is offline
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Default Re: Adding AVR to Capacitor Alternator?

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Originally Posted by Wayne 440 View Post
I'm not entirely convinced. But the effort required to prove or disprove the statement would be lots of work for little practical gain.
Most of the time the cheap generators are running with the pole shoes near saturation.
They pick up a little extra excitation from the harmonics generated inside the machine.

From a design perspective you can no avoid this noise and it gets worse as you load.
These are odd and even harmonics all kinds of crap....
This stuff blows throw a cap like fart in the wind.
How much extra does it provide? not very much but its better than nothing.
In the end you have machines designed to run just below the knee of the saturation curve and any extra flux they generate only helps a little.

Where do you find detailed technical information on this kind of thing.
I wish I knew.
I only know what I was told.

Quote:
Originally Posted by Jim McIntyre View Post
^Thanks! That looks like the same scheme in the patents I linked to, neither of which mentioned the 2nd harmonic current, at least that I saw...

It looks like this is the original source of this description:
https://books.google.com/books?id=M5...tor%22&f=false
This description is EXACTLY how the generators I mentioned used in the carrier refer units with no slip rings are wound.
They work....
Those little generators are rated around 2 kVA two pole and if you find one they are very very tough and reliable.
They just don't make very well regulated power.
They always work unless they have a mechanical problem, burnt winding or bad caps.
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