Posted by Tim Jackson on June 1, 2009, 12:42 pm
m II wrote:
> Tim Jackson wrote:
>
>> (even a 4-pole machine would be turning at
>> only 750/900rpm).
>
>
> It's my firm belief that a four pole machine would be turning around
> 1800 rpm for a 60hz output.
>
>
> These people share my delusions:
>
> http://www.engineeringtoolbox.com/synchronous-motor-frequency-speed-d_649.html
>
>
> mike
>
Yes, four poles = two magnets. Whatever. The point is still valid.
Practical small alternators do produce much higher frequencies.
When I was a kid there used to be a lot of war-surplus stuff around
rated at 400Hz, from aircraft systems. The technology is similar.
Tim
Posted by Ulysses on May 30, 2009, 10:50 am
> On Fri, 29 May 2009 08:06:06 -0700, in alt.energy.homepower, "Ulysses"
> >Hi guys. I attached the coils and rotor (the entire PMA) from a Honda
> >eu2000 generator to a 4 HP engine--direct drive, just like it originally
was
> Isn't the EU2000 an inverter type generator? I've read that many of those
> generate relatively high voltage internally, using the inverter to convert
> it to the 120v AC power you want. Supposed to be more efficient that way.
> IIRC the manual for my RV's 3400W generator says that it feeds 400 volts
to
> the inverter, so I wouldn't be surprised if you saw an open circuit
voltage
> of 600 or more.
Yes, it's an inverter type and it appears to me that the reason it is so
effective at low speeds is because of the high input voltage--it seems to
take a lot of load to exceed what the alternator is outputting. I just
didn't expect it to be as high as it is. My manual doesn't say anything
about the pricinples of operation. In any case it works just fine if
connected to it's original inverter, just not when I connect it to my
rectifier circuit. Time to get some bigger diodes and a much bigger
capacitor.
Posted by z on May 30, 2009, 11:19 am
>
>> On Fri, 29 May 2009 08:06:06 -0700, in alt.energy.homepower,
>>
>> >Hi guys. I attached the coils and rotor (the entire PMA) from a
>> >Honda eu2000 generator to a 4 HP engine--direct drive, just like it
>> >originally
> was
>>
>> Isn't the EU2000 an inverter type generator? I've read that many of
>> those generate relatively high voltage internally, using the inverter
>> to convert it to the 120v AC power you want. Supposed to be more
>> efficient that way. IIRC the manual for my RV's 3400W generator says
>> that it feeds 400 volts
> to
>> the inverter, so I wouldn't be surprised if you saw an open circuit
> voltage
>> of 600 or more.
>>
>
> Yes, it's an inverter type and it appears to me that the reason it is
> so effective at low speeds is because of the high input voltage--it
> seems to take a lot of load to exceed what the alternator is
> outputting. I just didn't expect it to be as high as it is. My
> manual doesn't say anything about the pricinples of operation. In any
> case it works just fine if connected to it's original inverter, just
> not when I connect it to my rectifier circuit. Time to get some
> bigger diodes and a much bigger capacitor.
Heya Ullyses
I had a look through the repair manual but didn't find anything talking
about raw voltages of the generator or specs that looked like they'd
help. It just says 'replace' a lot when talking about the inverter etc
:)
Here is a diagram of the eu2000 generator which shows the various
electrical components and how they all get along:
http://www.homebrewhydro.com/eu2000/eu2000_diagram.jpg
hope that helps & good luck
-zachary
>
Posted by Ulysses on May 31, 2009, 11:06 am
> >
> >> On Fri, 29 May 2009 08:06:06 -0700, in alt.energy.homepower,
> >>
> >> >Hi guys. I attached the coils and rotor (the entire PMA) from a
> >> >Honda eu2000 generator to a 4 HP engine--direct drive, just like it
> >> >originally
> > was
> >>
> >> Isn't the EU2000 an inverter type generator? I've read that many of
> >> those generate relatively high voltage internally, using the inverter
> >> to convert it to the 120v AC power you want. Supposed to be more
> >> efficient that way. IIRC the manual for my RV's 3400W generator says
> >> that it feeds 400 volts
> > to
> >> the inverter, so I wouldn't be surprised if you saw an open circuit
> > voltage
> >> of 600 or more.
> >>
> >
> > Yes, it's an inverter type and it appears to me that the reason it is
> > so effective at low speeds is because of the high input voltage--it
> > seems to take a lot of load to exceed what the alternator is
> > outputting. I just didn't expect it to be as high as it is. My
> > manual doesn't say anything about the pricinples of operation. In any
> > case it works just fine if connected to it's original inverter, just
> > not when I connect it to my rectifier circuit. Time to get some
> > bigger diodes and a much bigger capacitor.
> Heya Ullyses
> I had a look through the repair manual but didn't find anything talking
> about raw voltages of the generator or specs that looked like they'd
> help. It just says 'replace' a lot when talking about the inverter etc
> :)
> Here is a diagram of the eu2000 generator which shows the various
> electrical components and how they all get along:
> http://www.homebrewhydro.com/eu2000/eu2000_diagram.jpg
> hope that helps & good luck
> -zachary
> >
Exciter circuit? Oh jeeze z you are giving my poor tired brain too much to
think about. ;-)
If I remember correctly there are 18 coils that are for the 3-phase
alternator output PLUS three more coils that I assumed were for the DC
output. The description in the manual makes it sound like those three coils
are to power the brains of the eu2000. Why do you need an exciter for a
PMA?
Posted by Winston on May 30, 2009, 11:48 am
Ulysses wrote:
(...)
> Yes, it's an inverter type and it appears to me that the reason it is so
> effective at low speeds is because of the high input voltage--it seems to
> take a lot of load to exceed what the alternator is outputting. I just
> didn't expect it to be as high as it is. My manual doesn't say anything
> about the pricinples of operation. In any case it works just fine if
> connected to it's original inverter, just not when I connect it to my
> rectifier circuit. Time to get some bigger diodes and a much bigger
> capacitor.
What do you want to do with the alternator?
I got the sense that you would like it to produce say 120 V.D.C.
for powering lights and small universal motors. Is that the goal?
From Zach's scan, it's clear you need to take control of the
exciter winding using a separate regulator. Use a voltage
divider after your rectifier as a signal to the regulator.
As Tim Jackson implies, please use capacitors that have a voltage
rating in excess of the highest voltage you expect to encounter.
You will have a ~3.5:1 impedance mismatch between the output
of your alternator and your load, so please don't expect full
power output.
--Winston
--
We now return you to the economic collapse, already in progress.
>
>> (even a 4-pole machine would be turning at
>> only 750/900rpm).
>
>
> It's my firm belief that a four pole machine would be turning around
> 1800 rpm for a 60hz output.
>
>
> These people share my delusions:
>
> http://www.engineeringtoolbox.com/synchronous-motor-frequency-speed-d_649.html
>
>
> mike
>