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#71
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Genset voltage reg: capacitor vs. AVR
On Feb 21, 11:50*am, " >
wrote: > On Feb 21, 11:35*am, Transition Zone > wrote: > > > > > > > > > > > On Feb 20, 7:58*am, " > > > wrote: > > > > On Feb 19, 4:56*pm, Transition Zone > wrote: > > > > > 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).- Hide quoted text - > > > > Sigh..... > > > Oh, and with a split-phased capacitor, part of one phase can be used > > to help start a motor before its brought back to normal running the > > motor.- Hide quoted text - > > > - Show quoted text - > > Sigh... None of which has any relevance to how a cap is used > to regulate voltage in a cheap generator. Why expect to regulate voltage if its that cheap? |
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#72
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Genset voltage reg: capacitor vs. AVR
On Feb 21, 11:57*am, Transition Zone > wrote:
> On Feb 21, 11:50*am, " > > wrote: > > > > > On Feb 21, 11:35*am, Transition Zone > wrote: > > > > On Feb 20, 7:58*am, " > > > > wrote: > > > > > On Feb 19, 4:56*pm, Transition Zone > wrote: > > > > > > 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).- Hide quoted text - > > > > > Sigh..... > > > > Oh, and with a split-phased capacitor, part of one phase can be used > > > to help start a motor before its brought back to normal running the > > > motor.- Hide quoted text - > > > > - Show quoted text - > > * > *Sigh... None of which has any relevance to how a cap is used > > > *to regulate voltage in a cheap generator. > > Why expect to regulate voltage if its that cheap?- Hide quoted text - > > - Show quoted text - Another diversion into lala land. They apparently do it because: A - If you're not going to use an electonic voltage regulator which costs a bit more, then having SOME voltage regulation on a generator is better than none. B - Customers want and expect some kind of voltage regulation and the generator would probably be useless for most applications without it. C - A cap is cheap |
#73
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Genset voltage reg: capacitor vs. AVR
On Mon, 18 Feb 2013 11:18:45 -0500, Scott Dorsey wrote:
> Tim Wescott > wrote: >> >>Do you have a link to a site that sells the AVR ditty? If it's >>regulating the field current of the generator in response to the >>generator voltage, and if all the genset does is rely on the motor's >>governor for speed regulation, then it should give better regulation. > > As far as I know, every non-inverter generator works this way. How else > would you get a stable output voltage with varying loads? It's not like > field coil regulation is terribly expensive; it's not a whole lot of > current in there. With field coil regulation you should be able to keep the genset voltage dead nuts on target, with deviations only when the load changes suddenly. One wonders in what decade the technology stalled if they're allowing the crappy regulation that EA quotes. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com |
#74
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Genset voltage reg: capacitor vs. AVR
On Feb 21, 12:33*pm, Tim Wescott > wrote:
> On Mon, 18 Feb 2013 11:18:45 -0500, Scott Dorsey wrote: > > Tim Wescott > wrote: > > >>Do you have a link to a site that sells the AVR ditty? *If it's > >>regulating the field current of the generator in response to the > >>generator voltage, and if all the genset does is rely on the motor's > >>governor for speed regulation, then it should give better regulation. > > > As far as I know, every non-inverter generator works this way. *How else > > would you get a stable output voltage with varying loads? *It's not like > > field coil regulation is terribly expensive; it's not a whole lot of > > current in there. > > With field coil regulation you should be able to keep the genset voltage > dead nuts on target, with deviations only when the load changes suddenly. > > One wonders in what decade the technology stalled if they're allowing the > crappy regulation that EA quotes. > > -- > Tim Wescott > Control system and signal processing consultingwww.wescottdesign.com I don't know, but the generator head is made by Meccalte, an Italian manufacturer of real electric gear. You would think on a generator that costs $2800 you'd get electronic voltage regulation. But they apparently use a cap. |
#75
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Genset voltage reg: capacitor vs. AVR
Jim Wilkins > wrote:
>"Scott Dorsey" > wrote in message >> > wrote: >> >> Looking at how this works, it's not a conventional brush-type >> alternator at >> all, but an induction device almost like an induction motor in >> reverse. The >> patent shows a single pole rotor with a diode across the winding, so >> the >> rotor acts as a magnetic short in one direction and a magnetic open >> in the >> other. This diode is really the key to the trick. >> > >http://en.wikipedia.org/wiki/Magnetic_amplifier >"A relatively small DC current on the control winding is able to >control or switch large AC currents on the AC windings. This results >in current amplification." No, read the patent! It's not related to magnetic amplifiers at all; nothing is operating in saturation. It is a very cool trick! --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#76
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Genset voltage reg: capacitor vs. AVR
replying to Pete S, anonymous wrote:
sumec fireman....the smallest -- for full context, visit https://www.homeownershub.com/mainte...vr-736855-.htm |
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