"Scott Dorsey" wrote in message
...
wrote:
I think he's saying he has a cheap generator that uses
a cap for voltage regulation. They apparently do that by using
a cap in conjuction with the power source for excitation.
I'm not sure how that works.
The original AC voltage regulation system, which I think is called a
Tillen
regulator, and dates back to the 19th century, involves a buzzer that
produces a square wave whose duty cycle is inversely proportional to the
output voltage of the generator. This is integrated by a capacitor into
a voltage that is inversely proportional to the output and that drives the
field coil. This is how automotive alternators used to work until the
seventies.
(There is another method used with big generators that involves a DC
motor generator set used to regulate the field coil, but we are talking
small gensets here.)
Anyway, the Tillen regulator is history and as far as I know nobody is
using it today. Instead they use a solid state circuit whose output
voltage is inversely proportional to the AC input voltage. Early on
these used SCRs that acted as switching devices more or less like the
Tillen mechanism, but by the 1970s they were mostly using big bipolar
transistors. This is what I think the original poster is calling an
"AVR" and it's pretty much how regular constant-speed AC generators work
today.
Now.... the interesting thing is that today we have a whole new breed
of generators which are not constant speed. They generate AC, which is
rectified and then used to power an inverter that creates constant
frequency AC. This means the engine throttle can be adjusted to regulate
voltage as well as the field coil... and it means the engine is throttled
way back where it is quiet when there is little load and opened up all
the way when there is more load.
Which is what cars do, right?
In generators, I think they call it automatic idle, in the better units.
There's a lot more stuff inside the box
to go wrong and some of the inverters are kind of crappy (although I am
really amazed at how good a waveform and how little RF noise we get from
the Honda 2000i), so repair and diagnosis is a little trickier.
But if I were buying a baby generator (sub 5KVA) today, I would definitely
go the inverter route. In the 5-20 KVA range it would depend.
There's also the issue of "true sine" vs. std inverter output. True sine is
sig'ly more expensive.
But a better question might be
why would someone living in NYC, who has a critical need
to run CNC eqpt during a major power outage, be concerned
about spending $400 for decent voltage regulation? You think
that would have been in the decision for the generator from
the start.
Personally, if I were running CNC equipment, I'd get out of NYC as fast as
possible and get to a place with better support for manufacturing and
lower
tax rates...
AMEN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hopefullyl they'll let me into VanCouver, BC, Canada.... LOL
fuknBloomberg has no sympathy for people unwilling/unable to spend $1 mil on
a 1 BR apt, whose rent (before he and Guiliani gutted rent control) was
proly $500/mo.
"Buying" apts. is essentially mega "key money", which is illegal.
But when sed key money allows you to "flip" a hot potato to some other
sucker, which generates all kinds of minicipal revenue, then I guess it's
ok.....
Parts of NYC used to be machining meccas, partic. in the small parts
industry (spring-making, lighting, for example), and in knitting. Pre-1990,
parts of Brooklyn, Queens were the knitting capital of the world, I'm told,
with a large machining infrastructure (mom&pop machining, btw) to make the
many *very* intricate parts that would wear in the needle/knitting process.
--
EA
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."