I hooked up an o-scope to my Honda EU2000 generator and discovered
something interesting about the waveform. Initially the waveform
looked like a regular 60 HZ sine wave. When I changed the range to
10V/CM I saw that the 60 HZ waveform is actually a 10 volt peak to
peak 20 KHZ waveform varying at 60 HZ.
I guess this is a result of how the unit forms its output.
I decided to hook up the scope when I couldn't get a stable frequency
reading with a Fluke 87.
What do you mean by not stable? Less than 1 hz would be no big deal, in my
Are you testing with a load? If not put something like 50% on it and try
again. Set the hertz with 50% load and then check it.
By not stable, I mean it was jumping between 60 HZ and several KHZ.
Sometimes the fluke locked in on the 60 HZ and sometimes it tried to
read the 20 KHZ.
Adding a 500 watt load didn't change either the Fluke's behavior or
the scope presentation.
Has anyone else out there hooked up a scope to an EU2000?
This is pretty interesting.
Is it actually more efficient to generate DC and then use an inverter to
turn that into AC? I'm having a hard time believing this to be the case.
Why do they do this? Most generators I've seen just spin at 1800RPM or
so and derive AC directly using a true alternator.
Some new Honda & Yamaha generators actually produce high-frequency
(several hundred Hz) and 3-phase AC output and convert it to something
like 200VDC first, then they use an inverter to produce the 120VAC,
60Hz sinewave output.
If the 200VDC is not well filtered, then you could see ripples (or
sawtooth like waveform) at several thousand Hz riding on top of the
They are more expensive (over $1000 for 3000 watt generator), but they
can power computers, TV & other solid-state electronic loads far
better than some cheap generators whose output waveform looks like a
teenager's spiky hairdo (which will cause overheating of solid state
devices & damage TV's, computers, etc.).
If someone wants to power TV, computer & other electronic appliances
with engine generator, always verify that the output waveform is a
regulated & clean sinewave (i.e., computer-grade sinewave). Noisy
generator outputs can still power lights, refrigerators & heaters (in
other words, motors & resistor loads are OK), but one should never
power electronic loads (i.e., TV, computer, etc.)
What???Are you joking???The waveform coming from any inverter is not
sinusoidial, but square AND is destructible for most appliances, except
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"Tzortzakakis Dimitrios" wrote in
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You need to study modern inverter technology some more before you post
anything else. We test many inverter based generators and many produce
nearly perfect (less than 5% thd) sinusoidal waveforms. Cheaper inverters
do not. The square wave will not hurt electronic loads. Square wave output
can be troublesome for inductive loads, particularly motors.
Charles Perry P.E.
I too am impressed with the waveform produced by some of the newer
generators. I scoped the output of one model from Honda, and Yamaha, both
loaded, and unloaded. A fellow had asked me to determine if he could safely
run a computer from them. After looking at the waveform of both, I explained
to him that it was in some ways more suitable than that supplied where the
computers were currently located.
Is anyone aware of this type of inverter technology available as a stand
alone unit without a generator?
Zor> This is pretty interesting.
So the engine speed can be varied according to load to reduce fuel
consumption and noise as well as having a better frequency stability as the
frequency is set by the inverter.
A true alternator generator's frequency is a direct function of rotor speed
and the rotor must turn at 3600 or 1800 RPM regardless of load. A generator
running at 3600RPM is pretty load.
True, 3600 and 1800 RPM are possible speeds, but not the only ones. I
worked for several years with a 600 RPM diesel-gen set. And of course,
water turbine systems often run at slower speeds. Even many modern EMD
diesel-gen sets only run 900 RPM. The slower speed diesels last 'forever'.
Hello, all. We have two Honda EU2000I generator-inverters that were
purchased two years ago for field use. They are lightweight, very quiet
and have proven very reliable (as is typical of Honda products). My
question is does anyone know what is the frequency-determining element in
the inverter section? Crystal? R-C time constant? I am curious how the
Honda engineers designed the inverter to provide a nominal 60 Hz output
over a wide operating temperature range. It can get quite warm inside the
generator enclosure. Thanks for your time and comment. Sincerely,
John Wood (Code 5550) e-mail: firstname.lastname@example.org
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337
A similar Honda generator EB3000i that we looked at a couple of years
ago had used AC to DC converter to change high frequency (and
3-phase)raw AC output of the generator. The high voltage DC (around
200 to 400VDC, I think) was fed into an electronic module (inverter
module) which was filled with epoxy for protection against moisture &
vibration (also prevents reverse-engineering), so we could not really
see what circuit was used to get the precise 120VAC, 60Hz sinewave
inverter output. But that type of circuit is typically powered by a
small microcontroller with sinewave generating pulse-width-modulated
converter (all sinewave UPS and inverters use similar design circuit
nowadays). I thought it was a very good way to produce clean sinewave
at stable voltage & frequency. I don't know if the EU2000I (I am
guessing that their suffix I stands for Inverter - does anyone know
for sure?) uses the same kind of AC to DC & DC back to AC topology.
If Honda engineers can get reply, it would be super.
That souns like you are about to worship inverters, like has happened with
DVDs.'Before I post anything else'? I studied that technology when I did my
graduation study, it was about generation-transmission-distribution.The
wind-generators can't produce ALL the electricity in a system, because they
produce too much harmonics (not even more than 10%).
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