11kw 240vac 60(ish) hz 1 cyl diesel Generator "problem"

[James Lerch]

So, I built this generator a few years ago. The thing is based on
1930's technology, its just plain simple and works (for the most part)

My old BackUPS 1400 finally got to the point I was tired of fixing it,
so I erroneously replaced it with a SmartUPS 1400. Bad Idea, when I
switched over to generator power in preparation for this years
hurricane season the SmartUPS were too smart for their own good and
wouldn't switch back over to "utility" power.

A few years ago when load testing the generator, I noticed that the
stone age rotor power supply, while incredibly simple being built from
only a rectifier, didn't put out very clean power. On my "ToDO" list
was to build a more involved voltage regulator with an integrated
engine management system (mostly because it sounds like a neat
project, not because the system really needs it)

So anyway, I hoped that the noisy voltage output from the generator
was source of the SmartUPS problems. With a little experimenting I
found that 66vdc @ 5amps applied to the rotor winding made fairly nice
looking 250vac sine wave output at 60hz no load. When a load was put
against it, the voltage dropped down to 240vac and I thought for sure
the SmartUPS would be happy (the o-scope showed rather clean
sinusoidal waveforms). Not so much...

OK, SmartUPS must be un-happy with the frequency changing between
power strokes, maybe having problems "syncing up" or something.. But
fixing this is a problem.

#1 The ST generator head rotates at 1800 RPM to produce 60hz power.
#2 The 1 cyl diesel is direct attached to the generator head.
#3 While the diesel has a MASSIVE (24" diameter 2" thick) solid cast
iron flywheel, I can still see the frequency change during each of the
4 cycles of the diesel engine.

Bottom line, for each revolution of the engine I produce two complete
output AC waveforms from the generator. Every other revolution of the
shaft has a power stroke from the single cylinder diesel. So I get
one complete wave form during the power stroke, another during the
exhaust stroke, another during the intake stroke, and another during
the compression stroke. End result, the damn frequency of the
generator is constantly changing (would you call that a "sub harmonic"
or something?)

ANYWAY, the question to you scholarly folks is "What's the most direct
approach to get the SmartUPS back on-line during an extended power
outage"

Towards that end, here's my current thoughts, but I don't really like
any of them.

#1 Replace 1cyl diesel with 4cyl engine (yuk on many levels, but
probably the most "appropriate" solution. BTW, I now know why most
large generators use 4cyl prime movers.....)

#2 Just Don't use the SmartUPS during a power outage (duh). I mean
really, the cable company runs out of battery power in a few hours
anyway, so what could I be running that needs battery back up? But,
where's the fun in this solution

#3 Get a big battery charger and connect it to internal batteries on
SmartUPS, add extra cooling and hope SmartUPS doesn't cook itself
while running on batteries for extended periods. (YUK)

#4 Put "Something" between outlet and SmartUPS when on generator
power. Such as:

A) AC -> DC -> AC converter (wow redundant)
B) Transformer -> 60hz LC tank circuit -> Transformer
C) magic pixie dust.

So any other thoughts?
--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[Rich Grise]

So, I built this generator a few years ago. The thing is based on
1930's technology, its just plain simple and works (for the most part) ....
#4 Put "Something" between outlet and SmartUPS when on generator
power. Such as:

A) AC -> DC -> AC converter (wow redundant)
B) Transformer -> 60hz LC tank circuit -> Transformer
C) magic pixie dust.

So any other thoughts?

D) Ferroresonant tansformer, a la Sola constant-voltage transformer?

Good Luck!
Rich

 

[Gary Tait]

So any other thoughts?

Rewind and gear the generator (more poles) so that the variations aren't so
severe.

Redo the flywheel to provide the counterweight where it really is needed,
instead of the whole cycle.

Une a two or more cylinder engine.

Use an inverter, like the Honda and other generators use.

 

[[email protected]]

So, I built this generator a few years ago. The thing is based on
1930's technology, its just plain simple and works (for the most part)

My old BackUPS 1400 finally got to the point I was tired of fixing it,
so I erroneously replaced it with a SmartUPS 1400. Bad Idea, when I
switched over to generator power in preparation for this years
hurricane season the SmartUPS were too smart for their own good and
wouldn't switch back over to "utility" power.

A few years ago when load testing the generator, I noticed that the
stone age rotor power supply, while incredibly simple being built from
only a rectifier, didn't put out very clean power. On my "ToDO" list
was to build a more involved voltage regulator with an integrated
engine management system (mostly because it sounds like a neat
project, not because the system really needs it)

So anyway, I hoped that the noisy voltage output from the generator
was source of the SmartUPS problems. With a little experimenting I
found that 66vdc @ 5amps applied to the rotor winding made fairly nice
looking 250vac sine wave output at 60hz no load. When a load was put
against it, the voltage dropped down to 240vac and I thought for sure
the SmartUPS would be happy (the o-scope showed rather clean
sinusoidal waveforms). Not so much...

OK, SmartUPS must be un-happy with the frequency changing between
power strokes, maybe having problems "syncing up" or something.. But
fixing this is a problem.

#1 The ST generator head rotates at 1800 RPM to produce 60hz power.
#2 The 1 cyl diesel is direct attached to the generator head.
#3 While the diesel has a MASSIVE (24" diameter 2" thick) solid cast
iron flywheel, I can still see the frequency change during each of the
4 cycles of the diesel engine.

Bottom line, for each revolution of the engine I produce two complete
output AC waveforms from the generator. Every other revolution of the
shaft has a power stroke from the single cylinder diesel. So I get
one complete wave form during the power stroke, another during the
exhaust stroke, another during the intake stroke, and another during
the compression stroke. End result, the damn frequency of the
generator is constantly changing (would you call that a "sub harmonic"
or something?)

ANYWAY, the question to you scholarly folks is "What's the most direct
approach to get the SmartUPS back on-line during an extended power
outage"

Towards that end, here's my current thoughts, but I don't really like
any of them.

#1 Replace 1cyl diesel with 4cyl engine (yuk on many levels, but
probably the most "appropriate" solution. BTW, I now know why most
large generators use 4cyl prime movers.....)

#2 Just Don't use the SmartUPS during a power outage (duh). I mean
really, the cable company runs out of battery power in a few hours
anyway, so what could I be running that needs battery back up? But,
where's the fun in this solution

#3 Get a big battery charger and connect it to internal batteries on
SmartUPS, add extra cooling and hope SmartUPS doesn't cook itself
while running on batteries for extended periods. (YUK)

#4 Put "Something" between outlet and SmartUPS when on generator
power. Such as:

A) AC -> DC -> AC converter (wow redundant)
B) Transformer -> 60hz LC tank circuit -> Transformer
C) magic pixie dust.

So any other thoughts?
--

Someone beat me to it but the first thing that came to mind when
I read your post was a ferroresonant voltage regulator. The only
repairs I've had to make to such units was to replace the capacitor
or capacitors if the regulator has more than one. If you build your
own, I would suggest obtaining high quality caps or to have several
spares on hand. I found a company that manufacturers some
regulators but they only listed a max capacity of 2.5KW. A bit of
searching the surplus market could turn up parts or a whole unit
in your size because a new big one is quite expensive. Besides,
it's more fun to roll your own.

http://www.elect-spec.com/klr_$.htm

[8~{} Uncle Monster

 

[MooseFET]

D) Ferroresonant tansformer, a la Sola constant-voltage transformer?

With a changing frequency, that won't work.

E) Mag-amp
F) MG set with fly wheel

 

[James Lerch]

With a changing frequency, that won't work.

E) Mag-amp

Mag-Amp, as in Magnetic Amplifier? While this is my first exposure to
them (and from my research, they are pretty clever devices!) I don't
see how I'm going to fix the frequency variation with a Mag Amp......
(unless I feed the Mag amp a seperate 60hz control signal..)

F) MG set with fly wheel

Hmm, I didn't think they actually made such a thing Till I googled for
it.

Assuming a 60hz in - 60hz out MG set, will it filter the frequency
domain if its all running on a common shaft (even with external
flywheel?)

I need to work up the courage to put together a voltage divider and
plug my sound card into my wall outlet and digitize the generator
ouput error so I can actually measure how bad it is under a heavy
load... Hmmmmm


--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[James Lerch]

Someone beat me to it but the first thing that came to mind when
I read your post was a ferroresonant voltage regulator. The only
repairs I've had to make to such units was to replace the capacitor
or capacitors if the regulator has more than one. If you build your
own, I would suggest obtaining high quality caps or to have several
spares on hand. I found a company that manufacturers some
regulators but they only listed a max capacity of 2.5KW. A bit of
searching the surplus market could turn up parts or a whole unit
in your size because a new big one is quite expensive. Besides,
it's more fun to roll your own.

http://www.elect-spec.com/klr_$.htm

Yea, rolling my own is definetly something I enjoy

I had this crazy idea for "fixing" the frequency fluctuation.. Build
a voltage regulator that would modulate the Rotor voltage in an
attempt to fudge the zero crossing of the 60hz output. Not sure how
doable it is, but I'm guessing the smartups is measure zero crossing
to zero crossing to figure out frequency. If I can fudge the zero
crossing times I might trick the Smartups to go online

Of course, it might be smarter and easier to fudge JUST the power
going to the SmartUPS instead of fooling around with modulating the
Rotor Voltage on the generator head..

I also found out yesterday that once the diesel warms up a little and
the HVAC system stops running while the Fridge is off, the SmartUPS
will come on-line again (Basicly, only when there is a very small - no
load on the generator, which corresponds to very small frequency
wobble)...

On another Wild Tangent (which would make a good Business Name, but I
digress), I keep ponder how much mass I'd have to move inward on the
Flywheel to keep the Flywheel angular velocity a constant between
power strokes under a 10Kw load.. (Something like a centrifical
govenor, but on steroids and if it ever came apart at speed, would be
something interesting to observe from the safe side of a blast door
window..)

--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[Don Lancaster]

Yea, rolling my own is definetly something I enjoy

I had this crazy idea for "fixing" the frequency fluctuation.. Build
a voltage regulator that would modulate the Rotor voltage in an
attempt to fudge the zero crossing of the 60hz output. Not sure how
doable it is, but I'm guessing the smartups is measure zero crossing
to zero crossing to figure out frequency. If I can fudge the zero
crossing times I might trick the Smartups to go online

Of course, it might be smarter and easier to fudge JUST the power
going to the SmartUPS instead of fooling around with modulating the
Rotor Voltage on the generator head..

I also found out yesterday that once the diesel warms up a little and
the HVAC system stops running while the Fridge is off, the SmartUPS
will come on-line again (Basicly, only when there is a very small - no
load on the generator, which corresponds to very small frequency
wobble)...

On another Wild Tangent (which would make a good Business Name, but I
digress), I keep ponder how much mass I'd have to move inward on the
Flywheel to keep the Flywheel angular velocity a constant between
power strokes under a 10Kw load.. (Something like a centrifical
govenor, but on steroids and if it ever came apart at speed, would be
something interesting to observe from the safe side of a blast door
window..)

And the problem with using a VFD instead is....?

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[[email protected]]

Yea, rolling my own is definetly something I enjoy

I had this crazy idea for "fixing" the frequency fluctuation.. Build
a voltage regulator that would modulate the Rotor voltage in an
attempt to fudge the zero crossing of the 60hz output. Not sure how
doable it is, but I'm guessing the smartups is measure zero crossing
to zero crossing to figure out frequency. If I can fudge the zero
crossing times I might trick the Smartups to go online

Of course, it might be smarter and easier to fudge JUST the power
going to the SmartUPS instead of fooling around with modulating the
Rotor Voltage on the generator head..

I also found out yesterday that once the diesel warms up a little and
the HVAC system stops running while the Fridge is off, the SmartUPS
will come on-line again (Basicly, only when there is a very small - no
load on the generator, which corresponds to very small frequency
wobble)...

On another Wild Tangent (which would make a good Business Name, but I
digress), I keep ponder how much mass I'd have to move inward on the
Flywheel to keep the Flywheel angular velocity a constant between
power strokes under a 10Kw load.. (Something like a centrifical
govenor, but on steroids and if it ever came apart at speed, would be
something interesting to observe from the safe side of a blast door
window..)

--

Something else tickled my brain and floated to the front.
I was talking to a fellow who was having a problem with
damage to his drive system on a rock crusher. The
mechanical shock was breaking gears and couplings
to the electric motor. I suggested a fluid coupling that
was available at the local supply house. It's basically
a self contained torque converter much like the one in
the automatic transmission of an automobile that smooths
out the power pulses from the engine. It may work for
you. These couplings are available in many different
sizes.

http://www.twindisc.com/IndFC.aspx

http://www.rowland2.com/pdfs/fluid.pdf

[8~{} Uncle Monster

 

[MooseFET]

Mag-Amp, as in Magnetic Amplifier? While this is my first exposure to
them (and from my research, they are pretty clever devices!) I don't
see how I'm going to fix the frequency variation with a Mag Amp......
(unless I feed the Mag amp a seperate 60hz control signal..)

You can shift phase with a magnetic amplifier. Varying the phase can
correct for frequency modulations shifts that are smallish.

Hmm, I didn't think they actually made such a thing Till I googled for
it.

Assuming a 60hz in - 60hz out MG set, will it filter the frequency
domain if its all running on a common shaft (even with external
flywheel?)

The flywheel supresses short term variation in frequency. The more
massive it is, the longer "short term" means.

 

[James Lerch]

Something else tickled my brain and floated to the front.
I was talking to a fellow who was having a problem with
damage to his drive system on a rock crusher. The
mechanical shock was breaking gears and couplings
to the electric motor. I suggested a fluid coupling that
was available at the local supply house. It's basically
a self contained torque converter much like the one in
the automatic transmission of an automobile that smooths
out the power pulses from the engine. It may work for
you. These couplings are available in many different
sizes.

http://www.twindisc.com/IndFC.aspx

http://www.rowland2.com/pdfs/fluid.pdf

LOL

THIS is why I love doing off the wall projects like this. I get to
learn about sooo many cool things I didn't know existed

If I was smart and cheap, I could rig an old automotive transmision
torque converter to do the job.. I wonder how the real product deals
with heat disapation? Hmmm..

I like it on many levels!

Thanks
--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[James Lerch]

And the problem with using a VFD instead is....?

Well, it sort of falls into the AC -> DC -> AC category, and I doubt
the SmartUPS would like it's power as an input. For instance, I know
cascading SmartUPS isn't smart, or more to the point, it doens't
work..

So far, the most direct solution is probably a 1hp induction motor
spinning a large flywheel attached to a 2kw gen head. basicly a home
brewed MG set..

Hmmm, this is interesting

http://www.qsl.net/ns8o/Induction_Generator.html

I didn't think that would work.... Only need 700watts or so to feed
battery backups under normal conditions.

Hmmmm.... Could make for interesting experiments.
--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[Mark]

ANYWAY, the question to you scholarly folks is "What's the most direct
approach to get the SmartUPS back on-line during an extended power
outage"

I think your problem is related to the frequency variations.
The SmartUPS tries to phase lock its internal AC to the line before it
switches over from battery to line. Since your frequency is moving,
it can't achieve phase lock.

You may be able to make some changes to the control circuits of the
SmartUPS to make it less critical to the phase offset it wants to see
before it switches over. I have had a hard time finding schematics
for these and with a critical issue like this I'm sure you will need a
schematic to make any progress.

Have fun.
Mark

 

[James Lerch]

I think your problem is related to the frequency variations.
The SmartUPS tries to phase lock its internal AC to the line before it
switches over from battery to line. Since your frequency is moving,
it can't achieve phase lock.

You may be able to make some changes to the control circuits of the
SmartUPS to make it less critical to the phase offset it wants to see
before it switches over. I have had a hard time finding schematics
for these and with a critical issue like this I'm sure you will need a
schematic to make any progress.

OH it's probably worse than that, I probably would need the source
code for the PIC that's actually doing the work.

Although if I could find where the PIC (or electronics) got it's
reference voltage from, seperate that from the mains voltage, then
build a PIC to LIE to the Smartups electronics (or at least a little
fib) I might be able to get it to switch over. The problem would be,
My pic would have to tell convincing lies, and keep the SmartUPS in
phase (or close to it) with the actual power, lest the smartups does
something stupid because I'm lieing to it

I've also recently found out a plain old induction motor can be used
as a generator (if a few 100 uF of capacitance is added across the
line output). Which makes a home brewed MG set kind of
interesting....

OF course, if I wanted a real project, I wonder if I could pull the
Rotor out of an induction motor and replace it with a home built slip
ring based elctromagnetic rotor and build a more proper gen head. That
could be an interesting project (that is if the idea would work...)
--
Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

 

[[email protected]]

LOL

THIS is why I love doing off the wall projects like this. I get to
learn about sooo many cool things I didn't know existed

If I was smart and cheap, I could rig an old automotive transmision
torque converter to do the job.. I wonder how the real product deals
with heat disapation? Hmmm..

I like it on many levels!

Thanks
--

What you want is to keep it as simple as possible.
Thats what me me think of the fluid coupling for
smoothing out the mechanical power pulse problem.
Those fluid couplings don't heat up like the torque
converters in automobiles because they don't have
a lot of slip designed in. Remember an automotive
torque converter sits there churning away when you
have your foot on the brake and the transmission in
drive. If you use an automotive converter, try to find
one with a low stall speed (ie less slip) of the type
used in a small high mpg car. The torque converters
designed for towing and racing have higher stall speeds
(more slip) allowing a higher engine speed before the
converter tightens up. Perhaps one out of a little Honda
or Toyota would work.

[8~{} Uncle Monster

 

[Rich Grise]

On another Wild Tangent (which would make a good Business Name, but I
digress), I keep ponder how much mass I'd have to move inward on the
Flywheel to keep the Flywheel angular velocity a constant between
power strokes under a 10Kw load.. (Something like a centrifical
govenor, but on steroids and if it ever came apart at speed, would be
something interesting to observe from the safe side of a blast door
window..)

Do you mean you'd have some kind of servos on the flywheel itself that
moves the weights like a skater's arms, within a quarter-cycle, to
keep the speed constant?

But seriously, how about adding some weight to the existing flywheel?
You could cast a big lead ring around it... ;-)

I think rotational momentum is kind of like inductance, but I'm sure
I've got my terminology wrong and probably mixed units...

Good Luck!
Rich

 

[MooseFET]

Do you mean you'd have some kind of servos on the flywheel itself that
moves the weights like a skater's arms, within a quarter-cycle, to
keep the speed constant?

But seriously, how about adding some weight to the existing flywheel?
You could cast a big lead ring around it... ;-)

I think rotational momentum is kind of like inductance, but I'm sure
I've got my terminology wrong and probably mixed units...

How about sort of an electrical equivelent:

If a synchonous motor is spinnging a heavy mass, it will naturally
want to keep the frequency constant. If instead of a real synchonous
motor, you used a wound rotor 3 phase motor in its place, you could
drive the rotor field ahead and behind in phase to transfer more
energy in and out of the fly wheel than would naturally happen.

 

[[email protected]]

On Jul 20, 5:00 pm, James Lerch <[email protected]
seeds.rr.com>

I've also recently found out a plain old induction motor can be used
as a generator (if a few 100 uF of capacitance is added across the
line output). Which makes a home brewed MG set kind of
interesting....
-
Take Care,
James Lerchhttp://lerch.no-ip.com/atm(My telescope construction,testing, and coating site)http://lerch.no-ip.com/ChangFa_Gen(My 15KW generator project)

"Anything that can happen, will happen" -Stephen Pollock from:
"Particle Physics for Non-Physicists: A Tour of the Microcosmos"

" Press on: nothing in the world can take the place of perseverance.
Talent will not; nothing is more common than unsuccessful men with talent.
Genius will not; unrewarded genius is almost a proverb.
Education will not; the world is full of educated derelicts.
Persistence and determination alone are omnipotent. "

Another wild tangent idea. How about just connecting an induction
motor ( even better with a flywheel or big pulley on it ) to the
output of the generator.
It should act as additional load when the frequency is increasing and
an induction generator when the frequency is decreasing. Essentially
a way to increase the flywheel on the diesel engine using an
electrical connection instead of a mechanical connection.

Dan

 

[Chris Jones]

So, I built this generator a few years ago. The thing is based on
1930's technology, its just plain simple and works (for the most part)

My old BackUPS 1400 finally got to the point I was tired of fixing it,
so I erroneously replaced it with a SmartUPS 1400. Bad Idea, when I
switched over to generator power in preparation for this years
hurricane season the SmartUPS were too smart for their own good and
wouldn't switch back over to "utility" power.

A few years ago when load testing the generator, I noticed that the
stone age rotor power supply, while incredibly simple being built from
only a rectifier, didn't put out very clean power. On my "ToDO" list
was to build a more involved voltage regulator with an integrated
engine management system (mostly because it sounds like a neat
project, not because the system really needs it)

So anyway, I hoped that the noisy voltage output from the generator
was source of the SmartUPS problems. With a little experimenting I
found that 66vdc @ 5amps applied to the rotor winding made fairly nice
looking 250vac sine wave output at 60hz no load. When a load was put
against it, the voltage dropped down to 240vac and I thought for sure
the SmartUPS would be happy (the o-scope showed rather clean
sinusoidal waveforms). Not so much...

OK, SmartUPS must be un-happy with the frequency changing between
power strokes, maybe having problems "syncing up" or something.. But
fixing this is a problem.

#1 The ST generator head rotates at 1800 RPM to produce 60hz power.
#2 The 1 cyl diesel is direct attached to the generator head.
#3 While the diesel has a MASSIVE (24" diameter 2" thick) solid cast
iron flywheel, I can still see the frequency change during each of the
4 cycles of the diesel engine.

Bottom line, for each revolution of the engine I produce two complete
output AC waveforms from the generator. Every other revolution of the
shaft has a power stroke from the single cylinder diesel. So I get
one complete wave form during the power stroke, another during the
exhaust stroke, another during the intake stroke, and another during
the compression stroke. End result, the damn frequency of the
generator is constantly changing (would you call that a "sub harmonic"
or something?)

ANYWAY, the question to you scholarly folks is "What's the most direct
approach to get the SmartUPS back on-line during an extended power
outage"

Towards that end, here's my current thoughts, but I don't really like
any of them.

#1 Replace 1cyl diesel with 4cyl engine (yuk on many levels, but
probably the most "appropriate" solution. BTW, I now know why most
large generators use 4cyl prime movers.....)

#2 Just Don't use the SmartUPS during a power outage (duh). I mean
really, the cable company runs out of battery power in a few hours
anyway, so what could I be running that needs battery back up? But,
where's the fun in this solution

#3 Get a big battery charger and connect it to internal batteries on
SmartUPS, add extra cooling and hope SmartUPS doesn't cook itself
while running on batteries for extended periods. (YUK)

#4 Put "Something" between outlet and SmartUPS when on generator
power. Such as:

A) AC -> DC -> AC converter (wow redundant)
B) Transformer -> 60hz LC tank circuit -> Transformer
C) magic pixie dust.

So any other thoughts?

Before doing anything, can you figure out by experiment exactly what the UPS
is cranky about? E.g. can you temporarily hook up a motor and variable
speed drive to your generator, disconnect the engine or take out the glow
plug so it will turn over easier and then see:
(a) Even with correct RPMs can you ever make the UPS happy? and
(b) How close doe the RPMs and/or voltage have to be to get it working?

Chris

 

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Another wild tangent idea would be to use a synchronous belt drive
from the motor to the generator and make slightly oval pulleys. So
the pulleys would compensate for the speed shift in the engine and the
generator would run at a constant speed.


I don't think this is a practical solution as it would probably only
work perfectly at one load condition. Still might be good enough for
your purposes.

Dan