A tale of 2 generators
Lon VanOstran
5K (lp, 4 years old) generator. (actually rated at 120v and 40 amps
which computes to 4800 watts)
Problem: 3 HP air compressor which works fine in lower MI with Edison
type electricity. Cold, it works *once* to pump up, but when preasure
drops and motor tries to start it lugs, motor becomes very hot, and
breaker then pops at cabin breaker panel.
Cabin is wired to code, complete with 12-2 w/ground wiring. Garage 150'
from cabin with it's own 60 amp breaker box. 6-Gauge underground cable
to garage.
I went to our campsite 300 yards from cabin and retrieved Good Governor.
121v 61hz in cabin. 124v +62hz in garage. We shut off every other draw
on the generator and tried again. The Good Governor showed a voltage
drop to about 56 when the motor tried to start until the breaker popped
again.
We hauled the compressor to my motorhome where I have an Onan Marquis
(gas, new) 5k generator. (again, 120v and 40 amp which translates to
4800 w)
Energy management system gave us lots more info than we could get at the
cabin. Upon firing up the generator, I see a load of 5 amps (fridge and
converter) which I left alone and plugged in the compressor. Load jumped
to 43 amps for about 1 second or less and then dropped to 24 amps and
stayed. We cycled the compressor several times with the same exact
results. Perfect performance to my way of thinking.
Clearly my brother's generator is suffering from a lack of available
amps since the volts are there.
Questions:
1.Does anyone have suggestions regarding the poor performance of
brother's generator?
2.Probably not since the volts are there, but: Could this be caused by
running his exhaust underground via 2" pipe and bringing it up about 25
feet from the cabin in the back yard? (tractor type flap on the end of
pipe to prevent water infiltration)
3. Is lp generator less effective than gas?
Lon, who is baffled.
DsrtTravlr
wrote:
<A story of brotherly love snipped>
>Lon, who is baffled.
Everything was working fine when I was up there with your brother. He did do
some alterations to the generator and electrical system when we got there, and
before we left, too.
He said he does this every time he leaves so company won't stay as long.
Steve
Illigitimi non carborundum.
Ben Hogland
in the manual. Also, there is an adjustment for altitude as well. I had the
same problem on an older Onan 3.0 KW, fixed it with the carb adjustment.
Ben
"Lon VanOstran" <RV...@voyager.net> wrote in message
news:3915c7e4$1$95106$2c3e...@news.voyager.net...
Jesse
Gas generators which are converted to run on LP lose amps. For
instance, I have an Onan Emerald 4000. It puts out 33 amps on
gas, but when converted to LP it puts out 29 amps. You may be
reading the 'gas' gen specs. If this is not the case, there is
something robbing the gen of power. Check that all the filters
are good. Give it an oil change. I have never personally used
an LP gen, but you will want to check with Onan to see what kind
of service should be done. It may be due for some kind of tune-
up.
Good luck!
-Jesse
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
The fastest and easiest way to search and participate in Usenet - Free!
W F Sill
>Questions:
Notice I duck the ones I can't answer!
>2.Probably not since the volts are there, but: Could this be caused by
>running his exhaust underground via 2" pipe and bringing it up about 25
>feet from the cabin in the back yard? (tractor type flap on the end of
>pipe to prevent water infiltration)
A long run of exhaust will unfavorably impact performance, because it
takes power to push exhaust through a long pipe. I can't say that's
the cause of the reported problem, however, and I doubt it is.
>3. Is lp generator less effective than gas?
Yes, though rated power should be stated in tems of the fuel used. It
was not clear where you measured the 56v drop -- if that was many
yards away from the genset it raises the question of a hidden high
resistance in the feed.
Sorry I can't identify the true problem.
Will KD3XR ---- the Curmudgeon of Sill Hill
In order to become the master, the politician
poses as the servant. Charles de Gaulle
Pete Dumbleton
group), but isn't the voltage basically determined by how the generator or
alternator is wound? And the amperage is a function of how much
mechanical power can be input? (Presuming nothing burns or breaks) Seems
like lack of power (amps) equals weak motor for some reason, such as
tune-up, loss of compression, exhaust blockage, etc., or some combination
of minor problems.
> > 2.Probably not since the volts are there, but: Could this be caused by
> > running his exhaust underground via 2" pipe and bringing it up about 25
> > feet from the cabin in the back yard? (tractor type flap on the end of
> > pipe to prevent water infiltration)
> > 3. Is lp generator less effective than gas?
> >
> > Lon, who is baffled.
>
>
>
>
Lon VanOstran
W F Sill wrote:
>
> Not long ago, Lon VanOstran <RV...@voyager.net> wrote:
>
> >Questions:
>
>snip<
>
> >3. Is lp generator less effective than gas?
>
> Yes, though rated power should be stated in tems of the fuel used. It
> was not clear where you measured the 56v drop -- if that was many
> yards away from the genset it raises the question of a hidden high
> resistance in the feed.
>
> Will KD3XR
Measured at outlet of use, both, in garage 3' from box, and front porch
of cabin 28' from cabin box and generator. No change! The 6 gauge cable
to the garage *seems* more efficient than the 12-2 inside the cabin, in
spite of the fact that the garage is 150' away.
Lon, who thinks maybe a qualified service tech should check out the
problem.
AI Nut
extension cord) was too small for that distance and was robbing power
due to line loss. Try changing to 10/3 wire and see if it works.
HTH,
AI Nut
Lon VanOstran wrote:
>
> Scene: Brother's cabin in the north woods. No electricity. Onan Emerald
> 5K (lp, 4 years old) generator. (actually rated at 120v and 40 amps
> which computes to 4800 watts)
>
> Problem: 3 HP air compressor which works fine in lower MI with Edison
> type electricity. Cold, it works *once* to pump up, but when preasure
> drops and motor tries to start it lugs, motor becomes very hot, and
> breaker then pops at cabin breaker panel.
><<<snip>>>
Alan Robinson
Lon VanOstran wrote in message
<3915c7e4$1$95106$2c3e...@news.voyager.net>...
>Scene: Brother's cabin in the north woods. No electricity. Onan Emerald
>5K (lp, 4 years old) generator. (actually rated at 120v and 40 amps
>which computes to 4800 watts)
>
>Problem: 3 HP air compressor which works fine in lower MI with Edison
>type electricity. Cold, it works *once* to pump up, but when preasure
>drops and motor tries to start it lugs, motor becomes very hot, and
>breaker then pops at cabin breaker panel.
>
>
>
Lon, while I am not really sure from your post (1) that the generator is
located at the cabin, and (2) that the 56 volts was measured at the
garage/compressor, if so, its possible you have excessive voltage drop due
to a poor connection somewhere in the feed to the garage. Try hooking the
compressor up *at the cabin* and see what happens.
Second possibility would be a generator problem i.e. carburetor main jet
needs adjustment to allow the engine to develop full power and/or respond
well to sudden load changes.
Third possibility - (I'm not as familiar with the 5kw emerald as I would
like, so guessing here) - does your brother's Emerald have 2 circuit
breakers, or just one? If it has two, are the outputs of these tied
together? If not, you may be trying to draw a 43a surge from a winding rated
for 20a.
Hope some of this helped,
Alan
Lon VanOstran
Alan Robinson wrote:
> Third possibility - (I'm not as familiar with the 5kw emerald as I would
> like, so guessing here) - does your brother's Emerald have 2 circuit
> breakers, or just one? If it has two, are the outputs of these tied
> together? If not, you may be trying to draw a 43a surge from a winding rated
> for 20a.
>
> Hope some of this helped,
>
> Alan
Are you saying that my MH, having 30 amp service has both circuits
feeding one line thus providing the extra oomph to do the job?
(brother's generator is hard wired into the cabin/house feeding a normal
breaker pannel) Maybe the compressor has developed a problem which my
generator was able to overcome. Hmmmmmmmmmm. Another line of thought to
pursue.
Lon, who is still baffled.
Lon VanOstran
to find temps over 100 degrees. We hate air conditioning and don't use
it. I found when we first built this house and included central air that
suddenly we both started really suffering when we left the house. I
couldn't stand the heat outside during the summer and began to really
dislike summer. That was the end of using air for us. Now that we allow
ourselves to become acclimated to the heat, we love summer again. NO
MORE AIR.
Lon, who can do his 3 mile walk in 37 minutes even when it is 98 degrees
with 100% humidity outside.
Stan Birch wrote:
>
> Lon,
>
> Your generator has two separate circuits: A 30 A circuit for the coach
> and front A/C; and a separate 20 A circuit which is dedicated
> exclusively to the rear A/C.
>
> Ever noticed that when you turn on your rear A/C on, that your Power
> Management System shows no increase in current-draw? That's because
> when you are using your generator, the rear A/C completely bypasses
> the Power Management System, and uses a separate circuit which is
> dedicated exclusively to the rear A/C; and doesn't pass directly
> through the Power Management System.
>
Alan Robinson
Lon VanOstran wrote in message <39169521$0$39...@news.voyager.net>...
Lon, sorry for the confusion...was kinda late when I wrote the above, and on
review today, I find that I wasn't very clear in what I was trying to
say......my bad.
Ok, short lesson. Both your brother's Emerald, and your Marquis,
actually have 2 120v windings in them....one end of each winding brought to
the neutral buss in the control box, and the other end of each winding going
to a circuit breaker. Each winding, by itself, is capable of providing half
the output of the genset. Depending on the particular variation of the
Emerald or Marquis, both windings may be tied together and fed thru one
circuit breaker, or they may be fed to two separate circuit breakers. Most
Emeralds - until the most recent specs - did not tie the windings together
in parallel if there were two circuit breakers. This means that anything
connected to either circuit breaker is only being fed by half the capacity
of the genset, which limits the surge capacity available. On the other hand,
the Marquis, IIRC, has the windings jumpered in parallel at the input of the
circuit breakers. This means that, although continuous output on that
circuit is limited by the circuit breaker rating, the entire genset capacity
is available for short-duration surge loads (such as starting a 3hp [?] air
compressor). Check to see if there is a jumper from the input side of one
circuit breaker to the input side of the other circuit breaker in the
control box of your brother's Emerald. If not (and assuming your brother's
Emerald is connected for 120v only and not 120/240v), connecting a jumper
here will parallel the two windings, and double the surge load capacity
available to either circuit. Hope this was *a little* clearer.
Alan
Bobfuses
>>type electricity. Cold, it works *once* to pump up, but when preasure
>>drops and motor tries to start it lugs, motor becomes very hot, and
>>breaker then pops at cabin breaker panel.
The problem may be with the compressor. My four horsepower compressor has a
valve that opens when the compressor stops (making a noticable air venting
sound) and only closes after the compressor is started and up to speed. This
feature permits the compressor to start without a heavy load.
If this valve is stuck in the closed position it is highly likely that the
compressor will not be able to start and run in normal operation after the
initial charge. I would expect the circuit braker on the compressor motor to
pop but perhaps you do not have one.
In cold weather my compressor lugs down at first due to the oil that I use in
the compressor. After a few cycles the oil warms and all is well.
Bob in 92026
Neon John
Lon VanOstran wrote:
>
> Scene: Brother's cabin in the north woods. No electricity. Onan Emerald
> 5K (lp, 4 years old) generator. (actually rated at 120v and 40 amps
> which computes to 4800 watts)
>
> Problem: 3 HP air compressor which works fine in lower MI with Edison
> type electricity. Cold, it works *once* to pump up, but when preasure
> drops and motor tries to start it lugs, motor becomes very hot, and
> breaker then pops at cabin breaker panel.
This makes me think the air compressor's air unloader isn't
working. The unloader allows the compressor to start without load
so that a cheaper motor/smaller branch can be used. Look for an
aluminum air line running to the pressure switch. This line should
vent to air when the switch trips off. It should close when the
switch turns back on. If you're trying to manually turn the
compressor on when it still has some air in the tank, then this is
sure to be the problem. Most pressure switches have a metal lever
to manually turn the compressor off. The arm will also activate the
unloader valve. Turn the compressor off with this valve before
trying to start it on the generator.
If your compressor really is 3 hp (and not just 3 spec writer HP),
then you're really on the edge for that generator anyway. I suspect
that it is not 3 HP because a true 3 hp motor will have a hard time
starting on a 20 amp, 120 volt branch. My wheeled 2 hp Speedaire
industrial compressor will just barely start on my 4kw Yamaha
generator on 240 volts.
>
> Cabin is wired to code, complete with 12-2 w/ground wiring. Garage 150'
> from cabin with it's own 60 amp breaker box. 6-Gauge underground cable
> to garage.
>
> I went to our campsite 300 yards from cabin and retrieved Good Governor.
> 121v 61hz in cabin. 124v +62hz in garage. We shut off every other draw
> on the generator and tried again. The Good Governor showed a voltage
> drop to about 56 when the motor tried to start until the breaker popped
> again.
>
> We hauled the compressor to my motorhome where I have an Onan Marquis
> (gas, new) 5k generator. (again, 120v and 40 amp which translates to
> 4800 w)
> Energy management system gave us lots more info than we could get at the
> cabin. Upon firing up the generator, I see a load of 5 amps (fridge and
> converter) which I left alone and plugged in the compressor. Load jumped
> to 43 amps for about 1 second or less and then dropped to 24 amps and
> stayed. We cycled the compressor several times with the same exact
> results. Perfect performance to my way of thinking.
If it really is pulling 24 volts, then it couldn't run on a 20 amp
branch. You'd have to have a 30 amp dedicated plug. I wonder if
they really did make a compressor that requires a special branch or
if the MH panel is in error. What does the motor nameplate say?
> Clearly my brother's generator is suffering from a lack of available
> amps since the volts are there.
>
> Questions:
> 1.Does anyone have suggestions regarding the poor performance of
> brother's generator?
> 2.Probably not since the volts are there, but: Could this be caused by
> running his exhaust underground via 2" pipe and bringing it up about 25
> feet from the cabin in the back yard? (tractor type flap on the end of
> pipe to prevent water infiltration)
> 3. Is lp generator less effective than gas?
What does the frequency do? If the frequency is staying on target,
then the engine has enough oomph.
What you're seeing really isn't that odd. Small generators just
don't have the iron and copper to supply huge inrush. If you need
to make a given generator run a given compressor, there are some
tricks to try.
First thing to try is to try adding some capacitance to the starting
side. More capacitance will increase the torque and will usually
reduce the inrush current. We use that trick in the refrigeration
field to make compressors start on low voltage. Try approximately
doubling the start capacitance.
A large run cap across the main terminals of the motor will help
with the very low power factor when starting. In other words, it
will supply the reactive VARs that the generator can't. I'd start
with about a 160 microfarad motor RUN (different from a start cap).
Having another motor running, particularly if it has a heavy rotor
and/or flywheel, will also help. When the compressor comes on, the
other motor will act as an induction generator and supply power to
the starting motor. This is the trick I use to get my restaurant's
walk-in freezer compressor to start on my emergency generator. An
old motor is a lot cheaper than a new generator :-). Motor should
be larger than the compressor motor. The bigger the better.
Hope that gives you some ideas. To get any more detailed, we'd have
to instrument the thing and see in detail what's happening.
John
--
John De Armond
johngd...@bellsouth.net
http://personal.bellsouth.net/~johngd/
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"
Pete Dumbleton
> If your compressor really is 3 hp (and not just 3 spec writer HP),
> then you're really on the edge for that generator anyway. I suspect
> that it is not 3 HP because a true 3 hp motor will have a hard time
> starting on a 20 amp, 120 volt branch. My wheeled 2 hp Speedaire
> industrial compressor will just barely start on my 4kw Yamaha
> generator on 240 volts.
I think what they did was change the way HP for consumer electric motors
is measured. I moved overseas in 1986 and returned in 1992, and they
changed it sometime around then. In '86 I had a two HP electric (required
a 20 Amp circuit at 220V) motor on my compressor and the same compressor
also came with a five HP gasoline motor. In '92, they were *both* labeled
five HP, and a two HP electric was far smaller and would run on a 20
Amp/120V circuit. Same was true of my shop vac, 'tho on a lesser scale.
Sort of amazing what I noticed as different that others took for granted
because the changes had been gradual:
Flat-bed trucks replacing tow-trucks
Sandhill Cranes all over mid-Florida
Marked increase in truck tire debris (change in re-cap laws)
david_s...@my-deja.com
don't see a great benefit going underground. If you are trying to
reduce noise, get a better muffler and baffle the sound around the
genset itself. Or, put the generator in the garage (forgive me if it's
there already) and backfeed the house through the subpanel. I have set
up numerous emergency generators for family and friends in this manner
with great success.
DS
Sent via Deja.com http://www.deja.com/
Before you buy.