Low voltage out of Genset

[John Suter]

Hi Bob,

> John, excellent point, "assume" can get one
> into a lot of trouble. And yes, I was assuming
> that both leg voltages were nearly equal.
>
> But...Suppose leg 1 had a normal voltage reading
> of 120 VAC and leg 2 read the 95 VAC. Then it
> is possible because of heavy load on leg 2, maybe
> a hi-amp charge rate, or, dragging AC motor, the
> additional current requirement has decreased the
> voltage to 95 VAC and the genset is fine.

True. However, I was attempting to rule out a
potential stator/rotor problem which often presents as
differing leg voltages, regardless of load. I hope we
hear from Alan with information on each leg's voltage
when there is no significant load on either leg.

John

> The only assumption that can safely be made is
> that it did operate properly at one time.
>
> Alan, give us some more infomation on the voltage
> using a multimeter. Could be a defective gage as
> well?
>
> Bob Janes '87FC35 Greenville, SC
>
>
> --- In WanderlodgeForum@yahoogroups.com, John Suter
>
> wrote:
> >
> > Alan, we (the group) are assuming the low voltage
> you
> > report is equally low for both legs. If not,
> advise
> > the as we might have to modify the advice.
> >
> > John Suter
> >
> >
> > --- one_dusty_hoot wrote:
> >
> > > Alan, the genset puts out 2 cycles per
> revolution,it
> > > should run at 1800 rpm, govenor controlled. This
> > > would
> > > output 1800 X 2=60 cycles per second. As load is
> > > increased, the speed decreases, then more fuel
> is
> > > given by the govenor to maintain speed.
> > >
> > > Look at the governor next on the motor, there is
> an
> > > arm that goes against a stop when the generator
> is
> > > started. There at the stop point is the speed
> > > adjustment.
> > >
> > > Before you start adjusting the stop you need to
> know
> > > what speed your motor is turning. You can buy a
> > > vibration tachometer at small motor repair
> shops.
> > > You can move the wand in and out by turning the
> > > knob. When the harmonic frequency is reached,
> the
> > > extended arm will begin vibrating rapidly. Mayve
> > > $20?
> > >
> > > Do not attempt to adjust speed without something
> as
> > > a reference.
> > >
> > > Your problem may be that the motor is running
> sour,
> > > could be the air filter is clogged, and possibly
> not
> > > enough diesel by a dirty filter?
> > >
> > > Bob Janes 87FC35 Greenville, SC
> > >
> > >
> > >
> > >
> > > --- In WanderlodgeForum@yahoogroups.com, Curt
> > > Sprenger
> > > wrote:
> > > >
> > > > I'm not an expert but found this on the
> Internet.
> > > For an
> > > oscillating or
> > > > varying current, frequency is the number of
> > > complete cycles per
> > > second
> > > > in alternating current direction. The standard
> > > unit of frequency is
> > > the
> > > > hertz, abbreviated Hz. If a current completes
> one
> > > cycle per second,
> > > then
> > > > the frequency is 1 Hz; 60 cycles per second
> equals
> > > 60 Hz (the
> > > standard
> > > > alternating-current utility frequency in the
> > > United States).
> > > >
> > > > I recall the Onan guy adjusting rpms on our
> > > previous gen. set to
> > > get the
> > > > frequency to 60 and to increase voltage.
> > > >
> > > > Sounds to me you are on the right track. If
> you
> > > can, turn up the
> > > rpms
> > > > and watch for voltage increase. Good luck.
> Please
> > > keep us posted.
> > > >
> > > > Curt Sprenger 1987 PT38, Anaheim Hills, Calif.
> > > >
> > > >
> > > >
> > > > Alan wrote:
> > > >
> > > > > My 87FC35 has a 8.0 kW genset. I am getting
> low
> > > voltage out of it
> > > > > (around 95 volts). On my last onan genset
> (77
> > > GMC - carbed gas),
> > > > > this was a common problem and was simply
> > > corrected by increasing
> > > > > RPMs. (If this is the fix, how do I adjust
> idle
> > > speed? This fuel
> > > > > injection isn't as intuitive for me as I've
> been
> > > a carburetor
> > > guy.)
> > > > >
> > > > > I found an installation manual for the
> genset
> > > and it says to
> > > adjust
> > > > > some "taps" on a transformer regulator. It
> also
> > > says "output
> > > > > frequency is determined by engine speed and
> > > normally does not
> > > > > require adjustment." I'm not exactly sure
> what
> > > it means by "output
> > > > > frequency". Is that voltage??
> > > > >
> > > > > Is this problem more complicated than
> adjusting
> > > the RPMs? Maybe I
> > > > > don't have one of the Onan manuals..?? I
> have a
> > > parts manual and
> > > an
> > > > > installation manual.
> > > > >
> > > > > I have searched the forums and did not find
> a
> > > post that seemed to
> > > > > address my situation. Let me know if I
> missed
> > > it.
> > > > >
> > > > > Thanks in advance,
> > > > > Alan Johnson
> > > > > 87FC35
> > > > >
> > > > >
> > > >
> > >
> > >
> > >
> > >
> > >
> >
> >
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