Low voltage out of Genset

[Alan Johnson]

All,



Here's an update. I went by Parker Power Systems here in Dallas today to
pick up a service manual (I drove the coach over there just in case I could
get someone to help me.) .More of us should go in the APU business. They
are all backed up 3-4 weeks before they can work on something.



Anyway, one of the guys there was really helpful. He came out and spent
about 30 minutes on my genset. I have an Onan model "DKD". He said even
when the were new they were always a little low on the voltage. But since
mine was running around 59.5 hertz, that we should bump it up to 61 hertz.
So he did. We increased the rpms slightly till it was putting out right
around 61 hertz. That seemed to give me a significant boost in volts. I
think it will put me around 110-115v. I say "I think" because I haven't
finished tightening everything up and then re-checking voltages under
different loads.



Hopefully this will be the end of this issue. I'll send out another update
just to let everyone know for sure.



Thanks for all your help.



Alan Johnson

87FC35







_____

From: WanderlodgeForum@yahoogroups.com
[mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of John Suter
Sent: Thursday, August 24, 2006 10:59 AM
To: WanderlodgeForum@yahoogroups.com
Subject: RE: [WanderlodgeForum] Re: Low voltage out of Genset



Alan,

> It
> is only hot when the gen is running and it is hot
> regardless of how the
> switch is set. (It is hot when the
> Generator/Shore/Off switch is set to
> OFF.) I tested the voltages on those wires with my
> Fluke multimeter.

I assume you disconnected the shore power to
complete this test to eliminate the possibility you
would read voltage other than gen provided.

Be veeeery careful, as the fact you are able to
measure voltage with the disconnect switch off may
indicate you are measuring a neutral wire that is
being backfed from some other source, or the
disconnect switch itself has become faulty and is
passing current, or you are not measuring the leg(s)
you believe. The measured wire might be used for
metering, wherein it would drive an independent volt
meter somewhere, whether or not the power source is
coupled to anything else thru your disconnect.

Understand your digital Fluke meter presents a very
light resistive load so it can measure voltage;
however, the same measurement position, when coupled
with an appliance resistive load might drop the
voltage reading to zero on the meter, although the
full voltage could be present.

John Suter

--- Alan Johnson usa.com>
wrote:

> All,
>
>
>
> Here was my latest test. Under the sink going in to
> the Generator/Shore/Off
> switch, I found the wire that is apparently directly
> from the generator. It
> is only hot when the gen is running and it is hot
> regardless of how the
> switch is set. (It is hot when the
> Generator/Shore/Off switch is set to
> OFF.) I tested the voltages on those wires with my
> Fluke multimeter. With
> the genset running, I get the same results there as
> I do at the input side
> of the Main breakers.
>
>
>
> Based on what you guys are telling me, I think these
> are possibly my
> problems.
>
> 1. Regulator needs to be adjusted. (probably my
> best case scenario).
> Manual mentions that, but not much help on where the
> regulator is, or how to
> adjust it.
> 2. Circuit board problem (or regulator problem)
> 3. A corroded/faulty neutral right at the generator
> itself.
>
>
>
> My biggest disappointment when I was looking at this
> BB, was that the genset
> is NOT on a tray. :-( .And low, I'm already
> feeling the pain from that. I
> can't tell where the power comes out of the genset.
> Does anyone else have
> one of these 8.0 DKDs that don't pull out?
>
>
>
> Are there any last suggestions before I take this in
> for service?
>
>
>
> Thanks,
>
> Alan Johnson
>
> 87FC35
>
>
>
>
>
>
>
> _____
>
> From: WanderlodgeForum@
yahoogroups.com
> [mailto:WanderlodgeForum@
yahoogroups.com] On Behalf
> Of John Suter
> Sent: Wednesday, August 23, 2006 1:42 PM
> To: WanderlodgeForum@
yahoogroups.com
> Subject: Re: [WanderlodgeForum] Re: Low voltage out
> of Genset
>
>
>
> Alan,
>
> To Ralph's points (circuit board/regulator issues),
> the fact that the voltage drop appears excessively
> large when using the rear air, I would add the
> possibility of corroded/faulty neutral generator
> feed
> line. If you are sufficiently, technically,
> electrically-capable, you could run an additional
> temporary/parallel neutral to the rear air from the
> gen using #8 or so, to rule in/out the neutral
> problem. Don't try this if you have the least doubt
> about your capabilities, however.
>
> In your case, the "no load" rise from 108 - 108 to
> 104.5 - 110 under rear air load, is probably not
> significant enough to signal stator/rotor problems;
> Were it 90 - 130 or greater, I might have concern.
>
> Do not allow the rear compressor to run any longer
> than is absolute minimum time necessary to check the
> readings, or damage may result, and avoid any
> microwave or other electronics when 90v or below.
>
> John
>
> --- "Ralph L. Fullenwider" > net>
> wrote:
>
> > Alan:
> >
> > You have gotten some good advice on this. Do not
> > increase the RMS changing
> > the freq. It sounds like you have corroded
> > connections or weak breakers on
> > the gen set. Start by checking the voltage at the
> > breakers, the input side
> > then the out put. If the voltage drop is not found
> > there, check the
> > connections in the electrical box (should be just
> > inside the gen
> > compartment in the upper corner). Of course the
> > voltage being read at the
> > meters does go through shunts and those reporting
> > wire connections could be
> > corroded as well. With the readings below, your
> gent
> > set sounds like it is
> > fine. I do remember 2 occasions, after checking
> the
> > input side of the
> > breakers on the gen set, that the voltage was low
> > there and had to replace
> > the circuit board on one, and the regulator on the
> > other, which took care
> > of the problem in both cases.
> >
> > Safe travels,
> >
> > Ralph and Charolette Fullenwider
> > Ralph's RV Solutions, Duncan, Oklahoma
> > http://home.
> <http://home. <http://home.swbell.net/rlf47/index.htm>
swbell.net/rlf47/index.htm>
> swbell.net/rlf47/index.htm
> >
> > At 04:38 AM 8/23/2006 +0000, you wrote:
> > >Ok, here are my findings so far.
> > >
> > >1. Engine RPMs - right at 1800 (I bought a
> > vibration tach, as
> > >suggested.)
> > >2. Frequency stays right between 59.5 and 60.5
> > whether under heavy
> > >load or not.
> > >
> > > Leg 1 Leg 2
> > > ------ ------
> > >No (very little) load 108v 108v
> > >Front a/c only 104.5 110
> > >Both a/c's on 104 101.5
> > >Rear a/c only 100 91 (a/c
> > compressor is having
> > >trouble running)
> > >
> > >When on shore power I've got right at 120v. On
> the
> > generator, I'm
> > >obviously low on voltage all the time, but do
> these
> > different
> > >readings tell you guys anything? Do I just need
> to
> > up the rpms, or
> > >will that mess up my frequency??
> > >
> > >Thanks!
> > >Alan Johnson
> > >87FC35
> > >
> > >
> > >
> >
> >
>
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